Anyone "really" figured out the clunk sound/issue yet... ?

[Kevin the Clean 1]

I really don check this section too much anymore.

ASHLEY, or any other pro out there. Have any of you you fellas figured this issue out yet or not... ? :shrug:

 

[ShelbyGuy]

like 6 years ago now. its a stacking of tolerances between the trans and the rear end, mostly in the rear end. tighten up the backlash on your ring&pinion.

 

[Kevin the Clean 1]

like 6 years ago now. its a stacking of tolerances between the trans and the rear end, mostly in the rear end. tighten up the backlash on your ring&pinion.

Thanks for the advice. What are the specs for those rear gears... ?

 

[viper82489]

Thanks for the advice. What are the specs for those rear gears... ?

+1 on the specs Im getting ready to rebuild my rear

 

[BlownShift]

.008 - .015 backlash

.008 - .010 is probably what you want to shoot for

completing a shift before the rpms drop below 1800 always gave me a non-clunk shift

 

[LargeOrangeFont]

I still haven't swapped my diff yet. A bit of it in is the trans, but most is in the ring/pinion. Shelbyguy is spot on.

 

[hotcobra03]

clunk

fwiw,,i did the front bushings,,noise was 99 percent better...my thought is its an echo coming up thru the underbody..the rear is only supported by 3 points.2 in front and one in the rear. hard rubbers will make if quiet but worst on viberations..like a solid motor mount...ford put a 20lb weight to help hold rear still and to asorbe viberation... so in short i feel the rear moves to much..deal with it or go with a live axle.

 

[LargeOrangeFont]

fwiw,,i did the front bushings,,noise was 99 percent better...my thought is its an echo coming up thru the underbody..the rear is only supported by 3 points.2 in front and one in the rear. hard rubbers will make if quiet but worst on viberations..like a solid motor mount...ford put a 20lb weight to help hold rear still and to asorbe viberation... so in short i feel the rear moves to much..deal with it or go with a live axle.

When mounted with soild bushings, the rear diff does not move at all. It is not an echo, it is gear backlash in the tranny and diff.

 

[hotcobra03]

Clunk

clunk/thud call it what ever you want?Its a noise made from the rear(gear back lash ) and with an irs its more pronounced.when i did go to ford for new front bushings ,,they informed me more on that the rear diff bushing,they made 2 different ones(my guess is angle viberations)when my stock ones went ,the rear went up/down.thats the loud thud/clunk///back lash clunk to me would be heard when in gear and jerking throttle on/off to jerk the car and a clunk is heard///with my car when we tried as easy as we could change gears ,it clunked...before changing them it also would clunk loud with just moving clutch in/out,, so thats to different types of clunks,,

 

[hotcobra03]

the clunk

fwiw,,,i have manufactured and built custom driveshafts ,for 20yrs,,from race cars to tractor trailers,,viberations /brakes/wheel alignments.. only on the problem vehicles.when i said an echo ,,that is the noise sounding and traveling more than it should,,as the aluminum driveshaft works as an echophone to make noice travel,,as does the sub-frame to underbody of car..hence echo noises:beer:

 

[Kevin the Clean 1]

When mounted with soild bushings, the rear diff does not move at all. It is not an echo, it is gear backlash in the tranny and diff.

Thanks ASHLEY. I was hoping to hear from you on this bud. Now that I have heard from both you & ShelbyGuy, I guess I will just have to wait to get my diff cover dropped again & mess with/tighten up those gears back there...

 

[dan04gt]

When mounted with soild bushings, the rear diff does not move at all. It is not an echo, it is gear backlash in the tranny and diff.

And the inner cv . the tolerance on those forgings is way to loose.
Its not really a ring and pinion backlash issue, the backlash is coming from
the spider gears in the posi. I am hoping that the torsen carrier I am going to install will be better.

 

[MountainDew]

How do you tighten the backlash? Fairly easy to do?

 

[hotcobra03]

fords story on rear

ford still cant fix it...fords have always made noises/clunks/viberations..look at the new ford even why did they put a 2piece shaft in a 50inch overall lenght.... i still go for the rear is too loose and flexes up/down..the 2 front bushings are ok but the back moves ..my rear was just redone and the only thing not changed were the spiders,,it dosnt clunk...my buddys rear the main pin moves an eight of an inch and his doent clunk,,,, but im not a pro just the guy who keeps my cobra running as a trouble free daily driver,,,,,,,,,,,,,,,,SECTION 205-00: Driveline System — General Information 2003 Mustang Workshop Manual
DIAGNOSIS AND TESTING Procedure revision date: 03/18/2002

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Driveline System Printable View (526 KB)

Special Tool(s) Clamp Plate
205-320 (T92L-4851-C)
Clutch Housing Alignment Adapter
308-021 (T75L-4201-A)
Companion Flange Holding Tool
205-126 (T78P-4851-A)
Companion Flange Runout Gauge
205-319 (T92L-4851-B)
Dial Indicator with Bracketry
100-002 (TOOL-4201-C) or equivalent
Dial Indicator/Magnetic Base
100-D002 (D78P-4201-B) or equivalent
Vibration Analyzer
100-F027 (014-00344)
Traction-Lok® Torque Tool
205-022 (T66L-4204-A)


Inspection and Verification

Certain axle noise or vibration symptoms are also common to the engine, transmission, wheel bearings, tires, and other parts of the vehicle. For this reason, be sure that the cause of the trouble is in the axle before disassembling, adjusting or repairing the axle. Refer to Section 100-04 .

Certain driveshaft vibration symptoms are common to the front engine accessory drive (FEAD), the engine, transmission or tires. Be sure the cause of the concern is the driveshaft before repairing or installing a new driveshaft. Refer to Section 100-04 .

Certain symptoms may be caused by Traction-Lok® differentials (4026). Check the vehicle certification label and axle identification tag to determine the type of differential. Refer to Section 100-01 .


Noise Acceptability

NOTE: A gear-driven unit will produce a certain amount of noise. Some noise is acceptable and audible at certain speeds or under various driving conditions such as a newly paved blacktop road. Slight noise is not detrimental to the operation of the axle and is considered normal.

With the Traction-Lok® differential axle, slight chatter noise on slow turns after extended highway driving is considered acceptable and has no detrimental effect on the locking axle function.


Universal Joint (U-Joint) Inspection

Place the vehicle on a frame hoist and rotate the driveshaft (4602) by hand. Check for rough operation or seized U-joints. Install a new U-joint if it shows signs of seizure, excessive wear, or incorrect seating. Refer to Section 205-01 .


Analysis of Leakage

Clean up the leaking area enough to identify the exact source. An axle leak can be caused by the following.

Axle lubricant level is too high.
Worn or damaged axle shaft seals or differential seals.
Differential housing is cracked.
Flange yoke seat is worn or damaged.
Pinion flange is scored or damaged.
Axle cover is not sealed.
Vent is plugged.
Repair the axle as necessary. Make sure the axle lubricant is at the correct level. Refer to Specifications in this section.

Axle Vent

NOTE: If a plugged vent cannot be cleared, install a new one.

A plugged vent will cause excessive seal lip wear due to internal pressure buildup. If a leak occurs, check the vent. Make sure the vent hose is not kinked. Remove the hose from the vent nipple and clear the hose of any foreign material. While the hose is removed, pass a length of mechanics wire in and out of the vent to clean it. Connect the hose when done.

Flange Yoke Seal

Leaks at the axle drive pinion seal originate for the following reasons:

Seal was not correctly installed.
Poor quality seal journal surface.
Any damage to the seal bore (dings, dents, gouges, or other imperfections) will distort the seal casing and allow leakage past the outer edge of the axle drive pinion seal.

The axle drive pinion seal can be torn, cut, or gouged if it is not installed carefully. The spring that holds the axle drive pinion seal against the pinion flange may be knocked out and allow leakage past the lip.

The rubber lips can occasionally become hard (like plastic) with cracks at the oil lip contact point. The contact point on the pinion flange may blacken, indicating excessive heat. Marks, nicks, gouges, or rough surface texture on the seal journal of the pinion flange will also cause leaks.

When a seal leak occurs, install a new seal and check the vent and the vent hose to make sure they are clean and free of foreign material.

Axle Shaft Seals

Axle shaft oil seals are susceptible to the same kinds of damage as axle drive pinion seals if incorrectly installed. The seal bore must be clean and the lip handled carefully to avoid cutting or tearing it. The axle shaft journal surface must be free of nicks, gouges, and rough surface texture.

Differential Seals

Refer to Section 205-02A or Section 205-02B .


Analysis of Vibration

WARNING: A vehicle equipped with a Traction-Lok® differential will always have both wheels driving. If only one wheel is raised off the floor and the rear axle is driven by the engine, the wheel on the floor could drive the vehicle off the stand or jack. Be sure both rear wheels are off the floor.

Few vibration conditions are caused by the rear axle. On a vibration concern, follow the diagnosis procedure in Section 100-04 unless there is a good reason to suspect the axle.

Tires

WARNING: Do not balance the wheels and tires while they are mounted on the vehicle. Possible tire disintegration/differential failure could result, causing personal injury/extensive component damage. Use an off-vehicle wheel and tire balancer only.

Most vibration in the rear end is caused by tires or driveline angle.

Vibration is a concern with modern, high-mileage tires if they are not "true" both radially and laterally. They are more susceptible to vibration around the limits of radial and lateral runout of the tire and wheel assembly. They also require more accurate balancing. Wheel and tire runout checks, truing and balancing are normally done before axle inspection. Refer to Section 204-04 .

Driveline Angle

Driveline angularity is the angular relationship between the engine crankshaft (6303), the driveshaft, and the rear axle pinion. Factors determining driveline angularity include ride height, rear spring, and engine mounts.

Driveline Angle


Item Description
1 Bottom of the frame
2 Engine crankshaft centerline
3 Engine angle
4 Driveshaft and coupling shaft centerline
5 Driveshaft and coupling shaft angle
6 Rear axle pinion centerline
7 Axle pinion angle


An incorrect driveline (pinion) angle can often be detected by the driving condition in which the vibration occurs.

A vibration during coastdown from 72 to 56 km/h (45 to 35 mph) is often caused by an excessive U-joint angle at the axle (pinion nose downward).
A vibration during acceleration, from 56 to 72 km/h (35 to 45 mph) may indicate an excessive U-joint angle at the axle (pinion nose upward).
When these conditions exist, check the driveline angles as described in the General Procedures portion of this section.

If the tires and driveline angle are not the cause, carry out the NVH tests to determine whether the concern is caused by a condition in the axle. Refer to Section 100-04 .

Universal Joint (U-Joint) Wear

Place the vehicle on a frame hoist and rotate the driveshaft by hand. Check for rough operation or seized U-joints. Install a new U-joint if it shows signs of seizure, excessive wear, or incorrect seating. Refer to Section 205-01 .

Wheel Hub or Axle Flange Bolt Circle Runout

NOTE: The brake discs must be removed to carry out all runout measurements.

Position the special tool perpendicular to the wheel hub or axle flange bolt, as close to the hub or flange face as possible. Zero the indicator to allow the pointer to deflect either way.

Rotate the hub or flange until the next bolt is contacted. Record the measurement and continue until each bolt is checked. The difference between the maximum and minimum contact readings will be the total wheel hub or axle flange bolt pattern runout. The runout must not exceed 0.38 mm (0.015 inch).
Pilot Runout

Position the special tools as close to the hub or axle flange face as possible. Zero the indicator to allow the pointer to deflect either way.

Rotate the hub or flange one full turn and note the maximum and minimum readings. The difference between the maximum and minimum readings will be the total pilot runout. Pilot runout must not exceed 0.15 mm (0.006 inch).
Wheel Hub or Axle Flange Face Runout

NOTE: If the axle shaft assembly is removed, check runout of the shaft itself. The forged (unmachined) part of the shaft is allowed to have as much as 3.0 mm (0.120 inch) runout. This alone will not cause a vibration condition.

Position the special tool on the wheel hub or axle flange face, as close to the outer edge as possible. Zero the indicator to allow the pointer to deflect either way.

Rotate the hub or flange one full turn and note the maximum and minimum readings. The difference between the maximum and minimum readings will be the total face runout. The runout must not exceed 0.127 mm (0.005 inch).
Drive Pinion Stem and Pinion Flange

Check the pinion flange runout when all other checks have failed to show the cause of vibration.

One cause of excessive pinion flange runout is incorrect installation of the axle drive pinion seal. Check to see if the spring on the seal lip has been dislodged before installing the ring gear and pinion.


Axle Noise

NOTE: Before disassembling the axle to diagnose and correct gear noise, eliminate the tires, exhaust, trim items, roof racks, axle shafts and wheel bearings as possible causes. Follow the diagnostic procedures in Section 100-04 .

The noises described as follows usually have specific causes that can be diagnosed by observation as the unit is disassembled. The initial clues are the type of noise heard during the road test.

Gear Howl and Whine
Howling or whining of the ring gear and pinion is due to an incorrect gear pattern, gear damage or incorrect bearing preload.

Bearing Whine

Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by worn/damaged pinion bearings, which are operating at driveshaft speed. Bearing noise occurs at all driving speeds. This distinguishes it from gear whine which usually comes and goes as speed changes.

As noted, pinion bearings make a high-pitched, whistling noise, usually at all speeds. If however there is only one pinion bearing that is worn/damaged, the noise may vary in different driving phases. If pinion bearings are scored or damaged or there is a specific pinion bearing noise, new pinion bearings must be installed. A worn/damaged bearing will normally be obvious at disassembly. Examine the large end of the rollers for wear. If the pinion bearings original blend radius has worn to a sharp edge, a new pinion bearing must be installed.

NOTE: A low-pitched rumble normally associated with a worn/damaged wheel bearing can also be caused by tires.

A wheel bearing noise can be mistaken for a pinion bearing noise. Check the wheel bearing for a spalled cup, and spalled/damaged rollers. Check the wheel bearing for rotating smoothness and end play. Install a new wheel bearing if any of these concerns are detected.


If the wheel bearing is damaged, the roller surface on the axle shaft may also be damaged. Install a new axle shaft if any damage is detected.


Chuckle

Chuckle that occurs on the coast driving phase is usually caused by excessive clearance between the differential gear hub and the differential case bore.

Damage to a gear tooth on the coast side can cause a noise identical to a chuckle. A very small tooth nick or ridge on the edge of a tooth can cause the noise.

Clean the gear tooth nick or ridge with a small grinding wheel. If the damaged area is larger than 3.2 mm (1/8 inch), install a new gearset.

To check the ring gear and pinion, remove as much lubricant as possible from the gears with clean solvent. Wipe the gears dry or blow them dry with compressed air. Look for scored or damaged teeth. Also look for cracks or other damage.

If either gear is scored or damaged badly, install a new ring gear and pinion.


If metal has broken loose, the axle housing must be cleaned to remove particles that will cause damage. At this time, any other new parts in the axle housing must also be installed, if necessary.

Knock

Knock, which can occur on all driving phases, has several causes including damaged teeth or gearset.


In most cases, one of the following conditions will occur:

A gear tooth damaged on the drive side is a common cause of the knock. This can usually be corrected by grinding the damaged area.

NOTE: Measure the end play with a Dial Indicator with Bracketry and not by feel.

Knock is also caused by excessive end play in the axle shafts. Up to 0.762 mm (0.030 inch) is allowed in semi-float axles. The frequency of the knock will be less because the axle shaft speed is slower than the driveshaft.
Clunk

Clunk is a metallic noise heard when the automatic transmission is engaged in REVERSE or DRIVE. The noise may also occur when throttle is applied or released. It is caused by backlash somewhere in the driveline or loose suspension components; it is felt or heard in the axle. Refer to Total Backlash Check in this section.

Additionally, clunk may be heard upon initial drive-away. This occurs as engine torque shifts vehicle weight, forcing changes in driveline angles, preventing the driveshaft slip-yoke from sliding on the output shaft. To correct for this condition, lubricate the slip-yoke splines.


Total Backlash Check

Raise and support the vehicle. Refer to Section 100-02 .
Remove the driveshaft. Refer to Section 205-01 .
Install the special tool.
Clamp a rigid bar or pipe to the tool. Clamp the other end of the bar or pipe to the frame or a body member in order to prevent movement of the rear axle pinion flange.

Lower the vehicle so that one rear wheel is resting on a wheel chock to prevent it from turning. The other rear wheel will be used to measure total rear axle backlash.
Rotate the free wheel slowly, by hand, until the feeling of driving the rear axle is encountered. Place a mark on the side of the tire, 305 mm (12 inches) from the center of the wheel, with a crayon or chalk.
While holding the crayon or chalk against the tire, rotate the wheel slowly in the opposite direction until the feeling of driving the rear axle is encountered again.
Measure the length of the crayon or chalk mark on the tire.
If the length of the mark is 25.4 mm (1 inch) or less, the rear axle backlash is within allowable limits.
If the chalk mark is greater than 25.4 mm (1 inch), check for these conditions:
Elongation of the differential pinion shaft and holes in the differential case (4204).
Missing differential pinion thrust washer (4230) or differential side gear thrust washer (4228).
Galling of the differential pinion shaft (4211) and bore.
Excessive ring gear and pinion backlash. Follow the procedure for the type of rear axle to check backlash.
Axle Shaft Bearing Noise

Axle bearing shaft noise is similar to gear noise and differential pinion bearing whine. Axle shaft bearing noise will usually distinguish itself from gear noise by occurring in all driving modes (drive, coast, and float), and will persist with the transmission in NEUTRAL while the vehicle is moving at the speed in which the concern is occurring. If the vehicle makes this noise, remove the suspect axle shaft, install a new bearing and a new axle seal. Re-evaluate the vehicle for noise before removing any internal components.

Bearing Rumble

Bearing rumble sounds like marbles being tumbled. This condition is usually caused by a worn/damaged wheel bearing. The lower pitch is because the wheel bearing turns at only about one-third of the driveshaft speed. Wheel bearing noise also may be high-pitched, similar to gear noise, but will be evident in all four driving modes.


Symptom Chart

Symptom Chart Condition Possible Sources Action
Traction-Lok® does not work in snow, mud or on ice
Differential.
CARRY OUT the Traction-Lok® Differential Operation Check in this section. REPAIR as necessary. REFER to Section 205-02A or Section 205-02B .

Lubricant leaking from the pinion seal, axle shaft oil seals
Vent.
Damage in the seal contact area or damaged or worn seal.
CLEAN the axle housing vent.
INSTALL a new seal if damage is found.

Differential side gears/pinion gears are scored
Insufficient lubrication.
INSTALL new gears. REFER to Section 205-02A or Section 205-02B . FILL the axle to specification.

Incorrect or contaminated lubricant type.
INSTALL new gears. REFER to Section 205-02A or Section 205-02B . CLEAN and REFILL the axle to specification.

Axle overheating
Lubricant level too low.
CHECK the lubricant level. FILL the axle to specification.

Incorrect or contaminated lubricant type.
INSPECT the axle for damage. REPAIR as necessary. CLEAN and REFILL the axle to specification.

Bearing preload adjusted too tight.
CHECK the ring and pinion for damage. INSPECT the ring and pinion wear pattern. ADJUST the preload as necessary.

Excessive gear wear.
INSPECT all the axle gears for wear or damage. INSTALL new components as necessary.

Incorrect ring gear backlash.
INSPECT the ring gear for scoring. INSPECT the ring and pinion wear pattern. ADJUST the ring gear backlash as necessary.

Broken gear teeth on the ring gear or pinion
Overloading the vehicle.
INSTALL a new ring and pinion. REFER to Section 205-02A or Section 205-02B .

Axle shaft broken
Overloading the vehicle.
INSTALL a new axle shaft. REFER to Section 205-02A or Section 205-02B .

Misaligned axle shaft tube.
INSPECT the axle for damage. CHECK axle shaft tube alignment. INSTALL a new axle shaft. REFER to Section 205-02A or Section 205-02B .



Component Tests


Driveline Vibration

An analysis of driveline vibration can also be conducted using the Vibration Analyzer; follow the manufacturer's directions.

Driveline vibration exhibits a higher frequency and lower amplitude than does high-speed shake. Driveline vibration is directly related to the speed of the vehicle and is usually noticed at various speed ranges. Driveline vibration can be perceived as a tremor in the floorpan or is heard as a rumble, hum, or boom. Driveline vibration can exist in all drive modes, but may exhibit different symptoms depending upon whether the vehicle is accelerating, decelerating, floating, or coasting. Check the driveline angles if the vibration is particularly noticeable during acceleration or deceleration, especially at lower speeds. Driveline vibration can be duplicated by supporting the axle upon a hoist or upon jack stands, though the brakes may need to be applied lightly in order to simulate road resistance.

Raise the vehicle promptly after road testing. Use a twin-post hoist or jack stands to prevent tire flat-spotting. Engage the drivetrain and accelerate to the observed road test speed to verify the presence of the vibration. If the vibration is not evident, check the non-driving wheels with a wheel balancer to rule out imbalance as a possible cause. If required, balance the non-driving wheels and repeat the road test. If the vibration is still evident, proceed to Step 2.
Mark the relative position of the drive wheels to the wheel nuts. Remove the wheels. Install all the nuts in the reversed position and repeat the road speed acceleration. If the vibration is gone, refer to the tire and wheel runout procedure in Section 204-04 . If the vibration persists, proceed to Step 3.
Inspect the driveshaft for signs of physical damage, missing balance weight, undercoating, incorrect seating, wear and binding universal joints. Clean the driveshaft and install new universal joints or a new driveshaft if damaged. Check the index marks (paint spots) on the rear of the driveshaft and pinion flange. If these marks are more than one-quarter turn apart, disconnect the driveshaft and re-index to align the marks as closely as possible. After any corrections are made, recheck for vibration at the road test speed. If the vibration is gone, reinstall the wheels and road test. If the vibration persists, proceed to Step 4.
Raise the vehicle on a hoist and remove the wheels. Rotate the driveshaft by turning the axle and measure the runout at the front, the center, and the rear of the driveshaft with the indicator. If the runout exceeds 0.89 mm (0.035 inch) at the front or center, a new driveshaft must be installed. If the front and center are within this limit, but the rear runout is not, mark the rear runout high point and proceed to Step 5. If the runout is within the limits at all points, proceed to Step 7.

NOTE: Check the U-joints during re-indexing. If a U-joint feels stiff or gritty, install new U-joints.

Scribe alignment marks on the driveshaft and the pinion flange. Disconnect the driveshaft, rotate it one-half turn, and reconnect it. Circular pinion flanges can be turned in one-quarter increments to fine tune the runout condition. Check the runout at the rear of the driveshaft. If it is still over 0.89 mm (0.035 inch), mark the high point and proceed to Step 6. If the runout is no longer excessive, check for vibration at the road test speed. If vibration is still present, re-index the driveshaft slip yoke on the transmission output shaft one-half turn and road test the vehicle. If the vibration persists, proceed to Step 7.
Excessive driveshaft runout may originate in the driveshaft itself or in the pinion flange. To determine which, compare the two high points marked in Steps 4 and 5. If the marks are close together, within about 25 mm (1 inch), a new shaft must be installed and the vehicle road tested.

If the marks are on opposite sides of the driveshaft, the yoke or pinion flange is responsible for the vibration.


When installing a new pinion flange, the driveshaft runout must not exceed 0.89 mm (0.035 inch). When runout is within limits, recheck for vibration at road speed. If vibration persists, balance the driveshaft.

To balance the driveshaft, install one or two hose clamps on the driveshaft, near the rear. Position of the hose clamp head(s) can be determined by trial-and-error.
Mark the rear of the driveshaft into four approximately equal sectors and number the marks 1 through 4. Install a hose clamp on the driveshaft with its head at position No. 1.

Check for vibration at road speed. Recheck with the clamp at each of the other positions to find the position that shows minimum vibration. If two adjacent positions show equal improvement, position the clamp head between them.

If the vibration persists, add a second clamp at the same position and recheck for vibration.

If no improvement is noted, rotate the clamps in opposite directions, equal distances from the best position determined in Step 8. Separate the clamp heads about 13 mm (1/2 inch) and recheck for vibration at the road speed.


Repeat the process with increasing separation until the best combination is found or the vibration is reduced to an acceptable level.

Install the wheels and road test (vibration noticeable on the hoist may not be evident during the road test). If the vibration is still not acceptable, install a new axle driveline vibration damper first, if so equipped. If the vibration is still not acceptable, refer to Section 205-02A or Section 205-02B for differential case and ring gear runout checks.

Driveshaft Vibrates

Road test the vehicle to determine the critical vibration points. Note the road speed, the engine RPM, and the shift lever positions at which the vibration occurs.
Stop the vehicle, place the transmission lever in neutral and run the engine through the critical speed ranges determined in Step 1.
If no vibration is felt, balance the driveshaft. Refer to Driveline Vibration in this section.

Traction-Lok® Differential Operation Check

A Traction-Lok® differential can be checked for correct operation without removing it from the rear axle housing.

WARNING: A vehicle equipped with a Traction-Lok® differential will always have both wheels driving. If only one wheel is raised off the floor and the rear axle is driven by the engine, the wheel on the floor could drive the vehicle off the stand or jack. Be sure both rear wheels are off the floor.

With the engine off, raise only one rear wheel. Install the special tool on the wheel nuts.


Use a torque wrench with a capacity of at least 271 Nm (200 lb-ft) to rotate the axle shaft. Be sure that the transmission is in NEUTRAL, and that one rear wheel is on the floor while the other rear wheel is raised off the floor. The breakaway torque required to start rotation must be at least 27 Nm (20 lb-ft). The initial breakaway torque may be higher than the continuous turning torque.


The axle shaft must turn with even pressure throughout the check without slipping or binding. If the torque reading is less than specified, check the differential case. Refer to Section 205-02A or Section 205-02B .


Traction-Lok® Differential Check Road Test

Place one wheel on a dry surface and the other wheel on ice, mud or snow.
Gradually open the throttle to obtain maximum traction prior to break away. The ability to move the vehicle demonstrates correct operation of a Traction-Lok® rear axle assembly.
When starting with one wheel on an excessively slippery surface, a slight application of the parking brake may be necessary to help energize the Traction-Lok® feature of the differential. Release the brake when traction is established. Use light throttle on starting to provide maximum traction.
If, with unequal traction, both wheels slip, the limited slip rear axle has done all it can possibly do.
In extreme cases of differences in traction, the wheel with the least traction may spin after the Traction-Lok® has transferred as much torque as possible to the non-slipping wheel.

Companion Flange Runout Check

CAUTION: Pinion bearing preload must be reset if the pinion nut has been loosened or removed for pinion flange reindexing or installation.

Raise the vehicle on a twin-post hoist that supports the rear axle. Refer to Section 100-02 .
Remove the driveshaft. Refer to Section 205-01 .
Check the pinion flange for damage.
Position the Companion Flange Runout Gauge on the pinion flange.

Item Part Number Description
1 — Pilot (part of 205-319 [T92L-4851-B])
2 354845 Pinion nut
3 205-319 (T92L-4851-B) Companion flange runout gauge
4 — Bolts (2 Req'd)
(Part of 205-320 [T92L-4851-C])
5 205-320 Clamp plate (T92L-4851-C)
6 4851 Pinion flange

Position the special tools on the pinion flange.

Align the holes on the clamp plate with the holes in the pinion flange and install the bolts. Snug the bolts evenly.

Position the special tool as shown. Turn the Companion Flange Runout Gauge, and locate and mark the high spot on the pinion flange with yellow paint.

If the flange runout exceeds 0.25 mm (0.010 inch), remove the pinion flange, reindex the flange one-half turn on the pinion, and reinstall it. Refer to Section 205-02A or Section 205-02B .

Check the runout again. If necessary, rotate the flange until an acceptable runout is obtained. If the flange runout is still more than 0.25 mm (0.010 inch), install a new pinion flange.

If excessive runout is still evident after installing a new pinion flange, install a new ring and pinion. Repeat the above checks until the runout is within specifications.
Install the driveshaft. Refer to Section 205-01 .

Tooth Contact Pattern Check — Gearset

To check the gear tooth contact, paint the gear teeth with the special marking compound. A mixture that is too wet will run and smear; a mixture that is too dry cannot be pressed out from between the teeth.
Use a box wrench on the ring gear bolts as a lever to rotate the ring gear several complete revolutions in both directions or until a clear tooth contact pattern is obtained.
Certain types of gear tooth contact patterns on the ring gear indicate incorrect adjustment. Incorrect adjustment can be corrected by readjusting the ring gear or the pinion.
Contact Pattern Location

In general, desirable ring gear tooth patterns must have the following characteristics:

drive pattern on the drive side ring gear well centered on the tooth
coast pattern on the coast side ring gear well centered on the tooth
clearance between the pattern and the top of the tooth
no hard lines where the pressure is high
Acceptable ring gear tooth patterns for all axles.


Correct backlash with a thinner pinion position shim required.


Correct backlash with a thicker pinion position shim required.


Correct pinion position shim that requires a decrease in backlash.


Correct pinion position shim that requires an increase in backlash.



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[BlownShift]

if there is no problem with the backend (worn bushings, broken parts), you're better off learning to drive around it. My GT with a solid axle clunks and bangs and makes all kinds of racket too if I'm not working the clutch right. Learning to drive around it takes a day and then becomes second nature. Then you can drive around with no clunks and never have to worry about it again.

If you do decide to reset the gears, check your backlash before you tear it down and then let us know your before and after results when you get it done.

 

[Kevin the Clean 1]

if there is no problem with the backend (worn bushings, broken parts), you're better off learning to drive around it. My GT with a solid axle clunks and bangs and makes all kinds of racket too if I'm not working the clutch right. Learning to drive around it takes a day and then becomes second nature. Then you can drive around with no clunks and never have to worry about it again.

If you do decide to reset the gears, check your backlash before you tear it down and then let us know your before and after results when you get it done.

I have been driving way too long & have put way too much into the car for people to tell me to "drive around it". That is something I'm not going to do. I will eventually fix this... ;-)

 

[Taz]

And the inner cv . the tolerance on those forgings is way to loose.
Its not really a ring and pinion backlash issue, the backlash is coming from
the spider gears in the posi. I am hoping that the torsen carrier I am going to install will be better.

Amen on the inner CV's being prime suspects in many cases. The tolerances of the forged shells that the tripods slide into were really sloppy. Sloppy enough to produce a clunking sound when driving conditions allow the tripods to rock back and forth inside their shells.

It's easy to check if this is the source of your clunking by putting the rear end of the car up with the E-brake off and rocking the tire/wheel assemblies back and forth while lying under the car. You'll hear the clunking sound clearly coming directly from the inner CV boots if they are your culprits.

I've read that Ford has tightened up the tolerances of those shells, and new halfshaft assemblies supposedly minimize or eliminate the clunking. And although I've had no firsthand experience with halfshaft replacement as a remedy, I've read accounts by others who say this has stopped their clunking.

Anyway, as I said, it's easy enough to check if this is the source of your clunking.

 

[ShelbyGuy]

if there is no problem with the backend (worn bushings, broken parts), you're better off learning to drive around it. My GT with a solid axle clunks and bangs and makes all kinds of racket too if I'm not working the clutch right. Learning to drive around it takes a day and then becomes second nature. Then you can drive around with no clunks and never have to worry about it again.

If you do decide to reset the gears, check your backlash before you tear it down and then let us know your before and after results when you get it done.

An excellent point - good on your for bringing it up - this car will teach you smoothness on the pedals which is valued above all else when driving using the grand prix technique. smoothness and timing is EVERYTHING.

that plus your passengers really appreciate it. the herky-jerky is amplified when you're sitting in the death seat.

 

[BlownShift]

An excellent point - good on your for bringing it up - this car will teach you smoothness on the pedals which is valued above all else when driving using the grand prix technique. smoothness and timing is EVERYTHING.

that plus your passengers really appreciate it. the herky-jerky is amplified when you're sitting in the death seat.

I have 4.10s in the cobra and the GT (daily beater). It's been a few years since I drove the cobra but from what I remember this GT is more of a bitch to drive smoothly (love the 3.38 first gear). I get sloppy once in awhile and the car rewards me for it but I like it rough. Herky jerky makes it more fun.

I'll have to have someone drive it while I ride in the passenger seat to see how badly I have been abusing my passengers.

 

[whyte_03]

Thanks for the advice. What are the specs for those rear gears... ?

when i installed the urethane bushings in the front of the diff... it was like 80% of the clunk and play went away. thats all i have on this issue. peace