I've searched and read many threads pertaining to the 3:73 gear whine in the GT500 but I never read a reason why! Over the years I've had many 3:73 gear sets installed in my FOX body cars without any noise. What is it about the GT500 that is causing this issue? FOX bodies use a 8.8" rear also and you don't read all the whine threads on their web boards. I have a Ford Racing 3:73 gear set and Eaton Tru Trac sitting on my work bench that I'm hesitant to install in my GT500 due to all these negative threads.
Reasons for 3:73 whine?
- Thread starter Ackman70
- Start date
My 373s don't whine.
The GT500 and I think the Bullitt use a different high torque pinion bearing. I wonder if this is what's causing some whine issues. As far as I know this is the only difference. It may be that it requires a different bearing pre-load or it's just simply the bearing design itself. Or, it could be that this particluar bearing makes the pinion depth much more critical. I installed my own 3:73's (2nd time ever) and I have a very slight whine sometimes in 5th and 6th gear, but you have to be listening for it to really notice it. Some here have suggested a thicker oil, but i've yet to hear from someone that had whine issues that were remedied by this.
Mike
Mike
What concerns me is the thread that I read where someone commented on their FRPP rearend that came with the 3.73's already installed still having a whine. These gears have been in use for a few years now, and I hoped they would have figured out what the issue is and fixed it by now ... Hopefully by next summer I'll have my own GT500 (I'm waiting patiently to see if the 2011 alum block rumors are true), but with all of these threads about gear whine and no obvious fix I'm going to hold off on a 3.73 swap once I do get into a GT500.
Good plan.
Ford has stopped building there own gears and switched to Motive for the aftermarket sets. this is why they whine. Ask anyone who has installed the Motives and they all will tell you the same thing they are loud.
Ford did this from what I hear around mid to late 08. shops and dealers had some old sets and then new sets. people didnt like the old looking box so they grabed the new one and guess what IT WHINNED. then for the lucky few who got some of the last sets they were quiet. The 3.73 being the most popular for the GT and the 500 has run out of the old gears first and finding a old set is getting hard.
I just had a friend had the shop install 3 sets of FRPP gears they all made noise. My other buddy who got his in early 08 are as quiet as the stockers. Ask any body who got gears pre 09 and 99% had no issue and those who did got the new gears. Older sets from the back of a self in the dusty water stained box got the good ones on the second install.
Its the price we pay when Ford trys to save a buck to make a buck.
Ford did this from what I hear around mid to late 08. shops and dealers had some old sets and then new sets. people didnt like the old looking box so they grabed the new one and guess what IT WHINNED. then for the lucky few who got some of the last sets they were quiet. The 3.73 being the most popular for the GT and the 500 has run out of the old gears first and finding a old set is getting hard.
I just had a friend had the shop install 3 sets of FRPP gears they all made noise. My other buddy who got his in early 08 are as quiet as the stockers. Ask any body who got gears pre 09 and 99% had no issue and those who did got the new gears. Older sets from the back of a self in the dusty water stained box got the good ones on the second install.
Its the price we pay when Ford trys to save a buck to make a buck.
Me too is contemplating on installing the 3.73 gears, but will probably go with the rear axle assembly. Just wondered if the KR owners could chime in and say if their gears whine and if not what gears does Ford or Shelby use??
DON
DON
....The whine is 99% of the time caused by the difficulty in setting the backlash. Motive gears are well known to have a whine...but the FRPP gears are great, but must be installed by a tech who takes the time to correctly install them. It took 2 days working off and on for my tech to get my backlash dialed in correctly and was unable to use some of the shims that came with the FRPP install kit, but was able to find other shims that allowed him to feel confident about his installation. 9 months later and no whine.
However the lack friction modifier and/or the correct oil or the lack of a proper
break-in period can cause whine also.
However the lack friction modifier and/or the correct oil or the lack of a proper
break-in period can cause whine also.
I purchased a complete FRPP assembly (M-4001-A373) from Buyfordracing for $949 and installed it myself at the beginning of this summer.Joe Racer said:
The gear pattern as delivered was right on and the axle is absolutely as silent as the OE 3.31's were. This axle came complete with the latest Ford ring and pinion, which is manufactured using a different process than previous sets were. As FRPP puts it in their catalog...
FRPP said:
I've seen others that have said this. My new style FRPP gears are silent. These are the ones with the groove/bevel cut into them that are a few pounds lighter than the older style 3.73 ring and pinion. Here's a shot of the previous style gears (and Torsen T2R) that I installed in my fox coupe...Spawn said:
You don't need a KR owner to chime in. Just ask any guy that bolted in the FRPP 3.73 'Special Edition' assembly;-) as they are one in the same. The KR got this complete assembly installed on the assembly line before being shipped to the Las Vegas Shelby facility.DC Cobra said:
What do I believe?
bluediamond said:
Exactly what he said.
Tob
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the old FRRP 373's that did not have the 373N were much better made gears. ask any real master gear installer. also ford lapped the old 373s gears together with the pinion more times. which helped it wear in better. i have the old 373's in my fox that me an a friend installed back in 2005. i have never had an whine or anything. an that was my 1st an only time me an my friend installed gears. with the new 373N that a had a master gear installer(20yrs exp) install for about a year i new had any gear whine. they were setup perfect. but in the last couple months the gears have started to whine a little. nothing big gotta listen to notice. but i dont blame the installer at all. i really think the 373 gears are made cheap now. my friend had FRRP 410's installed in his car by the same installer an never had a problem. i really think that the new 373N are made buy crappy ass motive an for some people it gonna make noise no matter how good the gears were installed
After buying a set of 3.73's (not installed yet), it seems like a better deal in the long run to just buy the entire axle assembly and swap it in. Between the gears and installation, you already cover more than half the cost of the rear assembly, plus you have a back up if you should break it or need to return to stock.
I hate to say this, but as a Ford tech I have to tell yall that all these GT500 gear whine problems are simply from improper gear installs. There is no other explanation. I have done many ring and pinion installs and never had whine issues. Pinion depth and backlash are key. Ford does make special tools that get these measurements right every time. I've never even had to check tooth pattern as a matter of fact. GT500s do use a different pinion bearing also.
i would normally agree with you. but with the new 373N are made like crap. i had a master gear installer put them in with that little Ford tool an still got whine after about a year. so i am in no way gonna put the fault on the install. reason being is that if the gears were not setup right then you would get a whine or a howl right after the install or after the break in period.
The difficulty with the new machining process gear sets (motive or FRPP Hobb process) is that the side to side shims must be adjusted correctly not just pinion depth. The gear face dimension comes out slightly different. If the installer did not change the side shims locating the carrier assembly then likely the ring gear is in the wrong location. For years, it was only necessary to set backlash using pinion depth shims as every set of ford machined gears was within a couple thousandths of the same face dimension. This is no longer true. The hobb process FRPP gears are actually stronger than the old process machined sets, but are more trouble to install since the 3.31 production gears are traditional process machining.
Bottom line, if the 3.73s whine, then 99% chance they were just not installed correctly. There are defective gear sets, but less than 1%.
Bottom line, if the 3.73s whine, then 99% chance they were just not installed correctly. There are defective gear sets, but less than 1%.
Very good discussion here, I just had a new set of 3.31's installed under warranty due to whine under all driving conditions. (6000 miles) The new set also whines but only somewhat under decel, cruise and accel are quiet. The dealer had my car for a period of 3 days and said they had the gears in and out twice to get them setup "right". While they are not as good as the factory setup they will be tolerable until next season when I get a 3.73 swap set done. I suspect the installer was only being paid so much on the warranty time to do the job and after three days it began to cost the dealer money.
As the entire fix had the car down for 5 weeks, (2 attempts for proper diagonosis@2 weeks, 2 weeks for parts from the US, and then the install) of my short Northern driving season, I said it will have to do.
As the entire fix had the car down for 5 weeks, (2 attempts for proper diagonosis@2 weeks, 2 weeks for parts from the US, and then the install) of my short Northern driving season, I said it will have to do.
I agree with this 100%. I have installed countless sets of Ford 3.73's, and ANY whine is from a poor install. I've used all the different Ford Racing part numbers and I've been able to get all of them to set up correctly. Some took a significant amount of time to get right, which is the problem. Typical gear installs take anywhere from and hour and a half, to 3 or 4 hours. If they are being difficult, they can take up to 8 hours. Most techs won't take that kind of time to do them right and will get them close and ship them down the road. Close isn't good enough unfortunately.
Anyone who had gears installed that whine need to take it back and have them redone.
I purchased a complete FRPP assembly (M-4001-A373) from Buyfordracing for $949 and installed it myself at the beginning of this summer.
The gear pattern as delivered was right on and the axle is absolutely as silent as the OE 3.31's were. This axle came complete with the latest Ford ring and pinion, which is manufactured using a different process than previous sets were. As FRPP puts it in their catalog...
I've seen others that have said this. My new style FRPP gears are silent. These are the ones with the groove/bevel cut into them that are a few pounds lighter than the older style 3.73 ring and pinion. Here's a shot of the previous style gears (and Torsen T2R) that I installed in my fox coupe...
You don't need a KR owner to chime in. Just ask any guy that bolted in the FRPP 3.73 'Special Edition' assembly;-) as they are one in the same. The KR got this complete assembly installed on the assembly line before being shipped to the Las Vegas Shelby facility.
What do I believe?
Exactly what he said.
Tob
How much does the complete assembly weigh?
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