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8.8 TrueTrac Problems?

Discussion in 'Driveline' started by ricardoa1, Aug 9, 2010.

  1. CCS86

    CCS86 Member Established Member

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    Still loving my Truetrac as well.

    I still have the original Valvoline non-syn 85w-140 in it, and only occasionally hear any noise from the diff. I did realize that Valvoline sneak friction modifier in there without saying so on the bottle. A-holes.

    I'm going to make an attempt at running the fluid I really want to run, Amsoil Severe Gear 75w-140, and hope the Truetrac like it!
     
  2. Fopar

    Fopar Member Established Member

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    Chiming in on my experience, just finished my complete IRS rebuild with FTB delrin/aluminum bushings throughout. I rebuilt the diff my self, ALL new bearings, seals, Ford racing 4.10s. Perfect pattern, backlash .007-.009 .

    As soon as I started driving it I noticed the driveline slack. I think it's generally been understated thus far how insanely bad it is. I took out a clapped out stock IRS, with gears that had .017" of backlash and front diff bushings so beaten up you could push the front of the diff up and down with your hand about .2"... and the backlash from this trutrac is easily the same as that setup or maybe even worse.

    I actually jacked up the car after about 50 miles of driving just to check on it as it had started popping while I left a light in first in addition to the general driveline slack. I used my digital angle finder to measure the slack, I found you could rotate the driveshaft a full 15 degrees before the inner CVs would even start to move.... If I had known it would be this bad I would have chosen another carrier... Future buyers beware. Good for a track car, but if you want something that doesn't jerk you around while you try to go through a frickin parking lot stay away from this limited slip.

    Pic is of my pattern for reference
     

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    Last edited: Apr 8, 2018
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  3. Four Door SVT

    Four Door SVT Well-Known Member Established Member

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    Very interesting thread, I’m currently installing a true track and the reason I wanted it was because they say it was the quietest. Now that this old thread pops up I’m concerned.
     
  4. ricardoa1

    ricardoa1 Member Established Member

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    Mar 22, 2004
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    Boston, MA
    I no longer run this diff it’s not what I had hoped for, too race car like. Back to the traclok with carbon clutches. It will never be a oe application like the Torsten has been.


    Sent from my iPhone using svtperformance.com
     
  5. keith89

    keith89 Well-Known Member Established Member

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    I had the same experience but I never have any popping. just the driveshaft "bouncing" back and forth in rotation. Mine doesn't sound as bad but I can definitely rotate it about 10 degrees before the axles are engaged. I'm considering going back to the stock diff or maybe get a torsen instead. The trutrac has been great otherwise but the clunkyness over the past several years is getting tiring. If clutch engagement is sloppy from a start, it sounds like the car is going to rip itself apart.
     
  6. Stage 4.6

    Stage 4.6 Well-Known Member Established Member

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    I just had my Eaton trutrac, FRPP 3:55s, and all necessary bearings to redo my diff installed along with a Stifflers trans brace and my 2nd RXT twin disc installed all at the same time. They have a total of 175 miles on them so i have been babying the car. I purchased the trutrac based on its durability for street/strip and comments of here. I also re-did the RXT due to having so many issues with my 1st and thinking it was a bad install? My car is not a dedicated drag car but i do like to have fun in the summer and will be taking it to a few test and tunes.

    So far the rear diff seems to be solid but i do have a what seems to be a good amount of slack in the driveline and a slight howl at times? I read on the Eaton website that they recommend conventional gear oil and no friction mod. I went with Redline racing synthetic without friction modifier. iam considering changing out the rear diff oils to a mineral base type after the 500 mile break in period. During cruising the rear doesn't make any noticeable noise, but i will say that the slack/clunk combined with the chatter from my 2nd RXT twin disc has left little satisfaction in the last 175 miles of driving. I have full faith in my shop mechanic skills, he's good at what he does so i dont believe its anything he's done wrong.

    I have no doubt that both of these items can take a good beating at the track (yet to be proven) but the drive-ability is really starting to annoy me! i have well over $3K on my set up (2x RXT Clutch, gears, Trutrac, and rebuild kit) not including labor, truthfully i dont understand a lot peoples version of "it drives like stock" Mine definitely doesn't. I dont go cheap when it comes to my car and i try to do as much research as possible, but lately i have had little success. After reading all these issues with the trutrac I am really starting to regret my purchase. *Note i get a lot of NVH in my car which is expected with the types of mods i have done, but drive like stock it does not!
     
  7. CCS86

    CCS86 Member Established Member

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    When does it howl? I would be inclined to say that is your gear set, not the differential. When you are driving straight there is no differential motion.

    So, let me see if I have it right... You disregarded Eaton's oil instructions and are upset that it isn't operating quietly?

    They do have a significant amount of lash. You will feel more of a clunk when transitioning from accel to decel. The actual operation when turning or accelerating is very smooth and quiet.

    I started with their recommended dino oil and eventually took the risk on some synthetic Amsoil severe gear. It didn't really affect the noise level.

    Sent from my 2PZC5 using Tapatalk
     
  8. whitedevil95

    whitedevil95 @the03cobro Established Member

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    I have the Truetrac for a few thousand miles. I bought it mainly to be street friendly but strong at the strip. I am running the 33 spline version in an SRA. I think those of you that have the Truetrac in an IRS(especially with upgraded bushings) probably feel the driveline slack worse than those of us with an SRA and Poly bushings. Mine is noticeable but for me other than the little bit of slack mine doesn't make any noises, and I have beat the crap out of it at the drag strip with no issues so far.
     
  9. Stage 4.6

    Stage 4.6 Well-Known Member Established Member

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    1st: The howl is at decel, but like i said its slight, i am more concern with the "clunking" under normal driving conditions, and yes actual operations on turns are good no issues.

    2nd: NO i didnt disregard EATON oil intructions! I had asked several members on here using the trutrac and many had recommended RP synth, I did some more research, found EATONS website and thats when i read what they recomended, they also state that a synthetic base can be used as long as NO Friction MOD is included, so I decided to go with Redline Racing Diff oil which is 1 of the few that does not contain Friction Mod.

    My car also has the complete FTBR kit as "whitedevil95" stated above, maybe the upgraded bushings cause more of the effect? The hardened bushings definately produce more NVH.

    As previouisly mentioned i want to go through the diff/clutch 500 mile break in, before switching to the Dino oil, but i dont think its going to make a difference? There are few memebers here running the Trutrac w/synthetics and racing there cars hard at the track with good success.
     
    Last edited: Apr 10, 2018
  10. GodStang

    GodStang Well-Known Member Established Member

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    I have seen time and time again running Synthetics with the Truetrac causes noises. Swapping over to Dyno oil has helped many many people. I use Dyno oil and my car is dead quiet.
     
  11. keith89

    keith89 Well-Known Member Established Member

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    Mine doesn't howl but I've had the clunk with dino oil, rp synthetic, and redline shockprooof. I get a slight whine occasionally due to the delrin/aluminum IRS bushings but the clunkyness due to backlash in the differential worm gears is getting old.
     
  12. Stage 4.6

    Stage 4.6 Well-Known Member Established Member

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    Great! I finally got rid of the famous cobra clunk, after a costly FTBR kit, and bring back the clunk with the new Diff.
     
  13. 1wild-horse

    1wild-horse Relax! I'm a Doctor! Established Member

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    Just put in a tru trac last year and although the diff is a solid piece, I too am experiencing some undesirable feedback. I would more so describe it as a feel rather than hearing a noise. Im sure its driveline slack as I can also turn the driveshaft a significant distance before it engages and turns the axles. Backlash is at .010. Kinda disappointed in it in that respect. Hope it at least lives up to the rep it has for being bulletproof.
     
  14. Four Door SVT

    Four Door SVT Well-Known Member Established Member

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    The backlash spec is
    .008-.012. I just set mine at .010, I also used the spec ford pinion shim sizing tool. Although it’s time consuming I will change it if I’m not happy with it. I was very pleased with the contact pattern on the drive and coast but the .010 backlash looked to be more than I was expecting. Like I said tho I will run it and reduce it if I must.
     
  15. keith89

    keith89 Well-Known Member Established Member

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    The ring and pinion backlash isnt the problem. Its the backlash of the actual worm gears in the truetrac itself. Im pretty sure these cant be adjusted.
     
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  16. 1wild-horse

    1wild-horse Relax! I'm a Doctor! Established Member

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    Bump to give a little update on mine. When i put it together it was unclear if it needed the spacer. I found out awhile back it most certainly does not need it with cv shafts,(as expected), so I finally had time to pull an axle and fish it out. Did not improve driveline slack.
     
  17. Stage 4.6

    Stage 4.6 Well-Known Member Established Member

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    Iam pretty sure that slack is from the worm gear, ive had mine looked over, and over again, just cant get rid of that slack. Overall i just barely hit over 450 miles on my set up, except for that slack the diff feels pretty solid, no weird noises on turns, or cruching sounds as other mentioned, i still do get a slight howl on decel at times.

    I have not hard launched my car from a stand still but have rolled on the throttle and bang the gears. I do not feel any of that slack when running it hard, i will be taking mine to the track next month for the Street car shoot out so that will be its official test.
     
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  18. 1wild-horse

    1wild-horse Relax! I'm a Doctor! Established Member

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    Slack so far is my only complaint. The answer I got from the engineer at Eaton was that this is possibly how the differential is going to act in my "chassis". I fail to see how anything on the rest of the car can manipulate the diffy.
     
  19. 03 Cobra DSG

    03 Cobra DSG Active Member Established Member

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    I just did a SRA swap with a built 8.8 and I have the trutrac and use Lucas 85-140 non synthetic oil and don’t have any complaints..but my irs wasn’t really clunky either maybe I finally got lucky.


    Sent from my iPhone using svtperformance.com
     
  20. 1wild-horse

    1wild-horse Relax! I'm a Doctor! Established Member

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