Differential/ Rear end parts choice

teeje

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Getting closer and closer to getting this build done. Engine is built, t56 magnum is here and much more.

I want to know for those who have done it, your thoughts and opinions on some built rear ends.

I hear true Trac is the way to go, with the upgraded axles and c clip eliminators.

My t56 magnum has the 2.97 first. I'd like a decent cruising rpm while on the highway when in 6th. Granted, the gearing in the trans will already help with this, but what should I expect with other ratios? I'm used to the 3.55 with the stock 3650.

Thanks yall.

Also, I'd *prefer* an entire built assembly , as cost isn't a factor. If there is not a good option out there, I'll settle for a build kit.

I hear the stock diffentials from 07-09 gt500s hold up very very well, too so I'm a bit torn.

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stkjock

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Pentalab

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Get the Eaton detroit tru-trac. The 07-09 GT-500's used the 3.73 rear gear and oem LSD, same as the GT... but the GT-500 LSD used carbon fiber discs. The carbon fiber disc replacement was only $100.00... but the carbon fiber discs have a tendency to melt.. and the carbon fiber / standard discs in the GT-500 / GT is a pita to keep replacing. The tru-trac comes in 2 x versions. The HD version requires either Moser, or Strange Engineering 33 spline axles. VMP in Florida sells both versions. https://www.vmpperformance.com/Eaton-31-Spline-TrueTrac-Differential-for-05-14-8.8-solid-axle and the HD version is https://www.vmpperformance.com/Eaton-33-Spline-TrueTrac-Differential-for-05-14-8.8-BUILT-solid-axle

The standard duty tru-trac uses 3 pinion gears per side...+ 31 spline oem axles. The HD version uses 4 pinion gears per side....+ 33 spline moser/strange engineering axles.

The tru-trac is essentially maintenance free. Uses regular 75W-140 dino gear oil....(like Lucas, etc, aprx 3-4 qts). No synthetic, and no friction modifiers. I also installed a Bob's autosports rear end axle catch can. Built like a tank, heliarc welded, and installs on pass side. Without it, you will end up with gear oil all over the road. https://bobsmachine.com/product/mustang-2005-14-axle-reservoir-kr-style/
Plumbed into the oem axle overflow vent on pass side of axle. On a 2 post lift, with all 4 x wheels dangling down, they provided enough rubber hose, so slack available at full droop.
 

07 Boss

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Back in the day I wasn't a big fan of a helical gear diff for drag racing as far as durability in a street/strip application so I went with an Auburn Pro Series rear end with Richmond gears. Haven't had any issues and she has performed admirably. But with that said I just bought a Tru-Trac for my 9" rear end I'm building and she is going to be a Strip/street beast with the emphasis on strip. I bought the complete center section from Strange with multiple upgrades. I think the gears are Yukon. The shortened axle housing is from Strange also.






These are for an F-Body and a 9" and I'm not sure what they offer fr the 8.8", but for a complete rear end or diff I would recommend Strange. Their help from the initial researching of my needs through the buying process was top notch.
 

JEWC_Motorsports

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These are for an F-Body and a 9" and I'm not sure what they offer fr the 8.8", but for a complete rear end or diff I would recommend Strange. Their help from the initial researching of my needs through the buying process was top notch.
Could have sold you a Fab 9 diff we just pulled out of a T/A. sold it for a song too.
 

Sactown

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I literally pulled the trutrac out of my car 2 weeks ago to sell, it is sitting in a box in my garage. PM me if interested
 

teeje

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Well I went with the BMR Torque-arm and watts link and it came with the Strange axle housing so I went with the Strange center section too.
10-4

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teeje

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Well, I'm still in the market for a Rear end build. Finding a pre built rear end seems hard and the ones I find, don't seem to be for s197 and have the double uca mounts for sn95s. All I'm finding are housings. I already have the fancy tools and everything to do a rebuild. I just want it to handle up to 850-900 rear wheel torque so I don't grenade it on a dig. She's got the infamous 'load howls (for on gas and the rear end howls, foot off gas it's quiet) I'm going to assume the pinion bearing has slack in it now. I unfortunately think I missed out on the rear end deal from the other guy in here, I had a lot of things going on at the time he offered it to me. If I can get away with upgrading the diff (keeping 3:55), along with changing all seals and bearings, and adding a diff cover with the load bolts, I'd like to do that. I don't seem to be finding much information as to who has done what and how much horsepower and torque they're running to make a decision on what I want to do.

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Midlife Crises

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This is where I am with the stock 8.8 housing. Detroit TruTrac for 31 spline axles. Strange C clip eliminator bearing retainers and Strange 31 spline axles. Strange will assemble the axles with your choice of studs and mount the bearings, retainers and reluctor ring for you for a small fee. The Strange C clip eliminators require you to cut about 1” off the end of each tube but does not alter the backing plate mount. Welded the tubes to the center section. This is easy to do. I used 7018 stick and alternated 2” welds until complete and did not warp the housing. I am using the Ford Racing diff cover that has load bolts and provides a little more fluid capacity. This may interfere with a Watts link or Panhard bar. So far I have had no failures or leaks. I did just replace the Motive 4.30 gears with Yukon 4.30 gears because they howled at cruse and coast. I can’t say I set the Motives up perfectly but the Yukon’s went in easy. I also installed a solid bushing with shims on the pinion instead of the crush sleeve.
You could go with the HD TruTrac and 33 spline axles for more insurance but at that point a 35 spline 9” from Strange or Currie might by more cost effective considering all the work.
 

GriffX

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I like my TruTrac very much. The only thing I don't like ist the rumble/clicking noise on coasting from the force free worm gears inside, but, I was not able to get 75W140 dino oil in Germany, could that be the reason for increased noise?
 

07 Boss

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Here's some food for thought. If I were building my S197 to 1000 hp I would be looking at a 9" rear end. Now that might entail swapping into a 4-link but at that point you could get a shorter housing and maybe fit bigger tires. Most companies will do custom lengths, end plates and axles. And some may even have jigs to to weld up certain suspension packages. My ordered my housing 2" short and all of the suspension and shock mounts for the aftermarket BMR set up were welded on for me.
 

teeje

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This is where I am with the stock 8.8 housing. Detroit TruTrac for 31 spline axles. Strange C clip eliminator bearing retainers and Strange 31 spline axles. Strange will assemble the axles with your choice of studs and mount the bearings, retainers and reluctor ring for you for a small fee. The Strange C clip eliminators require you to cut about 1” off the end of each tube but does not alter the backing plate mount. Welded the tubes to the center section. This is easy to do. I used 7018 stick and alternated 2” welds until complete and did not warp the housing. I am using the Ford Racing diff cover that has load bolts and provides a little more fluid capacity. This may interfere with a Watts link or Panhard bar. So far I have had no failures or leaks. I did just replace the Motive 4.30 gears with Yukon 4.30 gears because they howled at cruse and coast. I can’t say I set the Motives up perfectly but the Yukon’s went in easy. I also installed a solid bushing with shims on the pinion instead of the crush sleeve.
You could go with the HD TruTrac and 33 spline axles for more insurance but at that point a 35 spline 9” from Strange or Currie might by more cost effective considering all the work.
This is very good information

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Sactown

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Here's some food for thought. If I were building my S197 to 1000 hp I would be looking at a 9" rear end.

Why would you be looking for a 9" rear end, I make well over 1000hp to the rear tires, ran the 8.8 with a tru-trac and 31 spline axles until just recently, I only changed to a spool to save weight. The 8.8 is a very good rear end with the correct parts.
 

Juice

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The 9" is something like 6% stronger than the 8.8. Insignificant in the grand scheme of things.
 

07 Boss

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The 9" is something like 6% stronger than the 8.8. Insignificant in the grand scheme of things.

Maybe out of the box but we are talking about building a rear end for the track. You can build a much stouter 9" than an 8.8" In fact there is not much that can compare to a built 9".
 

Sactown

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Maybe out of the box but we are talking about building a rear end for the track. You can build a much stouter 9" than an 8.8" In fact there is not much that can compare to a built 9".

My car only see's the track, cuts 1.2x 60fts and the 8.8 has worked great and held up to 1081rwhp and over 1200rwtq, for years. The only things that was switches was the installation of the tru-trac and after market gears (Ford Racing), ran the stock axles. Not say that a built 9" rear end is a bad thing by any means, I'm just saying is that it probably isn't a necessary expense.
 

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