Rebuild Trac-lok vs Torsen upgrade

[TA28]

Looks like torsen 2. But you really can't tell the difference of the t2 or t2r by looks . I find it easier to swap hole rear if I change gear ratios.
I had 3.73 rear 4.10 rear in car now and new 1 is 4.30 .
I called torsen up asked if they rebuild them or sold parts to rebuild them BIG NO! only part available is bolt that hold covers clap bar in! That's it. My feeling is 1k and not fixable wtf.
All my drag cars and road race boss 302 were Detroit lockers.

 

[TA28]

New rear has t2r used in it set up already but 1 axle spins 1 way the other reverse spin?
2 other rears spin both axles same way even if some one hold other axle! They lock up. Not this unit. Also 1 imsa team only ran lockers in there fr500c and boss 302R cars.

 

[Mad Hatter]

The Torsen is really not ment for Drag racing as its in corners where is comes in to play. At least in my case, I have been racing my boss for 10 years and the OEM torsen is working fine with zero dramas.

 

[blacksheep-1]

100% on pinion depth. You aren't removing the pinion when you change the diff so the pinion depth won't change and that is what sets most of the pattern.

The backlash is set by the shims between the case and the diff carrier bearings. I don't think I have ever had a 8.8 need different shims from just a diff change. Assuming it is on the OEM ring and pinion, it will probably be thick one piece shims, but regardless make sure that the cap and shim from the left stays on the left and the cap and shim from the right stays on the right. And the shims will be tight to put back in, you might have to use a hammer to get it all back together...this is the preload on the carrier bearings.

However, you will want new diff/carrier/side bearings. You will never get the old ones off without damage and new are cheap.

Diff work is not super hard, just take your time and don't overcomplicate it. I'd put it at a 5-6 on a difficukty scale of 1-10

DaveW

There are several diff how tos posted by me you can search them. 7.5 build is almost identical

 

[blacksheep-1]

Thread 'Gear installation' https://trackmustangsonline.com/threads/gear-installation.18062/

 

[ShifterX]

Thread 'Gear installation' https://trackmustangsonline.com/threads/gear-installation.18062/

Lot of good stuff there. Thanks.
I watched enough videos to know I didn’t want to get into overhauling the diff. I was not aware that just swapping the carrier with no gear changes is a possibility. It sounds about the same level of commitment as a TL rebuild. Only outside help I will need is pressing new bearings onto the carrier.

That said, I am still leaning to freshening up the TL. It sounds like there is some value in a good working TL relative to an open diff and even a much nicer Torsen. It’s cost effective, and there are plenty of other places to spend the money that would have gone to the new diff. Thanks,

 

[blacksheep-1]

You don't need a press to install those bearings, flip the old bearings over. Place them on top of the new bearings so you don't damage the new ones, and tap them on with a hammer.

 

[mavisky]

Had the Trac-Loc on my SN95 and my S197, the T2R in the GT350 opened my eyes to on throttle response and I'd never go back to a clutch style diff again.

 

[ShifterX]

I need some help diagnosing a possibly related issue to the diff.

The problem is when I abruptly steer the car back and forth (weave or slalom) there is an audible knock or clunk from under the car. If the right forces are generated, I can do it with each back and forth. I can’t tell if it’s coming from the front or the back. I can feel it in the floor, not the wheel.

It became noticeable after I added new springs and dampers because that’s when I started cornering a bit harder. I have replaced almost every suspension part on the car mostly just due to maintenance but some has been chasing this issue. The sway bars have been removed as well.

I am starting to think it has something to do with the rear axle. As an experiment, when weaving back and forth, I applied some brake pressure and felt a pulsation in the pedal about the same rhythm as the noise. Also the noise became harder to hear while applying the brake.

Moving my attention to the rear axle, I measured axle thrust play with a dial indicator. I came up with .080 left and .090 right.

So could a worn diff be causing this noise? Appreciate any help as this has been a frustrating issue to pin down.

thanks

 

[ShifterX]

Appreciate it if anyone can comment on the above...

Or my next question. I am going to rebuild the Trac-lok using the carbon kit from Ford. I keep reading posts about people over-stacking the clutch pack or (more interestingly) leaving the preload spring out. The idea behind leaving out the preload spring was to loosen up the locking action during low torque situations. Anyone have any experience with this?

Thank you!

 

[blacksheep-1]

Appreciate it if anyone can comment on the above...

Or my next question. I am going to rebuild the Trac-lok using the carbon kit from Ford. I keep reading posts about people over-stacking the clutch pack or (more interestingly) leaving the preload spring out. The idea behind leaving out the preload spring was to loosen up the locking action during low torque situations. Anyone have any experience with this?

Thank you!

My Mustang has the @TeeLew shims in it, my truck has a later model limited slip unit without the pre load spring. If I take it apart again, I'm going to use the TeeLew shims with no preload spring.

 

[ShifterX]

Well I already bought the ford carbon kit so that is what I will use. As stated above I had pretty excessive end play, so I thought for sure I would add extra shims to the ford kit. Nope. Installed as instructed, the right side came in at .005 end play. The left side .012”. I turned the c-clip around and measured .007. I am sure it will open up with first use, but I can’t get anything else in there without the cross pin hitting the axle end.

So that just leaves the question of spring or no spring. The factory spring pretty much fell out. So it’s that, the green spring with the kit or no spring at all.

Not sure how good this information is, but it’s making me lean to the green spring.

https://www.mustang6g.com/forums/threads/understanding-the-traction-lok-diff.154366/

Thinking that having a floor of clutch preload will make more predictable behavior. That is the most important trait to me. Of course I may be all wrong in my thinking.

 

[ShifterX]

Used the green spring. Will report results. After full assembly with spring, end play was .004 left side and .006 right. So the Ford kit was right on the money out of the box. The only thing I did was turn the C-clips around to eliminate the small wear pockets. This might have been worth .005 at most.

I will just throw this tip in for anyone who tries, this 100% works. I used line wrenches as they were a little deeper.

 

[ShifterX]

Just catching up on this thread. Rebuilding the track lock eliminated the issue I was having, plus the rear axle feels overall tighter. Less NVH. All in all, it was a pretty easy swap that restored the OEM performance.

That said, without even going to the track the limitations of the trac-loc are obvious. With the rear sway bar out the car tends to load the outside tire hard and under acceleration spins the inside tire. The good news is it still accelerates while spinning. Before, forward progress seemed to stop when the inside tire broke loose.

Once the rear swaybar was back in, under lateral load, throttle inputs can induce oversteer at lower speed. This was not really possible before the rebuild. I am already sensing a strangeness from the diff behavior though. I don't have a good handle on when it opens up or when it locks down.

More to come on that after a track day.

 

[MikeBard]

This thread is kind of going the direction I was looking. I have the ford racing carbon clutches in my rear diff and I was wondering how the check the wear. I put a hub adapter on it to be in the center and measured the torque it took to cause it to rotate with the other wheel on the ground. It was averaging around 30-35 to initially break free. I’ve seen people claiming they’re 80+ and even up to 150 fresh. I only have 3 TTs and a few autocrosses on it. Can’t imagine they’re worn out. It has 75w140 with a tube of transx limited slip additive if that matters.
My box came destroyed so we measured and stacked all of them by hand to try and get it as close to the same stack height as possible when we initially set it up. Would end play be a more accurate way to see what the wear is, or do I need to replace them?

 

[blacksheep-1]

This thread is kind of going the direction I was looking. I have the ford racing carbon clutches in my rear diff and I was wondering how the check the wear. I put a hub adapter on it to be in the center and measured the torque it took to cause it to rotate with the other wheel on the ground. It was averaging around 30-35 to initially break free. I’ve seen people claiming they’re 80+ and even up to 150 fresh. I only have 3 TTs and a few autocrosses on it. Can’t imagine they’re worn out. It has 75w140 with a tube of transx limited slip additive if that matters.
My box came destroyed so we measured and stacked all of them by hand to try and get it as close to the same stack height as possible when we initially set it up. Would end play be a more accurate way to see what the wear is, or do I need to replace them?

IMO, that preload can change depending on the clutch composition, and break in, type of lube, all contribute to how much torque it would take to break the clutches loose. It also changes with wear. I would highly suggest the @TeeLew steels.

 

[MikeBard]

IMO, that preload can change depending on the clutch composition, and break in, type of lube, all contribute to how much torque it would take to break the clutches loose. It also changes with wear. I would highly suggest the @TeeLew steels.

So would you say that is not a good way to measure wear then? A couple of us are trying establish some sort of wear rate using that. It seems like a few people have had them start to get pretty loose and spin the inside tire without a full season on them yet. I saw the @TeeLew steels mentioned elsewhere but I haven’t had much like finding out about them.

 

[TeeLew]

So would you say that is not a good way to measure wear then? A couple of us are trying establish some sort of wear rate using that. It seems like a few people have had them start to get pretty loose and spin the inside tire without a full season on them yet. I saw the @TeeLew steels mentioned elsewhere but I haven’t had much like finding out about them.

Well, you're going to have a hard time finding out much about these because there are only 2 cars on the planet running them, LOL. I made them for myself and gave Blacksheep a set because I wanted someone else to get some test time and, well, because he's Blacksheep.

I've had enough interest in these that I'm going to make a small run and see where it goes. Give me a couple months and I'll have them available. I've got a lot of irons in the fire at the moment.

I've been running the 5x5. It's got a lot of preload and a good bit of locking. It sounds like a metal plate differential when you're making a slow 90 deg corner in a parking lot....click, click, click, click...so don't expect OEM silence. This is just part of the gig. Full disclosure, they're not cheap pieces to make. It's 10 floating and 10 fixed plates, so the cost isn't a hell of a lot less than a Torsen. I need to get a fresh quote. I'm sure what it was 3 years ago when I made them and what it is now are 2 different things.

Torsens are very user friendly and work well most of the time. They don't like situations with a big mu splits side to side, but other than that, there aren't a lot of complaints in the driving of them. Mostly you can put them in and forget they're there.

I think there are a lot of advantages to plate differentials. The 5x5 is a hell of a lot more tunable than a Torsen and it also gives the option of adjusting lock or preload independently, which the Torsens can't do. The Trac-Lok is lighter and runs cooler. And last, changing diff plates is a much easier job than changing the actual differential. That install isn't cheap if you have to pay to have it done. A well-trained chimp could change the plates. If the standard Ford Traction-Lok was such a bad design, they wouldn't have used it for the last 75 years. It's just tuned to be quiet and benign to drive. That's why they've always sucked.

I personally feel that I can put quite a bit of preload in the diff and/or lock department on a GT car before anything negative happens. Mostly, it just feels better and you go faster.

 

[MikeBard]

Well, you're going to have a hard time finding out much about these because there are only 2 cars on the planet running them, LOL. I made them for myself and gave Blacksheep a set because I wanted someone else to get some test time and, well, because he's Blacksheep.

I've had enough interest in these that I'm going to make a small run and see where it goes. Give me a couple months and I'll have them available. I've got a lot of irons in the fire at the moment.

I've been running the 5x5. It's got a lot of preload and a good bit of locking. It sounds like a metal plate differential when you're making a slow 90 deg corner in a parking lot....click, click, click, click...so don't expect OEM silence. This is just part of the gig. Full disclosure, they're not cheap pieces to make. It's 10 floating and 10 fixed plates, so the cost isn't a hell of a lot less than a Torsen. I need to get a fresh quote. I'm sure what it was 3 years ago when I made them and what it is now are 2 different things.

Torsens are very user friendly and work well most of the time. They don't like situations with a big mu splits side to side, but other than that, there aren't a lot of complaints in the driving of them. Mostly you can put them in and forget they're there.

I think there are a lot of advantages to plate differentials. The 5x5 is a hell of a lot more tunable than a Torsen and it also gives the option of adjusting lock or preload independently, which the Torsens can't do. The Trac-Lok is lighter and runs cooler. And last, changing diff plates is a much easier job than changing the actual differential. That install isn't cheap if you have to pay to have it done. A well-trained chimp could change the plates. If the standard Ford Traction-Lok was such a bad design, they wouldn't have used it for the last 75 years. It's just tuned to be quiet and benign to drive. That's why they've always sucked.

I personally feel that I can put quite a bit of preload in the diff and/or lock department on a GT car before anything negative happens. Mostly, it just feels better and you go faster.

Haha well that makes sense then. I saw your name mentioned here and then on another forum I believe but nothing else other than that. They may be outside the realm of what I can get away with in my class.
Being the shims are a ford service part, I think I could possibly shim the diff tighter and still be within the spirit of the rules, I just couldn’t find any good numbers on how much is too much.
Also is there any merit to stacking the plates a different way? I saw something about changing the order of them and adding an extra friction plate. I have my old ones still and they’re not completely worn out.

 

[TeeLew]

Haha well that makes sense then. I saw your name mentioned here and then on another forum I believe but nothing else other than that. They may be outside the realm of what I can get away with in my class.
Being the shims are a ford service part, I think I could possibly shim the diff tighter and still be within the spirit of the rules, I just couldn’t find any good numbers on how much is too much.
Also is there any merit to stacking the plates a different way? I saw something about changing the order of them and adding an extra friction plate. I have my old ones still and they’re not completely worn out.

The shims are what we use to adjust the preload. It has a big effect, but there's only so much you can do with what Ford gives you. The wear material on the plates means that any initial setting goes away in short order. My initial though was just to sand the friction material off, but then you're left with butter soft plates that have been stamped, so they're not even remotely close to flat. What are you supposed to do to flatten them, surface grind mild steel? You might be able to, but it seems a fool's errand. The plates I made are from ground and hardened tool steel, to they are *FLAT*, which means they make excellent surface contact plate to plate. I think this probably accounts for as much increased locking as the added plates.

I also need to source some shims that are thinner than the stock preload shim. Those are really only for coarse adjustments.

If you just have to stay with the stock parts, I'd try the carbon fiber friction plates and get as much preload shim in it as you can. Stack them alternating floater/fixed to have as many faces engaged as possible.