Torsen T2R Issue

[Trublu]

At Cressen I seem to have had an issue in the diff where the torsen didn't seem to lock up as it should. Noticeable in mid corner and seemed most noticeable on a left hander. No inside wheel spin but really had to feather the gas pedal mid to late in the corner.

I'll pull it later in the week but reading other forums it seems this might be an inherent fault that our friends at Torsen don't acknowledge or help with.

Anyone had similar issues?

Can the T2R be rebuilt or is it easier (considering cost vs result) to buy a new one?

Is there a better center for the 8.8"?

Appreciate info

Craig

[Trublu]

So the Torsen issue seems to be the result of a missing letter, although my Torsen has the spring pack between the side gears (as in T2R) it is a T2 from a Ford Ranger and not a T2R. The T2 is only capable of redirecting about 30ftlbs of torq from the light inside wheel to the loaded outside wheel and the rest is allowed to spin at the friction plate on the outside of the side gear for the inside wheel. This was very prevelent on the off camber corners at Cressen.

If you want some sunday fun pull apart a Torsen and then upon finding nothing wrong put it back together. Mr Rubix and his cube have nothing on Mr Gleeson and his diff. It will/does go back together.

Anyway I have a plan to solve the missing letter issue.

For me the lesson learnt here was that despite a bucket load of ill founded internet info the best source was from the engineer at Torsen through a phone call. Despite what the internet might lead you to believe they are very forthcoming with technical info and advice.

[michaelmosty]

Ugh, that sucks.
I bought a T2 back in 2007 thinking it would work w/ our low HP limit but IMO it just doesn't function properly. I have run the T2R since middle of 07 without issue.
I still have the T2 that I ran for 2 events that I'll make a smokin deal on if someone wants it. ;^)

[Trublu]

I'm with you there. I guess the saying goes "pay to learn" and I learnt a bunch about diffs with this experience. T2R should be here from Torsen by Friday

Make that 2 smokin deals on T2.

[GlennCMC70]

Did they tell you the bias ratio on the T2R? Any tech info you want to share w/ those of us who have T2R's?
Cost?

[Trublu]

No secrets here mate.....

The cost from Torsen $670 plus shipping (3-4 days) for a round total of $700. No tax applicable.

The bias ratio of the T2R as stock is 4:1 and Torsen would recomend no higher without loads more horsepower. The 4:1 was mainly designed for autocross but suits our HP on tight technical tracks well. Increasing the bias ratio is achieved by replacing the friction washers and also the contact pattern (and TPI) of the planetary and side gears. Basically increasing friction in the assembly increases the bias ratio. At least that's as best as my feable mind comprehended.

Oil is not a significant factor (in their opinion) as long as you have some in there. They did concede that a higher viscosity has some slight negative effect on locking but it is minor. Adding friction modifier will decrease noise but have no noticable effect on performance. I said I intended using Redline 75W90NS and they thought that would be a good choice.

Torsen dont recommend disassembly (which is partly why they have lifetime warrantee even for race application) although it is fairly easy once you undersatnd some of Rubix principals (instead of changing the colors on the cube mark the planetary gears for location and orientation prior to disassembly). The unfortunate thing is once disassembled Torsen wont sell you component parts (again warranteeing to avoid bad press from poor mechanics)

[GlennCMC70]

Great info. I would love to send mine in for a re-fresh.
Are there any vendors who sell a new one for less than $700? I recall these bing in the $500 range a few years ago.
Thanks for the fluid info. I just drained mine and was trying to remember what it took.

[Trublu]

I looked around a bit for price comparrison but eventually convinced myself that sticking with OEM direct would give less hassle should I ever need to use the warrantee. The guy at Torsen said they watch their distributor pricing (Ford Racing in particular) to make sure they are close.

[Trublu]

Glenn,

If I understand the design correctly this is actually a case of "if it aint broke dont xxxx with it". Aparently the best check (short of disassembly) is to jack up one rear wheel and apply torque to the other, the resistance should be high. If resistance is low then the friction plates are worn and the diff needs rework.

[marshall_mosty]

Torsen should be able to provide the "breakaway torque" for the unloaded wheel. Ford has a specification for their stock Trak-Lok diffs (which I still use with much success).

A Note on Ford Trak-Lok diffs:
It does require a refresh every year or two with new shims to tighten things up. I've been running the same clutches/steels for 7 years (20+ weekends for me since I haven't ever really made a full season except 2011).

[Trublu]

OK, back on the phone to Torsen.

If a solid axle assembly has a total available traction (limited by tire traction) of X+Y with X being the light or unloaded inside wheel and Y being the loaded outside wheel then the T2R can transfer 4 times X across to Y. This is because the T2R has a torq bias ratio of 4:1.

There's a catch.... If the light wheel is unloaded and off the ground then be definition it has zero traction and therefore 0 x 4 is still 0 and no torq will be transfered. This is because the diff is limited slip with a high bias ratio but not a true locking differential.

Trick is keep traction to both wheels and the key is in roll stiffness.

[Trublu]

Forgot to add, it stands to reason that once the torq transferred to the outside wheel is greater than the traction of the tire then white smoke will appear.

[nasa-rm]

OK, back on the phone to Torsen.

If a solid axle assembly has a total available traction (limited by tire traction) of X+Y with X being the light or unloaded inside wheel and Y being the loaded outside wheel then the T2R can transfer 4 times X across to Y. This is because the T2R has a torq bias ratio of 4:1.

There's a catch.... If the light wheel is unloaded and off the ground then be definition it has zero traction and therefore 0 x 4 is still 0 and no torq will be transfered. This is because the diff is limited slip with a high bias ratio but not a true locking differential.

Trick is keep traction to both wheels and the key is in roll stiffness.

Ok. Time to resurrect an old thread. When I got the Mustang back, they had replaced the trac-lock with a T2R. I hate it with the current setup. I get nothing but a spinning inside wheel in the air. This was painful at TWS exiting T4, through the carousel and exiting 14.

Michael, I need to look at your roll stiffness at ECR and figure out how you are keeping the rear tire on the ground.

Or, I need to put the trac-lock back as it seemed to work quite well. Easy enough to freshen every few years.

[MikeP99Z]

If the inside wheel is spinning, the torsen is done.

[ShadowBolt]

Dave,

I have had a really stiff set-up (1000/275) and a really soft set-up (whatever I have now). With either set-up my T2R does not do the one wheel peal. When I had the T-Lock it was a problem every two or three weekends. I'm looking forward to ECR with the T2R. With the T-Lock, even with brand new clutches my car would spin the inside wheel like a MoFo in turn seven. That is a climbing left hander after the long back straight. I'm guessing something is wrong with your T2R.

JJ

[marshall_mosty]

I guess I like the KISS principle, but I've used a stock Track-Loc in my AI car and have to reshim every 5-6 weekends. Not too bad really for what a rebuild costs. Each "refresh" really is just adding shims. I built the car in 2003 and only did a fresh rebuild then. Every other teardown has just been to add shims. I did utilize the alternating stackup and NOT the OEM stackup.

[nasa-rm]

If the inside wheel is spinning, the torsen is done.


I'll pull the cover when I get a chance. If it is toast, I will go back to the trac-lok. Never had an issue with it and only changed oil once (no reshim) in three years (or 20 days or so of race time).

[Suck fumes]

Make sure you have the right T2R. They make two models, one being more aggressive than the other. Running a stiff vs soft setup will not make any difference on a good diff.

[michaelmosty]

Dave, it sounds like a T2, not T2R.
I bought a T2 for mine back in 07 thinking it would work fine w/ the low HP. It ended up being a piece of crap and spun the inside tire everywhere. I ran it for 2 events and then replaced it with the T2R. The T2R has been great for over 5 years now.

On a side note, I still have the T2 in its original bag and box if anyone would like to buy it. It is a great piece and will do awesome in any race car!! ;^)

[ShadowBolt]

Make sure you have the right T2R. They make two models, one being more aggressive than the other. Running a stiff vs soft setup will not make any difference on a good diff.

I agree with Aaron about the stiffness not making a difference. At least it has not for me in my two cars.


JJ

[ShadowBolt]

On a side note, I still have the T2 in its original bag and box if anyone would like to buy it. It is a great piece and will do awesome in any race car!! ;^)

Except the 11 CMC Mustang

[edrock96GT]

+1. I've had a T2R in my car since it's nitrous & slicks days in '04. It still works great.

[AI#97]

You guys are funny....

<---same eaton since 2002. No wheel spin even with 430+ to the wheels.

[Trublu]

FYI, wheel spin on the inside rear when cornering is a set up issue not a differential issue (unless you are running a locked rear end). Although the torque bias ratio of a T2R is high at 4:1 it relies on both wheels to be planted to be able to transmit this torque across the driveline. The Torsen engineers will confirm this for you. For a practical understanding put the car on stands and have someone hold one wheel while you turn the other, there will be resistance but the wheel will turn (albeit at a higher torque than a T2). For the same reason that the wheel turns in this scenario it will spin if completely unloaded. The key is to ensure there is no bind in the rear end suspension and that both wheels remain in contact with the black stuff (no matter how fragile the contact might be with the inside wheel).

Take it a step further and (systematically) pull a T2R completely apart (not recommended by Torsen), making sure to note position and clocking of the planetary assembly. After a full afternoon and several head scratching beers you'll work it out. It looks nothing like the drawing you'll find on the internet, which shows all available T2&R options rather than a specific configuration. It will eventually go back together but may require more beers and head scratching plus a contorted expression....

There's an a Eaton and a T2 sitting on my shelf for anyone who misses out on Michael's offer.....

[Dulaney]

<---same eaton since 2002. No wheel spin even with 430+ to the wheels.

+1. 2009 Eaton, never rebuilt, zero problems.

[cobra132]

T2R since 05 with no issue.

[ShadowBolt]

FYI, wheel spin on the inside rear when cornering is a set up issue not a differential issue (unless you are running a locked rear end). Although the torque bias ratio of a T2R is high at 4:1 it relies on both wheels to be planted to be able to transmit this torque across the driveline. The Torsen engineers will confirm this for you. For a practical understanding put the car on stands and have someone hold one wheel while you turn the other, there will be resistance but the wheel will turn (albeit at a higher torque than a T2). For the same reason that the wheel turns in this scenario it will spin if completely unloaded. The key is to ensure there is no bind in the rear end suspension and that both wheels remain in contact with the black stuff (no matter how fragile the contact might be with the inside wheel).

Take it a step further and (systematically) pull a T2R completely apart (not recommended by Torsen), making sure to note position and clocking of the planetary assembly. After a full afternoon and several head scratching beers you'll work it out. It looks nothing like the drawing you'll find on the internet, which shows all available T2&R options rather than a specific configuration. It will eventually go back together but may require more beers and head scratching plus a contorted expression....

There's an a Eaton and a T2 sitting on my shelf for anyone who misses out on Michael's offer.....

You may be right. When I was really having issues the car also would not turn right without pushing like a dump truck. Turned out to be the left rear was in a bind due to the strap that was installed to keep the shorter spring from falling out when you jacked up the car. When I put a longer strap on the push during right turns went away. I had installed a new T2R before I figured out the turning issue. The diff may have been okay.

JJ

[blk96gt]

I'll likely be upgrading to the T2R before January, but I was curious if everyone was sticking with the 28 spline or upgrading to 31? Is the 31 overkill for our application?

[ShadowBolt]

You don't need the 31. 28 spline is fine at CMC power levels.

[mach1]

Im running the FRPP Boss 302 T2R and I am not a fan, I have been spoiled with os giken though in my miata. When I ran the car at cresson without sway bars it was terrible, once I got some bars on the car is was much better but still not great, had some issues at hallet, would always spin the inside at turn 9, I am thinking about going to a clutch style diff, sounds like eaton may be a good route.

[blk96gt]

Im running the FRPP Boss 302 T2R and I am not a fan, I have been spoiled with os giken though in my miata. When I ran the car at cresson without sway bars it was terrible, once I got some bars on the car is was much better but still not great, had some issues at hallet, would always spin the inside at turn 9, I am thinking about going to a clutch style diff, sounds like eaton may be a good route.

Interesting. For those with an Eaton, has the maintenance been basically change the oil and keep driving? That has been Dulaney's experience above. Any others? I like things that I can put on the car and forget about, so that's why the T2R had always been on my list. I may have to consider the Eaton as well.

[AI#97]

Interesting. For those with an Eaton, has the maintenance been basically change the oil and keep driving? That has been Dulaney's experience above. Any others? I like things that I can put on the car and forget about, so that's why the T2R had always been on my list. I may have to consider the Eaton as well.

Eaton. Changed oil after 7 years. Checked clutches and were fine. Fresh oil and moving on.

[marshall_mosty]

I like the stock track-lok. It's been rebuilt (alternating clutch/steel method) twice in 9 seasons... And it came with the car... I've only bought one $50 rebuild kit and each time I rebuild, I just lay all the clutches on the table, take the thickest of the bunch, shim it until I can barely get it together, and slam it back together.