Limited Slip Recommendations

[cjlmlml]

$76

[AI#97]

Torsen T2R

Matt: Interesting, got "tech"?

Boudy

My experience in having driven them all including the auburn I just put in my truck is that the torsen can and will light a single rear tire and can either be overpowered and not work, or takes that miniscule fraction of a second and allows some slip of one tire, then bites and causes a very slight "chirp". this has all been in cars of 300+ rwhp. CMC cars might not have the power to do it, but you guys are generating nearly the same torque as my AI car. However, the lack of torque could compound the problem in the T2/R as it takes power to generate the pressure bias...?

The clutch type diffs are all as good as you set them up. Ford Trac Locs are all rebuilt with additional clutches to make them last....or make them work nearly as tight as a spool. Eatons use a kevlar clutch pack that can take a TON of abuse and the gears are of much higher grade steel...billet I believe as opposed to the cast crap in a ford unit. My Eaton had the 400# preload springs in it and I just upgraded to the 800 lb springs and LOVE it!!! If you want to put your foot in the gas and rotate the car, it does it instantly and very predictably and equally...especially in transistions like 13, 14 and 15 at TWS. The car did start to push a little and was fixed with a rear bar adjustment.

I have seen people for years look for ways to eliminate bias and "induce" spool like behavior with springs and thicker clutch packs. Personally, I could care less if the inside tire "scrubs" in the parking lot...I don't race there. also, consider standing starts...don't want ANY bias there especially if different grip levels from left to right.

I too would like to try a spool but just don't need to at this time. Maybe if I go to a monster motor I might just for strength.

YMMV but that is my "expert" impression of having driven them all except a spool.

BTW, Auburns are rebuildable. If they put it together, it can be disassembled and rebuilt. The story of not being rebuildable was because Auburn wouldn't sell the parts. Yukon gear used to sell kits to do so but I have not personally done it. After looking at the one I just put in my dodge, it would be easier than rebuilding my eaton.

[AI#97]

Oh, and if you are looking to eliminate rotating mass....a spool usually weighs 5 to 10 lbs less than a clutch type diff.....

[Boudy]

Thank you sir.

Boudy

[Greg_FW]

Lots of great information from the best source: experience. Thanks for all the feedback!

[Hood]

I like Marshall's post in that it tells you the mechanics involved with both types of diffs. However, the feel of each diff can be, at times, drastically different. Having driven my CMC car with a 'spool' I can tell you that the car feels way different than with a clutch-type or gear-type posi. First the spool...The car has an unstable feel under braking, especially if there is any transitional elements in that particular part of the course. Turn-in suffers as you transition off the brakes and will tend to understeer more as you add throttle (unless you are in a high horsepower car and can just hang the tail out Trans-Am style). I had to alter the shock settings in order to drive the car comfortably at the limit. Otherwise, massive trailbraking was required to get the car pointed in the right direction. This shock alteration further enhanced the bad stability problem under braking and I quickly realized that something needed to change. I put a clutch posi in and immediately the car was eager to turn in but would allow some inside wheel spin (not enough clutch preload) resulting in a slower exit speed. I was a die hard clutch posi advocate until I recently tried a Detroit TrueTrac. Wow! is all I can say. The car was instantly more stable under braking, had better mid corner behavior and I could apply throttle sooner without making it push OR oversteer. With the clutch-type posi, when throttle is applied, it wants to become very close to a locked diff. It allows some differential wheel speed at higher loads but acts more like a locked diff than not. This can also cause a push. With the gear-type posi, it always allows wheel speed differential while both wheels are being powered. This causes less of a push. Again, as Matt was saying, these are my observations based on using all of these in different environments (autocross, drag racing, road racing, etc) Yeah, I know, drag racing may not be relevant in this case but you get your experience where you get it.

[HoustonNW]

I had a lot of one wheel spin at Cresson. I can probably drive around it at TWS but may as well not show up to Hallett with a bad rear diff.

Is the Detroit TrueTrac still a good choice? Do I have to remove the ring and pinion to install it? If yes then I'll have to find a shop in Houston, any suggestions?

Paul Costas with Witchdoctor Motorsports (do you know him Gary?) makes an argument on frrax.com for a Powertrax No-Slip for a driver at my level. I like the idea of installing it without disturbing the ring and pinion but I cannot figure out if they offer one for the 1998 Camaros:

http://www.richmondgear.com/powertrax/chevycarns.pdf

Can anyone read that application chart and confirm yes or no?

Thanks.

[Casey_SS]

I had a lot of one wheel spin at Cresson. I can probably drive around it at TWS but may as well not show up to Hallett with a bad rear diff.

Is the Detroit TrueTrac still a good choice? Do I have to remove the ring and pinion to install it? If yes then I'll have to find a shop in Houston, any suggestions?

Paul Costas with Witchdoctor Motorsports (do you know him Gary?) makes an argument on frrax.com for a Powertrax No-Slip for a driver at my level. I like the idea of installing it without disturbing the ring and pinion but I cannot figure out if they offer one for the 1998 Camaros:

http://www.richmondgear.com/powertrax/chevycarns.pdf

Can anyone read that application chart and confirm yes or no?

Thanks.

Me too...but only in Little Bend and Buzzard's Neck. Where was your wheel spin happening? Did you make suspension changes for Cresson? I went up ~25% in spring rates and think that was more of a factor than the diff "going bad". I went with the Auburn Racer's diff (clutch style diff w/ 800lb preload springs) before Hallett last year and it's been flawless up to now. I still can't say anything bad about it. The slippage I got at Cresson was pretty easy to drive around with just a line change - braking later w/ more trail-braking to slide the rear, turning in 1/2 car length earlier, then hard on the gas to stop the slide and straighten the car completely fixed it. No 1 wheel peel at all. Dunno if it was any faster but it sure was fun With a smoother radius sort of line, it would spin the inside tire from apex to track out. Just a data point for you to play with...may or may not help.

What diff is in your car now and how old is it? Was last weekend the first time you noticed the problem?

[rpoz27]

Matt Bought me an eaton and gears for the GN off ebay for $630 for Xmas. get the eaton and be done with it.

[Alien]

I think the powertrax can be installed without removing the ring gear since you are reusing the carrier. Tho I *think* it MUST use an open diff carrier. If you have the T2 that was stock in the LS1 cars, I believe you'll have to replace the carrier (from a V6?) and that may be why it's not listed in that link. Pretty sure you'd use the 10-bolt 7.625" 28 spline one, 92-0776-2805 or 92-0776-2885

With any diff swap, I don't see why you'd have to remove the pinion gear. I've done it by just swapping over the ring gear to the new carrier (LEFT HAND THREADS!) and checking the backlash/pattern. Have never needed to shim anything so far since I've always reused the gears in the rearend, YMMV. If you're installing new gears, it's a whole 'nuther story.