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  1. #1
    OVER-BOOST!! svono50's Avatar
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    Apr 2002
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    3,915
    SVO's: 86 1C

    Torsen differential or keep the clutches??

    I would like to hear some feedback from folks on here that are or have run either the Torsen T2 or T2R in their cars or at least a Mustang. Hearing before/after results on either auto-x or road courses would be preferred, since that is what I generally do with mine. I know my factory trac-lok unit is getting worn and I am trying to decide to either rebuild it or throw in a T2R. I know some folks who run on road courses have their preference, so let's see what you have to say.

    My main issue I am trying to reduce/eliminate is spinning the inside rear tire on corner exit. I am going to work on 'tuning' my rear setup with sway bar size first and always have my Fays2 Watts link to play with as well. Regardless, I want to be able to put down all the power all the time...oh that sounds so simple, doesn't it?!?
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  2. #2
    14 PSI Boost
    Join Date
    Oct 2005
    Location
    Ooltewah, TN
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    83
    SVO's: 1985 1/2 9L
    Like I said on the other post, I did put a T2R in my car with the 3.73 ratio and have run three autox with it since. I have the Fays2 and the same rear swaybar as you have but have the stock SVO front bar. I have H&R race springs which I think are a bit stiffer than the ones on your car, especially in the front. I have OEM wheel size and Hankook R-S3 which are probably similar to your RE01R but yours are much wider so your grip is likely a lot better than mine. My engine is BONE stock.

    I have not noticed your situation on my car where the inside rear tire spins with the Torsen. I don't really recall it doing so with the OEM 7.5 Trac-Lok either, but I had all stock suspension with the 7.5. The T2R seems like it would be the right thing in your case since it specifically sends much more torque to the tire with the most grip. The Trac-lok can never do that. Along with no clutches to wear out and it's likely unbreakable in a 4 banger application, it seems like the right way to go, at least it did to me. It's pricey, but you should be able to put it in and forget it.

    I set up my diff with the torsen and new Ford Racing 3.73 gears and it is as quiet as a mouse. The housing was a '89 GT.

    BTW, I tried reading thought that "Roll axis and understeer" thread on CC and went away with "WTF"!!! I'm an engineer too (electrical) and suffered through statics and dynamics, but holy cow are these guys talking another language to me!
    Last edited by ciscokid; 09-26-2014 at 06:08 PM.

  3. #3
    OVER-BOOST!! svono50's Avatar
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    We have somewhat similar setups, I will need to check what the difference is in our rear spring rates. I do know that the calculated stiffness increase between the stock SVO sway bar and the Eibach unit is 366%, from 61 to 285 lb/in. I am thinking of tossing the GT bar I was running back in to soften it up a bit. If I still get inner rear spin I can go down to the SVO bar. One thing to consider is my RE01R's have aged out this season, since they were actually cast in 2008 and are getting hard, which isn't helping matters in any way. Next season I will have a fresh set installed, still wavering between the RE11A's and new ZII Star Specs. In any case, this did help point out a weak spot in my system's 'tune'.

    My current diff is a Ford Trac-lok unit that was rebuild by the guy I purchased the 8.8 rear from. I swapped out the 3.73's that were in it for 4.10's, since I drag raced at the time. The mechanic who did the swap confirmed that the diff had new clutches in it, but I have seen quite a bit of friction material in my fluid the past couple of changes, so I am guessing my unit is pretty loose at this point.

    I would love to move up to a T2R, but add that on top of the new tires and my wife's budget meter will go off. I have also been looking at the Detroit Truetrac unit, since it is priced a bit closer to the T2, but has a variable bias that floats from above the T2 unit to just under the T2R. Apparently some folks like the 'feel' of the unit better than the T2R. Could I tell the difference...probably not, but the price point is less steep. With my car only pushing just over 300 lb-ft to the rear wheels, I am not worried about grenading one of these units, but it would be nice to not question the operation of it again.

    Yeah, a lot of guys over at CC go a bit overboard with their 'knowledge' dump on subjects. Whether they really understand the mechanics/dynamics can certainly be debated, as they seem to simply quote a lot of information out of publications. I could do that too, doesn't mean I really understand it. I do like the way the one guy who responded to my post stated that the sway bar is 'fighting' the spring to keep the tire on the ground...helped me better visualize the forces going on which I should have seen up front, but was fogged by too many other variables. I have always tended to overcomplicate my visualations with things like that...go figure.
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  4. #4
    OVER-BOOST!! svono50's Avatar
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    Cisco, I got a spare moment and went over my spring and sway bar data. The H&R race springs are way up the scale from my Pro kit, your fronts are 750-850 lbs compared to my 457-571 lbs and rears run 260-280 lbs compared to my 200-251 lb units. With that much front spring, your front is much stiffer in comparison to the rear stiffness, but then you beef up your rear rate with the larger rear bar. Here is what the different rear bars calculate out to: stock 17.3mm bar = 61 lb/in, GT 21mm bar = 142 lb/in (+132%) and Eibach 25mm bar = 285 lb/in (+366%).

    Based on that I am going to only step down to the GT bar to begin with, since it should not over power my rear springs. If the rear bar has more force potential than the spring above it, it is no wonder I was lifting my inside rear when pushing it through the corners! Your rear springs are a better match for the 25mm bar and combine that with the heavier front springs, I am sure yours handles pretty neutral too. I am hoping I don't loose much of my current balance and shift back toward understeering. I guess I will find out at the Reunion auto-x, since I will throw the GT bar on the car before heading down.

    Just for giggles, what is your Watts pivot bolt height from the ground?? I just checked mine and it is 8-3/4" from the ground to the center of the pivot. I am still debating on lowering it one notch, but will try the rear bar first.
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  5. #5
    OVER-BOOST!! svono50's Avatar
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    Just a quick update, I did swap over to the GT rear bar and ran the auto-x at the Reunion. It was an improvement, but still spinning the inside rear...less than before but still there. The seal coating on the auto-x lot didn't help any, but did allow me to feel/hear what was still going on. One of the guys who was watching from the sidelines stated that my car was still cornering very flat compared to the other SVO's out on the course, but ultimate tire grip was somewhat low on that lot and likely had a hand in that situation. With that said and now with my car 'put away' for the winter, I will swap down to the stock SVO rear bar for my next track day to see how that ultimately goes.

    Of course, I am now eying the H&R Super Sports that list spring rates of 700-760/275-300 (F/R). I think the Race units may be a bit much, as I still do a fair amount of street driving. A friend has the Super Sports in his '03 GT, so I need to get a ride in his car with those springs to see just how stiff things are. He feels they are not bad for the street, but way stiffer than the FMS B springs he was running.

    Cisco, can you measure up your ride height for me?? I am looking for the distance from the bottom of the fender lip to the wheel center on the front and rear. Just curious where your Race springs put you for height. Thanx.
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

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