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IMHO the fitment of twin truetracs in a Automatic vehicle is far better, as using the brake gently to aid traction turns these diffs into almost lockers, they are that positive:) It is very difficult to do this in a manual one for obvious reasons. This is an observation based on driving 2 twin TT equiped D1's, 1 auto and 1 manual through the same terrain.
JC
My bad, the T2 Torsen is similar to the Quaife ATB and Tru Trac which all use parallel axis planetary worm gears.
The Torsen T1 (the original design) is a fair bit different with the worms going across the axis.
Quaife ATB
http://www.import-racer.com/2/quaife-cut.jpg
https://www.aulro.com/afvb/images/im...009/08/844.jpg
Torsen T2
http://www.torsen.com/images/T2b.jpg
http://www.torsen.com/images/T2color2.jpg
T-2
Detroit Tru Trac
https://www.aulro.com/afvb/images/im...009/08/845.jpg
T1 Torsen
http://www2.zhome.com:81/ZCMnL/tech/Torsen/Figure1.gif
Torsen White Paper
http://www2.zhome.com:81/ZCMnL/tech/Torsen/Torsen.htm
Hi Rick130 excellent posting good tech, the Quiife/TT used with left foot braking is good but if you have traction control they are fantastic. as the Traction control applies just enough brake to engage the ATB. Regards Ian Ashcroft
thanks Ian (or is it Dave this time ?)
Yep, I don't know if you remember, but a couple of the boys that founded the Outerlimits forum found how well a torque biasing diff can work when they made their own pneumatic TC system and used it on a comp buggy with Tru Tracs.
re the original Torsen, now termed the T1 (and FWIW was designed by a Mr Gleasman and a durable, workable model only able to be finally produced by Gleason, everyone confused yet ?? :D)
I'd read in the past in a tech book, and the white paper I linked to confirms better than 6:1 bias ratios are achievable which would indicate it's a better proposition for the rear axle in an off roader than the simpler to make parallel axis models
From what i've read, the T2/ATB/Tru Trac are a better proposition in a steering axle thanks to the milder bias ratios, and whoever is now the owner of the Torsen production often use a different bias ratio (and i suspect Quaife do too, but they don't divulge) in a front steering axle to rear in AWD models.
Hi Rick Dave is on Holiday so I am temp reinstated, we tested a number of T1 Torsen which were sent to Land Rover for evaluation, they just did'nt survive, the little gears at the side sheared off in very short time and the cases split, this was off road comp safari racing. e.g. failed after one circuit of a comp safari. I have never seen a T2 for the Rover but believe they are used on other 4X4, as you note the T2 is identical to the others except for axial gears, possibly to get round some design protection. Regards Ian
Hi Ian,
that's exactly what I read happened on circuit race cars years ago too.
Too many small bits taking high torque loads coupled with cases not strong enough for race use.
Apparently most of the gear problems were overcome, what I read it took a company with Gleason's metallurgical resources to do it, but one of the other downsides with race use was the high moment of rotational inertia and the friction (heat) involved in it's operation.
There were some aftermarket steel cased units made in the US that overcame Gleasons ductile iron case problems too, the iron cased versions were a grenade waiting to happen apparently.
Have you ever seen inside a Weisman locker ?
Would it have any application as an off roader diff ?
While a torque biasing diff they lock 100% under torque, open in coast.
Were very popular in F5000, F1, F2, Can Am, etc in the seventies/eighties.
Does anyone make them anymore ?
May be of interest, I have in front of me a description of a Torsen type differential (unfortunately with a not very good picture) named a M & S or Brown-Lipe-Chapman. The book it is in was copyrighted 1909-1926. It seems that the basic design goes back a lot further than anyone is prepared to acknowledge. Probably either not successful, or, more likely, too expensive to make; certainly it would not be very strong given the metallurgy available then, but powers available were nowhere near what became possible after WW2.
John
I'm not surprised John.
The Dual Drive differential that is now known as the Torsen was patented by Vernon Gleasman in 1958.
I remember seeing the ads for the Dual Drive differential in the US magazines 'Four Wheeler' and 'Off Road' that Dad bought when I was a little tacker in the early seventies.
Interestingly, one of my race car tech references states "Gleason wrote the book on gears in the 1920's, all we've learned since then is metallurgy"
There are similar "surprises" when you talk about just about any "new" ideas in motoring, or probably most other fields for that matter. The lag between when an idea is first thought of, or even first tried, and when it becomes accepted or common, can be many decades. This can be for a wide variety of reasons, but probably most commonly because there is no real need for it when first thought of.Quote:
Originally Posted by rick130
John
John