I’m hoping to fit a 2.88 diff to my S3 shortly.
It currently has a 3.31 which I believe is a Salisbury Limited Slip Differential which operates on the principle of clutches that allows a degree of slip but also a degree of binding between the two sideshafts.
Does the Dana work on the same principle?
I believe the the Jaguar Dana diff is almost identical to the Jeep Dana diff,
and they have clutch plates, same as Jaguar LSD
There is a clearly visible difference with LSD diffs, an open carrier one can clearly see the spider gears, the LSD carrier the internal parts are more enclosed
You could always put a Detroit Locker in it, and be endlessly amused by the “click-click-click,” rounding corners!
A guaranteed method of losing the rear end in a powerful rear wheel drive car.
Fantastic in a 4x4 though.
An eaton true trac might be a better choice - if they were available for the jag diffs.
Quaife make LSD for E Types both as a complete pumpkin (new word for me) and as a replacement center section. LS is provided by gears as opposed to clutches. They are as close as your wallet. https://shop.quaife.co.uk/catalogsearch/advanced/result/?vehicle=4&product_type=11&sub_type=16&manufacturer=63&model=385&q=
Truetracs are a very good design, in that they have a much more positive method of preventing wheel slip than a clutch pack LSD.
They do exist for Dana 44, which is what Jag used when they had Dana
I cannot see any obvious reason why an Eaton D44 centre could not be fitted into a Jag Dana, with or without a gear change
I did see a diff on this principle is advertised online for Jags, for about $A1370, it may be the Quaife
The Eaton Trutracs look like a Quaife inside but are half the price. There is complete specs for them at http://www.eaton.com/ecm/groups/public/@pub/@eaton/@per/documents/content/ct_128302.pdf
Will need to dismantle a stock diff and do some measurements.
I understand that Summit calls “Truetracs” Detroit lockers. That is most incorrect.
A Truetrac is an LSD whereas Detroit locker is an automatic positive locker. I had several Detroit lockers in my 4x4.
When in good condition and with the correct GL5 spec oil, the Detroit Locker makes the faintest of ticking sounds when cornering. In my 4x4, I had to wind the window down to hear those ticking sounds.
When the locker became worn or the oil contaminated with water, it became noisy and eventually reluctant to unlock going around corners. Ask me how I know…
I repeat that a Detroit is only good in a 4x4, and I would go further saying that it’s only good in a 4x4 with permanent 4wd like a land rover. In a selectable 4wd or rear wheel drive car, the true trac is a safer choice.
Hi Terry
I replied on the forum but should add that truetracs are absolutely silent. It’s only the Detroit lockers that make those ticking sounds.
I have a stripped-down Dana 44 Housing intend to build for my Jeep,
will be taking many measurements, as it is presently in 10 boxes.
It has an ARB airlock centre to be re-installed
let me know exactly what measurements you would like
I also have a '68 non-LSD complete pumpkin from a MKX
the thing would be to see if a Jeep D44 diff centre will fit in a Jag Dana or Salisbury pumpkin
Having said that, the main benefit of a Truetrac is they will still deliver traction if one wheel loses
all traction (ie becomes airborn). A clutch LSD will not
guys that have Truetracs in the front diff of their 4x4 really like them
Sure it will, that’s what the clutch does - link the two wheels. Not as much as torque-induced lock-up but to the full extent of clutch grip there will still be traction.
Does the TrueTrac use the same principle as a Torsen diff?
I can not comment on LSD, but I know for a fact that a truetrac CAN behave like an open diff in that when one wheel loses all traction, all power goes to that wheel. Seen this on 4x4s.
The truetrac manual actually recommends (or used to…) that in such situations, “gentle left foot braking” be applied to restore torque to the wheel with traction.
I’ve seen this technique lead to a few broken sideshafts and CVs…
Similar perhaps, but from what I understand not “the same”.
Tony – Having rebuilt only two, I’m not anywhere near an expert on differentials, but what I see as issues would be: 1) Will the stock Jag crown gear bolt to the carrier – that is bolt spacing and size compatibility, or do you need to buy a new gear and pinion, 2) Are the hub axle sizes and spline pattern (number of splines) on the stock differential compatible with the Truetrac. There is considerable variation in sizes and spline patterns in Dana 44’s, 3) Are the bearing sizes on the each side of the carrier the same as the Jag carrier. I’m sure there are more questions an expert would ask. It may be that you’d need to have the center sections out of a Jag diff and physically compare it to a Truetrac on the bench. I need to talk to a friend who has more knowledge about these, but can’t get at that until next week. If one of these will fit my car I’ll probably buy it, as I’m going to get into my diff on my autocross car this winter. I’m acutely conscience of the warnings by Quaife that these are difficult to install and should only be done by an expert. They speak in their material of a need to buy a pin to preload the bearing– huh? I know about preload but the pin? If I get one I won’t install it myself.
When the Quaife came out I wrote to customer services to see what ratios. They only did 3.54 at first, so I guess the carrier flange would work for the mid-range 3.XX ratios if it fit any stock gear at all. More recently I believe I saw a ratio advertised that would need one of the other two carriers, but I don’t recall which.
me either, but I do know someone built thousands.
I can check bearing size of Jeep D44…I have to rebuild it from scratch, I need to measure the side bearings to establish axle centreline, pinion depth etc. Can provide spline count for axle and pinion.
a lot of info here…go to page 4 for the technical details!
my experience an understanding, Torsen,Quafe, Truetrac all work very much the same (worm & screw instead of clutch packs)
my experience from 4wd, if a clutch LSD has one wheel in the air, there will be ZERO transmission of torque to the other wheel…it has to be packed with rocks to work
from the literature, and anectdotally, a Truetrac style can be made to work in this situation by using some brake, the internal gears will lock up
( a bit of handbrake will make a rear LSD with a wheel up work)
I believe it does. I have one in my V8 powered Mk1 Cortina. Around town, it behaves just like an open diff, but when you romp on it, it seamlessly transfers power to the wheel with traction…quite amazing.
Their one (functional) weakness is if a tire losses contact with the ground, it will just spin that wheel, and not transfer the torque effectively. If the car has one tire on the asphalt, and one on wet grass, no problem…but it your car has a tendency to pick up a rear wheel, there may be better choices in diffs.
Overall, I’ve had a very mixed experience with my Truetrac. When it’s working, it’s brilliant, and I love it. However, my first one failed very quickly, and was repaired under warranty, then recently failed again…that’s two failures in less than 5,000 miles. I’m now on an entirely new unit, installed by a different shop, so we’ll see how this one does. I hear of a lot of people who beat on theirs without issue, so maybe I’m just unlucky…that would be par for the course for me.
When I changed out my 4:27’s for 3:54’s I had to machine the carrier to clearance the new ring gear and now I may have to add a spacer when I remove the 3:54 for a lower ratio, How far can I go with a carrier that fits 3:54?