STaSIS diff

[hiloran]

Apparently for old torsen you need to have AS 3552 (1mm thickness) thrust plates and for newer torsen AS 3047 thrust plates.

For old one you need 2 for upper needle bearing, 2 for lower needle bearing and 2 for middle bronze bearing.

Each side of bronze bearing you have two 1,5mm thick shiny washers not sure if those are worth of changing?

One spiral pin broke while pulling them out. They are 5x50mm. Not sure if spring pin would be Ok as they are more available?

[jade]

Sorry for delay been a bit busy lately to write up a proper report. I still want to do a back to back test on the dyno so by looking at the raw data we should be able to determine the exact change in power distribution.

there are several things that I have noted so far which indicates that the modification has worked, although until I have dyno figures to correlate what my butt dyno is telling me I don't wish to commit to it.

1 - When it was Icy mid month last month and I accelerated hard in 2nd gear the back of the car kicked out violently, previously the whole car used to sidestep.

2 - Going round a large roundabout in the dry, my tires used to star squealing at around 45mph and the car would start to understeer if I stayed on the throttle, now I can go round the roundabout at the national speed limit of 60mph with no squealing tires and carry on feeding the throttle out of the corner with what feels like no understeer, instead possibly a tiny bit of oversteer as if I had more camber on the rear suspension setup.

3 - There is steep hill near my house where at the bottom there is a bumpy roadsurface at the T-junction. Before driving the 30mph speed limit and coming to a hold at this junction when heading down the hill I used to ever so slightly get the ABS to kick in as I hit the uneven roadsurface. Since having changed the spec of the diff the car no longer applies the ABS under the same conditions. No change in brakes or brake fluid or anything other than the diff has been changed to achieve this.

Which prompted me to try the final test:-

4 - Driving the local lanes with the diff mod, I am able to brake later into corners whilst driving the 60mph national speed limit. Similar to the braking situation in no.3 the car feels less unsettled when braking hard going into corners compared to before when it used to oversteer and plough the nose down. The nose still goes down but there doesn't seem to be the same oversteer going into the corner under heavy braking allowing me to start feeding the throttle again sooner.

My butt dyno tells me that the car feels more positive in cornering response under acceleration. It's not tail happy as my old V8 Capri nor is it understeer galore as found on a FWD motor. There appears to be just that little bit extra to allow me to feed the throttle in nicely whilst cornering for a rapid exit without being tail happy like a beemer, or starting to drift towards the hedges as it used to do unless you fought with the steering.

Such a pleasure it has been to drive that it has now prompted me to finally upgrade my brakes from stock as for the first time ever I managed to get brake fade in this car

I'm going to be converting another diff in the next 7 or so days on my friends quattro'd passat to get his feedback too.
What we'll try and do is run his car up on the dyno before changing it over so we can also see the actual power distribution. Just to make sure I'm not imagining things. But as it stands I think we cracked it

JP

So what ever happened here I was keen on this mod

[JP]

Yes can still do them. Been so busy forgot about this thread. If doing track stuff definitely a plus. If doing drag racing I would say stock setup is better.

[A1quattro]

I have one of the strasis 01e Modded center diffs in the rally car , have had it for 5 or 6 years i am 100% sure it gives more rear biass and helps to reduce understeer [ but ive always got the hand brake to un -settle the rear end if req ] i dont think the average driver on the road would notice the difference wth a modded diff, i also feel for me i would prefer a permanant 60/rear 40front plated center diff , this way i could be certain the car would do the same every time, but i wouldnt be able to use hand brake unless it had an expensive handbrake release system [more to go wrong]

[diesel des]

Jp are you still doing these torsen mods?

[JP]

Yes and no. Can do them however i need mine out of my box to copy as the timing instructions have gotten lost over the years.
If enough demand I'll pull my diff out my box to copy and rewrite the instructions.

[diesel des]

Jp Isn't it just brass shims replaced with steel ones to give the higher friction? Then timed up as was? I have a spare diff I could send you. Give me an idea of price. Cheers des.

[JP]

Hahaha. Nope nothing to do with shims. It's to do with altering the gear timing to create different loading behaviour. Get the timing wrong and it'll either not go back together or **** itself.

[diesel des]

Ahhhhh I see. Is that what stasis do too? Aprox how much for the work?

[butchone]

I have one of the strasis 01e Modded center diffs in the rally car , have had it for 5 or 6 years i am 100% sure it gives more rear biass and helps to reduce understeer [ but ive always got the hand brake to un -settle the rear end if req ] i dont think the average driver on the road would notice the difference wth a modded diff, i also feel for me i would prefer a permanant 60/rear 40front plated center diff , this way i could be certain the car would do the same every time, but i wouldnt be able to use hand brake unless it had an expensive handbrake release system [more to go wrong]

any idea were the 60/40 plated diff can be bought/modified?

[terrybullwon]

Gripper

[butchone]

I have asked gripper they will only plate them, an cant split torque

[diesel des]

I have done a bit more research and stripped some of the diffs down. You need a later diff as the early ones have a different shim stack and won't adapt easily or in the same way. Bother early and late 01e centre diffs are t1 torsens. They are not t2. T2 have gears that run in a different way to ours. So calling them t1 and t2 is wrong. Just early and late t1.

Anyhow if you put it together with the gears in a different position the diff is tight to turn. But this is only distributing the torque unevenly within the gears in the diff and will kill it quickly. Before it dies it may well be doing interesting things to the bias. It does seem to be the friction of these washers that affect how the gears react to each other. The gears need timing up as factory.

I have found a fella in the states that supplies steel washers to replace the Teflon or brass covered center washes in the center of the stack. These are only used for the friction property. There are steel shims in other positions to trim each diffs clearances. Both late diffs I looked at had the same dimensions for the friction washers. I found a source in the USA for the high friction washers and have ordered 3 sets. I will do both the later diffs I have and see how I get on.

Cheers des.

[andy10v]

If they are T1 does this apply to our diffs?

http://torsen.info/fsae/fsaefaq.htm

14. What does “timing the differential” mean? The timing refers to the orientation of the spur gear teeth on the ends of the element gears in relation to the helical teeth. The differential must be timed properly - that is, the gears must be orientated together properly to operate correctly.


15. How do I time the differential? The timing information is given in the Timing Chart in the lower left-hand corner of the M021-DHU print. Windows 1, 2, and 3 refer to the element gear windows, viewed form the top, in the counterclockwise direction. Install the bottom gears first, around the side gears. Start with each gear’s timing mark straight upward, on the left side of the gear. Rotate the timing mark toward the outside of the differential the number of teeth given in the Timing Chart for each gear. Repeat for the top element gears. When completed successfully, the differential should roll (differentiate) freely.


16. What will happen if the differential is not timed properly? Proper timing is required for equal load sharing among all the gearing. It is possible to build the differential incorrectly, and have it still roll (with some difficulty). However, the internal loads will not be evenly balanced among the gears, and some will be severely overloaded. This will lead to eventual failure, often catastrophic.

19. Can the University Special be modified to increase performance? Yes, to some degree. Since performance (torque bias ratio or TBR) is a direct function of the unit’s internal resistance to differentiate, changing the resistance will change the TBR. Most of this resistance comes from the gear design itself, and cannot be altered. However, there are other frictional factors that can. One of these factors is the friction coefficient of the washers, which the side gears thrust against when torque is applied. We use a variety of different washer types to adjust the TBR. Higher friction washers include plain steel, steel with nickel plating or FNC heat treating, and hardened bronze. To reduce friction, we also use needle bearings as well as washers with a Teflon-based coating.

For the 012000, the torque bias ratio is about 2.6:1 in drive (throttle-on) and 4:1 in coast mode (drop-throttle/reverse) if the differential is mounted in the car with the large input spline toward the left (normally considered driver’s side). Switching the thrust washers that are situated between the side gears and differential housing end for end will reverse the torque bias ratio for drive and coast modes. This gives a drive mode increase in TBR that is normally favorable for this type of car. If the large spline is on the right when installed in the car, then the washers are already in the correct location to do this.

For the M021-DHU, the needle bearings between the side gears and housing/cap can be replaced with steel washers of the same dimensions. Another variation would be to replace only the bearing on the left side of the differential (as installed in the car) with a steel washer. This may offer a better balance of performance between throttle on and off.

Using less viscous oil will also raise TBR. A more viscous fluid will lower it. If you are changing the oil, be sure that you still use a GL-5 specification lubricant.

[andy10v]

I have found a fella in the states that supplies steel washers to replace the Teflon or brass covered center washes in the center of the stack.

Ethan Creeger?