help needed please!!

[tbdgriff500]

we need to get hold of a 3.31 power lock diff from an early xjs/xj6 to fit in the tasmin.
struggling to find one any where and we have tried all the usual places.
any advice welcomed.
also if any one wants a 2.89 diff (non power lock) we have one!!
cheers
tim.

[Graham]

I wouldnt fit a powerlocker in a v6 taz, unless your going to do some drastic mods to the internals to cope with the lack of weight and torque compared to the jag.

Otherwise it will totally feck the handling...

You'll get cracking traction off the line and out of the corners, but it totally unbalances the car in the corners..

G

[tbdgriff500]

thanks for the advice,(now even more confused) about what to do!!

[NTEL]

tbdgriff500 said:

thanks for the advice,(now even more confused) about what to do!!

Unfortunatley I can't help with your diff but I have been given the same advice off a number of people in the know regarding the Powerlock i.e don't go there. Having spent a lot of time speaking to lots of companies it would seem that the Quaife ATB is the way to go. Trouble is they are about £700.00 plus VAT plus installation so that, for me, will have to wait until next year.

[Graham]

When we first built the Taz we were offered a brand new powerlocker, and it seemed like a really good idea.

we then struggled mid pack for a few years with an evil handling car, not having the experience to know where the problem was.. Eventually we bunged in an open diff, totally the wrong ration ( too high) and with no other changes to the car took half the lap records and the class win that year...in a car widely acknowledged to be one of the lowest powered at the time.


for the birkett that year we put the p/locker back in as the ratio was a lot lower... I only managed a few laps before the engine dropped a valve, but in comparision the car was undrivable, very very twitchy on the back end.


My tas currently runs a quaife, and if you can get one thats what you need... The power locker can be modified to lighten the action but I dont know anyone who can.


one other solution is to run the back a little softer and add an anti-roll bar. at places like mallory where the hairpin can be a killer we ran no camber, almost positive camber in fact on the inside rear to try and keep it in contact with the ground.

hope that helps a bit

G

Edited by Graham on Friday 20th June 17:32

[tbdgriff500]

thanks for all that info, i thought i had learnt a lot about diffs and quaife dog boxes in the last few days but always room for more information!
knowledge is power (but a little knowledge is dangerous)!!
so do you agree that the way forward for now (cheap) is to put in a 3.31 open unit,
i have worked out the top speed reachable using steve heaths converter chart on his web page (thanks steve, brilliant)should be about 130 mph running 15" wheels. is this enough ? or would a 3.07 open diff, wich would give us 142 mph be a better option, although that doesn't seem a big enough jump from the 2.89 that we have (gears way too long).
cheers
tim.

[heightswitch]

tbdgriff500 said:

thanks for all that info, i thought i had learnt a lot about diffs and quaife dog boxes in the last few days but always room for more information!
knowledge is power (but a little knowledge is dangerous)!!
so do you agree that the way forward for now (cheap) is to put in a 3.31 open unit,
i have worked out the top speed reachable using steve heaths converter chart on his web page (thanks steve, brilliant)should be about 130 mph running 15" wheels. is this enough ? or would a 3.07 open diff, wich would give us 142 mph be a better option, although that doesn't seem a big enough jump from the 2.89 that we have (gears way too long).
cheers
tim.

There is a jag breaker in Radcliffe near Bolton which Breaks lots of XJ6's and you may get lucky there. last 3.54 powerlock I bought was approx £250 I think. if you fit a jag unit to a light weight TVR then you should have it re-built and the pre-loads altered so that the LSD doesn't come in as quickly. being built for a heavy jag, the first thing that happens when it operates in a light car is severe understeer. your ratio will depend on your max revs, gearbox and whether you have 4 or 5 gears.
i am running a 3.31 powerlok in mine due to a 5800 RPM limit and 4 gears. if you have 5 gears then a 3.54 with a close ratio 5 speed with long first and secon could well be a better option

just found the address

Jaguar Breakers Ltd Mount Sion Rd, Radcliffe, Manchester, M26 3SJ

Tel: [phone]

you may need to look around the yeard yourself and take some tipex so you can check the ratio for yourself.

A powerlok is very heavy though? A lighter ford diff may take a bit more work to fit but will save weight.

Mr Read can build powerloks or knows a few very knowledgable men who can.

Don't listen too much to Graham, he is just a modern front wheel drive boy at heart and hasn't learned the fine art of powersliding out of corners yet
N.

Edited by heightswitch on Friday 20th June 18:22

Edited by heightswitch on Friday 20th June 18:24

[tbdgriff500]

we have a 4 speed quaife dog box (4th is 1.1) with 6800 rpm.
the guy i am speaking to at the moment says you can turn the gears round
to make it less locked about 45% instead of 75% ?

Edited by tbdgriff500 on Friday 20th June 18:30

[heightswitch]

tbdgriff500 said:

we have a 4 speed quaife dog box (4th is 1.1) with 6800 rpm.

2.88 is commonest jag ratio.
3.07 is resaonably easy and was actually the original griffith Diff (not sure if 3.07 was available as a powerlok but you are free to swap around CWP's

3.54 is the hardest powerlok to get because all of the replica cobra builders want them.

3.31 should be reasonably easy to get since I think this was the auto XJS diff? but I may be wrong.

N.

3.31 sounds like the best ratio with 4 gears and your rev limit.

N.

Edited by heightswitch on Friday 20th June 18:31

[tbdgriff500]

thanks for the contact details i will shop around and see whats available, then make a decision when i know what the choices are,
cheers
tim

[Graham]

heightswitch said:

the first thing that happens when it operates in a light car is severe understeer.

We never had much of a problem with understeer, the old taz would flick the back end out quite well.. The problem was in anything other than a tight corner, the diff would constantly lock and unlock, unbalancing things.. The worst place for this was obviously Gerrards at mallory.

On a test day one of the other guys was following me round, right up my chuff, needing not much more than one hand on the wheel. In contrast I was having to hang on for dear life, work at about 120% just to get round with the back end wagging around...


Front wheel drive whats that, I though FWD meant four wheel drive and four wheel drifting... Landrover man me...

[heightswitch]

Graham said:

heightswitch said:

the first thing that happens when it operates in a light car is severe understeer.

We never had much of a problem with understeer, the old taz would flick the back end out quite well.. The problem was in anything other than a tight corner, the diff would constantly lock and unlock, unbalancing things.. The worst place for this was obviously Gerrards at mallory.

On a test day one of the other guys was following me round, right up my chuff, needing not much more than one hand on the wheel. In contrast I was having to hang on for dear life, work at about 120% just to get round with the back end wagging around...


Front wheel drive whats that, I though FWD meant four wheel drive and four wheel drifting... Landrover man me...

I have just gotten me a trooper. Are you at Anglesey Graham?

My car is still not there but My mechanicing will probably still be required with Geoff. its getting closer though.

N.

[Graham]

heightswitch said:

[

Are you at Anglesey Graham?
N.

50/50 at the moment