LSD? Now - Diff Housing Stip?

[philwaters]

I'm working on finding the solution to a handling problem I've been suffering for a while - since I fitted an LSD in fact....

 

If you've got one, could you jack up one wheel (the OSR) and put a torque wrench on the central nut and see what torque is required to make it start spinning (whilst the other wheel is stationary on the ground.

 

I've done Steve Foster's, which came in at ~15 ft/lb. I was recommended 25 - 30ft/lb.

Mine is currently set at 50 - 55 ft/lb !

In my head this means the wheels are more tightly locked together and the back end wants to go straight more than it wants to turn a corner... which is what my 🙆🏻 is telling me when I drive it.

 

Just trying to decide on what I should get it adjusted to... the 15 or the 25-30 region. I know someone who had an axle built by the 25-30 'people' and I seem to remember him always complaining of understeer, and I'm wondering if this might have bene his problem.

 

Thanks

 

Edited by - philwaters on 31 Dec 2005 19:10:16

[Normans_Ghost]

Phil, I'll check mine in the morning as it's a bit cold out there at the moment.

 

Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here

You and your seven to The French Blatting Company Limited

 

Edited by - nverona on 30 Dec 2005 19:03:23

[oldbutnotslow]

Phil You don’t say what type the LSD is.

On the basis of a ZF or similar plate dif the standard preload is way too high. It is set at around 55 as you have found with yours as the car its designed for is much much heavier than a 7.

It needs to be reduced this but it is something that I would not muck about with. I would say that you need either someone who really really knows what they are doing or get a specialist company like Road and Race to modify it for you. The chap to speak to at R&R is Phil. They are located in Sevenoaks, which is not millions of miles away from you. This should do the trick

 

If you take the whole diff to them they will modify the ramp angles if this has not already been done and set it up correctly whilst you wait.

 

Happy New Year!!

 

 

Grant Taylor - OBNS Motorsport

 

😬 183 BHP of Black and 'Stone Chip' excitement. 😬

here

 

Edited by - oldbutnotslow on 30 Dec 2005 19:25:02

[STEVE GILBERT]

Yours is a Tran-X isnt it?

That sounds abit much.

 

I had one of these. You can change the pre-load by the order of the clutch pack, how was it loaded when you installed the diff?

 

On the Tran-X your options are 25/30lbft or 65/70lbft. It sounds like yours is the latter with worn clutch plates or a bellview washer that's lost some of it's spring (probably a bit of both).

 

Unfortunately you need to take the diff itself completely to bits to change the load on the clutch pack. While your at it I'd check you have the cross pin cup set right to give your desired ramp angle, as this has several positions depending on what you want (id think 35/90)

 

I'd be happy doing this myself. It's quite straightforward really. just measure the backlash with a dial guage at 6 marked points around the CW, (after degreasing CWP with carb cleaner) mark the bearing cups so you can see how much pre-load has been added (and count the turns as you take them out) when your CW and diff are out whip off the end plate, re-arange as required then re-assemble back to your noted backlash numbers. You'r bound to do a bit of side to side past the markings on your side cups but as long as you maintain the overall pre-load you won't go far wrong.

 

Or if you can't be arsed RR will probably do it for a ton!

 

HTH

 

Steve

 

HTH

 

Steve

 

See My Caterham Fireblade Here.

[philwaters]

Thanks all,

 

Steve - did you have yours set to the 25-30 setting? Was the handling ok with this.

I was under the impression that you could adjust it by grinding down some shims to get what you wanted...

 

Typical really, when I want to speak to people everywhere is shut..

[Normans_Ghost]

Phil, I haven't forgotten but I've got standard ZF diff from Sierra so will not be worth measuring for you.

 

Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here

You and your seven to The French Blatting Company Limited

[philwaters]

Cheers Norman, but I actually posted to try to gain a general feel - if everyone came back saying 15 - 20 ft lb, then I would question the 25-30 setting, and certainly my 50+ ft lb. I can't see that the diff type would make a large difference, the effect on the handling would be similar...

[philwaters]

Right - how do I proceed from here? here. I've got the diff housing out of the axle and it is currently draining of oil (stinky smelly stuff ☹️).

Is it safe to just undo the bolts holding the CW and LSD in place - I'm a little nevous of the one holding the plate into the holed plate you can see in the picture.

 

Oh, and I'm proud of my slide hammer here - although it didn'ttake much to get the half shafts moving.

[old captain slow]

Man the tool maker - brilliant.

 

C7 CDW

[STEVE GILBERT]

Are you planning on doing this yourself?

 

If so I would:

1) de-grease the CWP with carb cleaner/ wd40 etc so you can accurately measure backlash.

2) mark 6 teeth (1-6) evenly around the CW

3) devise a method of locking the pinion flange against the housing to stop it turning (nut/bolt usually)

4) set up a dial guage so it's real steady for measuring backlash at the end of the CW teeth

5) lock the pinion and measure backlash at point 1. record setting

6) unlock, move to point 2, lock and measure, record. Repeat for all 6

 

If you are not confident you have accurately been able to measure the exhisting backlash, do not proceed.

 

7) Mark the bearing cups relative to housing (the ones with the lock tabs)

8) remove the lock tabs

9) Make a tool with pegs to undo the bearing cups.

 

Stop for a cup of tea 😬 Check your happy to proceed. (hey the worst is you hand a bag of bits to some bloke to put back together!

 

10) Undo the pre-loaded side bearings counting the turns that got you to your marks (1 side at a time)

11) Remove the big bolts in the end caps. don't get them muddled up. I have no idea what the torque setting is for these and you will need to find out.

 

Obviously the diff can be removed now. Don't get any of the bearings/cups etc muddled up

 

12) Take the end plate off the diff to re-arange the clutch pack/ cross pin holder. The arangement is detailed in the info you get with the diff. You should probably renew the bolts, use thread lock and tourque up to something. Ring Tran-x about this

 

I think your going to struggle to test the breakaway torque on a bench without spending forever making tools/ chopping up old 1/2 shafts etc. I'd go with the makers settings if I were you

 

13) reassembly is the reversal of removal 😬

 

Your going to have to re-set the backlash while maintaining the pre-load IYSWIM and this is why you marked the bearing cups. To do this you are moving the whole diff from side to side, the original pre-load will be maintained as long as advancing a cup on one side is balanced with retarding on the other.

 

This whole job is a time consuming and painstaking process but rewarding if you can be bothered

I'd rate it as 'Haynes 5 spanners' but once you have done it once, the next time will be twice as fast.

 

Enjoy

 

Steve

 

 

 

 

See My Caterham Fireblade Here.

[STEVE GILBERT]

Anyway

 

How exactly are you testing the existing breakaway torque?

 

There is no nut in the center of an Escort 1/2 shaft

 

Steve

 

See My Caterham Fireblade Here.

[philwaters]

Thanks for that Steve - I'll have a read and decide if I feel up to having a go myself - a bit scary at first glance!

 

As for measuring - I used the flat bar you can see in my make-shift slide hammer, bolted accross the wheel nuts and with an M8 nut and bolt through the centre. The other wheel was left on the ground.

I then stepped the torque wrench up in stages until it started to turn the wheel, rather than 'click'. This method was suggested by Raceline and gave me te 50 off reading, on both wheels and repeatable. Obviously we used the 41mm nut on the hub of Steve Foster's which gave the 15lb reading.