Limited Slip Diff - How warm is to hot?
Discussion
As a man possessed by finding braking perfection why is the rear end of my S running so hot?
My rear wheels are running hotter than the fronts???
New everything almost
Master cylinder
Stainless braided flexies
Recon front and rear callipers
Slack in the hand-brake cables etc etc
Even tried an adjustable balance valve
Tomorrow will be servo-pedal pushrod adjustment for 'some more slack' in the system
so where is the heat coming from? If its not this then........could it be the LSD? How hot does yours run and how hot do they get on a straight fast run of say 3 miles at 70?
Are the wheels 'you have been braking' warm, when you haven't? and bloody hot when you have done 10 miles at pace with little braking?
if its the LSD - how do i stop it?
My rear wheels are running hotter than the fronts???
New everything almost
Master cylinder
Stainless braided flexies
Recon front and rear callipers
Slack in the hand-brake cables etc etc
Even tried an adjustable balance valve
Tomorrow will be servo-pedal pushrod adjustment for 'some more slack' in the system
so where is the heat coming from? If its not this then........could it be the LSD? How hot does yours run and how hot do they get on a straight fast run of say 3 miles at 70?
Are the wheels 'you have been braking' warm, when you haven't? and bloody hot when you have done 10 miles at pace with little braking?
if its the LSD - how do i stop it?
If you jack the car up can you spin each wheel freely? There may be a little bit of noise but no noticeable resistance from the pads just touching the disc.
Diffs do get hot, if you ever follow something like a tipper truck, where you can see the back axle, in the rain the diff will be bone dry.
Get one of these to give yourself a better idea of "what's going on"
Might be nothing to do with it, but here goes.
On my S2 the wheels ran hot and the more you drove the more the brakes seemed to be holding you back without any pressing of the pedal. I refurbed the calipers, swapped over to braided hoses and tried various other things before someone told me what it was.
The brake light switch was badly adjusted and was holding the brake pedal on ever so slightly. As it all warmed up and stuff expanded then the brakes came on progressively more.
3 seconds of bending the mounting bracket away from the pedal completely cured the problem for zero cost.
It only took 4 months to track it down.
HTH
Bob
On my S2 the wheels ran hot and the more you drove the more the brakes seemed to be holding you back without any pressing of the pedal. I refurbed the calipers, swapped over to braided hoses and tried various other things before someone told me what it was.
The brake light switch was badly adjusted and was holding the brake pedal on ever so slightly. As it all warmed up and stuff expanded then the brakes came on progressively more.
3 seconds of bending the mounting bracket away from the pedal completely cured the problem for zero cost.
It only took 4 months to track it down.
HTH
Bob
Hi All
Would agree with Ray on this, not much chance of heat from the diff finding it's way to the brakes, would have thought hot brakes are due to a bind of some sort or bearings on there way out. Pads constantly in contact with the discs or hard driving and brakes to small to dissipate heat, wrong pads on the rear, I do know some of the green and red stuff gets stinky hot.
Alan
Would agree with Ray on this, not much chance of heat from the diff finding it's way to the brakes, would have thought hot brakes are due to a bind of some sort or bearings on there way out. Pads constantly in contact with the discs or hard driving and brakes to small to dissipate heat, wrong pads on the rear, I do know some of the green and red stuff gets stinky hot.
Alan
Maybe we need to consider other evidence...I presume that you have just finished you brake upgrade....
So questions to also consider;
- how massive are the discs you have added on the front and back
- I presume the huge discs are not rubbing on the wheels...are they....
- how is the brake balance affected
- the earlier point about brake rubbing could be the issue
- wheel bearings on the new rear hubs?
So questions to also consider;
- how massive are the discs you have added on the front and back
- I presume the huge discs are not rubbing on the wheels...are they....
- how is the brake balance affected
- the earlier point about brake rubbing could be the issue
- wheel bearings on the new rear hubs?
AutoAndy said:
...I presume that you have just finished you brake upgrade....
New rear pads?Were rear caliper pistons fully "wound back" ?
they don't just push back like the fronts do
Apologies if I'm telling you stuff you already know but when offering advice on a Forum not usually sure of the posters level of knowledge/competance? Someone posted on one of the other TVR forums that he was totally dissapointed with his new car, it handled like a "death trap", turned out to be nothing more than his nice new tyres were pumped up to 40psi!
phillpot said:
...... his nice new tyres were pumped up to 40psi!
That sounds familiar 
phillpot said:
... If you jack the car up can you spin each wheel freely? There may be a little bit of noise but no noticeable resistance from the pads just touching the disc....
What was the outcome?Have you checked the hand brake cable?
Pistons are wound back fully, no air found, bearings are new, handbrake cable not tight, appropriate free play at pedal and at master cylinder.
Annoyed.
Went for a 3 mile run without using brakes. Rears are hot.
Jacked ar up fully its a bit stiff turning either wheel - but there is a bit free play at the discs with wheel off before trying my rotating of discs actually starts to shift the drive shaft & diff.
Diff very hot. Pulled diff filler out.....and on the magnet we have some metallic flakes.......
Hmmm. Is this the source of the heat?
Unlikely I know. But its fecking hot. Time to suck the old out and stick some new in. No sucker though......
Annoyed.
Went for a 3 mile run without using brakes. Rears are hot.
Jacked ar up fully its a bit stiff turning either wheel - but there is a bit free play at the discs with wheel off before trying my rotating of discs actually starts to shift the drive shaft & diff.
Diff very hot. Pulled diff filler out.....and on the magnet we have some metallic flakes.......
Hmmm. Is this the source of the heat?
Unlikely I know. But its fecking hot. Time to suck the old out and stick some new in. No sucker though......
Top Gear TVR said:
.... bearings are new.......
Are they taper-rollers on the rear? If so, did you leave a little bit of "slack" to allow for expansion when running?As above, hard to see how heat could bleed past the CV joints. Try going for a a drive with the hand-brake cable disconnected.
Edited by v8s4me on Saturday 2nd August 12:06
v8s4me said:
Are they taper-rollers on the rear?
Rears are similar to fronts, a friggin big nut tightened to silly tight and a bit 
Don't know "how hot" a diff should get but, as said, unless driveshafts are "untouchable" that's not why the brakes are hot (imho)
Is the fixed part of the caliper central over the disc, definitely not touching/rubbing?
Long shot but when you tighten wheel nuts do they definitely clamp up the wheel and disc and not bottom out on the threads?
Hows about jack back end up, wheels off, wheel nuts back on (with washers if need be) run engine....watch it all go round and look for issues?
Top tip: don't wear a tie while doing this
OK - Ive run without handbrake cable and it loose.
Rears are still so hot its wrong. Jacked up and checked it all coming from the diff. Brake aren't binding at all ever now - its all heat from the diff.
Its so hot!
I wonder do these ford LSDs eventually slip internally creating heat?
Would it prefer a friction modifier to reduce slip? or a special oil?
Does it need 'tightening'
or does it need air ducts? a radiator? or chiller unit?
Rears are still so hot its wrong. Jacked up and checked it all coming from the diff. Brake aren't binding at all ever now - its all heat from the diff.
Its so hot!
I wonder do these ford LSDs eventually slip internally creating heat?
Would it prefer a friction modifier to reduce slip? or a special oil?
Does it need 'tightening'
or does it need air ducts? a radiator? or chiller unit?
Top Gear TVR said:
I wonder do these ford LSDs eventually slip internally creating heat?
Would it prefer a friction modifier to reduce slip? or a special oil?
No expert but as I understand it the "limited slip" bit is done by a sealed for life compartment (for want of a better word) within the diff. The oil you can drain/refill is "normal" oil Would it prefer a friction modifier to reduce slip? or a special oil?
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