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P38 Paul

Wheels !

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Hi everyone , just a quick question .

Is it possible to turn the road wheel ( when jacked up ) on a P38 without having to disconnect the prop shaft ?

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Front, yes, but should be very stiff.

Rear, no.

This is assuming just one wheel off the ground.

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Yes, you can turn both front and rear wheels, but only with the handbrake off and gearbox in neutral (so chock those wheels still on the ground!). It will turn heavily, because of the resistance in the center viscous coupling. A 2ft breaker bar should get it to move, at a slow constant speed because of the dampening effect of the viscous. This is in fact the procedure to check if the viscous is seized or not.

Filip

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Ok , thanks for the replies , I needed to know as I think I have a warped front brake disc & no way to check which one it is without spinning the wheel , I recon I will change them one at a time to find the problematic one . If its the drivers side I recon that I have a problem as this is 3rd time I have done this within 20'000 miles & each time being a warped drivers side disc .

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Why do you think you have a warped disc? Brake judder? If it's felt through the steering, it's probably the front. But there are other causes besides a warped disc. The viscous won't allow you to spin the wheel fast enough to determine if it's the disc. You could take off the front prop.

Filip

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Thanks for your help guys , I replaced the discs & pads again yesterday & low & behold " it was the drivers side disc again " I cant keep going on like this  , are they not supposed to last more than 10,000 miles ? The passenger side one was perfect so I am going keep that one with its pads & fit that on to the drivers side if " or should I say when " the drivers side warps again .

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I'd be putting a caliper on then... Would appear to be sticking if you're frequently warping discs on just that corner.

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If by "warped" you mean twisted out of shape by normal braking action, then this is very unlikely.  Discs don't warp like this.

Look at the hub/disc seating in case that is damaged, plus any play in the suspension.

Judder is often caused by pad material being deposited on the disc surface by stopping and holding the brakes on while hot, or some sort of contamination e.g. oil.  Also poor disc materials.  All can give the appearance of being "warped".

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Also worth pointing out that you should never change just the brake components on one side of the vehicle.

My first port of call would be the caliper on that side if you're repeatedly having issues on one side.

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UPDATE  , the disc has just started to grab again although not to bad at the moment , just give it time , it was trouble free for 3000 miles this time & I know without stripping the brake disc off again that it is going to be the o/s one that has started to run out again .

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On 8/27/2019 at 8:04 PM, P38 Paul said:

UPDATE  , the disc has just started to grab again although not to bad at the moment , just give it time , it was trouble free for 3000 miles this time & I know without stripping the brake disc off again that it is going to be the o/s one that has started to run out again .

https://kwik-way.com/techdoc/blog1.php/rotor-runout

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You must have a seized calliper generating a lot of heat in that disc.

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3 hours ago, Chicken Drumstick said:

Thanks for the detailed info on this brake problem , I recon the next move is to put the disc on a lathe to prove that its the disc that has warped again or if I have to go a little deeper into the problem , I just find it strange that when a new disc is fitted its fine for a couple of thousand miles or so & then gradually it starts to happen again . 

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51 minutes ago, Snagger said:

You must have a seized calliper generating a lot of heat in that disc.

Hi Snagger , the calliper is free & moves in & out with no issues , however just for piece of mind I will check it again maybe this weekend .

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2 hours ago, P38 Paul said:

Thanks for the detailed info on this brake problem , I recon the next move is to put the disc on a lathe to prove that its the disc that has warped again or if I have to go a little deeper into the problem , I just find it strange that when a new disc is fitted its fine for a couple of thousand miles or so & then gradually it starts to happen again . 

That’s pretty much the sum of it. You can get the disc machined to match the runout on your hub. But I struggled to find anyone willing. EBC does or did have some good info on run out on their website.

The other option would be to look at replacing the hub. 

Edited by Chicken Drumstick

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When you say the calliper slides in and out ok.... do you mean the piston or the sliding part of the Calliper assuming they’re like a D2 one. If not, anything restricting the brake fluid returning on that line? Able to get it on a brake test roller? That would show the dragging pretty well. 

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If you replaced both front discs with the same brand, and each time it is the same side that warps, then it must be heat generation.  However, if you replaced just the one disc recently, that could be a quality issue, and since LR have been having Gen Parts discs made in India for some time now, I would be suspicious if it is a genuine one, not just Britpart.  EBC do some good discs for sensible prices, but there are other good brands out there too.  If you do suspect disc quality rather than the calliper, and replace the disc again, be sure to have matching discs on that axle..

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19 hours ago, landroversforever said:

When you say the calliper slides in and out ok.... do you mean the piston or the sliding part of the Calliper assuming they’re like a D2 one. If not, anything restricting the brake fluid returning on that line? Able to get it on a brake test roller? That would show the dragging pretty well. 

The calliper & piston are both free moving , when the car is jacked up I have got a little free play on both of the front wheels & can move them back & forth a bit with my finger with no apparent sign of dragging , the better test would be if I could spin the wheel but the drive train set up wont allow that .

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10 hours ago, Snagger said:

If you replaced both front discs with the same brand, and each time it is the same side that warps, then it must be heat generation.  However, if you replaced just the one disc recently, that could be a quality issue, and since LR have been having Gen Parts discs made in India for some time now, I would be suspicious if it is a genuine one, not just Britpart.  EBC do some good discs for sensible prices, but there are other good brands out there too.  If you do suspect disc quality rather than the calliper, and replace the disc again, be sure to have matching discs on that axle..

Both discs & pads were replaced each time , all of the makes have been different each time with the last set up being Mintex which I have never had a problem with before .

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26 minutes ago, P38 Paul said:

The calliper & piston are both free moving , when the car is jacked up I have got a little free play on both of the front wheels & can move them back & forth a bit with my finger with no apparent sign of dragging , the better test would be if I could spin the wheel but the drive train set up wont allow that .

Guessing you've got an LSD then?

19 minutes ago, P38 Paul said:

Both discs & pads were replaced each time , all of the makes have been different each time with the last set up being Mintex which I have never had a problem with before .

It's got to be something specific to that side then. Any damage to the brake lines that might be restricting the return flow of brake fluid? 

 

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1 hour ago, landroversforever said:

Guessing you've got an LSD then?

It's got to be something specific to that side then. Any damage to the brake lines that might be restricting the return flow of brake fluid? 

 

Not that I know of but I will put it onto my check list .

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If you have bot wheels on that axle off the ground, you should be able to spin them freely in opposite directions.  If you can’t, you either have some sort of locked or LSD, or mechanical problems in the axle like seized bearings or a seizing shaft.  Both of those would generate heat and could distort a disc.

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3 hours ago, Snagger said:

If you have bot wheels on that axle off the ground, you should be able to spin them freely in opposite directions.  If you can’t, you either have some sort of locked or LSD, or mechanical problems in the axle like seized bearings or a seizing shaft.  Both of those would generate heat and could distort a disc.

Hi Snagger , please read the second & third posts at the start of this topic as these wheels don't turn freely at all , maybe you could be right .

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Paul, Snagger is right, if you have both wheels of an axle off the ground, you should be able to turn them through the open diff. They will of course spin in oposite directions and some resistance will be felt, but not too much. You should certainly be able to spin a wheel fast enough to check for sticking brakes, bearings etc. 

Filip

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