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One front disk brake runs hot


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Even after a short (5km's) run, the left front brake disk is very hot, and the wheel is not running free when mounted on a bridge.

I just renewed brake oil (dot4) and the brakes work very well, but the left disk seems stuck.

What are your suggestions?

Greetings,

Erik Arckens

PS: this is for TR4 1964, as original

Edited by earckens
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21 minutes ago, earckens said:

Even after a short (5km's) run, the left front brake disk is very hot, and the wheel is not running free when mounted on a bridge.

I just renewed brake oil (dot4) and the brakes work very well, but the left disk seems stuck.

What are your suggestions?

Greetings,

Erik Arckens

 

Flexible brake hose collapsing internally.

Stuart.

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19 minutes ago, earckens said:

Would this be the one:

https://www.moss-europe.co.uk/brake-hose-girling-stainless-steel-braided-tt3142.html

While ordering, what else should I get replaced?

 

 

If your having a problem with one I would go for replacing the pair

Stuart.

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+2 Both sides removes the doubts.

Mick Richards

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In addition to above, you might also check the Caliper pistons or the pads in the body of the caliper are not seizing, especially if you’ve bled and pumped the brakes quite hard. 

Kevin

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Go for all three.  Do the rear one while you have the desire to replace bleed the entire system

Peter W

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10 minutes ago, BlueTR3A-5EKT said:

Go for all three.  Do the rear one while you have the desire to replace bleed the entire system

Peter W

All three? You mean:

1. Flex hose

2. Caliper piston

3. Caliper pad

..for both sides?

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2 minutes ago, ntc said:

You have shimmed the callipers so they are true to the disks?

To be honest I am not sure what you mean? Can you please explain?

Fact is that I have not done anything to the braking system apart from brake oil purge, and the brakes had been doing fine for years.

I realise there might have been degradation I had not been aware of until just now.

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In all my years I have never encountered a collapsed hose, and I have run some dubious stuff in my time, but I have had plenty of seized caliper pistons, especially in cars that get little use.  I would be taking the pads out first and checking that the pistons move freely before suspecting the hoses.

Ralph

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This was my previous Daimler SP250 callipers that worked ok with the old pads as it works operating with the non rusted part of the piston. 

when I went to fit new pads you can guess I had issues pushing the pistons back. All hidden behind the rubbers gators. The rust would have ruined the rubber seals in the calliper body. So new stainless rebuild kit sorted it.

this was just after a hose collapsed that virtually locked the nsf and cooked a disc.

I learnt a lot !!

Erik

all the above posts are great advice.

i understand all you have done is change the brake fluid but sometimes the jobs we do can trigger another issue  that seems to be old cars for you !!

I would start with a check for the free movement of the pads in the calliper they should slide fairly smoothly on the calliper surface / pins by hand then check pistons move in and out but be carful that you don’t pump them out too much that you can’t get something in between to push them back again.

then the hoses , but you say you have braided ? These should be better than standard but how old are they ?

some food for thought.

H

5D542B36-A6A1-4E0B-8D6C-4B3D12926683.jpeg

07D13CC3-67F9-4951-A9C3-9E4623E37EA8.jpeg

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The brake hoses are braided, but I have no idea how old they are; certainly more than 5 years (the time I bought the car).

Ok, I will take down the brake calipers and inspect the pistons etc..

Question: how best to avoid draining brake fluid all over the place when disconnecting the upper part of the braided hose?

 

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If its braided-type hose then AFAIK they dont 'block internally', so your issue is most likely a partially seized caliper. How to stop the fluid draining out? 

1) Put 'Cling Film" from the kitchen over the top of the master cylinder and loosely fit the cap on-top.

2) Find a rubber cap or plastic cap of a pen that will fit over the ~11mm end of the flex hose when you remove it from the caliper.

Getting a seized piston out of the caliper is difficult...Make an adapter and use your grease-gun to force them out (its messy but safe - no risk of something going bang)... likely the piston is corroded, it can be cleaned-up but will corrode again. Consider a full kit from Bigg Red with new stainless pistons https://www.ebay.com/itm/283802279001?hash=item4213ef1c59:g:e4QAAOSwPhdU-DCs

Or just buy a whole new caliper (take care to get the one with the imperial flex hose connection -- NOT metric!)

https://www.moss-europe.co.uk/brake-calipers-tr4-6.html

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A couple of years ago, David Ferry was selling calipers, fully reconditioned by Big Red, at a very competitive rate - might be worth sending him a PM in case he has some remaining.

Ian Cornish

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This is what I found: looking at the surface border of this piston it seems to have been battered, so most likely this problem is not new.

Now trying to extrude these pistons :huh:.

IMG_20210714_140620.jpg

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1 hour ago, ianc said:

A couple of years ago, David Ferry was selling calipers, fully reconditioned by Big Red, at a very competitive rate - might be worth sending him a PM in case he has some remaining.

Ian Cornish

Hi Ian, thanks for your info; how could I get hold of David Ferry?

Grts,

Erik

 

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22 minutes ago, earckens said:

This is what I found: looking at the surface border of this piston it seems to have been battered, so most likely this problem is not new.

Now trying to extrude these pistons :huh:.

IMG_20210714_140620.jpg

That will be of no detriment are the pads worn even?

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4 minutes ago, ntc said:

That will be of no detriment are the pads worn even?

Yes, I think they are; even front-back, up-down.

IMG_20210714_163050.jpg

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23 minutes ago, ntc said:

They look good so check the run out of the disks 

That too is good: no ridges, even wear although there is virtually none (no ridge on the edges)

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