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Wheels Too Hot To Touch


Best Answer detroitmini , 17 October 2019 - 03:42 PM

Well, idk how, but this topic can be marked as solved. Took the vehicle for a long test ride last night and the wheel is no longer blazing hot.

 

Root Cause: Dragging brake shoes

 

Solution: Since vehicle is Canadian spec, has inertia brake valve under rear subframe. Valve was not mounted nor plumbed properly. Valve was remounted with brakes line rerun.

 

Thank you everyone for the help/conversation!

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#1 detroitmini

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Posted 19 July 2019 - 03:00 AM

All,

 

1978 Austin Mini Saloon. Stock brakes (drums all around). After driving without excessive braking, 3 out of the 4 wheels are super hot to the touch. The 4th (left rear) is just warm which is what I would expect. The interesting fact is that the left rear is adjusted tighter than the right rear which leads me to believe this is not a brake drag issue. Any ideas what could be causing it? Wheels bearings?

 

Thanks,

Spencer 



#2 Rorf

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Posted 19 July 2019 - 05:50 AM

Brakes shoes are binding or wheel bearings are defective. What is adjusted tighter on the left rear - the bearings or the brake shoes. You need to give us a bit more history; have the brakes been worked on recently, have the bearings been replaced or re greased recently??

 

Drum brakes in good condition should never be super hot especially if the brakes have not been used excessively.


Edited by Rorf, 19 July 2019 - 05:52 AM.


#3 detroitmini

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Posted 23 July 2019 - 12:57 AM

The shoe adjuster is tighter on the left than the right. I think I might have a few things compounding to my problem.

 

In the rear, I think my e brake could possibly be hanging up. Does any have a picture of the proper routing, especially where it makes the first 90 degree bends toward the outboard side of the car?

 

The rear brakes were completely rebuilt except for the wheel cylinder. I recently bought new cylinders for both and will be replacing.

 

I have not touched the wheel bearings yet. I might order a set and replace. I tried regreasing but not sure it is enough. 



#4 Ethel

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Posted 23 July 2019 - 10:01 AM

I'd say binding brakes, can't imagine you'd get that sort of heat out of a bearing for long without it being very noisy and failing.

 

I think you need to get the drums off to see it's all assembled correctly (especially pull off springs), check for shoe wear, leaking wheel cylinders....

 

You should be able to pull the handbrake cable enough sideways on the straight runs to see if it's moving freely - with the hand lever released natch.



#5 detroitmini

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Posted 05 August 2019 - 12:59 PM

Alright so update. I rerouted the handbrake using pulleys to ensure no binding. I replaced everything in that corner (backing plate, brake cylinder, shoes, spring, wheel bearing). I reassembled and the wheel spun free. I adjusted the brake and went for a ride, its still getting hot and smoking within a few minutes. The only thing left i can think is that corning isn't releaving the pressure after pedal apply. I have a front-back separated system. Only back right is locking up, not back left. Would the relief work this way?



#6 MiniMadRacer

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Posted 05 August 2019 - 01:21 PM

How old are the drums, have they been "whacked" to get them off.... they may be warped... maybe you could swap over the rea drums as a test, and drive very carefully to check it under braking



#7 MiniMadRacer

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Posted 05 August 2019 - 01:21 PM

rear.. (typos city today)



#8 detroitmini

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Posted 05 August 2019 - 01:49 PM

Hmm ok. I will have to try that. Drums are unknown age but I have put to separate drums on and the issue is still there. I have the single line front back system which means I have the brake regulator valve mounted to the rear subframe. Does that only control apply pressure or also relief pressure? Does it regulator the corners separately or together? The price keeps me from blindly replacing that part...... 



#9 MiniMadRacer

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Posted 05 August 2019 - 02:02 PM

If I recall correctly the rear drums and front drums have different width shoes...so if you swap drums around from to rear you can get all sorts of fun with different wear patterns. I always use some sand paper on the inside of the drum to try to get them as clean and debris free as possible when I put them back on. I also rub the paper over the shoes themselves.. lightly

 

The regulator valve is in the line plumbed to the rear from the master cylinder so its one line in, and two lines out split left and right (if that makes sense) so it regulates the pressure to both rear wheels at the same time. I am not aware of any serviceable parts in the limiter valve and thought it just has a spring in it which is unlikely to have broken / failed (Yes they are expensive). I guess in theory with bad fluid maintenance the valve could stick but that should affect both (I would have thought)

 

I would start by checking the brake hoses.. they can collapse internally and not let the brake fluid retract back up to the master cylinder. I have suffered that a few times on a clutch hose, and you cant tell by looking at the outside of the hose



#10 detroitmini

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Posted 05 August 2019 - 02:11 PM

Hoses look good but if they can collapse without visual warning, ill replace them (lucky for me i have those in stock). 

 

Are both shoes and drums different widths? Is there a measurement or visual check i can do to make sure i do not have them mixed up?



#11 MiniMadRacer

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Posted 05 August 2019 - 02:17 PM

If the hoses are "old" well worth replacing them anyway.. Shoes I think are 1" 1/4 at the rear and 1" 1/2 at the front but others will prob know exactly. Certainly when you have front and rear shoes together you can easily see the difference in width. I think the drums (apart from very very early ones) are all the same width so in theory interchangeable but if for example (I now you havent done this) you swap a rear on to the front you will have a massive "no wear " ridge which will bind up the fronts....



#12 detroitmini

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Posted 05 August 2019 - 02:20 PM

Alright. Yeah a look further into shoes on minispares shows fronts can be 1.5" or 1.25" and all rears are 1.25". Tonight I will try swapping drums/inspecting drums and also replacing those brake hoses.

 

Thanks!



#13 MiniMadRacer

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Posted 05 August 2019 - 02:24 PM

Might be worth getting a 2nd opinion and see what some of the other guys on hear think



#14 MiniMadRacer

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Posted 05 August 2019 - 02:27 PM

And when I say guys, I means gals as well so as not to offend or exclude any one



#15 detroitmini

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Posted 11 September 2019 - 12:52 PM

Found out I was running 1.5" shoes on the rear. Replaced with 1.25" shoes, still super hot. Checking all corners, Front Left and Back Rear are super hot (2,1 respectively) with the front right and back left being what I would expect.






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