Rear O/S wheel getting crazy hot! (Mk.1 Eunos)

[NiceCupOfTea]

I'd appreciate a bit of fault finding advice please chaps.

A spot of background: not been using the car a huge amount over the winter, but have been using it a reasonable amount over the last few weeks. Always park up in gear, handbrake off to prevent calipers seizing.

Anyway, had a run last night (15 miles or so), first after a few days, no problem.

Drove to first site today (10 miles or so), all fine.

About an hour and a half later, drove to second site, noticed an acrid smell a couple of times so suspicions were aroused. When I parked up (3 miles?) the rear o/s wheel was so hot I couldn't get near it, lots of smoke pouring off it, acrid smell

I assumed the brakes were binding somehow, but too hot to do anything, so left in gear with h/b off.

Came back to the car an hour or so later. Car rolls fine, so brakes not binding. Drive a mile to next site, no problems.

After I have finished there, I removed the wheel to inspect.

Inside of wheel looks like a bin bag has melted on it, and then realisation dawns that it is the paint on the inside of the wheel (black) - it has blistered and pretty much come straight off

Again, hub turns freely, with just the normal amount of drag you would expect. Pads and discs look OK.

Can't see anything *except* what looks like a tiny weep from something on the back of the caliper. Brake fluid level fine though. CV boot clean and dry. Greasy/oily residue on inside sidewall of tyre

Wiped off as much of the bubbled/flaked paint as I could with turps, refitted wheel, on to next site (3-4 miles, no problem), and home (8 miles). No extreme heat from wheel (disc possibly slightly warmer than on n/s, but could still touch it for a second without burning).

So, thoughts?

As simple as a sticking caliper, making the wheel so hot that the paint melted, but has freed off now? Slight weep coincidental?

Or, did fluid leak blister and damage paint (only to the back of the wheel), but then why did it get so hot, and only on the one short journey?

Or, sticking caliper heats up wheel, melts grease in wheel bearing which coats tyre?

Any thoughts?

Couple of picture (excuse my thumb in the first )

[rovermorris999]

It has to be the brakes. Nothing else can generate that heat. So either a sticking caliper or more rarely an internally collapsing flexible brake pipe which can hold the brake on. For piece of mind I'd change both. You might want to check the rear bearing for grease after such a cooking.

[Eighteeteewhy]

Not sure how the handbrake works but the mech could be seizing on the calliper. More so because you don't use it much. Work it loose and lubricate.

[Richyvrlimited]

NiceCupOfTea said:

Always park up in gear, handbrake off to prevent calipers seizing.

That's going to make it more likely the callipers seize. You should use the handbrake often to keep it moving about.

The only way you can get that much heat is by the calliper sticking, dis-assemble the calliper from it's bracket and ensure the calliper moves freely on it's slider pin. If it does the piston is sticking.

Easiest job is to replace the entire unit, but rebuild kits can be bought for £30-£40

[snotrag]

Yup, caliber needs rebuilding/refreshing, it's just that it has freed itself offbefire your second journey. The grease will have cooked too on the sliders.

Checking the wheel bearing is a good call too.

[NeoVR]

Prob need to do brake fluid too from that amount of heat!

[NiceCupOfTea]

Just got back from garage - caliper was weeping slightly as well as binding from time to time. New caliper and new brake fluid.

In the last mile or two I could hear some squealing from the rear o/s wheel, and it is hot to the touch after getting home.

bks.

What could be causing it? What can I check before I drive back to the garage?

[snotrag]

Are you sure they know how to adjust the handbrake properly? Many don't.

I'd suggest getting both wheels up
And totally starting afresh with the handbrake adjustment.

[rovermorris999]

Yes, I'd check the pads have been adjusted correctly.
Have a look here: http://www.mx5oc.co.uk/forum/forums/t/250.aspx
and here:
http://www.mx5oc.co.uk/forum/forums/t/254.aspx

[NiceCupOfTea]

He really knows his onions.

I will go through the procedure in the Rod Grainger manual when I have a chance. Would it explain the squealing though?

Edit: and check the pads.

[NiceCupOfTea]

Could it be a wheel bearing?

[Eighteeteewhy]

Pads could need some copper slip to stop the squealing?

Has the bearing been changed?

[NiceCupOfTea]

I can see the copper slip on the back of the pads! Wheel bearing not changed.

[Eighteeteewhy]

NiceCupOfTea said:

I can see the copper slip on the back of the pads! Wheel bearing not changed.

Jack it up and spin/rock the wheel. You'll easy tell if the bearings shot.

[NiceCupOfTea]

Just had a chance to get the wheel off - definitely too much drag on the wheel, I suspect the handbrake adjustment. Manual states both wheels off to adjust h/brake but I don't have enough room. Can I just adjust the side in question? TBH what I want to do is hook the cable off the caliper so it's just acting on the one wheel and get it back to him so he can do it properly as I don't trust myself with safety critical stuff like brakes.

How can I get the cable off the caliper?

[NiceCupOfTea]

Just slackened the handbrake cable - still can't get it off the caliper though, is there a trick to it?

Anyway, it is still binding really heavily. Any more suggestions?

[SimJen]

my Mk1 did the same wheel got really hot and would drag, no amount of messing with the handbrake could sort it.
It was corroded slider pins. Took them out, spun them in a drill with some emery paper to remove the rust, re-greased and reinstalled. Problem solved.

[mad4amanda]

NiceCupOfTea said:

Just slackened the handbrake cable - still can't get it off the caliper though, is there a trick to it?

Anyway, it is still binding really heavily. Any more suggestions?

You dont need to take the wheels off to do the handbrake caliper adjustment its just possible to do if you can jack it high enough (axle stands needed )
there are 2 bolt heads on the back of the caliper. one I think is a mounting bolt the other id a blanking plug IIRC its the one at the rear of the car .
its only a small bolt and wont be too tight, under that is a smallish 5mm? allen key that adjusts the pad pressure .

[MX-5 Lazza]

That's not the handbrake adjusment, that just presets the pads after a pad change and is to do with the calliper auto-adjustment (i.e. adjusting for pad & disc wear).

[NiceCupOfTea]

Just to clarify, I slackened off the handbrake with the adjuster at the lever, enough for there to be play in the cable at at the caliper, but the arm hasn't moved back with it and the brake is still dragging. Not sure what needs adjusting.