Spitfire Rear passenger brake drum smoking - Mk1 Spitfire

[JBann]

Hello everyone,

I was out for a 'spirited' drive this evening with my spitfire. I wanted to test braking limits and hard braking at speed. And my they surprised me! They'll lock up the tires and bring you down from speed quickly! Towards the end I did one very HARD stop from 50-55mph (sadly leaving some skid marks in the process). Again, I was impressed.

Thereafter I cruise back home satisfied. I pull into the driveway and stop the car. I notice my rear passenger brake smoking white and quite profusely (mind you I had a very easy 4mile drive back home after the last heaving braking). Both rear hubcaps were very hot(felt equal) to the touch, but it was only the passenger side drum smoking. I first check to see if I can see brake fluid leaking anywhere and I check the fluid res. No visible leaks and no fluid missing from the reservoir. Then I thought perhaps the shoe was sticking and it was smoking because of friction. However, there was no pull or hesitation when moving the car. Then I stuck it in neutral and pushed it back and forth to see if there was anything clamping or sticking. But I felt nothing. After 5-10min there was no more smoke coming from the drum.

I am kind of lost as to what happened and I thought someone would be able to enlighten me. I have not yet taken off the wheel and cover to see how the drum looks inside. Hopefully it is nothing serious. I have never seen this before when driving and braking normally or even more spiritedly. As I said however I was super hard on the brakes to see what they could do.

Anyway, Thanks ahead of time

Jan

 

[tdskip]

Once it stopped smoking was your braking effectiveness uneffected? Pads new or drum very recently resurfaced?

 

[Andrew Mace]

Jan, it's difficult to speculate as to whether anything at all is "wrong" with that side, as it did roll freely. It could just be coincidence that the one very hard stop (presumably on top of several others, from what you said) was enough to really heat up that one side, possibly because it's adjusted a bit tighter than the other side? BTW, what did the smoke smell like? The smell of very hot brake linings is pretty distinctive!

I would definitely pull both drums, though, and take a good look at everything. There might have been a bit of grease or brake fluid on the one lining to cause the smoke. If there's any evidence of that, the cause needs to be found and fixed, of course! While you're in there, you might want to check to be sure that the wheel cylinders are free to slide back and forth; it is that action that optimizes rear brake performance on these, much like a single-piston sliding disc caliper as found on most modern cars. (Other cars with rear drum brakes, such as the TR7, have "double" wheel cylinders, with one piston acting on each shoe.) If they don't slide, they need to be removed, the area cleaned up, and then reassemble with just a bit of white lithium grease where the cylinder contacts the backing plate and where the tips of the shoes contact the wheel cylinder or the adjuster.

If all's well, center up the shoes, put the drums back on, recenter the shoes with the handbrake, adjust (and repeat if necessary), and you should be good to go.

 

[billspit]

Andrew gives good advice.

It could be leaking brake fluid. You won't know until you go in.

I helps to know if you have already performed any repairs or maintenance. One thing to consider is how old the brake lines are. Sometimes they age, the interior swells and blocks fluid. Thus, once you apply the brakes, the hose tends to keep the pressure on and the brake overheats.

 

[tomgt6]

Doesn't dot3 expend when hot so you may not see that you lost any fluid? But most likely what Andy said.