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britishcarfreak
10-25-2003, 04:59 AM
My right rear brake on my 2500 saloon has been giving me the ****s.

Recently it would be smoking when I stopped and the wheel was too hot to touch. I was getting some wierd handling over bumpy roads and tail wiggles and strange lunges sideways when braking at high speed. (one such braking experience was a sudden jump on the brakes just after an overtaking manouver at 120kmp/hour - the tail started to come around to try and meet the front of the car - so I lifted off the brakes and gently steered back into the direction of travel).

As you can imagine this was alarming.

I was also getting spinning of the rear left wheel and some strange rear wheel steering when taking off. This was terrible in wet weather.

After a smoking brake issue I once stopped the car and jacked up the wheel and it turned freely. I assumed that it was a freak occurence but have since decided that raising the wheel would have slackened the hand brake cable to that wheel.

I found that the right handbrake cable was tight and the left was loose (when hand brake off). I checked the self centering bit in the middle of the cable and sure enough it was biased to the right. After adjustments and loosening of the cables I have not yet had another smoking brake or burning hot wheel - HOWEVER - the right rear wheel is still warm to the touch after a drive but the rear left is cold or luke warm.

Could the lining on one brake shoe have come loose?

There is no fluid loss from any of the bleed nipples.

Do people on the list also have warm rear wheels after a drive?

Bugeye58
10-25-2003, 02:30 PM
Glen, pull both rear drums and check to see if you have perhaps lost a return spring on the right side. A lost or weakened spring could cause the right brake shoes to maintain a slight contact with the drum, and warming it up. If everything looks ok, I would just readjust both sides properly, and go for a test drive.
When I get back after a spirited drive, ALL my brakes are warm!
Jeff

britishcarfreak
10-27-2003, 10:08 PM
Yes I will pull the drum on the weekend and see what's in there.

I don't reckon there will be much pad left on the shoe - best be wearing a dust mask when that drum comes off.

britishcarfreak
11-03-2003, 02:16 AM
I pulled the drum on sat. Nothing wrong in there. Not that I could see.

Return springs fine and tight - handbrake cable was slacking off.

Took it out for a run and ended up with a wheel so hot that the 490deg C paint on the drum started to discolour.

I let it cool down and took the drum off and loosened the self adjuster all the way back.

Drove it again and ended up with another burning wheel.

The only theory left was that the wheel cylinder was sticking and not letting the shoes come back off the drum. I was on a club run yesterday and there were a few mechanics on the run - it had them baffeled.

In the end we had to cut the brake line to the rear and drive it home with only the fronts working.

Next weekend I'm going to have to do a full rebuild of the rear brakes with new shoes - machined drums - new wheel cylinders and replacement backing plate.

Either the backing plate is warped - the wheel cylinder sticking - or some alien activity.

Regardless - I will not have this happen again.

KLUTZ
11-03-2003, 03:21 AM
Glen.... Are they the correct shoes for your car? Was sold the wrong set for my 7 with the same result.
Just a thought.

Paul

Mark Beiser
11-03-2003, 04:12 AM
Both of the TR7s I have owned had some really wild things going on with the rear end on acelleration after braking. Both of them turned out to have wheel cylinders that would randomly lock up temporarily.

I have had wheel cylinders lock up on other cars, but never with quite the same handling phenomena as when its happened on my TR7s, lol.

[ 11-03-2003: Message edited by: Mark Beiser ]</p>

britishcarfreak
11-03-2003, 07:24 PM
Well quite a few mechanics assumed that someone had recently worked on the brakes and put the wrong part somewhere or some piece back to front.

Thing is - nobody's touched the brakes for about 2 years.

I know that when I had a new exhaust fitted it was fouling the cable slightly on that side so maybe the cable was causing the dragging brakes or confusing the self adjuster. Maybe after getting hot so much from the cable being tight - it may have damaged the wheel cylinder and caused it to stick.

Bob Claffie
11-06-2003, 01:58 AM
Since this is an old crock, their is a remote possibility that the flexible hose running to that wheel is collapsing on the inside. Foot power on brake will force the fluid through but the return springs are not strong enough to push it back. Very similar to MGB and Spitfire flexible clutch hoses which I have had happen to me on two different cars. Bob

britishcarfreak
11-07-2003, 01:45 AM
Good suggestion - BUT - the brake lines on 2500's are solid all the way. Metal pipe stuff.

I pulled the wheel cylinders last night off both drum brakes. The right one (the bad one) was knackered - I couldn't move either piston in the cylinder - not even with multigrips on them. The cylinder from the left (supposedly O.K.) only had one piston moving. It moved very freely indeed and it worked like a water pistol squirting out the remaining brake fluid.

I had a quote today to bore and sleeve both cylinders with stainless steel. The quote was $100Australian per cylinder. I couldn't believe it.

Anyway - it seems that they are definitely the cause of the poor braking and the locking wheel.

piman
11-07-2003, 03:55 AM
Hello Glen,
a slight correction, your car has two flexible brake hoses, one on each swinging arm, which then picks up the solid lines into the drums.
However your duff cylinder looks to be the culprit. I would check your flexes nevertheless.

Alec. graemlins/thirsty.gif

britishcarfreak
11-09-2003, 06:46 PM
Yes you were right - I forgot about the 7 inches or so of hose near the trailing link/body connection.

Anyway - I pulled both cylinders and only 1 out of the 4 pistons was moving - the rest were rusted up on the outer surfaces (the bits past the rubber seal) so they couldn't retract back into the cylinder but could take some push from the fluid in the lines. Hence the sticking brakes and lack of any real braking power at the rear.

I stripped and reassembled the whole lot on both sides and now have a car that brakes better than any other time I've driven it since purchase.

I recommend that anyone with hard feeling brake pedal and not much braking ability go and rebuild their brake wheel cylinders.

What a difference!