I was having problems getting the rear brakes even on my Starlet, and having a few spare parts on hand, tried a different drum on one side, then woke up to the fact that it was from a car without ABS, so lacked the sensor ring, and of course the ABS light stayed on. Switched it back, but how do I now clear the fault so that the ABS light goes out?
franc123,
May 18, 11:22am
Just drive it for a while, stop and switch it off, restart it and repeat a few times. If it eventually stays off then fine, if its not you could try disconnecting the battery.
rpvr,
May 18, 1:37pm
Thanks, I've left the battery disconnected overnight so we'll see what happens in the morning.
intrade,
May 18, 2:31pm
old cars battery disconnect . snap #2 otherwise a launch scantool with obd1
rpvr,
May 19, 4:02am
I was surprised that even after leaving the battery disconnected overnight, the problem remained. However I found the solution on the net, insert a jumper wire between two of the terminals in the diagnostic socket, turn on the ignition and press the brake pedal a number of times, switch off ignition and remove the jumper. ABS light now behaving normally. Whew!
intrade,
May 19, 6:33am
Yea just make sure to not jumper wrong pins .
rpvr,
May 19, 7:31am
So back to my original issue. I had failed the wof because the rear brakes had a 22% imbalance. After fiddling around with adjustment imbalance was down to 19%, so passed the wof. I believe up to 20% is ok? But I would like to know why that amount of imbalance still remains, when it all looks clean inside and the linings are in good condition. Would having the drums skimmed help?
franc123,
May 19, 7:37am
Yes 20% is the limit. If you have the checksheet handy can you post all the figures on it including those for park brake for me to look at?
kazbanz,
May 19, 8:01am
Go back one stage--is it 19% just on the pedal or is it 19% both pedal and park brake? Did you try swapping drums side to side? My first thought was a tiny weep in the cylinder to bottom part of shoes second was proportioning valve
rpvr,
May 19, 8:01am
VTNZ check sheet, and they have not entered any figures for the park brake. I wonder why not? Anyway the figures shown at the first check were front L 240 R 210 imbalance 5%, rear L 80 R 100 imbalance 22%. Then at recheck front were the same, rear L 80 R 90 imbalance 19%. This was after I had taken both drums off, cleaned out all dust etc, and fiddled with the adjustment so there was just slight resistance from the shoes when pushing the drums on.
franc123,
May 19, 8:08am
Ok the park brake imbalance is in itself not a fail but is normally recorded, its useful to know so a possible lazy wheel cylinder can be eliminated. Swapping the drums side to side would have been the first thing to try. You are probably going to find the imbalance will come back if left as is.
rpvr,
May 19, 8:08am
AS I mentioned above, VTNZ didn't show any park brake figures. Looked back on some of my old check sheets and it seems they were doing so up to 2019, stopped doing it in 2020.
rpvr,
May 19, 8:14am
Thanks, I'll keep it in mind. It's the left side that's consistently low so it may be worth changing the cylinder at some stage before the next wof, they're cheap enough.
kazbanz,
May 19, 8:49am
Wot he said. ^^^^^
redhead18,
May 19, 9:10am
General rule of the experienced thumb being. If it is down on the Left rear on pressure(foot pedal application) twill be a proportioning valve probleemo. Sometimes a fluid flush can rectify or replace prop valve. K
intrade,
May 19, 10:46am
You want to measure your drums internal diameter it will be at the limit on one drum and paired with cheap material thin brake shoes one would move past the travel the brake cylinder can do and have not enough braked force. New drums are like 60 bux . we fitted some to the corolla i swapped for my astra to solve imbalance problem. Autostop Takanini
rpvr,
May 19, 11:09am
Excuse my ignorance, but is the proportioning valve the device on the firewall that the brake lines go to?
rpvr,
May 19, 11:10am
Thanks, will look into the availabliity of brake drums.
tygertung,
May 19, 11:35am
Drums can be a real nightmare on older cars getting good balance. Sometimes it pays to get a WOF at a smaller garage which doesn't have a brake machine where they just do a road test.
aprilguy,
May 19, 1:27pm
My corolla had an imbalance in the rear brakes a while back - the left side was weak. The cause was the wheel cylinder and after replacing it the balance went back to just a few per cent difference side to side. I would replace your cylinder first to rule it out. A new cylinder is cheaper than drums.
intrade,
May 19, 1:31pm
Yea a leak of the cylinder caused by A to large of a drum with little pad material.
redhead18,
Aug 6, 8:43am
Yes that is where they become diagonal split where the left front and right rear are on the same circuit. And the right front and left rear and often a simple bleed will clear the crud causing low pressure to the left rear
Edit to add if there were handbrake readings and they were even then it simply points directly to a prop valve as low left rear.[Handy to see the machine readings. ]
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