I have mentioned Nick’s Vitesse before, when I fixed an issue he had with his ECU. Show day is coming, and it’s a rush to get his car ready. Today we checked off another WOF issue; the hand brake.
Nick has a list of things that he needs to fix on the car before it goes for a WOF check. On that list was to adjust the hand brake as it engages at the top of the lever travel.
Having replaced the hand brake cable on Effie recently I had a good understanding of how to adjust the setup, so thought to myself “oh that’ll be a quick one to knock off the list”. Well, it took most of the afternoon.
We got the car in the air and I started by removing the cable connections from the levers on the back of the rear brakes, and then backed off the adjuster nut at the hand brake under the car with a 17mm spanner.
Next I adjusted the LH end of the cable to have tension when the compensator was at 30 degrees, with the cable attached to the lever on the brake. I then attached the other side, and tightened the adjuster under the car. This left me with a hand brake lever that still went up too many clicks, but at least now the brakes locked…. But we soon noticed that the LH side didn’t release. It was jammed on. Pushing the lever on the back of the brake by hand would free the wheel off, but this wasn’t good.
Nick had just recently been in here to replace the seized wheel cylinders on each, so we knew the shoes were OK and that everything should be assembled correctly. We also removed the wheel and drum from the RH side so we could compare as that side worked correctly.
The SD1 drum brakes are actually quite simple really. Two shoes, held in tension by a pair of springs, one on each end attached to both shoes. One end of each shoe is engaged into a slot in the wheel cylinder (on the left in above photo) and the other end of the shoes pivot in a small bracket mounted on the backing plate. When the brake pedal is pushed, brake fluid expands the wheel cylinder, pushing the shoes outwards against the drum, causing friction and thus, braking. The springs pull the shoes back away from the drum when the pedal is released so they don’t drag or bind.
In the photo above you can also see the auto adjuster that takes up the slack of the shoes and allows you to remove the drum if a lip has worn into it. To the left of the orange spring is an oval hole. This hole lines up with another hole in the back of the backing plate, so when you stick a screwdriver into that backing plate hole (from behind the brake) it also goes through that oval hole. You push down on the oval hole (up on the end of the screwdriver), and this will release the ratcheting effect of the auto tensioner and the springs will pull the shoes inwards, towards the center. This tensioner means that the shoes are always held out, close to the drum. If they weren’t, the pedal travel to move the shoes far enough would be huge or the brakes just wouldn’t be effective.
In the photo above you can see the end of the hand brake lever to the right of the orange spring, going through the shoe. This lever pivots on another piece (where the spring above the orange spring is in the photo) when the cable is pulled. This pushes the lower shoe downwards, and against the drum. It’s a simple setup really, not as daunting as I originally thought (or as others had made it sound).
What was happening in this instance was that the lever wasn’t pivoting freely, so when the cable pulled the lever on the back plate, the shoe would be pushed down but the spring couldn’t overcome the resistance of the pivot, and couldn’t return.
To fix this we stripped both shoes out (including removing the hand brake lever spring, from the top of the mount) and using lots of brake clean and WD40 the pivot was cleaned and operated over and over again until it moved freely. Initially it took heaps of force to move the lever, now it almost hangs freely on the pivot.
This is how free it should move when assembled
Before reassembly we thoroughly cleaned all traces of WD40, and then applied a small amount of copper grease to the pivot in the hopes that it will keep it operating freely. Too much grease or lubricant in here is a risk of getting on the shoes and ruining both the shoes and the braking power.
Everything was reassembled, the engine was run so the auto adjuster could do its thing when the brake pedal is pressed, the cable was adjusted again, and then tested. Now it has a maximum of four clicks to lock the wheels, and both wheels free off correctly with no dragging.
All in all it was a great learning experience, It took longer than expected but at least we now know it works and should continue to work correctly. This also gives me more confidence in working on my own rear brakes.
It was so good in fact, that we took the car for a quick spin up the (closed) road for some testing. This is the first time in a couple of years the car has left the shed and been driven. It’s had a lot of work done on it recently, and I must say it feels good. Nick was even so kind as to let me have a drive, and considering the 237,000Miles (381,000KM!) on the clock, it runs and drives really well; I’m impressed. Credit to it’s current, and previous owner. There is still more work to be done before the show, but Nick is cracking on, so hopefully we can get it there.