| Author | Message | ||
     Bob uk Unregistered guest Posted From: 94.197.122.76 |
Today I went to look at a rolling chassis that has just been built by these hot rod guys. The brakes feel terrible all mushy, which they are trying to sort out. They have extended the brake pedal and disconnected the servo temporarily and the travel is huge and the brakes marginal. So I suggested they check out RR mechanical servo which they liked because of the sort of antilock on the front brakes when the rears lock up. The gearbox is a BW model 66 which does not have a servo cross shaft. So I have been inventing. The servo has a disc bolted between the out put flange and the prop shaft. On the disc is a small caliper that is free to rotate with the disc. The caliper pulls a lever which pushes the master cylinder for the brakes. 2nd idea is to fit each brake rotor with a 4 piston caliper that is split into pairs of pistons. On pair of pistons is fixed the other pair of pistons are free to rotate with the disc. The moving caliper pushes a piston in the fixed caliper which applies hydraulic pressure to the fixed caliper. The fixed caliper has a master cylinder inside. Between the calipers is a strong spring. The calipers working direct from the brake pedal master are small so that the pedal moves little. The weight of the car applies the big calipers. The small calipers have to be large enough to give adequate reverse braking. Both these ideas are a development of the Hispano system. (Message approved by david_gore) | ||
| Bob uk Unregistered guest Posted From: 94.197.122.77 |
Read the instructions. The front calipers on the above chassis are AP General purpose 4 pot racing calipers. They fitted the calipers upside down with the bleed nipple at the bottom. When they in desperation read the instruction a mention of the position of the bleed nipple and the penny dropped. I wish I had been a fly on the wall when the penny clanged from a great height. 5 people including me missed the school boy error. The calipers are handed and they fitted them wrong sides. (Message approved by david_gore) | ||
| Bob uk Unregistered guest Posted From: 94.197.122.72 |
I have realized that the above has a deeper moral than read the instructions. The brakes should have been right when first fitted but they weren't. Instead of looking for the fault we decided that the design was wrong and in a way saying that AP racing don't know what they are doing. I can't help but draw parallels with some of the discussions on this site. (Message approved by david_gore) | ||
| Jan Forrest Grand Master Username: got_one Post Number: 666 Registered: 1-2008 |
I had the same problem with the hydraulic clutch on my Dodge motor home. Some fool had swapped the inlet pipe with the bleed nipple. How he had managed to bleed out all the air is a mystery I'll never solve. Unfortunately the seals were also leaking, so even swapping the connections only gave temporary relief before the air lock returned. | ||
| Bob uk Unregistered guest Posted From: 94.197.122.91 |
I have seen a few clutch slaves fitted upside down because the feed pipe obstructs the nipple. It will bleed with difficulty. Amateur mechanics think bleeding one very simple slave cylinder is difficult so when they get problems they think it's par for the course. I have fitted quite a few slaves and if the master is good a 3 seconds bleed and the job is done if not the master maybe on its way. Clutch slaves tend to respond well to a service kit. I use lots of red rubber grease. If the bore is scruffy polish with emery paper on a wooden dowell in a pistol drill. If the seals are hard to get measure bore and match up with another make. Dodge PB seals are available from Nelson Brovex, camelford, Cornwall. They also will have the flexible hose, which also collapses like SY hoses. It's one of those bits of knowledge that once known is blindly obvious. Normally this mistake is not made on cars that are factory built when mechanics work on them. A much a do about nothing and all's well that ends well. The brakes much to their relief now feel good, at 10 mph that is on a tapley meter. (Message approved by david_gore) |
