We had hoped to do the Classic & Sportscar Meeting last weekend, but ran into some nasty clutch issues. Both cars had the same disease when we took them out of the shop for a test drive. As soon as the engine was started, the clutch pedal went limp.

I think we more or less exhausted the internet and overseas gurus trying to find the cause, and nobody came up with a proper solution. First, we found that there are several types of clutch forks. We had at least 4 variants…and there’s only one that should be used. Secondly, we’ve pulled the engine on both cars so many times now, I’m sure we’d win an Imp engine swap World Championship easily! Everything that could possibly cause the problem was changed, and UPS had a field week posting overnight stuff to us. We changed slave pumps, master cylinders, bearings, slave cylinder pushrods, made adjustable pushrods, etc ad infineum. To no avail. The pedal would feel ok, and it would all release when pushing the car about in the garage.

Doc looking at the engine of his racing Imp

Due to an apartment located on the floor above our shop, we’re not allowed to fire up the cars indoors, so, naively we thought everything was ok. So we had quite a logistics project each time we had to move the cars outdoors for a test: moving several other cars, parts, winching them back up the hill to the door and so on.

Finally, after weeks of this, we talked to our gearbox guru Dave Weedon, and he had a few tips that helped with regards to modifying the fork. We run AP sinter clutches on both cars, and have done so for many years without problems. So we put our heads together, chopped down some trees to get a peek at the forest, and found that the only difference to last years’ setup was that we’ve changed the engine blocks from B1 to old straight-edge Imp blocks (#¤”%#¤!!! HTP). And therein lies the answer.
On a B1 block, the clutch sits quite a bit closer to the gearbox – so much in fact, that it is necessary to use special bolts on the flywheel so it won’t foul the box casing. A sinter clutch is much lower than a standard item. Out problem has been that the release bearing and fork sit too far away from the clutch, so when the engine fires up, the vibrations will make the release bearing operate at a bad angle, hence not proper operation.
With Dave Weedon’s tricks of adding a Mini-style adjustment/stop bolt to the fork, and a spring to hold the bearing straight, then setting everything up nice and tight, we’ve nailed it. So last sunday, we had the pleasure of doing some dirt-tracking around the shop.

It would be nice to give the engines a mild start with a proper rolling road test/setup plus a shakedown test, and with only one race remaining this year (and Doc out travelling the weekend before) we probably won’t fork out (ha ha) the dosh for licenses etc just to do a test race, but rather aim for a track day and some time at the rollers. Then NEXT year (again!?) we’ll be ready from the outset. We think, pray and hope!

The short run in the Imp certainly helped me gain some motivation back – it’s been all to long doing carpenter’s chores in our house rather than fiddling with racecars. This will actually be the first year since 2004 I haven’t entered a single (car) race. Uuurgh!