When I originally built the engine I sourced a new clutch and Flywheel. I was told that it would be good for 300 BHP as I explained that the engine I was building would be that sort of power. Unfortunately this turned out not to be the case.
I suspected that it was not quite up to it, as I got the impression that it was starting to slip at the higher rev range, but put this down to possibly my over cautious clutch use and the fact that the clutch seemed to operate at the very top of the pedal. Therefore my foot hovering on the pedal could have been enough to slightly disengage it.
However I was able to prove that the clutch was at fault by driving up a steep section of motorway in high gear and then flooring the throttle. Without touching the clutch pedal it was clear that the engine started to race showing clutch slip.
After doing some research I found that there are essentially two companies that supply up-rated clutches for the Rover V8 for modified vehicles etc. these being AP Racing and Helix Autosport. There was not much in it as far as cost was concerned but availability meant that it take approx 6 weeks to get a Helix unit whereas AP Stockist TechCraft had stock. So I decided to get the AP Racing version.
There are actually a few ways of getting a clutch that will handle the power, unfortunately as the flywheel is of the 4 wheel drive variety, i.e. 10.5" Dia rather than the more common 9.5" Dia there is only really one option for this, being the up-rated cover plate as used in the Lamborghini V12. The only down sides to using this are the COST and the fact that the pedal pressure required to operate the clutch increases significantly. Another way is to replace the Flywheel with that from a 2 wheel drive vehicle that will accept the 9.5" cover plate. I decided to leave the flywheel in place and use the 10.5".
AP Racing part Numbers:
|Lamborghini V12 cover plate||CP2789-5|
|32 spline Driven plate||CP2790-5|
I decided to change the clutch over the bank holiday weekend as there would be plenty of time. So after dropping into the main dealer in Southampton and picking up a few bits that I might need, such as Rear crankshaft oil seal (Just in case) and a new Clutch release bearing I set about getting everything ready. So on Saturday morning my mate Guy came round to give a hand with the heavy and large bits. As the gearbox cross member is not removable the body work had to come off. Just after I had carpeted and put the new seats in!!!
After wasting time trying to find a hand winch or similar to enable me to remove the gearbox I gave up and decided to use what I had laying around. This ended up being a metpost, two tie down straps and a piece of rope. One benefit of having a Rollcage over the motor is that you have a ready made frame from which you can hang/support things from.
Here you can see the the way the gearbox was slung from the roll cage via the metpost and tie down straps. The last photo shows Guy lying around on the job. It was a lot easier than I thought it would be as once we had disengaged the gearbox from the engine, it was moved backwards far enough to be able to pull the bell housing end to one side and up over the chassis rail to give enough room to get to the clutch.
The old one came off and the new one on. Then with a little bit of wiggling and adjusting heights up and down and up again then turning the propshaft a little to get the splines to line up then on went the gearbox. After bolting the bellhousing back and putting the slave cylinder back in position, a quick test of the clutch to make sure it was working correctly proved that all was well. I also found that the clutch pedal was not as hard as I had been warned. In fact it felt no heavier than the clutch on the old LT77 Box that used to be there.
Anyway the body was all back on again by about 6.30 and then the rest of the little bits and pieces where all back together and tightened up by 7.30. I was taking it for a spin by 8 to try it out. It is much better, the clutch now seems to operate nearer the middle to bottom of the pedal without adjusting anything. It is also definitely not slipping now. It may just be my imagination but it actually feels faster now. Maybe it was slipping slightly whenever accelerating hard.
First thing Sunday drove to the Classic Car show at Breamore. :-)