CR3171 Finally going back together!

[Aussie Mike]

With the clutch bolted up it was time to check the clutch clearance. This was something I hadn't really understood when I first assembled the clutch and gearbox. I took for granted that the guys from SPEC who sold me the clutch would have the clearance pre-set.

So what I've found since messing with these a gearboxes is that there is often insufficient clearance between the slave cylinder when fully compressed and the fingers of the clutch. When the clutch wears the fingers steadily move further away from the flywheel face. This brings them closer to the release bearing/slave cylinder. If the release bearing can't go back any further the result is the pressure plate being slightly disengaged and the clutch starting to slip.

We don't think about it with a conventional clutch fork as there is usually plenty of external adjustment and travel. The Hydraulic throw-out bearing has no adjustment so needs adequate clearance set before assembling the whole thing.

To check you need to put a straight edge across the bellhousing and measure the distance to the fingers. in this case it's 53.57mm



Next we check the throwout bearing. Remove the spring and fully compress the hydraulic throwout. Measure from the bearing face to the front of the gearbox (where it bolts to the bellhousing). In this case it's 54.34mm



Subtract the available space between bellhousing and clutch fingers from the space used between gearbox face and throwout 53.57mm - 54.34mm = -0.77mm. That means my setup is running with the pressure plate fingers compressed by 0.77mm before I've even pressed the clutch pedal.

To rectify this I'll have to machine about 6mm off the mounting face where the slave cylinder meets the front of the gearbox. Fortunately I've made a fixture to make this an easy job on the milling machine.

If I'd put it back together as it was it wouldnt have been long before the clutch was slipping and stuffed.



Cheers

[Aussie Mike]

The gearbox is in a million bits while I freshen up the internals. My own box was the first one I built and I'd done a fair bit of development since then. It was time to roll that back into the original one.



A mod I've been doing to a lot of the T56 boxes is changing out the pressed steel synchronizer keys for much stronger billet steel ones. When I first built mine aftermarket retaining springs weren't available for them and I had to use the originals. The spring has a hook on the end of it that's designed to engage in the hollow back of one of the pressed steel keys. This stops it rotating and potentially popping one of the keys loose. The issue with that is there is no hollow in the back of the billet keys, they are solid. The spring hooks over the side of the key instead and there is a chance the spring could rotate and one of the keys pop loose. I set them up so the rotation of the gear would keep the hook snug against the side of the key but it still worried me. The aftermarket springs have hooks on both ends so they can't pop loose (Green one on the right).



Another upgrade I figured I'd do is to change the stock plastic pads on the selector forks for some bronze ones. The plastic ones can distort under hard shifting. I had one older gearbox come in where the 1-2 and 3-4 pads were stuffed and I replace them all. The bronze ones should be a lot tougher and provide a more positive shift feel.



A fun job I finished off today was the engine cross member. A few hours on the mill and I whittled away a lot of material out of it. I removed a lot of weight and improved the aesthetic while keeping it's strength.



Looks pretty cool bolted in place.



Cheers

[1 TUF AC]

I love watching this work of art getting put together. It will be one hell of a car when it's finished. I would love to see it when it's finished and this car only lives 15 min away from me. keep up the good work.