[Big D]

Hi all,

The Covid lockdown has slowed things down for me on the M8 but some progress has been made since we moved to Level 2 lockdown.

I fixed the joints around the water pump elbow and thermostat housing where coolant was seeping out. So far, so good, so hopefully that will cure my leaking problems. I refitted the lower engine panels around the engine. I couldn’t find an easy way to fit the panel on the exhaust side without removing the length of exhaust header which is bolted to the manifold. Has anyone else found this? I would have thought the panel would have been made so that it could be removed without disturbing the exhaust header pipe. The fitted panels certainly make the area around the engine bay look nice and neat.

I am not satisfied with the Hydrovac vacuum setup that I have so I will tidy that up a bit more over the next week. I have fitted the repaired voltmeter back into the instrument panel and that is working well.

I resolved my clutch issues by replacing the pressure plate. I’m not really sure how this did it, as the plates looked identical. However, I was did confirm that my original measurements were out by some 12mm so my original diagnosis of the problem wasn’t as bad as I had thought. I fitted the new pressure plate and gradually tightened it, while periodically sliding the transmission into and out of place and ensuring that there was still contact between the release bearing and the pressure plate fingers right through until I had fully tightened the pressure plate. I can only guess that the other pressure plate needed some adjustment. I am happy that it is resolved now though.

Once I was sure I had the clutch physically working I bled the clutch hydraulics using the pressure bleeder. This pressure bleeder does work well. What do you guys do for the bleed screw on the clutch slave cylinder? I have the original military type with the small ¼” ‘dust cap’ screw in the top of the bleed screw. I’ve found that during bleeding using the original bleeder, with the tapered thread, the fluid tends to come up the threads and spill out around the base of the bleeder before it works its way up the centre of the bleeder (with the dust cap off) and into the hose going into a jar.

I actually replaced the bleeder with a modern bleed screw with a bleeder nipple built into the top. It was the same thread (7/16-20) but what I didn’t realise is that the original bleeder has a tapered thread and the new one with the straight thread doesn’t seal properly.

How were these cylinders originally bled? Was it done the same way? Was it just a matter of them being loosened during the bleeding and allowing fluid to come out over the side of the cylinder? Is there a bleeder available with a tapered thread and a proper bleed nipple on the top?

The clutch now does work hydraulically and there is some satisfaction in seeing the slave cylinder operate while pushing the pedal! Thanks to Jonathan for his video of the clutch arm in operation as this showed the correct movement of the arm, and confirmed that I had everything set up correctly. The next time I am in the workshop I will run the engine with the drive-shafts disconnected and see if the clutch allows me to work my way through the gears in the gearbox which will tell me I have the clutch adjusted right. It looks good so far though.

I adjusted all the brakes and they have a good feel to them. However, I now have a problem with the wheel cylinders. The wheel cylinders were all stainless steel sleeved and I used NOS cups on the pistons which looked and felt good before I fitted them. After bleeding though, I noticed that four of the wheels were leaking hydraulic fluid though. I took two wheels off and the fluid appeared to have worked its way past both top and bottom cups on both wheel cylinders on both wheels, creating a small pool of hydraulic fluid at the bottom of the drum. One wheel was considerably worse than the other. I removed both cylinders on both wheels, pulled them apart and couldn’t see anything wrong with the cups or the bores.

My initial thought was that the original cups weren’t as effective with the modern brake fluid (Dot 4) and that perhaps the brake fluid back then had a higher viscosity. My other thought was that it was possible that the sleeves were made slightly too big for the original cups, but this was all done by my brake guy so it seemed unlikely. In the end, I took a wheel cylinder and pistons to a seal manufacturer and they made me a small number of new cups, enough to do two wheels.

When I got them back I found the new cups to be a very tight fit on the pistons and they looked to have a bit more material contacting the bore. I fitted these and bled the brakes, confident that it would solve my leaking problems. However, within a day of bleeding the brakes, the cylinders appear to be leaking again. I now wonder if the guy who fitted the sleeves didn’t seal the sleeve inside the cylinder properly and that the hydraulic fluid is working its way out between the sleeve and the cylinder. I plan to remove the drums again, remove the wheel cylinder caps and get a buddy to press the brake pedal gently to see if I can see where the fluid is coming out. I’m not sure how easy that will be to see but otherwise I figure the best bet is to return a couple of these cylinders to my brake guy so that he can bench test them.

Apart from the wheel cylinder problems, it is a good feeling knowing that all the hydraulics do actually work; throttle, clutch and brakes.

That is all for this week….