DB4 Slave Cylinder installation

[Rick Ross]

I have a question concerning DB4 slave cylinder clearances. I recently obtained a new Saab 9000 based annular slave cylinder assembly with a Tilton piston and a 38 mm release bearing. I am using the stock Swift spacer to mount the cylinder to the oil tank. I have a Tilton OTIII 5.5" metallic twin disc clutch. The discs have some wear and are currently about 0.103" thick (each). Pressure plate and floater have been checked and are in good condition.

The problem I have is that with these particular components there is absolutely no free-play between the release bearing and the diaphragm fingers. In fact, the bearing actually contacts the fingers and depresses them slightly if the oil tank is bolted to the engine. I need to reduce the overall "height" of these components by approximately 0.170".

I am trying to determine the best way to acheive the proper free-play between the bearing contact surface and the diaphragm fingers. I can think of a few options:

- Replace the slave cylinder piston and/or bearing with shorter components
- Machine the Swift spacer to reduce its thickness (moving the entire slave cylinder aft)
- Find alternate clutch components which have a reduced stack height.
- Obtain a completely different slave cylinder assembly.

I know that there is a lot of DB4 experience among Apexspeed members. Any comments would be appreciated. Thanks!

[Paul LeCain]

As I recall, we shortened the center (non-moving) section of the Saab slave cylinder. Also, as I recall, the problem is that the Tilton outer cylinder (the moving part) with the 38mm bearing hits the center section piece on the inside diameter.

Finally, the clutch fingers are going to move backwards (towards the slave) as the clutch wears, so you have to provide extra room for that when you measure it.

[Rick Ross]

Thanks, Paul. I'm pretty sure that the center section has already been shortened, but I will confirm. I will also check to see if there is interference between the moving piston and the center section.

At this point I suspect that the black anodized Swift spacer will need to be machined to allow the slave cylinder to be located farther aft away from the clutch. I plan to provide a gap between the diaphragm fingers and the bearing to allow for clutch wear.