RTS - Thrust bearing contacts top hat, preventing wok install
Turbo Mini Forums

I have built an RTS clutch for my 1275 A+

All went well until I tried to put the wok back on and found it is prevented from seating by the thrust/release bearing contacting the top hat. The gap is approximately the same as the second spring I installed. (It may look bigger in the photo as the wok is just held on by one bolt and probably wasn't square at that time)

I have searched this site and am not the only one to have a similar issue, however there hasn't been a definitive answer (well not one I came across) on what to do. The best solution seemed to be to machine material off of the flywheel posts in order to get the spring to sit flatter.

To me this seemed a bit drastic.

I followed the RTS guide to the letter and re-read it many times after I encountered my problem to make sure I didn't make a blatant error. Obviously I have, but I cannot identify it.

I am thinking that removing a small amount from the pedestals that I had made by an engineer, (they all measured the same height and correct to what the guide said - "existing height plus the thickness of the new spring") might be the way to go. As the pedestals are approximately halfway towards the centre I assume any removed height will be doubled at the fingers. At first I thought this would affect clamping pressure but further thought brought me to the conclusion it would only affect the pedal travel or bite point, not clamping force or pedal effort. (Think of a lever and fulcrum - changing the height of the fulcrum does NOT affect the forces required like changing the lever length would).

Of course I could be completely wrong on this, most probably actually :(

Sorry for the long winded post, but if anyone could help me understand what is going wrong, why, and how to remedy the problem, I would be most grateful.

They said "Smile - things could be worse!"
So I smiled, and sure enough, things got worse.

I'm sure removing material off the pedistals should move the top hat towards the engine, ( trying to visulize it in my head..)

what thrust bearing have you got in there?

I encountered the same issue with my install when initially using an uprated and a turbo spring.

I disassembled the unit more times than I care to count trying to find the issue.

Another member kindly dismantled his wife's car wife's car to establish a few datum measurements for me as I had no stock clutch assembly to use to establish any bench marks.

I ended up biting the bullet and machining the posts in small increments and measuring the effects while swapping the new friction plate with a very worn one and noting the change in position at each stage of the top hat which moves with friction plate wear.

Before going past the point of no return with the machining I purchased a used 998 cover to dismantle and check for difference and reassembled my unit with the 998 spring in leiu of the turbo spring (new spacers made accordingly) with the same results.

I conceded and proceeded to machine more material off the posts until I could install the unit with both new and used friction plates without any interference with the release bearing and top hat.

The amount machined off did seem quite significant compared to anything I could find mentioned on here.
After a call to MED they did tell me there are two variations of their flywheel which I used with a difference in the height of the posts which I could argue as the difference in what I'd found in measurement discrepancy.
I'd have to find my build notes to clarify both amounts machined off the posts and the measurement differences given to me by MED.

The last thing I did with the complete assembly was to set it up on the hydraulic press and measure the release pressure compared to the values I'd found here.

The only thing I'd say is my spring assembly does appear to sit quite flat in comparison to some I've seen, at the time I did find mention/conversation of the cause/effect of the spring being flatter but for the life of me I cannot recall in which thread.

Ive not put massive power through mine yet (tops 150HP) but so far the results have been reassuring.

There are a couple of members on here that have built multiple units and may be able to offer more sound advice.

Shane

Edited by Splod on 24th Feb, 2021.

They said "Smile - things could be worse!"
So I smiled, and sure enough, things got worse.

If you dismantle the clutch and reassemble with a layer of shim stock (brass shim sheet) around the circumference of the flywheel friction face (effectively reducing the distance from flywheel friction face to top of the flywheel posts) you can use this to roughly gauge the amount required machining off the posts.
Add increasing layers until the top hat sits where you want it (allowing clearance to accommodate wear)
It's a repetitive task of trial and error but will save machining the posts too far.

Shane

They said "Smile - things could be worse!"
So I smiled, and sure enough, things got worse.

If tasked with doing this again I'd go with testing with shim stock prior to machining, no risk of going past the point of no return.

Shane

They said "Smile - things could be worse!"
So I smiled, and sure enough, things got worse.