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I am expecting my replacement FTE KG19070 1.6 clutch master cylinder this week (along with the part rigid, part flexi hose between master and slave). Part supply seems soooo much better in US than UK for 928!
I have seen in the many wonderful posts here, some suggestions to check the size of the piston and to re-use the older spring when replacing an older MC with newer one.
I must admit to being a bit confused about whether this step relates just to 78/79 cars and what to think about when replacing my old *** clutch MC with the new FTE one.
Should I still be disassembling the new unit and comparing piston length etc?
Looking forward to the bleeding adventures thereafter but don't want to get this early step wrong !
Please get the old MC and the new MC take them apart and post pictures,
of the pistons and springs and the body length of the MC
after that I will tell what to do.
I have modded 4 of them in the last 3 months
This only reinforces why I will never buy a new clutch master or slave ever again for a 928, as long as places like White Post Restorations exists and continue to provide a superior product. If a "new" part must be modified to work properly, it's not the correct part.
So you'll receive these measurements & advise what to do with this particular clutch master. Many people will read this thread & assume such measurements are good to go going forward. The problem is, in the world of non-original car parts (especially for vintage cars) these tolerances can change without any warning or notice. Tolerances for such parts are nowhere near the quality and consistency of when they were new 40 years ago.
Disassembly, glass-bead cleaning, boring oversize, installation of a brass sleeve and sizing of your brake parts back to original specifications. Many rebuilders do not offer sleeving as part of their service. The longevity is significantly reduced for components that can be sleeved but are not.
Replacement of all seals, gaskets, diaphragms, etc.
Application of proper exterior finish:
Most cylinders, calipers, & valves: Cast iron gray epoxy or satin black (upon request)
Booster finish restored to O.E. specifications: Satin black, silver/clear zinc, or yellow cadmium
ALL units are hydraulic or vacuum tested for leaks and to insure proper operation and performance
Eric the thing is you could be sending off a part that was already swapped out and is not in conformance with the original;
thus the rebuilder will make it to the same spec that you give them.
In this case in this 928 arena we know what the differences are between the originals and the later versions .that were changed for some reason.
It takes about 20 mins to make the mod and put the MC back together.
NOTE Im not the only one suggesting to mod your MC nor making this modification, this info has been out for many years
I know that you have the skills to do this as well, you already own a few 928s so you learn to make things work.
I do agree that having a outfit that can rebuild parts that are not easy to get new is a great option,.
its really a great option for a DIY guy as waiting for a month to get a part sent off , rebuilt, and the returned,
is not really a feasible idea when the customer wants his car in two weeks.
NOTE new parts are reasonably priced and can be had in two days or less,
the modding takes 20 mins or less once you do two of them.
Well, my FTE parts are now in the UK at least, so I'll be able to take the two MCs apart and compare very shortly.
Meanwhile, the cleaned up fan resistor pack is back in the car and the new fuel lines are ordered. Sticky driver's window regulator might get a look in if the MC doesn't arrive tomorrow.
Eric the thing is you could be sending off a part that was already swapped out and is not in conformance with the original;
thus the rebuilder will make it to the same spec that you give them.
In this case in this 928 arena we know what the differences are between the originals and the later versions .that were changed for some reason.
It takes about 20 mins to make the mod and put the MC back together.
NOTE Im not the only one suggesting to mod your MC nor making this modification, this info has been out for many years
I know that you have the skills to do this as well, you already own a few 928s so you learn to make things work.
I do agree that having a outfit that can rebuild parts that are not easy to get new is a great option,.
its really a great option for a DIY guy as waiting for a month to get a part sent off , rebuilt, and the returned,
is not really a feasible idea when the customer wants his car in two weeks.
NOTE new parts are reasonably priced and can be had in two days or less,
the modding takes 20 mins or less once you do two of them.
1) Stan - I am about to embark changing out the clutch master on my 84. I was doing a full swap using the fish line method. Are you saying that I need to take both of these apart before doing this?
2) With Brake master cylinders now pushing $450, rebuilding one may be worth the wait. Thanks Eric for the link to this company.
It would be a good idea to open up the clutch master cylinders to measure the piston length,
the new version is 80 MM long the old one is 75mm long.
You should remove about 4.5MM from the tip of the new part after verifying its length. then put a slot in it so fluid can get by.
Also the spring needs to be cut down 2 coils then rebent so it sits flat
NOTE cut down the big end of the spring.
NOTE if you have time to wait for a rebuild then you could send off your MC and have it rebuilt.
please take before and after pictures so others can see the work, thanks
Just as a data point, the clutch master in my car (that came from a manual trans donor car) was marked as ***. No clue if it was ever rebuilt before. I didn't measure the new vs old piston, but both looked to be the newer style with the extra appendage on the end, so I didn't modify (also didn't clamp off the blue hose well enough and had to work fast because fluid started leaking out of the master, fortunately had a rag under it). My double disc clutch was tricky to bleed initially (with the old master), but otherwise functions fine, no dragging.
It would be a good idea to open up the clutch master cylinders to measure the piston length,
the new version is 80 MM long the old one is 75mm long. You should remove about 4.5MM from the tip of the new part after verifying its length. then put a slot in it so fluid can get by.
Also the spring needs to be cut down 2 coils then rebent so it sits flat
NOTE cut down the big end of the spring. .
Ok. This just got interesting. Ever since I've owned the car, I have never been impressed with clutch response. Installed a new slave. Upgraded to greg brown's hose that runs over the starter. Still no significant improvement. It also would start to sag if it sat and/or has a tendency to squeek. All things pointed to clutch master at this point. However, since I pretty much was dropping all available time in the prussian blue 85 euro, this took a back seat. I ordered a CMC a long time ago, so I finally pulled it out and removed the guts. I also removed the guts in the car of the existing one. Here are the results:
Top one is the new one. Notice the body changes are different. old spring length New spring length FTE CMC I just opened model number model number
I have no idea when the last CMC was put in, but I'm guessing it's newer since the seals didn't look bad....
This has me wondering though. Sure you'd get a bit more stroke on the pedal, but in the case if your bite point is sufficiently above the bottom out point, wouldn't this have a similar effect to using a clutch stop, albeit not an adjustable one, to limit travel to what is needed? My old *** one measures 80.4mm as well. Pretty sure the new FTE one was the same. Has me wondering if it's worth taking the new one out again to shorten it.
06-14-2020, 06:19 PM
FTE CMC replacing ***
