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Clutch / Flywheel Questions
https://ausmini.com/forums/viewtopic.php?f=2&t=98657		 Page 1 of 1
Author:  timmy201 [ Thu Jun 06, 2019 9:26 pm ]
Post subject:  Clutch / Flywheel Questions
Hi All,

I'm after a bit of help to see if the parts I've got in the shed are any good for my build. Luckily up until now I haven't had to replace a clutch :lol:

I have 2 flywheels, both have very good smooth surfaces (one looks freshly machined). 1 x one-piece and 1 x two piece. Is there any particular preference for either (with a good clean up of course)?
Image

I have one diaphragm which is a Repco Australia R87-201.
Image

Pressure plates:
2 x 22A539 in good condition
1 x 2A3509 in poor condition
1 x AYA0085 (number is hard to read) in good condition

Engine will be a reasonably modified 1098
Author:  drmini in aust [ Fri Jun 07, 2019 10:30 am ]
Post subject:  Re: Clutch / Flywheel Questions
I like the 2 piece but 1 piece cast iron ones are OK for a road car.
You should get it lightened whichever type you fit. Then balanced.
[edit] or buy a light steel flywheel. The Minispares race one is too light IMO, I'd get their road one.

Throw away the old green dot diaphragm and fit a Cooper S Borg and Beck kit. You get a blue dot diaphragm, decent clutch plate, and a release bearing.
Set the assembly up on the bench and check the diaphragm is near flat. If not, the backplate lugs need machining.
They usually need machining because people faced flywheel and backplate for 50 years without checking this. Then wonder why the clutch feels heavy, but slips...

PM sent.
Author:  simonw [ Fri Jun 07, 2019 1:06 pm ]
Post subject:  Re: Clutch / Flywheel Questions
Doc I’m setting this up at the moment and am interested in this getting it flat business.....
Would you have any pictures showing the difference...I having trouble visualising


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Author:  mickmini [ Fri Jun 07, 2019 3:10 pm ]
Post subject:  Re: Clutch / Flywheel Questions
simonw wrote:
Doc I’m setting this up at the moment and am interested in this getting it flat business.....
Would you have any pictures showing the difference...I having trouble visualising


Sent from my iPad using Tapatalk


Search is your friend!

Here
and Here
and Here
and the original source article by Marcel in Canada Here
Author:  miniron [ Sat Jun 08, 2019 5:24 pm ]
Post subject:  Re: Clutch / Flywheel Questions
Make sure that the ridge the diaphragm spring seats against is parallel with the flywheel face.
I had clutch shudder from day 1 that the dealer couldn't/didn't fix.
After having clutch shudder to a greater or lesser extent for 40 + years I finally found the spring ridge wasn't parallel to the flywheel face.
I had replaced covers, driven plates of differing lining types, drive straps, bolts etc to no avail and then the light bulb moment happened and no more clutch shudder.
I suspect it was wrong from day 1 and was not due to wear over the years.

RonR
Author:  lomin [ Sat Jun 08, 2019 7:28 pm ]
Post subject:  Re: Clutch / Flywheel Questions
Hi, I agree with DR Mini on a new kit, and using 2 piece flywheel. If you keep the used one then there are several areas to check... If it is 1275 especially then the internal condition of the taper is critical , the top area round the centre where the clutch diagram spring sits as mentioned, ring gear condition and how flat it is where the clutch plate runs..... And then set up post heights accurately and it will work correctly. That green diagram is around .080" thick and is only 850 - 1100 IMHO. The blue is around .092" thick and will work on most road cars ... people seem to think heavier is essential, but it is harder on the clutch bearing, crankshaft thrusts and left knee. I am also a believer in balancing the entire assembly, its hanging almost 100mm out the back of that rear main bearing and an out of true and balance assembly must look scary in there at revs.
Also if you buy a new flywheel, by the time you add a diagram and backplate it won't be in balance.
Cheers Lindsay
Author:  clip [ Mon Jun 10, 2019 9:09 pm ]
Post subject:  Re: Clutch / Flywheel Questions
I’ve been thinking of fitting a lightened flywheel, but not sure what the full impact is for a small capacity mini. I know some engines that don’t like a lightened flywheel at all.

Following is taken from a mini engine parts site:

Effects of lightening rotating engine components: (0.5 x n2 x r2 + R2) / R2 n = total gear ratio (gear ratio x diff ratio) r = radius of gyration R = Radius of wheel/tyre This formula gives what accelerative weight the engine sees of the car per lb. Radius of gyration of a transverse engine's flywheel is approx. 3.75" So to determine "weight loss" for a flywheel weight of say 18 lb to 10 lb, the engine would see an overall weight loss of the car to accelerate in first gear of: 3.33 = 1st gear of 4 synchro 'S' box 3.44 = diff ratio (0.5 x (3.33 x 3.34)2 x 3.752 + 9.52) / 9.52 = (0.5 x 131.2 x 14.06 + 90.25) / 90.25 = 1012.59 / 90.25 = 11.22 lbs

So for every 1 lb removed from the flywheel, the engine sees 11.22 lbs less to accelerate off of the total car. Therefore by lightening the flywheel by 8 lb, the engine sees a total reduction of the cars accelerative weight of 89.68 lb -which is pretty significant in a mini!
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