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77 RS clutch slipping
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- Posts: 81
- Joined: Sun Oct 13, 2019 2:47 pm
77 RS clutch slipping
I bought a 77 RS from an estate and the PO had told me the clutch was slipping. The bike is a very low mileage bike so it sat for a long time. When I removed the clutch I found all the parts looked and measured like new except the pressure spring which measured too low. I replaced everything just to make sure and checked the rod and bearing and they looked good. I drove the bike normally not looking to test the clutch (roll on the throttle in 5th at 75mph) for 3000 miles to let everything bed in. The other day while on my morning ride at 75 mph in 5th I felt the clutch slip going up hill. I checked all adjustments were right on, took the clutch arm off and the bearing is good and the rod is free. I have noticed it does not take much pressure in the clutch lever to release the clutch.
Has anyone ever come across a flywheel the is too deep? I can not find a spec for it in any of my books.
Thanks for reading all this, Jim.
- schrader7032
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Re: 77 RS clutch slipping
http://www.rubberchickenracinggarage.co ... stment.pdf
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
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- Posts: 81
- Joined: Sun Oct 13, 2019 2:47 pm
- schrader7032
- Posts: 9081
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
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- Been thanked: 40 times
Re: 77 RS clutch slipping
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- schrader7032
- Posts: 9081
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
- Has thanked: 3 times
- Been thanked: 40 times
Re: 77 RS clutch slipping
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
-
- Posts: 81
- Joined: Sun Oct 13, 2019 2:47 pm
Re: 77 RS clutch slipping
First the pressure plate is in correctly.
Second while riding on the freeway I can just pull in the clutch lever a tiny bit and it will release.
The complete action of the lever is somewhat easy compared to my old R75/5 and about the same as my 83 RS that I have been riding since 95. (I know they have completely different assemblies)
I’ve had the transmission out twice now everything was replaced with BMW parts. There are no oil leaks or anything to make it slip.
I’m positive there is no hang up of the release parts to keep any pressure on the plate so I am hoping to get the depth of a known good flywheel to compare mine with.
Thanks, Jim.
- schrader7032
- Posts: 9081
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
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- Been thanked: 40 times
Re: 77 RS clutch slipping
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
-
- Posts: 81
- Joined: Sun Oct 13, 2019 2:47 pm
Re: 77 RS clutch slipping
Thanks, Jim
- schrader7032
- Posts: 9081
- Joined: Fri Oct 27, 2006 3:00 am
- Location: San Antonio, TX
- Has thanked: 3 times
- Been thanked: 40 times
Re: 77 RS clutch slipping
https://vintagebmw.org/library_data/Doc ... b89ce1.pdf
I think 2mm at the hand lever is too little. If I remember correctly, it's more like 5mm. That's what is it on my /7.
If you've increased the free play at the lever past 2mm to more like 5 and you still get clutch slipping, then I can only think something internally is wrong. Something is not letting the disk be squeezed tight enough to keep slipping.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
-
- Posts: 81
- Joined: Sun Oct 13, 2019 2:47 pm
Re: 77 RS clutch slipping
You are right about the 90 deg adjustment I was having a senior air head moment. S.B. Is Snow Bum.
I think if something in the release parts was hanging up my free play at the lever would increase. Also if the piston was sticking the bearing would not last very long.
I am going to try the adjustments one more time just to be sure but I am hoping someone can give me the depth of the flywheel to check against mine if I have to pull it again.
The bike has had this problem before me so after replacing all of the clutch parts and running it for 3000 miles and it still slips something is very weird and I have to find out what it is.
Thanks, Jim