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Replacing front fork springs
Update
Overall I think everything is good to go. The new springs are much different than what was in the bike. I hope that helps.
Tomorrow I will put it all back together with some new O-rings and washers.
- Attachments
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Replacing front fork springs
I rebuilt the front forks when I restored the bike two years ago. Not really knowing anything about these bikes I reinstalled all the parts I found when I took it apart. They included a generic spring, the anti dive spring in the bottom, a 1" PVC spacer at the top and 7.5 weight fork oil. Ive tried 5, 7.5 and 10wt fork oil. No real difference.
The plan is to go through the front suspension, remove the short anti dive spring in the bottom and install new Wilburs progressive springs.
chuck
R 90 S Forks
head bearing re-packing/adjustment. A stronger Toaster Tan upper brace/tree is also a thought.
1962 R 69 S 1975 SS R-90 S
Past:1974 SS R 90 S, 74 R 90 , 77 R 100S, 1960 R 50/2,1973 R 75/5, 1977 R 75/7, 1977 R 100 , 1972 R 75 /5
Springs
head bearing re-packing/adjustment. A stronger Toaster Tan upper brace/tree is also a thought.
Much better. I took out the anti-dive springs in the bottom. Installed Wilburs springs and filled with 7.5 wt fork oil. I also reused a 1" PVC spacer in the top for preload. I may drop it down to a 5 wt oil but the ride is much better.
40 years ago I changed my
Mike
69 R60/2 76 R90S 78 R100RS
70 Triumph w/Spirit Eagle Sidecar
Fork oil
Mike ..... I have to ask. Why? Cheaper? Better performance? Im just curious.
With the BMW fork oil I had
Probably, the first change was when the shop was closed and I needed to fill the forks. Used what I had on hand that was ~5wt. Worked so well that I never changed back or questioned the change. Mobil 1 is cheaper than fork oil.
Mike
69 R60/2 76 R90S 78 R100RS
70 Triumph w/Spirit Eagle Sidecar
oil
Probably, the first change was when the shop was closed and I needed to fill the forks. Used what I had on hand that was ~5wt. Worked so well that I never changed back or questioned the change. Mobil 1 is cheaper than fork oil.
Mike
Thanks for responding. Any benefits from using the multi weight oil?
chuck
- schrader7032
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I have to wonder what the
As a comparison Snowbum has a range of discussions on viscosities on this page:
https://bmwmotorcycletech.info/viscosity.htm
Viscosity is expressed as centistokes at a given temperature. Hard to make any meaningful and direct comparison because he doesn't list the fluids involved above. But he does have this which is centistokes at 100degC:
- Belray fork oil 10 (well known maker of fork oil) - 5.8
- engine oil grade 5 (I think that means 5w) - 3.8 to 4.1
So that seems to suggest that at 100degC, engine oil might be less viscous and flow better. But we'd need to know the readings at room temperature to really know.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
oil
Probably, the first change was when the shop was closed and I needed to fill the forks. Used what I had on hand that was ~5wt. Worked so well that I never changed back or questioned the change. Mobil 1 is cheaper than fork oil.
Mike
Thanks for responding. Any benefits from using the multi weight oil?
chuck
Probably not. It is possible the oil doesn't thin as much on a really hot day, but I don't ride hard when the weather is really hot (or cold).
Mike
69 R60/2 76 R90S 78 R100RS
70 Triumph w/Spirit Eagle Sidecar