Rocker bearing size: 1975 R90/6

[Rohls]

Hi,

I'm a bit confused.

I have a 1975 R90/6 manufactured in 05/1975 according to the nameplate.

I need to change the rocker bearing for the left side intake and exhaust.

I have been fed conflicting information about the correct needle bearings to purchase, as I believe they changed them right around that time....

I have not measured them yet, since this is my daily driver...I can this weekend.

Is BMW part number 11 33 1 261 712 correct for my bike? These have a 20mm outer diameter as far as I can tell.

Thanks,

Nick

[Kurt in S.A.]

The issue was that some of the poorly manufactured bearings had the cage rolled over too far which then rubbed on the rocker shaft. That was subsequently fixed. That should be a good part number. As long as they are not NOS, they should be the right parts.

Another issue is that some of the bearings had 30 and some had 31 needle bearings. They were slightly different diameters. You can't mix and match. If you are just replacing, no problem with that. But if you spill the needle bearings and get them mixed up, that could present a problem.

Kurt in S.A.

[Rohls]

Thanks Kurt!

I'm not sure if the bearings are NOS..I'd be guessing no...how could I tell before I spend the $$?

[Kurt in S.A.]

I'd be hard pressed to know for sure...I've never had them out or a set in my hands. I think one could tell if you had both types side by side. If the edge is rolled to far, it won't clear the rocker shaft. That is my understanding...I haven't been able to find pictures on the web.

Kurt in S.A.

[George Ryals]

http://www.largiader.com/tech/rockers/ This article may be of help on all rocker arm related questions.

[Rohls]

Thanks again.

I've read that article, but it gets a bit fuzzy about the 1975 /6 series. I have a mfg date of 5/195...is this 'early'...?

I am planning on bearing inspection this weekend...I'll report back with info.

[Rohls]

Alright,sorry for the delay.

I measured my bearings; OD 20mm, 16 ID and about 18mm wide.

Mine have 31 roller bearings; does PN 11 33 1 261 712 have 31 individual roller bearings?

Also, where can I get rocker shafts?? Mine looks a bit worn and I'd like to replace.

Thanks!

[Kurt in S.A.]

I think the thing is that you order a set and you get what you get...maybe 30, maybe 31. But you just end up using that as a set...don't try and mix needle bearings around. Some are slightly bigger OD (thus only 30 of them), the others are slightly smaller (31 of them).

Shafts are PN 11331336942...look to be under $50...pricey I guess. Probably best to get new?? There are salvage yards out there.

Kurt in S.A.

[Rohls]

Thanks Kurt!