76 RM250/370A rear brake plate

[Rossvickicampbell]

which site is this from?

[Oldfart]

76...  Rm 250-370  has a smaller dia hole thru plate that axle just paces thru  .... from memory around 15.5mm ??

[LWC82PE]

CMSNL but its the same drawing on Alpha-Sports.

Yes i would of thought the A model is just a straight 15mm hole too, but i cant work out what the parts book shows those bushes in the plate.

Anyone actually have the correct 250/370 A printed parts book?

[Rossvickicampbell]

Partzilla is the same albeit with different numbers.

[LWC82PE]

I have just found a combined 76-78 microfiche dated june 80 so i will see what that shows. Cant see it clearly enough with the pocket viewer so i will have to put it in the full blown reader tomorrow.

[LWC82PE]

So I looked up the parts numbers on the microfiche and there are 3 plates listed for the A model inc a magnesium one.
Parts 13, 14, 15 & 4 are listed in a way that suggests they are to be used with any of the 3 A backing plates. There is nothing that says they are only used from  certain frame number onwards or only with one of the 3 backing plates. I also checked the C2 model plate and its a different number and actually uses a bearing, so these A model bush parts are nothing to do with a full floating brake either, i do not understand their reasoning as to why they would be required on a non floating plate.

I guess i will jsut have to try find one of the 3 A model plates and then if it turns out it requires parts 13, 14, 15 & 4 then i will have to get them after.

Has anyone seen a A model plate that has a 15mm hole straight in the backing plate or are they all machined out bigger and then reduced to 15mm with parts 4 & 13?

[TT5 Matt]

maybe they were going to do a floating rear brake and decided not to [bean counters deemed it too exspensive!] as b models are solid or left over parts from rh/rn's

[Oldfart]

yes I have a NOS plate

[crs-and-rms]

i have two a/b backing plates one is the magnesium and the other is the standard plate both have the steel insert in them with the hole 15mm in dia looks like they are cast into the backing plate. just had a look at the parts book  think mine are b,c backing plates not a

[LWC82PE]

i have two a/b backing plates one is the magnesium and the other is the standard plate both have the steel insert in them with the hole 15mm in dia looks like they are cast into the backing plate. just had a look at the parts book  think mine are b,c backing plates not a

B model is for 17mm axle so if both yours are 15mm then they are both 76 A.

I thought that maybe the bushes were just for the magnesium plate to add more durability but the parts fiche does not indicate that.

Oldfart what is the part number for the NOS plate you have that does not use parts 13, 14, 15 & 4? Thats the one i prefer.

[Oldfart]

64210-41102      with a number on inside of plate 430... mine is alloy not magnesium.

[LWC82PE]

Great, now I know the one to find. Doubt there's many magnesium ones around.

[LWC82PE]

Tried Paul Miller and he has none of the plates.

[matcho mick]

i have a bare one,it's 17mm axle,has 490 on the inside?,

[LWC82PE]

Thanks but

15mm = 76 A
17mm = 77 B

I am after 76 A