Hi,

I have dismantled the front forks to change the oil seals and got a bit of a surprise. There seems to be a double seal. The top seal came out OK ( size as expected,  31x43x12.5 ) but it sits in a steel bush which has another seal in it. I have managed to damage this. My question is, is this second seal part of the steel bush and should I be trying to remove it or do I just put a new, normal seal in? The bike is a 2K4 series ( with matching frame and engine numbers ) which I bought a few years ago from Germany. I think the forks are original but they don't match exactly any of the the picks in my Haynes manual so I'm stuck.

Thanks for any help.

Nick.

Have you looked here

https://www.cmsnl.com/yamaha

 

 

are these forks the leading axle version or the ones where the axle is central to the fork leg?

Hello Airhead, thank you for your reply. The axle is central to the fork leg with a removable cap on one leg and a pinch bolt on the other. The dust cap above the seal is a metal 'press on' cap, not rubber and and there is a hard plastic spacer/ring between the oil seal and the circlip. There are no mudguard brackets on the leg. Internally, I was surprised to find no spacer above the spring but I haven't measured the spring length yet.

Nick.

Thanks Jimmy,

I've looked at their diagram... not my forks.

If you cannot find the Yamaha part number or confirm the fork manufacture,

 Are there any identifying numbers or brand name on the seals, if there is, take a note, measure the inner diameter the outer diameter the seal height and count the number of sealing lips, normally one but can be two, then call up a seal manufacturing supplier give over the info and ask them for the best option, there is a whole industry out there that specialise in supplying seals for industrial rams of all sizes, the bonus could be that you get to find an industrial version of the seal that might be cheaper than the Yamaha or pattern supplied part

 

http://www.athenaparts.com/eng/products/view/8419/fork-oil-seal-mgr-rsd-32x44x10-5

 

I think this is the part a 1981 DT 175 MX uses, the DT is listed on the, View all couplings tab,

Edited April 28, 20186 yr by nayruf

photos would be good