Bump rubber replacement

[DR]

The bump stop rubbers on my old remote res Kayaba's on the 400C and 125C have all but vanished. How costly is it to have new bump rubbers fitted as I don't see any way of disassembly and shock surgery is not something I'm familiar with. Thanks

[LWC82PE]

i have a 78 Rm shock and there is one crimp line. you have to cut below that line to get the shaft out, but you can get the seal head/wiper etc out once the body cap is removed. Do yours have a press in body cap? The lower eyes on my RM shocks are permanantly attached to the shafts and dont uncrew. I would have to have a closer look at mine to see if there is at all any possibility to machine off the lower eyelets and then put a thread on the shaft  and put a new bump stop on and then screw on a new readily available end eye, but i have doubts this is possible to do with out loosing some shaft travel...... hmm yes just grabed a RM shock shaft you would loose about 10mm stroke and overall length. You could make up for the overall length by fitting a longer lower eye no problems but you would loose a little travel. You could make up for this buy using a shorter bump stop than the original to give you more exposed shaft before contact with the bump stop is made. Most OEM RM twin shock bump stops i have seen are 37-39mm long, so you could fit one thats shorter than that.

Other option is to get something like some Polyurethane adheasive sealant like Sicaflex and mould one onto the shaft with out pulling the shocks apart. you could slowly build it up and then finish it off by brushing over it with paint thinners for a smooth appearance. Sicaflex is strong stuff and i think it would work fairly well. You could even tape a little bit of thin clear plasctic around the shaft first (like plastic off a blister pack ) and then put the sicaflex onto that. Then the bump stop can float around on the shaft like original

Maybe also consider RAD shocks to just pull the shocks right apart and do it for you for a couple hundred dollars. I think they still charge about $200-$350 for a complete overhaul?

[evo550]

Doc,
The only way I know to replace the bump stops is to put the shocks in your car, take 'em to rad's, return in a few days with some money and exchange it for shocks and hey presto, new stops plus fresh oil and nitrogen........your shocks will love you forever.......not that they don't now

Don't be tempted to buy some then cut them in half and slide around the shaft, they may disappear very quickly.

Not much help really am I, one day I hope you will return the favor

[JohnnyO]

Doc you can get them from Shock Treatment in the Sydney area. They have Kyb and Showa in different sizes for about $30 a pair. You'll have to clamp the shock shaft with soft jaws in a vice and heat the shaft where the end screws on with a heat gun to soften the loctite then it should undo so you can fit the new bump rubber.

[LWC82PE]

Yes Johnny but only if the lower eyes uncrew. Many KYB's have the lower eyes permanantly fixed to the shafts and they are not threaded on

this is the closest KYB bump stops i can find for the twin shocks
http://www.teknikracing.com/s.nl;jsessionid=0a010c441f435fd06e3b760d4d4a8187e663e6dece21.e3eTa3aSaxmTe34Pa38Ta38Pb350?it=A&id=2039

i just saw the price they seem to have gone up since i last ordered. Shock treament http://www.shocktreatment.com.au/ sell the exact same bump stops in Race tech brand and they might be cheaper.

i have plans to get the original red ones re-made

[JohnnyO]

Ok i've never tried to pull those kyb's apart, i was referring to most other shocks. If that's the case it aint easy Doc..

[brent j]

Sorry Doc the only way I've been able to replace the bump stops was to convert the shocks to rebuildable.

KYB's have the eye welded on. I do have one set with screw on eyes but this was done to experiment with different lengths and as Lieth said you loose travel.

[JohnnyO]

I reckon the best way to replace the bump rubbers on those kyb's is to throw them in the bin and bolt a set of ohlins on.

[LWC82PE]

good point but maybe he wants to keep them for originality and the bike is not a racer.

[DR]

hmmm..thanks guys...this is kinda what I was fearing. I don't really want to have the shocks rebuilt but if it requires disassembly for just the rubbers then I'd be a bit silly not to have them re oiled and gassed at the same time. $ I don't have right now. Okay here's a theory that's been rattling around in the void where my brain should normally reside, 'if' I were to find some nice urethane (however it's spelt) bump stops what's the chance of slicing it to slip over the shaft and then affixing the whole deal under the stop to the shaft with a little adhesive? I figure the spring on the outside and adhesive on the inside may well work?? Any thought's as to why it wouldn't. Obviously the bump rubber has deteriorated over time from age and not from compression as I rarely bottom the suspension with my flyshite weight

  Johnny, you're talking Utopia! Ohlins would be nice but not in this lifetime for the piddly amount of riding I have left in me Leith I want to keep them because for me it's the most practicle thing to do..if something ain't broke don't mess with it wouldn't say they are broke but my back maybe if I don't see fixing it somehow

[brent j]

Maybe make a bump stop, or find something suitable, and cut it in a spiral so it wraps around the shaft.
That might just help it stay in place.

[JohnnyO]

I think you've got the answer doc if you can find the right glue to stick them together..

[DR]

Araldite Johnny gotta love the stuff

I like the spiral idea too Brent but it sounds a little hard to do without losing fingers   the TM bits will leave tomorrow by the way, I been a bit slack

[LWC82PE]

if i were to slide something over or cut a slit in a bump stop and then glue it back together, i would always be riding along worried about it comming off. I think my idea of using urethane sealant out a tube is pretty good and alot more re-assuring. You can get it from places like supercheap auto. Sicalfex is the brand name stuff but you can buy it in a cheap black and gold type brand called 'moto' something? you then just need a dispenser to squirt it out. I use that stuff on side car grab rails and when its stuck to the grab rail its on there it makes a nice rubbery grip for the swingers and will stay on there for ever and will never come off. Another possible soloution is to use a normal rubber or foam bump stop and sand it down a bit all over, then cut a slot in it, fit it around the shaft, then glue it togther with urethane aheasive i mentioned before and then cover the whole bump stop in the stuff and build it up a few mm thick to make up for the amount you sanded off. That way it will have a good covering and hopefully the slot in the bump stop wont pull apart, but if you use the urethane adheasive i think it should be Ok.

[DR]

Leith the bump stop rubber can't really fall out when it's much larger than the gaps between the springs, there is nowhere it can go except up the shaft so I think I'll go with this plan. I don't mind using a nice thick larger dia rubber instead of the piddly little stock item. I was thinking of maybe as Brent says and make the cut a little spiralled which will aslo reduce the chance of it slipping straight off. Will have a play over the weekend.

Wasp, the bump rubbers you have, is $12 for the pair or individually? cheers