dr770 Posted May 11, 2017 Report Share Posted May 11, 2017 Hello; I have realised there is no damping left in my shocks. So i made my mind to take them apart and inspect. first of all I am happy its a a rebuildable design. İt has a threaded cap that lets you to reach internals.I opened the cap and saw the spring on the bottom of the piston rod is broken. I can make a new spring thats not big deal. The shocks are twin tube design the o rings and seals are far gone. I can replace the o rings but the shaft seals seems to be very narrow design . I can not find any information on rebuilding this kind of shocks. they are not gas shocks . Any information will be very helpful. Major problem is the seal dimensions and availability, amount and type of oil. I have to rebuild these shocks there is no alternative product here and no chance to be imported. I will rebuild these or stick with chinese stuff Quote Link to comment Share on other sites More sharing options...
iconic558 Posted May 11, 2017 Report Share Posted May 11, 2017 Where are you?.....post gets to most places....I've even sent a letter to the North Pole Quote Link to comment Share on other sites More sharing options...
dr770 Posted May 11, 2017 Author Report Share Posted May 11, 2017 3 hours ago, iconic558 said: Where are you?.....post gets to most places....I've even sent a letter to the North Pole Well, i am in turkey, and it seems like i am the only one in here with a twin shock trials bike which was accidentally brought here by a Spanish family with a caravan and left over here 8 years ago. This means i have to refurb or fabricate everything by myself. Luckily i am mechanicaly mean and have good experience :-) Quote Link to comment Share on other sites More sharing options...
iconic558 Posted May 11, 2017 Report Share Posted May 11, 2017 Quote Link to comment Share on other sites More sharing options...
feetupfun Posted May 11, 2017 Report Share Posted May 11, 2017 There is a bloke in the USA who makes new shaft seals for 1970s Betor shocks. I've bought and used some in the Betor shocks that came on Alpinas and OSSA explorer. I saw them listed on eBay by this person about a year ago. I looked for ages and have not seen them available from anywhere else. These might not be the right size for your Betors though because some 1970s trials Betors have a thinner shaft than the one I rebuilt You can always turn up a new seal retainer for your shocks and use whatever hydraulic seal is available locally to suit your shaft size 1 Quote Link to comment Share on other sites More sharing options...
dr770 Posted May 12, 2017 Author Report Share Posted May 12, 2017 10 hours ago, feetupfun said: There is a bloke in the USA who makes new shaft seals for 1970s Betor shocks. I've bought and used some in the Betor shocks that came on Alpinas and OSSA explorer. I saw them listed on eBay by this person about a year ago. I looked for ages and have not seen them available from anywhere else. These might not be the right size for your Betors though because some 1970s trials Betors have a thinner shaft than the one I rebuilt You can always turn up a new seal retainer for your shocks and use whatever hydraulic seal is available locally to suit your shaft size Hi I will probably machine the existing retainers to suit a proper hydraulic seal. Any ideas for the oil (10wt?) and level? Quote Link to comment Share on other sites More sharing options...
feetupfun Posted May 13, 2017 Report Share Posted May 13, 2017 I don't remember the amount now but I usually put in just enough so that they don't snore. You can test for this before screwing the top on. 5WT is better than 10WT for them Quote Link to comment Share on other sites More sharing options...
dr770 Posted May 13, 2017 Author Report Share Posted May 13, 2017 8 hours ago, feetupfun said: I don't remember the amount now but I usually put in just enough so that they don't snore. You can test for this before screwing the top on. 5WT is better than 10WT for them Well i searched for seals today and get the same answer in the industrial equipment shops"this is a very specific seal you can't find it". And yes, they are specific. 11x24.5 mm like a disc. But they don't appear to be completely gone. I have manufactured the valve springs and tested. There are 2 adjustments for rebound. 1st the valve opening amount 2nd preload. But what ever i tried the shock is either have a free play about 15 mm or it is going hydro lock just before bottoming. May be i have to put a bump stop about 20 mm to prevent a hydro lock. But the shocks are working with less free play when they are upside down??? There is no pressure valve so the level of oil inside the inner tube is under the piston level, if i add more to keep the piston in oil when fully extended, then it hydro locks before bottoming. Any suggestions? Quote Link to comment Share on other sites More sharing options...
feetupfun Posted May 13, 2017 Report Share Posted May 13, 2017 Sounds odd. Maybe the oil is leaking down out of the inner tube when the shock is not moving. Does the free play go away after a few rapid strokes? (mounted on the bike so you can work it quickly) Quote Link to comment Share on other sites More sharing options...
dr770 Posted May 13, 2017 Author Report Share Posted May 13, 2017 1 hour ago, feetupfun said: Sounds odd. Maybe the oil is leaking down out of the inner tube when the shock is not moving. Does the free play go away after a few rapid strokes? (mounted on the bike so you can work it quickly) Yes exactly, the oil is leaking to the outer tube. I thought this was normal. I think i have a problem. This is the first time i have attempt to rebuild a shock. When i pressurise the inner tune with my breath, i can hear air leaking from the bottom. So i guess there should be a 2 way valve on the bottom of the inner tube. There was a nut that i didn't unscrew i guess thats what i should deal with. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted May 13, 2017 Report Share Posted May 13, 2017 It isn't much of a problem though because it will prime itself again as soon as you start riding 1 Quote Link to comment Share on other sites More sharing options...
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