Fork seal replacement
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Hi all,
Just about to give my forks a bit of a refresh as one of them are leaking. I want to make sure i have everything set and ready for the job and i have a feeling im going to have a bit of a nightmare with the bolts on the bottom of the forks to release the damper rods. Does anyone know of the tool i can use to release the damper rod from the inside of the fork tube if the allen key at the bottom rounds off or something? Or even just the size of the hex that needs undoing so i can manufacture something for the job? Thanks in advance
2005 Yamaha Dt 125
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If the forks are the same as the early bikes you need a 10mm allen key/hex bit for the allen bolt at the bottom of the slider, and a 27mm hex bit to hold the damper rod which will allow you to undo the bolt:
https://www.uktools.com/27mm-12drive-hex-impact-socket.html
The damper rod is actually the same size hex as the rear wheel spindle (but 12-sided) so if you have an old spindle with the 27mm head in good condition but with knackered threads you can cut off the threaded part, then grind an 18mm hex onto the shank so it fits into an 18mm six-sided deep impact socket. Then just loads of 1/2" drive extension bars down the stanchion and a breaker bar on the end.
You might need an impact wrench to get them undone, IIRC I buzz gunned mine off the last time I did a set.
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@HOTSHOT-III said in Fork seal replacement:
If the forks are the same as the early bikes you need a 10mm allen key/hex bit for the allen bolt at the bottom of the slider, and a 27mm hex bit to hold the damper rod which will allow you to undo the bolt:
https://www.uktools.com/27mm-12drive-hex-impact-socket.html
The damper rod is actually the same size hex as the rear wheel spindle (but 12-sided) so if you have an old spindle with the 27mm head in good condition but with knackered threads you can cut off the threaded part, then grind an 18mm hex onto the shank so it fits into an 18mm six-sided deep impact socket. Then just loads of 1/2" drive extension bars down the stanchion and a breaker bar on the end.
You might need an impact wrench to get them undone, IIRC I buzz gunned mine off the last time I did a set.
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@HOTSHOT-III Absolute perfect response mate was just what i was hoping for haha thanks mate. I dont have a spare spindle unfortunately but i could definitely knock something up to do the job perfectly just needed those sizes you've provided. Cheers for that
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@CalDT125 im rebuilding my fork too at the moment, i made a little tool that consisted of a bolt and a nut welded, i lost it and now i just used the rear spindle with a bolt from the thermostat that has a little hole and i placed a rivet to hold it together
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@Hybrid_Theory01 (torque it to 25NM)
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@Hybrid_Theory01 said in Fork seal replacement:
@Hybrid_Theory01 (torque it to 25NM)
Do you mean the damper rod bolt at the bottom of the fork leg? This should be tightened to 62Nm with a new copper washer and Loctite. It's a safety critical fastener.
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If you’re replacing the seals you may as well replace the bushes at the same time (Brooks suspension sells top & bottom bushes)…
You can use an old broom handle to tap into the 27mm female fitting inside the fork and turn/hold it with pipe grips…
Any seize/sticking is usually the 10mm Allen bolt head being corroded to the ally fork bottom (not the threads) White crusty crap builds up between the two different metals. I use silicon sealant to fill & seal the gap between the two, or at least cover and waterproof the bottom of the forks…I’ve had to drill out the Allen bolts from both sets of forks I’ve worked on. I drilled them out to 10.5 - 11mm then hammered the Allen key into them and got good purchase. Loads of heat was needed! Even after I’d undone and removed the inner (with a 27mm tool-bit I bought for £22) and it was just the bolt head stuck in the fork bottom!!…
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@SpookDog said in Fork seal replacement:
If you’re replacing the seals you may as well replace the bushes at the same time (Brooks suspension sells top & bottom bushes)…
You can use an old broom handle to tap into the 27mm female fitting inside the fork and turn/hold it with pipe grips…
Any seize/sticking is usually the 10mm Allen bolt head being corroded to the ally fork bottom (not the threads) White crusty crap builds up between the two different metals. I use silicon sealant to fill & seal the gap between the two, or at least cover and waterproof the bottom of the forks…I’ve had to drill out the Allen bolts from both sets of forks I’ve worked on. I drilled them out to 10.5 - 11mm then hammered the Allen key into them and got good purchase. Loads of heat was needed! Even after I’d undone and removed the inner (with a 27mm tool-bit I bought for £22) and it was just the bolt head stuck in the fork bottom!!…
Oh god i hope i dont have the same issue with that allen bolt at the bottom of the fork but i do have a feeling i will as i had a go a while a ago and cracking one free and it didnt budge just thought i was going to round it off so i stopped. I have bought the 27mm for the inside and i do have an impact gun now which may help free up that bolt at the bottom. I will definitely apply a load of heat like you mentioned and ive soaked it in a tonne of penetrative fluid also. Aim is to give it a go tomorrow so wish me luck haha. I was hoping that the bushes will be ok to be reused as there's no play that i can feel in it. Just oil and dust seals and some fresh oil and i do have a tub of copper crush washers that im sure will have the right size in for the bottom of the fork. Worst case i will have to drill the allen keys out, any ideas where i could pick up a couple new ones of them from if so?
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@SpookDog The one leg stripped nice and easily. I left the one i suspected to be a nightmare last and it is. Head of the allen bolt ceased in the bottom of the fork leg. Tonnes of heat and a meter long breaker bar with my fat self bouncing off the end of it still wont crack it free
. Impact gun wont free it either. May run it to a car garage local and get one of their windy guns on it. By the state of the first stripped leg i will be replacing bushes too. Brooks suspension you mentioned a few posts ago i looked at but i cant seem to see them stocking the ones i need + all i can find is pyramid ones being sold everywhere which i remember someone mentioning was crap?. Any ideas where else to try? Also there was no 27mm hex on the top of the damper rod it was just smooth . Tapped a broom stick into it though and worked fine thankfully, wish the same could be said for the other 
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The bushes are sold by size, not listed by make or model. I’ll post the size in a couple hours when I get back to the batcave
The fork inner has a female 12-sided hole that takes a 27mm Allen key type tool. I’m glad that the broom handle worked though!
Maybe get a needle and try scratching away at the bit between the bolt head and the ally? It took a stupid amount of heat when I did mine. You can try turning it the other way (righty~tighty) a bit as well, it cracks them off sometimes! Good luck, keep at it. It will come out eventually
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Upper bushes: 45mm x 12mm x 2mm
Lower bushes: 41mm x 20mm x 1mmThey are sold in pairs, I made the mistake of thinking they were single and ordered 2 of each and ended up with 4 of each! They are good quality with Teflon coating on the relevant side for extra ‘slippy’
…Let us know how you get on bud…
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Managed to strip down both fork legs and cleaned them all up. Few replacement parts i need to get hold of. Main thing being all 4 bushes, cant seem to find them anywhere but can find somewhere that sells various sizes just not under the name of the bike so if anybody knows the size or where i can find the sizes for the bushes needed for a 2005 DT125x id be massively appreciative.
Will also be replacing the clip above the oil seal, the O ring around the top nut and the allen bolts at the bottom with the crush washers and of course the oil and dust seals. Already found most of that but just need to know where to get the bushes from or at least know where i can find the dimensions for them. Cheers people -
Check the post above! They are the fork~bush sizes for a dtr125 which have 41mm forks. I don’t know if dtx’s are different. (Edit!) I checked the Haynes manual and it just says ‘DT’ models, so I’m guessing that the above sizes are for Dtx forks as well. They work out about £20 or so if I remember correctly…
The clips are 56mm and about a fiver for stainless steel ones on eBay. Again, the Allen bolts (genuine) are £17 a pair on eBay…
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@SpookDog Ace mate cheers for that! Will get them ordered up
. Yeah it did finally crack after a hell of allot of heat and effort . I'll get the dremel on it and open up the base of the leg a tad so the tolerance isn't so close between the bolt and fork perhaps. One crush washer is ceased solid in there so hopefully that'll allow me to get that out a bit easier too to replace. I'll no doubt strip them again next winter and get them powder coated as they are in a bit of a state but the aim is just to have a bit of fun this summer while i get my other bike sorted. Also the damper rods in my forks dont have the 27mm hex or infact any kind of way of undoing them from the inside its just smooth so i'll be getting a refund on that £24 tool i bought the other day haha thankfully the broom handle saved the day . Slight pitting high up on the stancion not really in reach of the seals unless i go flying off an mx jump to flat but any ideas with whats best for sorting them out a bit? From what ive seen online people use a bit of 1500 grit to take the high points off and maybe even using some kind of expoxy resin to fill the pits if needed. May look into that a bit more in the meantime too. Thanks again mate for the help, much appreciated -
I left my seized washers in and used them again last time, not the best solution but it worked!…
I use silicone sealant on the bolt heads before fitting them in. After it’s all torqued up I cover the bolt and hole as well…I use fine wire wool to remove rust, aluminium foil works as well. Any pits I fill with chemical metal/epoxy filler-adhesive. I’ve used it on bad pits in the ‘seal zone’ before with good results. I’m sure that there’s better, proper methods of repair that I don’t know about
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@SpookDog Yeah i may have to do that if it comes to it then. Hitting dead ends everywhere trying to find a set of bushes though. Cant find anywhere with the measurments you privided. I have phoned around and everywhere to main dealers and suspension specialists and all im getting is that the parts for these forks have been discontinued. May have to just look into doing a fork conversion if i cant find any or just hope that the bushes i have that come out them initially arent as mashed as they look
. Not ideal but i cant see any other options
