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So, disclaimer - this isn't my first rodeo. I've been rebuilding high-end full-suss bikes for years with rarely a problem, but I've met my match this week and I could do with a bit of advice.
In this case, the bike is an older 26" Intense Carbine SL with a VPP linkage, more or less the same as you'd see on many SC, Intense or Pivot bikes. In the case of this bike, it's been about 3 years since it last had a bearing service and they are pretty knackered from top to bottom, with a fair amount of play at the back end as a result. Nothing challenging and I've done plenty before...
The problem with this one is that the upper linkage won't come apart. One of the bolts that secures the rear triangle to the upper carbon link bolts through the bearing an into an aluminium captive thread, bonded into the upper link. And this captive thread has worked loose and now turns in the carbon rocker, so it cannot be undone:
(in this photo, you can see the end of the bolt sticking through the aluminium retaining thread. It's this circular piece that is turning in the carbon moulding)
This is a view from the other side so you can see what it looks like when dismantled:
I've been trying to get this off for a week now. So far, I've tried epoxying a lever to the outside of rotating piece to hold it in place (no chance - not enough surface area to get a good bond), as well as drilling a small hole through the ring to insert a steel pin through into the carbon rocker to lock the two pieces together - it bent a hardened steel pin like it was made of cheese.
I'm talking to Intense about getting a replacement upper link, but I think this quite unlikely given the age of the bike, so I really need to get it apart more or less intact. It doesn't matter if the threaded part is damaged as I can sort a replacement for that without too much difficulty.
So, STW, any suggestions? It's worth noting that the owner of the bike *loves* it. She's not overly precious about what it looks like, but as she is very short (< 5ft), there aren't so many bikes around that suit such a small rider and she's very attached to this one.
Can you drill 2 small holes in the part that's come unbonded, and use a pin spanner to hold it while you undo?
I'd try lots of PlusGas over a few preceding days and maybe heat as a last resort as well.
Can you drill 2 small holes in the part that’s come unbonded, and use a pin spanner to hold it while you undo?
I'd pondered it, but my pin spanner, while pretty small, still has pins that are 2mm wide, which would take most of the width of the thread ring and with two holes drilled through would, I'm sure, cause it to snap in half. This may be something I have to accept to get it off though.
I’d try lots of PlusGas over a few preceding days and maybe heat as a last resort as well.
Already done PlusGas, but loathed to apply heat due to all of the bits being carbon and as it's an aluminium bolt in an aluminium receiver, both will expand at the same rate and I don't think it will help release it (unlike, say, a steel bolt in an aluminium frame, or a steel bearing in an aluminium shell). It may come down to it yet though... 🙁
The bolt looks hollow. Can you drill out the inside of the bolt with increasing diameter bits until the bolt collapses or snaps free.
Drill / grind (die grinde dremel etc) the head off the cap head. Remove the linkage. Now you as I understand you have captive nut with (probably) a bit of cut off stud. Looks like if the captive nut will then pull out of the carbon to be cleaned up and rebonded.
Thanks all - I need to check if I can even source the bolt, which is itself a bike-specific thing:
...and fits into a recess against the bearing:
That said, I suspect it'll be easier to source a bolt than a carbon link!
Just holding fire for now as it seems those coarse-threaded bolts are very hard to get hold of at the moment - possibly even more so than the suspension linkage itself - so if I need to sacrifice something to get this apart, I'm going to wait until I am 100% sure that I am sacrificing the right bit first!
You ought to be able to get an engineering workshop to machine up a bolt to match, if necessary.
I think i would be retrying the drill through and pin but with a bigger pin, maybe a rolled pin if possible provided that won't weaken the carbon too much.
I think i would be retrying the drill through and pin but with a bigger pin, maybe a rolled pin if possible provided that won’t weaken the carbon too much.
It's a bit hard to tell from the photo, but the area to drill through on the aluminium insert is only a few mm across, so if I drill much larger than I have done already, I'm effectively going to split the part in half (especially if I drill two holes for a pin-spanner) which will make it much harder to get a decent repair when putting it back together.
So far, an upper link is £60...*if* they can get hold of one. This is a no brainer (bearings will probably cost £30-40 anyway) and if I can get the coarse-threaded bolt too, my options will certainly become much more medieval... 🙂
Couldn't you drill everything out and get replacements machined up for bonding back in?
Try brilliantbikes for Intense bits if no luck with Intense themselves. They seem to have some older stuff: https://brilliantbikes.co.uk/188-intense-spares
Try brilliantbikes for Intense bits if no luck with Intense themselves.
Thanks - have already dropped them an email (have used plenty of times before!) but no reply. Will give 'em a call anyway...
Couldn’t you drill everything out and get replacements machined up for bonding back in?
May come to this, but it'll be a pretty expensive option...
I put an old intense frame in the bin yesterday (cracked )
But....I do have one of those bolts
Sitting on the side in the garage. Let me know if you want it
But….I do have one of those bolts
Sitting on the side in the garage. Let me know if you want it
Wow! Yes, indeed I do! I'll drop you a PM offline if that's ok, thanks.
I went a bit quiet on this topic, partly because I needed a bit of time to think things over, and partly because of the kind offer from @mrh86 above to send me some spare parts, including the elusive coarse-threaded bolts used on this linkage. Having the confidence of some spare bolts makes a huge difference when trying to decide how to attack this, especially when Intense spares are somewhat thin on the ground...
I'm pleased to say that the linkage is now apart! In the end, I used a 1mm drill to drill a hole right through the aluminium thread insert and the carbon link moulding. I then machined a spoke down to the correct diameter, and inserted it right through. With a gentle application of heat to release the threadlock (another suggestion from another friendly local mechanic!) and a fair amount of heft on a hex key, the bolt finally released with a sturdy "crack" and came apart, with no other damage to either bolt or thread:
I then used the same spoke and epoxied it into the hole as a permenant fix which, when cut down after the epoxy had set, produced a pretty clean-looking repair and, hopefully, will work fine when reassembled.
The new link axles arrived today (last set in the UK, I think!) so I am just waiting on a couple more bearings and hopefully it'll be done this week and out of my workshop at last! Will post again when it's all done.
bloody hell
Nice work, looks like a neat repair, bet you're pleased with it. With some fine grade filler, some wet and dry and a rattle can you'd never know it was there at all.
Lucky to get a linkage.
Tried getting one for my old 6.6 but none anywhere so I ended up machining my own (and bolts).
You’ve earned a chocolate biscuit 🍪
Lucky to get a linkage.
Tried getting one for my old 6.6 but none anywhere so I ended up machining my own (and bolts).
Fortunately, and with a bit of care, I was able to repair the upper link and re-use the fasteners (although, thanks to @mrh86 I now have a couple of spares!) so didn't need to source any replacements. This was fortunate as trying to get information on older bikes out of Intense was a bit painful :-/ I was able to get the expanding lower axles as a kit from the distributor, but I think these were the last set they had and I suspect they'll be increasingly hard to source for older bikes.
Rebuilt it last night and it went together without further problems. New bearings throughout, new linkage axles on upper and lower link (they had started to show signs of wear, resulting in rear-end play), a thorough inspection and regrease and it's (nearly) as good as new! The owner is utterly delighted to be getting her bike back again!
I've done many, many linkage rebuilds over the years, but this one has been an absolute pain. To quote my local mechanic when I asked him what he would do with it: "I'd run away - I hate mountain bike linkage jobs!"
Time for a biscuit, definitely 🙂
Two biscuits at least ! Nice job. Just done the frame bearings on my bike. Fortunately alloy, but it doesn't half make you jump when you're pressing the bearing out, then goes bang as the tension releases and the bearing pops out. New bearings pressed back in like a dream, but when they have been in there for 4-5 years (regularly re-greased) they are 'stuck'.
New bearings pressed back in like a dream, but when they have been in there for 4-5 years (regularly re-greased) they are ‘stuck’.
Yeah, sadly most manufacturers seem to press them in "dry" and they can seize into the seats if they've been in for a long time. It's one reason why I don't mind if people do an early bearing change before the bike is too old, so they can be fitted in a way that means they will definitely come out again when they really need doing in the future! I recently did Whyte G160RS that hadn't been touched since it was new and I was worried that I'd have problems - especially given how many bearings it has - but in the end, it was no problem at all and both came apart and went back together perfectly.
A bit of gentle heat goes a long way. I'll nearly always run kettle water (100C is a good temperature to heat things up without risk of damage) over bearings before removing as the different expansion rates of aluminium and steel mean that the bearings installed via their outer race (as is typical on bikes) will loosen off in their seats and push out much more easily. Using this technique, I find that 99% of bearings come out first time, even if utterly knackered, which saves a load of grief.