1994 Manitou DH, Beneke Replica

syncrosfan":wlutrm1a said:

Nice! I love the Manitou FS and DH frames. I got a '94 manitou FS myself which I have to get around to do some work on it (crack free!). Since you have the rear fork apart: how do the black plungers at the bottom of the stanchions attach to the main fork legs? Is it just a guide hole with a pin in it? Or are they bolted on? I'm trying to convert mine to Englund air cartridges front and back. While the front one is a drop in solution, the back one would require more work but it should be solvable. Then I would be free from the tyranny of the crumbling elastomer stacks!

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Benandemu":wlutrm1a said:

I decided to sort the rear end of this last night. Things look a tad simpler than the fronts, so without the use of a manual, I took the plunge.

Start by pulling some more of the stanchion through the crown so that you can a get a decent grip on the blue adjuster knob. Unfortunately my adjusters had seized pretty badly, and needed heavy mechanical assistance to undo them. This was always going to cause further damage to the beautiful turquoise anodising too.



Undo the blue adjusters and pull out the elastomer skewers. Mine were in a terrible state, and took ages to scrape and polish back up to a useable standard.



These are the original elastomers, and they are very dry and hard. Luckily they've not melted and left the stickiest substance known to man everywhere. The internal adjuster (Black knob) has seized solid on both sides too.

So, just like the fronts, dismantle everything, clean it, and then rebuild using new elastomers and plenty of grease.





Although there is a specific kit to renew the rear of this frame, I'm not sure why the elastomers provided don't quite match in terms of length or width. Anyway, it's all I've got, and I'm certain they'll work!



Before we reinstall the skewers, we need to inspect the stanchion bush, dust seal, and circlip. Carefully lift up the outer plastic seal so it's out of the way.
Well, in true fashion on this build, the circlips had to have a Dremel on them to get them out. They'd actually rotted away that badly, they'd become part of the rubber dust seal. I managed to salvage them both, albeit slightly shorter than previously.



The rebound elastomers need extracting and replacing next. For this task I need a very long 6mm Allen key, or a series of extension bars on a 6mm Allen head socket. The socket needs to go all the way inside the stanchion and feel for its hole. This will remove the plastic rod and rebound elastomers by unscrewing it.



This came out of one side...



And this mess came out of the other...



New rebound elastomer installed, and the both sides screwed back in.



Once you've replaced what's worn so far, and fitted new outer seals if required, then turn attention to checking that all the rear triangle's pivot points are free and moveable. You have to drop the stanchions out of their crown for this. Guess what? All, yes ALL, of my pivots were bloody seized. Rather than opt to have the bushes pressed out and then new nylon washers back in, I thought I'd try the old WD40 as the nylon washers look really healthy. One whole hour of swinging each pivot back and forth whilst liberally dosing the joint with WD40 every 2 minutes seems to have freed them off enough to work with.



Once you're happy, pop the stanchions back into their crown, leaving an extra inch pulled through (this is the point where you'll need to add the new stanchion seals or bellows. Take each elastomer skewer and thread them back in. I actually added an extra elastomer each side because the ones provided just didn't seem happy. Once you've screwed them down, push the stanchion back down and tighten the bolts.



Everything seems to have worked.

Now, the next job is going to be awful, as I need to try and remove all the pitting and oxidisation on the alloy. After testing different methods in small places, I realised that wet 'n dry was the only way. Started off with medium course flexible foam backed paper, and worked through to fine grade. The end result isn't perfect, but much cleaner. Somehow, it offers a much better authenticity and patina for the finished bike. I used medium wire wool and WD40 to buff up the Titanium.












The most important part of all this? The suspension actually works!

Marin headset to go in next, then I might do bars, seat post, and brakes.

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