Bomber bushing issue

[Rik]

I'm having all sorts of dramas with my Mr T fork (same internals as a 1998 Z1).
I bought it in "new" condition, it'd only been installed once and the bushings had to be replaced as they were dead out of the box.
Now even though it supposedly has new bushings, there is a whole shitload of bushing play. I am not very familiar with Marz internals yet, but I am under the impression most Marz forks use the same size stanchions and bushings, so it couldn't be the wrong bushing fitted, could it?

The fork has to be rebuilt, and I need to sort out some bushings. Now I'm worried that there's something wrong internally, and installing another set of bushings will just result in the same amount of play.
I have the crazy idea of shimming up the fork so the bushings are a bit tighter on the stanchion, is this viable? Ie, taking the bushing out, wrapping the outside in a few layers of duct tape, and reinstalling it with the hope the tape around the outside will make it tighter, and rid the fork of play.

Has anyone else experienced anything like this, and would my duct tape solution be workable? I am sick of working on these forks, it seems every week there's something new wrong with them, I just wanna get the bike going and ride it! So any ideas to solve the problem are much appreciated.

Oh, and right now it's running 7.5wt oil and extrastiff springs, and even with the damping adjustments are wound all the way in she's still waaaaaay too bouncy, will making the jump up to 12.5wt oil be too big, or should I stick with 10wt? Note that for my uses I want something with somewhat slowish rebound, so I'm thinking 12.5 would be better.

 

[nicklouse]

dont use duct tape. (if you are talking about the fabric based one! if you are talking about the metal one still NO the glue will cause problems.)

you can get thin sheets of metal(like cooking foil but abit thicker) use this round the bushes to tighten them up.

the Mr t's should be fitted with one long bush in each leg (the size should be ok as there is only 30mm and 32mm) and yes there was some shimming needed doing to some of the older forks to get them feeling good.

re the oil go to 12.5 as you has the heavy springs or fit some lighter springs and use 10w.


makes you think about only fitted once forks! why?

good luck with them as they are (were) good when working well.

 

[Rik]

Hmm, good thinking regarding the glue. I guess some aluminium cans will have to be sacrificed to the bomber gods to make this fork work better. Full rebuild will be done on monday, oh yay.

 

[Rik]

Oh great, pulled the forks apart, threw new bushings in, and..... there's still heaps of play.
Is this common? Are my lowers rooted?

I can't warranty them, so what's the best way to get them working without play, just shim them up?

Oh, and the oil was horrible, it was grey murky sludge, and there was bugger all oil in it. Hrm, interesting.

 

[nicklouse]

quite often the new bushings need to be shimmed as you said first.

pop cans a bit on the thick side try cooking foil (baco foil in the uk) or whatever you lot have down there!

 

[nicklouse]

the grey is normal (sorry just read the reset of the post) it is just bits of aluminium from the internals.

sounds like needs to see a fork doc to check there is nothing seriously fked.

i would shim the bushes and replace the seals and of course the oil.

 

[Rik]

I've used aluminium foil to shim the bushings... 4 folds of it wasn't enough, 5 folds is a little bit too much, but right now I'd rather it on the tight side than the loose side, plus there's no oil yet so we'll see how it goes when it fills up.

As for the seals, since the forks are new, as are the seals. I got them out without much trouble, so they aren't damaged, and I'm too cheap to buy new seals just yet.

Tomorrow morning I'll get some oil (fucken useless brother didnt bring me home any tonight), and hopefully it'll all come together with no hassles.

I'll post pics of the operation when I can be bothered.

 

[lupine128]

sorry i didn't get back to you sooner, been a bit busy here.
soda cans are probably the best fix here if you don't want to go to the trouble of getting shims made to fit.
folded alfoil will break down fairly quickly, and add to your grey sludge problem.
with the fork completely stripped, wash everything clean, and wipe down with a little light oil. fit the soda can sections so they can't slide or shift at all. check to see what your clearances are like then.
with the oil, pour a little oil in, and cycle the fork a cpl of dozen times, to flush the oil all through the internals, then tip it out, and fill with the correct weight and volume for your fork. this just ensures that any remaining gunge is flushed out.
the problem with shimming the bushing out is that just a tiny bit to much, and they'll stick like hell, to little and they'll feel sloppy.
just keep working at it until you find the right amount.

 

[Rik]

Unfortunately, aluminium cans are too thick, I've already had a go with them.
Right now I've only tried stuff that wraps the full way around the bush, if I were to use a can I'd have to have it only partially wrapped around the bush, and then there'd be all sorts of issues with uneven contact between stanchion and bush.

The fork's had a really good cleanout, I pumped the damper full of degreaser, same with everything else, so it's all nice and clean now.

 

[lupine128]

the other option is to get some shims made out of sheet ally in the right thickness, and kepp them for ever.
it's a really tricky annoying job, so expct an engineering place to hate you and charge you mucho mula, but it's an option. so is leaving the alfoil in there, saying screw it, and going and having a beer.....

 

[Rik]

Too early for a beer, but that'll be my only option for now.
I could imagine how much an engineering place would swear if I were to go in there with my piece of foil folded over 5 times, saying "I need a shim this thick"
:shock:

 

[Rik]

Alrighty, fork is back together, and seems to be working well enough. No play in the bushes, but there's still a little bit of disc-induced flex, not much I can do about that though.