P/Coating S/A with bushes fitted?

[sprint]

I picked up a NOS B31/33/GS/RGS swinging arm at the Kempton auto jumble a couple of weeks ago. As a NOS item it has been painted and the bushes fitted. However, it has been blasted and all the paint removed, so it  needs re-spraying.

I really do not wan't to be having to remove perfectly good bushes with all the agro and hassle you have to go through, plus the cost of replacement.

The question is can you get away with putting it through the oven without removing the bushes?

Have spoken to the powder coaters and they advise that the oven temp is usually around the 200 deg mark with a min of 180 deg being required. Time in oven is usually around the 20 mins but they could reduce that to 15 mins?

Has anybody had any experience butting the installed bushes through the oven or can advise if it can be done?

[RichardL]

Sprint,

I have no experience with doing this, but it does not sound like a great idea to me. The swing-arm is not so exposed, so maybe this is a good place to just use spray cans. Anyway, I went looking for some tech data on the subject and came up with this chart: http://www.jjshort.com/Rubber-Properties.php

I am assuming that you are citing temps in Deg. C., so 180 C. definitely exceeds the maximum temp for what would seem to be the most  likely formulations (Nitrile, Neoprene and Butyl). I bet someone here knows what it actually is.

Richard L.

[sprint]

Thanks Richard

Hopefully I can get a coat air drying etch primer on it, or very low bake, and then do it with gloss Hammertie, which I have used before unless others can recommend an alternative as I still want a reasonably durable coat to take the everyday knocks one gets without it chipping and falling off around the spindles.

[The Artful Bodger]

Funny enough I've just had a similar dilemma, fortunately for me a lot easier to solve. I do my own powder coating and welded an extension to a foot rest on my Suzuki (foot problems). There was some rust on them and I will always powder coat as opposed to painting on most bike parts, however they have rubber mounting bushes. Fortunately the bushes pressed out easy enough in a hydraulic press so they got sandblasted and powdered.
  I'm not an expert but would suggest that removing them would be the best bet, painting just isn't as tough as powder which I feel is the best option, I've not come across any paint (including two pack) which is as chip resistant as well applied powder. But to leave them and have them fail from the heat after a short time would mean taking the swing arm off again and having to pos. re-finish it after fitting the new bushes.
Colin

[sprint]

if it were just a simple task of pressing/drifting the bushes out it would not be a problem.

Unfortunately you have to totally destroy the old assy. You have to burn the rubber out and then try to remove the thin walled sleeves. I don't have access to such equipment so removing the old bushes is a bit of a problem for me.

So I either need a low bake paint or it will have to be done with an aerosol. Does twin pack also need to be baked at high temp?

I remember having a car wing done some years ago where they dried/cured the paint with an infrared lamp! 

[The Artful Bodger]

Two pack air dries. How old is the NOS swing arm? The bushes will look fine (since they've never been flexed) even if they're hardened and past their sell by date, if they're old might be a good idea to change them now anyway.
 I haven't changed swing arm bushes, been lucky so far, but keep reading about burning them out. Is it possible to chain drill through the rubber (with a lubricant) and using a pad saw (hack saw blade in a handle) to cut through the outer shell most of the way before collapsing them inwards with a chisel?
 As I say I haven't changed a set but thought I was going to need to on my Ariel and was going to try this. Seems the major problem with the Ariels is the center bolt seizing in the spacer. Fortunately, or not as the case might be, my bushes (and bolt) were fine and wear on the frame was causing the problem. Cost me time to build up and re-shape the  frame with hard facing rods, but since I had the rods already, fortunately no money.
Colin

[bsa-bill]

much easier to just drill the rubber out, the thin outer sleeve is not too much of a problem - make a longitudinal cut with a pad saw ( no big deal if you mark the inside if the S/A a little) tap the cut bit in on itself to collapse the sleeve to assist it's removal.

biggest problem I had was trying to fit the new (wrong size) bushes from a BSA Guru trader whom I've never bought from since, got proper ones from C&D

[RichardL]

First. I think you should avoid replacing the bushes unless it is absolutely necessary. I think I have heard, maybe, one story on the forum about an installation effort that was not life changing. Mine certainly was. Forgot who it was, maybe Chaterlea25 or Orabanda, who machined the outer sleeve to a better fit, then froze the bushing and heated the arm. If you are thinking of doing something like this, please find the actual post and don't go by my questionable memory.

Second, it would be oxygen or UV that would destroy the rubber and, other than the exposed ends, the bushes are spared from these destructive agents. I am willing to bet [all the beer you (Sprint, not "all of you") can drink in one night when we get together at the pub (but not the airfare to get together)] that there is at least one member here running original bushes that are still working fine. (Notice that my bet is really a no-lose proposition, as I will be drinking alongside.)

Richard L.

[sprint]

I don't have access to such large drills and only have limited workshop hand tools.

I think I will try to find somebody locally who can do 2/2K Pack.

[RichardL]

When Bill was talking about drilling out the rubber, he meant a small drill that fit between the sleeves. I also think Bill must be talking about solid spindle bushes, because the rubber thickness is so small with the hollow spindle that getting a drill in there and doing much damage to the rubber seems very tricky.

Richard L.

[sprint]

I am sure that in the day BSA and/or the various workshops must have had a tool/equipment to simply press the old bushes out, as I can't believe that they would have to go through the hassle of burning the old ones out, removing the sleeves and then repair the paint just to change them?

[Topdad]

Is this job the last before you start to build? Or is it part of a long term rebuild ? If you want to ride the bike as soon as poss go 2pack see how it fairs ( mine was sprayed with cans and after 8years isn't showing any signs of rust etc ) if not powder coat but I wouldn't give much for the bushes survival, bobh

[RichardL]

Taking a closer look at the swingarm, I noticed something I haven't seen before. Maybe I wasn't paying attention then, either. If this is truly NOS, then it seems like BSA had sleeved-down the I.D. to take a solid spindle in hollow-spindle bushes. Maybe this is how they made RGSs once the rest of the line was using right-side-pull full-width rear hubs and hollow swingarm spindles.

Richard L.

[wilko]

Just two pack it. Why all the fuss?

[Brian]

The direct answer is no, you can not get it powder coated with the bushes in place. If you do not want to replace the bushes then it will need to be painted.