The BSA A7-A10 Forum

Technical => Frame => Topic started by: bl**dydrivers on 15.05. 2011 21:52

Title: Swing arm silent bloc bushes
Post by: bl**dydrivers on 15.05. 2011 21:52
shall i fit new ones before i get my swing arm powder coated or after?

Im confused because if i do this after wouldnt it crack the paint? and if i do it before wouldnt the heat melt the rubber bushes?
Title: Re: Swing arm silent bloc bushes
Post by: bsa-bill on 15.05. 2011 21:57
Remove them before you get them powder coated, fit new ones after but remember to plug the tube
Title: Re: Swing arm silent bloc bushes
Post by: bl**dydrivers on 15.05. 2011 22:04
what shall i plug it with? just masking tape
Title: Re: Swing arm silent bloc bushes
Post by: chaterlea25 on 15.05. 2011 22:58
bl**dydrivers
""what shall i plug it with? just masking tape???"""

2 choices threaded bar nuts and washers or tinfoil balled up into plugs!!

HTH
Regards
John
Title: Re: Swing arm silent bloc bushes
Post by: RichardL on 16.05. 2011 01:43
If yours turn out to be anything like those I had (and some others here), the extraction and installation will be major tasks. There are new bushes out there that are a couple thou too big. Mine were, and I ended up honing the inside of the swingarm to approach a fit. Even then, using 3/4" nuts on all-thread rod and a very big breaker bar to squeeze them into the swingarm, it was a monster, sweat and curse-filled job. Had I known better, I would have tried to machine the bushes to a closer press fit. Remember, after powder coating, I doubt you will want to heat the swingarm to expand its I.D. and you won't have the means to freeze the bushes. Even if you could do both those things, it is doubtful you could maintain them long enough to squeeze in the bushes.  One reason I'm saying this is to warn that you really must keep all powder coating out of the the I.D. If I'm reading John correctly, his first suggestion is to run a rod through the swingarm and close the ends with washers. This sounds the best. I think the foil would allow in traces of powder and that would scare me.

Finally, if it was mine to do, and the existing bushes were good, and I was not building concourse, and knowing what I went through the first time, I would have a major decisison to make regarding keeping the existing bushes and spray-painting the swingarm.

Richard L.
Title: Re: Swing arm silent bloc bushes
Post by: andy2565 on 16.05. 2011 09:10
surely theres got to be a better method than a metalastic bush,i remember reading somewhere roy shearwood doing a convertion to a featherbed style bonze bush and sleeve,or even needle roller,when i get round to it,i will go down this road,its got to give more solidity than a rubber bush,
Title: Re: Swing arm silent bloc bushes
Post by: bsa-bill on 16.05. 2011 09:21
Agree with Richard and John
The heat will damage your bushes if there is any oil ingressed into the rubber, mine looked a bit perished so I changed them.
As Richard said there are bushes out there that are NOT correct but sold as the real thing, I bought bushes off a BSA trader and club official that were wrong, ended up crunched up rather than drawing in.
I bought new  replacements from C&D Autos that they had made by the original firm from original drawings, they went straight in no problem also they have a rounded leading edge on the outer sleeve, makes starting them in easy.
To remove the old ones my method (there are others with equal merit) is to drill out the rubber from between the sleeves, then you can drift out the inner sleeves, next make a cut (hacksaw or an air saw is brilliant) in the outer sleeves , be careful but it's not big issue if you nick the S/A tube a wee bit, then collapse the outer sleeves in on themselves and drift out.

If you take your time it's not sucj a bad job

good luck
Title: Re: Swing arm silent bloc bushes
Post by: bsa-bill on 16.05. 2011 09:48
Don't know about that Andy, most bushes are replaced due to getting the S/A powder coated as in this case, other than that most of them still seem to be working well enough after fifty odd years, and with absolutely no maintenance.
I could well be wrong but can't recall anyone saying there bushes where not working, I changed mine as they were a bit perished but just on the ends I think and I thought oil might have got in there.

Can't see a metal bush lasting as long
Title: Re: Swing arm silent bloc bushes
Post by: andy2565 on 16.05. 2011 10:15
the bushes would be easier to replace if necessary,and easier to fit,shafts wouldnt rust in place,we used to have metalastic bush's in our grasstrack bikes,but they've all been replaced with nylon bush's now,the metalastic bush's have some side to side movement when under stress,do road racers use metalastic bush's ? not to sure,i've had the experiance of removing the silent block bush's,and don't relish the idea of doing it again,cheers andy
Title: Re: Swing arm silent bloc bushes
Post by: muskrat on 16.05. 2011 11:10
Done the cafe with bronze bushes 20 years ago and I think I have only greased them twice.
Cheers
Title: Re: Swing arm silent bloc bushes
Post by: bl**dydrivers on 16.05. 2011 15:00
I can only imagine how difficult it must be, it looks and sounds difficult.

I was thinking of taking it to a machine shop to hydraulically press them out and the new ones in.
Thinking of getting the bushes from SRM as theyre reputable.

Title: Re: Swing arm silent bloc bushes
Post by: RichardL on 16.05. 2011 17:48
As I recall,  there is an internal shoulder that would prevent their being pressed out.

edit: If I only halucinated this shoulder in a fatigue-induced stupor following the install of my silent-blocs, hopefully, someone will let us know.
Title: Re: Swing arm silent bloc bushes
Post by: 850norton on 16.05. 2011 22:09
I was curious about this myself as the B44VS I have was in a right state when I got over a year ago. From the looks of it, it had sitting outside for years. The fork stanchions are rusted badly so they need to be changed out.

The silent block bushes I wondered about and decided that as this is a basket case and parts are missing in a big way and is going to get more or less a ground up rebuild, those would get changed too.

Was just wondering how to get them out and the new ones in. Will oil or WD40 damage them in anyway as a means to aid installation. I was thinking of the threaded rod with spacers/whatever as a way to draw them into place and WD40/oil to help them along. I sthiis OK or would that b*gger up the bushes?
Title: Re: Swing arm silent bloc bushes
Post by: RichardL on 17.05. 2011 05:05
850norton,

I suppose there may be several ways to get them out but I know two. One is explained by bsa-bill earlier in this thread. My method was to use a reciprocating saw with a hack-saw blade to cut through the inner sleeve, then set fire to the rubber (I do believe the statute of limitationsis is up on any crime that might have been). Then, the inner sleeve came out fairly easily. Then, sawed through the outer sleeve, prised it up and it loosend adequately to be pulled out.

As far as WD40 damaging the rubber goes, I am quite certain there is no concern there. I am also quite certain that it won't make the installation of the bushes any easier if they are of the oversized variety. If they are sized with about a 0.001" to 0.0015" interference fit, they might go in with gentle urging if the bushings are first frozen and the swingarm well heated. But I am just speculating on this, since my own exereince was just south of WWIII. 

Richard L.
Title: Re: Swing arm silent bloc bushes
Post by: bsa-bill on 17.05. 2011 08:46
Richard  you weren't hallucinating , mine had a shoulder

I also used  a similar saw I think, it's an air tool and looks like it's going too slow to work but it's a great tool.

I think I would stick to replacing them dry, the ones I got from C&D drew in just fine with threaded rod, don't think you want any kind of lube in there as it's the rubber that needs to flex not the bushes turning in the tube.

I have my suspicions that quite a few of the older/wiser members on here will be wondering why we bother changing the things, would somebody please tell me their bushes had disintegrated to the point they no longer worked, then I'll feel better about the time and expense
Title: Re: Swing arm silent bloc bushes
Post by: KiwiGF on 17.05. 2011 11:28
I have my blocs out by using the cut spindle drill rubber melt rubber collapse bloc using a drift and hammer out using big drift technique.....but im waiting for new blocs so new ones not in yet

 I'm not looking forward to fitting them given the comments here

How can one sure the new bushes will be the right size?

My Reason for replacement was the spindle was worn where it fits through the frame holes i guess as the spindle was not tightened enough? This causing play on the swing arm assuming the spindle cannot be done up so tight it cannot move and to get things apart I had to cut the old spindle

I would advise not to attempt to force the spindle out of the old blocs as the frame can be easily distorted around the holes ask me how I know

The frame holes have too much clearance on the new spindle for my liking on my bike but I'll make a very thin bush if necessary maybe 010 wall thickness to get rid of the clearance
Title: Re: Swing arm silent bloc bushes
Post by: BSA_54A10 on 17.05. 2011 11:38
Usually you have to spring the frame slightly and use a blade to cut through the spindle.
Title: Re: Swing arm silent bloc bushes
Post by: Triton Thrasher on 17.05. 2011 12:43
My experience is that they never need to be replaced and people find them difficult to remove, difficult to find new and difficult to replace.

But don't let that put you off.  There are probably prizes for "best powder-coated swing arm" at prestigious events.
Title: Re: Swing arm silent bloc bushes
Post by: 850norton on 17.05. 2011 13:45
850norton,

I suppose there may be several ways to get them out but I know two. One is explained by bsa-bill earlier in this thread. My method was to use a reciprocating saw with a hack-saw blade to cut through the inner sleeve, then set fire to the rubber (I do believe the statute of limitationsis is up on any crime that might have been). Then, the inner sleeve came out fairly easily. Then, sawed through the outer sleeve, prised it up and it loosend adequately to be pulled out.

As far as WD40 damaging the rubber goes, I am quite certain there is no concern there. I am also quite certain that it won't make the installation of the bushes any easier if they are of the oversized variety. If they are sized with about a 0.001" to 0.0015" interference fit, they might go in with gentle urging if the bushings are first frozen and the swingarm well heated. But I am just speculating on this, since my own exereince was just south of WWIII.  

Richard L.

I had heard of the method and amy give that a try....the WD40 I was thinking if the bushes were correst size, not oversized like I had been hearing of earlier in the thread.
 
Title: Re: Swing arm silent bloc bushes
Post by: andy2565 on 17.05. 2011 19:29
i think unity equip do an a10 conversion to the manx sleeve type bush setup.its somewhere in their catalogue.
Title: Re: Swing arm silent bloc bushes
Post by: Topdad on 18.05. 2011 14:08
H
Title: Re: Swing arm silent bloc bushes
Post by: Topdad on 18.05. 2011 14:26
Hi everyone Bob hebdon, newish to forum so hope you don't mind my 2 pennyworth on this! I've had 2 experiences with these b****Y things thankfully seperated by nearly 35 yrs. First one done in bedroom ( you do these things in strange places when you're only 16 ) fortunately only had to fit 'em and the went in easy using long threaded bar ,nuts and various washers plus lot's of washing up fluid. 2nd time time ,well I nearly pulled the shed apart heaving and straining etc ,gave up went to a local bike shop and he ,after nearly an hour pushed out and new one's back in using the shops large press .The pressure required he said was off the clock and we heard the bang when they gave way nearly 40 feet away and through 3 closed doors .Don't seem to recall a step inside it and he didn't mention one to me. I'd only do if nescessary ,however, if they need doing and you're going to get the swinging arm powder coated I'd do it after as I have been told the heat of the process will definately kill the new bushes, best wishes Bob.
Title: Re: Swing arm silent bloc bushes
Post by: bsa-bill on 18.05. 2011 14:37
Hi Bob - you beat me to the post as I had short reply to your even shorter first half pennies worth *smile*

You can pull a mailing back and alter it with "modify" ( top right of the posting window)
I use that a lot due to my secondary modern education in spelling, thankfully though we have spell checkers to help to some degree.

My first restoration definitely had a shoulder, the last one though ( a 59 I think maybe didn't )
Title: Re: Swing arm silent bloc bushes
Post by: Topdad on 15.06. 2011 17:11
Hi Bill only just seen your post don't remember doing that ......must be my age, regards Bob.