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exhaust to frame mounting rubber bushings

Posted: Wed Nov 12, 2014 6:21 pm
by mikefealk
well im down to a bare frame now in my restoration. 74 gt 750. where the exhaust pipes mount to the frame, there are two rubber bushings pressed into the holes on the frame on each side of the bike. i tried to press them out but to no avail. can i leave these in when it is powdercoated? or will they melt? i dont know if you can even get replacements so i really didnt want to mangle them up? i tried pb blaster, torch, etc, and they will not budge. anyone?

Re: exhaust to frame mounting rubber bushings

Posted: Wed Nov 12, 2014 6:33 pm
by Coyote
Absolutely leave them in place. Heat from the powder coat process will not harm them at all. I have had 3 frames powder coated. I left the bushings in 2 of them. I took the bushings out of the other one. Never again. They are a super bitch to get out and near impossible to put back in. I just had my 550 frame powder coated 2 weeks ago. Bushings in -- no problem.

Re: exhaust to frame mounting rubber bushings

Posted: Wed Nov 12, 2014 6:37 pm
by mikefealk
sweet thanks for the info. i wish i had known that an hour ago before i semi buggared them up lol. oh well, not like they are the most important component on the bike. thanks!

Re: exhaust to frame mounting rubber bushings

Posted: Thu Nov 13, 2014 2:38 am
by yeadon_m
Mike,

While not the most important, that they work IS very important to how the bike feels when riding. It is essential that, when the exhaust bracket is bolted up tight to its mount on the frame, the exhaust stack on each side is free to wiggle on that bushing. If it cannot float then (i) you will feel unpleasant vibration and maybe hear noise you don't want and worse (ii) your exhausts might crack (I've had header failures on a GT550 where the pipes had been tightened solidly to the rear frame mount!).

Cheers,
Mike

ps: my bushings also have been through powder coating and are fine

Re: exhaust to frame mounting rubber bushings

Posted: Thu Nov 13, 2014 12:57 pm
by petead23
Mike I replaced mine recently. Just put a big drill through the middle. Then prised out the casings. They can be bought from the usual places. To put them in is difficult as they are an interference fit. I just fed a bolt with a large washer through from inside the frame and then through the bushing then a large washer and finally a nut. Just make sure its straight and wind the nut up and it will pull it in flush. Removed the nut and bolt. Hey presto! Good luck!

Re: exhaust to frame mounting rubber bushings

Posted: Thu Nov 13, 2014 3:33 pm
by Coyote
You got lucky. I con caved 36 washers and stacks of washers, stripped grade 8 bolts and nuts and never did get them fully in. Turns out the interference fit was .010 . If I had measured things first, I would have had the bushings ground or turned to a reasonable .001 - .002.

Re: exhaust to frame mounting rubber bushings

Posted: Thu Nov 13, 2014 4:26 pm
by GT750Battleship
8) Hi,a little difficult yes to get them out...hacksaw carefully through the bush "without" touching the frame. :oops: ...hit with old screw driver or something suitable & the bush will collapse & come out easly :up: These bushs don't last forever,they do fail due to age & service,as Mike points out they are a source of vibration.when they fail & if the mounting bracket is not spaced by a washer to stop the mount being solidly pulled up tight against the frame :(
Cheers,
Roger

Re: exhaust to frame mounting rubber bushings

Posted: Tue Nov 18, 2014 10:54 am
by mikefealk
thanks guys, i left them in and took the frame to powdercoat shop yesterday. the powdercoat guy said, "you got some rubber bushings in there", and i replied, "I know". bake em. lol