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Polybush Suspension Bolts
Sideshow_Bob - 21/8/07 at 12:23 PM

As mentioned in a previous post I am just about to assemble all the suspension components - front and back. Front is polybush, and rear is live axle rose jointed. In initial playing i noticed that there seemed to be a lot of play between the bolt and the crush tube, and the rosejoint inner and the bolt. This is using 1/2" bolts. (polybush from rallydesign and 1/2" unf rosejoints)

What bolts are all you guys using for your suspension setup.? I'm concerned that the play in the bolts will cause impulse fatigue damage. Especially concerning the rosejoints.

Cheers

Bluemoon - 21/8/07 at 12:26 PM

The crush tube should be compressed and thus tight once you do up the bolts? i.e. the play is not importent once tightened, I guess the same goes of the rose joints?

Dan

[Edited on 23/8/07 by Bluemoon]

procomp - 21/8/07 at 01:50 PM

Hi it's a comon problem with some of the manufacturers. They supply bushing at 1/2" and bolts and brackets at 12mm.

All because it's cheaper and easier to supply metric bolts. So customer then has to drill/ream out brackets to 1/2" and buy new 1/2" bolts.

Just relying on the crush tube being tigtened with the play still in there is not acceptable IMHO.

cheers matt

Sideshow_Bob - 21/8/07 at 02:54 PM

Yeah that was my view too Matt. I was wondering whether anyone is using 1/2" shoulder bolts - this should provide running clearance, but eliminate the play? If so do you know where to get hold of them?

My guess is that it is more important for rosejoint applications to prevent premature wear.

I might being very pedantic about this ...so if I am someone please tell me.



Cheers

Alan B - 21/8/07 at 04:38 PM

quote:
Originally posted by Sideshow_Bob
Yeah that was my view too Matt. I was wondering whether anyone is using 1/2" shoulder bolts - this should provide running clearance, but eliminate the play? If so do you know where to get hold of them?

My guess is that it is more important for rosejoint applications to prevent premature wear.

I might being very pedantic about this ...so if I am someone please tell me.



Cheers



I'm puzzled by "running clearance"....the bolt is NOT acting as pivot shaft, purely a clamping device for the crush tube. Or did you mean some small clearance for assembly?

Either way I wouldn't use a shoulder bolt in this application. Ideal is an aircraft type bolt with just sufficient threads to be bolted up correctly and a close toleranced shank.

I guess good quality, correct sized HT bolts should be fine though.

Bluemoon - 23/8/07 at 03:54 PM

Indeed Alan B hence my comments, bolts not a pivot, the tube is!

Dan

Angel Acevedo - 23/8/07 at 09:37 PM

quote:
Originally posted by Bluemoon
The crush tube should be compressed and thus tight once you do up the bolts? i.e. the play is not importent once tightened, I guess the same goes of the rose joints?

Dan


[Edited on 23/8/07 by Bluemoon]



Dan,
It`s my understanding that Crush tube and Bracket are acting as one piece once torqued up?
Thanks in advance

Bluemoon - 24/8/07 at 08:38 AM

Yes.

procomp - 24/8/07 at 08:45 AM

Hi that 0.7 mm of play will eventualy start showing up and giving problems. This has showed up on most of the cars with some milage on them that where done this way.

And all for the sake of the manufacturer supplying the right size bolts in the first place.

I know its locost but where do you draw the line.

cheers matt

MikeRJ - 24/8/07 at 11:21 PM

quote:
Originally posted by procomp
I know its locost but where do you draw the line.


Totaly agree. Locost means using your head to solve problems inexpensively, not bodging stuff together. Personaly I'm not very impressed at the rear axle I bought from a supplier where the panhard rod mounting is M12, but the rose joints in the panhard rod are 1/2". No need for it when either M12 rod ends are easily available, or the axle could have been designed with a 1/2" thread.

[Edited on 24/8/07 by MikeRJ]