Board logo

how snug does a lower wishbone bush bolt hole need to be?
Chris_Xtreme - 30/9/16 at 03:07 PM

HI all,

I had a rusted together and broken lower bush on one side and had to cut it out.. ended up getting a plate welded on etc to make it good.

I replaced the bush and all seems good.

I decided to do the other side, it was indeed rusted together, but this time the bolt head sheared the bolt inside the hole, so I thought I would drill the bolt down, this worked well, but it made the hole a bit bigger than the bolt, say 11ishmm rather than the 10mm it was for the bolt to fit in snug.

is this a problem? should I do what I did before I welt a plate on to get me back to a tight fit?

cheers for any words of wisdom!



Slimy38 - 30/9/16 at 04:16 PM

I may get shot down for this, but since the bracket is clamped between the bolt head/nut and the crush tube, I don't believe it should matter that much?

(blindfold is on, fire away... )


Chris_Xtreme - 30/9/16 at 04:20 PM

which poses another question for me then - should I be doing these up mega tight?

I haven't done, but I've only ever adjusted them on this car and as the previous bushes were rusted up, they were spinning on the outside of the bush.


JC - 30/9/16 at 04:37 PM

If you are worried, weld a thick washer on of the appropriate size? I seem to remember seeing this suggested in a magazine once....


Chris_Xtreme - 30/9/16 at 05:13 PM

quote:
Originally posted by JC
If you are worried, weld a thick washer on of the appropriate size? I seem to remember seeing this suggested in a magazine once....


I guess you are right, being that I have posted the question, makes me think I should do something about it anyway.

a thick washer would save me cutting up and drilling a bit of metal, interesting idea.

I'd still like to know, if anyone knows, if it is necessary or not.


cheers


coyoteboy - 30/9/16 at 06:56 PM

Unlikely to use the bolt as the locator unless the shank extends all the way through normally. It will just use the clamp force to resist movement. I'd just go for Max recommended torque for your fastener.


Chris_Xtreme - 30/9/16 at 07:09 PM

quote:
Originally posted by coyoteboy
Unlikely to use the bolt as the locator unless the shank extends all the way through normally. It will just use the clamp force to resist movement. I'd just go for Max recommended torque for your fastener.



the shank doesn't go all the way through the hole, just the bolt.

I'd best be going back to the guys who made up the bush for me to find out a suggested torque setting!

cheers, Chris


ashg - 30/9/16 at 07:27 PM

just weld a washer on.

its a pretty common thing to do when you want to use a 12mm bolt on a suspension bracket with a 1/2 inch hole. the clamping force between the suspension bracket, the bush and the bolt is what holds everything in place.

having a hole that is slightly too big makes suspension alignment tricky as you can never get everything back in exactly the right place if the hole is too big and your taking the suspension bolts in and out to do maintenance.


Chris_Xtreme - 1/10/16 at 10:10 AM

thanks all - I'll weld some bits on.


Banana - 5/10/16 at 05:26 PM

So would it not be better to get crush tubes with 12mm ID?

I was putting mine back together today and was slightly concerned by the amount on play the bolt has in the tube.

I know its meant to be clamped so the bolt size doesn't really matter, but if i was going to get some stainless tubes made up, would i be better getting some with an ID on 12.1mm maybe? Has anyone else done this?


CosKev3 - 5/10/16 at 06:50 PM

quote:
Originally posted by Banana
So would it not be better to get crush tubes with 12mm ID?

I was putting mine back together today and was slightly concerned by the amount on play the bolt has in the tube.

I know its meant to be clamped so the bolt size doesn't really matter, but if i was going to get some stainless tubes made up, would i be better getting some with an ID on 12.1mm maybe? Has anyone else done this?


Your tubes could be for 1/2 UNF bolts,so about 12.8mm?

You are right ideally you need the correct bore tube for the bolts,as the movement you talk of can cause issues if you have to undo the bolt after you have had the geometry set up.