Big T
|
| posted on 3/3/23 at 09:38 AM |
|
|
Problems with my bushes
As per title, I am having problems with my bushes and they’re driving me a little bit bonkers. Such a simple aspect of the build and it seems to be
fighting me the whole way. From my limited experience with polyurethane bushes I suspect that there is something too tight in the fitting and I am
hopeful this is easily overcome.
They are top hat style bushes with a steel crush tube running through the centre. Both top hats will push in with no real problems. I can place the
bush tube on the bench and push the top hats in by hand. No problem there. The problem occurs when I then push by crush tubes in.
When the crush tube is pushed in it goes in fine initially. It takes a good bit of force to get it in but once going it’s all good. The problem occurs
once the crush tube passes half way and starts to get pressed into the second top hat. It seems to start pushing the second top hat out of the bush
tube. I am using some plates either end as big washers, along with a threaded bar and some nuts to push these bushes in central and square. Once I
undo the press the exit side of the bush (the opposite end to where I pushed it in) the bush deforms out by perhaps 2/3mm from where the top hat edge
should be sat. Therefore the wishbones won’t actually fit in the brackets on my chassis because the bullying makes them too wide.
Points that I think are relevant.
* My bush tubes are the correct I/D, they are not yet painted or coated so there is no reduction to the I/D of the bush tube. (Can’t remember the
figure off the top of my head but these are checked and ok)
* The bushes measure the same dimensions as stated in the book
* The bushes are the updated shore 95 compound so are a bit firmer than standard.
* My crush tubes appear to be correct at 19mm O/D.
* These are being pressed in with grease where required however when the crush tube is pressed in the interference between the two parts is so close
it pretty much removes the lubrication from the surface it is applied to.
If I am missing something glaringly obvious here please let me know! It’s all too easy to over think things. I am wondering if it is worth turning
0.5mm off of the O/D of my crush tubes reducing them to around 18.5mm and then trying to push this into my bushes and see if that stops the second
half getting pushed out. My only concern with this is that over time as the bushes wear through use and get “broken in” it will result in an abnormal
amount of slop and play or result in them failing prematurely. I will also contact the bush manufacturer to see if I can get some of their input as to
why this is happening.
I will try to upload some photos later today of the parts to help explain what I am trying to describe.
Any help, guidance or advice would be great fully received.
Cheers guys! Big T
|
|
|
|
|
JAG
|
| posted on 3/3/23 at 11:38 AM |
|
|
What you describe sounds about right - it's how I remember it happening when I fitted mine.
I recall having to force the wishbone over the Bush after I'd fitted the Bush to the Chassis. By 'force' I mean I used a soft faced
mallet to explain where I wanted the wishbone to go 
Although the wishbones were very stiff to move I assume that the Bush must have returned and absorbed the previously bulging material. I would have
worried if the wishbone had shave off the Bush - but it didn't.
I fitted the bolt and I haven't had any issues since.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
|
|
|
Big T
|
| posted on 3/3/23 at 11:49 AM |
|
|
Thanks for the reply.
So In your case you just bashed the wishbones into the brackets and all was ok?
Problematically my bushes are bulging significantly to the point they’re no where near fitting the brackets. IIRC the wishbone bracket I/D is 44mm. My
bushes have probably popped back out 3mm or so, giving my an overall width on my bushes of about 47/48mm.
Annoyingly without the crush tube installed the bush fits inside the bracket with just a minor amount of force.
[Edited on 3/3/23 by Big T]
|
|
|
JAG
|
| posted on 3/3/23 at 12:17 PM |
|
|
Hmmm it does sound like your Bushes are bulging more than mine did!
Other than giving the Bushes a bit more of a squeeze (to reduce the bulging) I don't have any other advice. Sorry 
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
|
|
|
Mr Whippy
|
| posted on 3/3/23 at 01:04 PM |
|
|
I'd put a chamfer on the crush tube so it doesn't push the top hat out or, put a chamfer on the inside ID of the bush. I wouldn't
concern yourself with it being tight, as soon as it wears it won't be tight anymore and these kind of basic joints should be taken apart every
year or so to service. Personally I think metalastic bushes are vastly superior for normal road use, born out by the shear number of production cars
that use them.
|
|
|
Big T
|
| posted on 5/3/23 at 11:06 AM |
|
|
I think I have figured this!
It seems like a combination of a few things resulted in the crush tube pushing the back bush out of the bush tube. I think this was a combination of
things but most notably, the temperature.
I brought some of my bush tubes into the house and left them for a little bit, thought I’ll assemble two sets to photograph and post on here to show
what the issue was and then hopefully we could figure it out between us. I left them for a while and popped them together, absolutely fine! Back into
the garage to do another few thinking I’d solved the problem, nope, pushed the 2nd bush out the back again.
So I am thinking the 0 degrees out in the garage had made them go cold and hard which was giving me grief pressing them in.
I could be miles off, who knows, but when they’re warmer they go together fine!
|
|
|
Mr Whippy
|
| posted on 6/3/23 at 07:50 AM |
|
|
maybe just pop them in a kettle to help soften them, then just quickly push them in?
|
|
|
Prof_Cook
|
| posted on 6/3/23 at 08:36 AM |
|
|
Many thanks Mr T for posting this - and the apparent solution. I'm long way from getting to that stage but your thinking seems right to me.
|
|
|
rusty nuts
|
| posted on 6/3/23 at 10:19 AM |
|
|
Before you actually fit the arms check the crush tubes are long enough for the job, nip each eye of the arms in a vice with the bushes assembled so
the crush tube is nipped, then check the arm rotates easily. A lot easier than assembling the car and finding the suspension isn’t compliant . Do a
search on here for crush tubes
|
|
|
.jpg)
