Dave J
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| posted on 6/1/04 at 04:59 PM |
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polybushes
Hi all,
I've just fitted the polybushes into my wishbones and unlike what seems to be the norm, mine didn't require the usual massive effort to
fit. Now, I'm no Swartzennegger, but I managed to push them in by hand, quite hard but do-able. As for the steel anti crush bushes I have had to
employ a G clamp to press those in ( I have as couple which actually slide in quite easily..no play though)
Is the megga tightness an issue? or do you think my reasonable interference fit will be ok (0.2- 0.3mm diference between bush od and wishbone id)
I suspect once everything is bolted together, it will be solid, but your comments would be appreciated.
Thanks
Dave
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dozracing
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| posted on 6/1/04 at 06:25 PM |
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Hi Dave,
Have you silicon lubed the inserts and bushes? They will need this to move freely.
Kind regards,
Darren
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PLEASE NOTE: This user is a trader who has not signed up for the LocostBuilders registration scheme. If this post is advertising a commercial product or service, please report it by clicking here.
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Dave J
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| posted on 6/1/04 at 06:48 PM |
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Hi Darren, Thanks for the reply
Yes, although I have used copper grease.
I'm still wondering if my bushes are tight enough. I think to achieve the sort of press in fit that seems to be the norm, the difference between
the poly bush od and the wish bone id has to be around 0.5mm (in engineering terms thats hell of a lot)mine are 0.2-0.3mm. Of course the tighter the
fit the more the bush bore is reduced ( squeezed in) making the steel liner incredibly tight to fit.
Anyone like to comment on this observation?
Is it really necessary to have them vice tight?.
Maybe making an oversize bush and pressing that in would achieve the same effect should your bushes be too easy a fit.
Many thanks.
Dave
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Hornet
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| posted on 7/1/04 at 08:03 AM |
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Hi m8
I had a similar problem last year (search thread if you want) where my crush tubes were too tight inside the poly. This meant my suspension
didn't want to move when everything tightened up. I got hold of a 16mm reemer as my crush tubes were 15.98mm OD and this cured the problem.
I would say your bore on poly bushes is incorrect, or bushes are incorrect. You cant leave it like that.
Hope this helps.
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Dave J
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| posted on 7/1/04 at 08:58 AM |
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Thanks Hornet, that is a help. Glad to know I'm not alone on this. I'll check the free movement once everything is bolted up and take it
from there.
All the best
Dave.
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flyingkiwi
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| posted on 7/1/04 at 10:32 AM |
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almost answered my problem, what size bolt are you using with your bushes? have measured up the steel tubes and they have a i.d. of just under
13.75mm. I can't get hold of 13mm bolts and was wondering if you just drill em out to 14mm.
cheers
It Runs!!!!! Bring on the SVA!
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Hornet
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| posted on 7/1/04 at 11:01 AM |
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I am using 12mm bolts as my crush tube has 12.5mm bore (made on lathe) however, in my opinion, once you tighten the bolts onto the crush tube, you
would not have a problem with 12mm bolts. What size of hole do you have in your brackets? this is more important.
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Dave J
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| posted on 7/1/04 at 03:48 PM |
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Hornets spot on, you must consider the holes in your brackets. It's quite a size jump , make sure you don't weaken the brackets (no doubt
there is plenty of meat to spare)
Another thing, if you open up everything to 14mm and don't leave sufficient clearance for the bolt, then unless you've been super accurate
with your brackets, you may find you have fun and games lining everything up.
Been there , done it etc
Just a thought
All the best
Dave
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Dave J
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| posted on 7/1/04 at 03:57 PM |
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addition to the above:
The above is only relevent of course if you up the bolt size to 14mm.
I'm using 12mm bolts with 12.3mm tube id
If it was me, I think I would look to replace the crush tubes if you can't use 14mm bolts, there is alot of movement potential in 1.75mm
clearance should anything become loose.
Cheers
Dave.
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type 907
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| posted on 7/1/04 at 06:17 PM |
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Hi Dave
Your bush should be a tight fit in your wishbones otherwise they will turn in the w/b instead of turning on the crush tube. I made my
w/b's in stainless and used 25mm o/d bushes. Bored the bush tubes to 25 which shrank when I welded them (.05mm). Fitted them with the aid of
the vice. This as you say shrinks the i/d of the bush, which I then reamed on the lathe to ensure perfect alignment with each other. When fitted to
the chassis they just need light pressure (one hand) to move them.
The crush tube i/d / bolt size isn't an issue IMHO as when the bolt is tightened nothing can move except the bush on the crush tube.
Paul G
Too much is just enough
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Peteff
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| posted on 7/1/04 at 08:17 PM |
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Poly bushes don't compress when you fit them into the bush tubes, the rubber Triumph ones do. You could loctite them into the bush tubes if you
are worried about them turning there instead of on the crush tube.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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flyingkiwi
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| posted on 7/1/04 at 11:20 PM |
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bit of a puzzle that as the crush tube's are the one's supplied by mk. As to the size of the brackets the current holes are 12mm, so I
think I will be making some new crush tubes, are they just mild steel?
Cheers guys
chris
[Edited on 7/1/04 by flyingkiwi]
It Runs!!!!! Bring on the SVA!
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Hornet
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| posted on 8/1/04 at 08:07 AM |
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Most are mild steel m8, but if you can get something better then go for it, for example a ground finish would be best.. it is after all a bearing
surface you are gona create. for what its worth, mine are mild steel and polished .
Cheers.
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locoboy
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| posted on 8/1/04 at 09:10 AM |
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how far out of the ends of the bush do the crush tubes protrude? anyone got any pics, i think my crush tubes may be a bit short when inserted.
ATB
Locoboy
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Hornet
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| posted on 8/1/04 at 10:52 AM |
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Col.. mine stick out by 0.5mm each end. 
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Dave J
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| posted on 8/1/04 at 11:28 AM |
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Thanks paul G your info was very helpful.
My crush bushes are harder to push in, but the poly bushes seem to be turning on them rather than the wishbone tube. I have applied some copper
grease to stop the creaking.
Chris, my tubes are mild steel and polished on the od.
Setting the lathe speed to 750+rpm and having the feed rate as fine as possible, that together with a good tool (preferably carbide tip as you will
not need coolant)
Should give you a decent enough finish.
If you want to make them really smooth, give em a light rub over with worn emery with the lathe rpm at 1000+ negligable material will be removed.
Col
My steel bushes are a combination of sticking out about 0.1mm or flush with the outer face of the poly bushes.
I figure that should there be a slight compression of the poly bush faces when bolting down hard onto the crush bushes, then this wouldn't be a
bad thing (I'll probably change my mind later when everything locks up solid )
Thanks all for the replies, certainly helps to keep the old stress levels to a minimum.
All the best Dave.
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locoboy
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| posted on 8/1/04 at 11:48 AM |
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Yes good info in this thread, helps you get the basics right so you cancentrate on the more "interesting" bits of the build, i will mesure
mine tonight but i think they may be recesses into the bush a bit.
they are not my own fabricated bones and the bushes were already in when i got them. if the tube is not protruding i guess its eithr because the bush
was not pushed home fully or the tube on the end of the bone that the bush slides into it slightly too long to alow both halves of the bush to meet in
the middle.
Anyone any advice on removing bushes without destroying them? and advice on how to identify what bushes i need to replace it with if it is destroyed
as i have no idea where they came from.
ATB
Locoboy
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Dave J
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| posted on 8/1/04 at 04:09 PM |
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Hi Col
There is about a 8mm gap between my bushes when pressed in. I managed to tap mine out from the centre by using a piece of plastic rod with the end
slightly radiused (is that a word??) so as to not damage the bushes. By tapping evenly from side to side, mine came out ok. The bushes are quite
forgiving.
Fortunately I have access to a lathe so I was able to modify the polybushes by turning a small amount off the inside face of the bush flange thus
allowing my crush tubes to protrude.
If you dont have a lathe and lets face it not many of us do, then how about finding some steel washers that will sit just inside the poly bush bore to
take up the gap and drill them out to suit your bolts. This will allow your crush tubes to be clamped solid against the washer/s, you probably would
only need one on one side. This would also eliminate the need to take out your bushes.
I also applaud the good folks out there who take the trouble to explain some pretty basic stuff, but to us new to this game, its the " almost
too embarrassed to ask" topics that cause us the most grief.
Anyway hope this helps.
Thanks again guys.
Dave
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locoboy
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| posted on 8/1/04 at 04:22 PM |
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Cheers Dave,
I will have a closer look at mine and see how they go together and think it may be the washer option as i dont have access to a lathe 
ATB
Locoboy
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locoboy
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| posted on 9/1/04 at 09:00 AM |
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Having had a closer examination of the BLACK bushes that are in my wishbones that have 4.25 moulded on to the widest part of the bush (the bit that
stops it going all the way into the tube)
Anyone any idea what that is? possibly a rating for hardness/softness?
ATB
Locoboy
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Dave J
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| posted on 9/1/04 at 10:34 AM |
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Hi col
Not really sure on that one, but the thickness of the poly bush shoulders on mine is approx 4.2mm, could the figure thats moulded into yours possibly
be the thickness ? My bushes don't have any numbers on them.
perhaps give the supplier a bell and see if they can shed some light on it.
Cheers
Dave
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locoboy
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| posted on 9/1/04 at 12:42 PM |
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Thats half the problem, i cant find any contact details for Triton
I bought the chassis second hand complete with wishbones etc.
ATB
Locoboy
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flyingkiwi
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| posted on 9/1/04 at 10:42 PM |
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still puzzled as to why my crush tubes have such a large i.d. Has anyone out there got a crush tube from mk loafing about and wouldn't mind
checking the dimensions for me
It's not easy finding 1m or so of steel tubing around Yeovil, anyone got any suppliers they know off?
Cheers
Chris
It Runs!!!!! Bring on the SVA!
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Dreckly
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| posted on 9/1/04 at 11:04 PM |
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Polybushes
Hi Col.
This might seem daft but ask Darren @ GTS Tuning, if you get my drift (Pardon the Pun)!!
Cheers. Ken.
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locoboy
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| posted on 10/1/04 at 10:03 PM |
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Cheers Ken, will do that.
ATB
Locoboy
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