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suspension bushes
Lars - 7/6/03 at 08:15 PM

How tight are these meant to be in the wishbone tubes?
I got the ones suggested in the book, but the bushes seem to slide in and out of the tubes very easily.

[Edited on 7/6/03 by Lars]


Mark Allanson - 7/6/03 at 08:55 PM

By sheer coincidence I just finished my upper bones today, I have book bushes (Y419's), they will push in 1/8" by hand but will need a vice or the press at work to fit fully, the ID of my tubes are 21.00mm and the bushes measure 21.62mm without any excess pressure applied to the vernier (if I push hard I can get this down to 21.45mm)

At least this will tell you if you have sloppy tubes or skinny bushes

Mark Rescued attachment DCP_0818.JPG
Rescued attachment DCP_0818.JPG


Lars - 7/6/03 at 09:50 PM

sounds like either the tube or the bushes i've got aren't right.


elewayne - 8/6/03 at 03:35 AM

I used seamless 1" tubing with .095 wall thickness. that fits the Triumph bushes perfactly. I polished the inside of the tubes with fine sandpaper and applied a small amount of dish soap to the inside of the tube to get them to go in with the help of a vice. They should be a good tight dry fit.


Mark Allanson - 8/6/03 at 11:00 AM

I am going to use rubber solution glue as a lubricant, it will also bond the bushes in. I dont want to use soap as it contains salt which will promote corrosion. BMW do a bush lubricant supplied with the new bushes which is also an adhesive (probable rubber solution glue!)


splitrivet - 9/6/03 at 11:08 AM

How about bonding em in with araldite,you'd never get em out again unless you burnt em out.
Bob


Mark Allanson - 9/6/03 at 04:53 PM

Araldite goes brittle with age and would start to chew up the bush


Lars - 17/6/03 at 03:36 PM

i just had a look at the bushes, don't have the right measuring tool at hand, but using a ruler it looks like they are about 21mm not 21.6, which is probably why they don't fit that tight.
I think i'll do what elewayne did and use seamless 1" tubing with .095 wall thickness, which should give an inside diameter of about 20.3mm


DaveFJ - 17/6/03 at 03:57 PM

Put poly bushes in the fridge for a few hours before fitting.... makes the job a LOT easier


andrew-theasby - 26/6/03 at 10:06 AM

Sorry to change the subject a bit but im going to be fitting my bushes soon, and was wondering whether the steel part inside the rubber bushes should act as a distance tube, ie to tighten the bolt up against or whether it should be free to move ? If so do you just tighten the bolts till it just about nips or is there some other way of setting them? Thanks.


kingr - 26/6/03 at 10:13 AM

There's a long thread abuut this elsewhere, so I'd recomend that you read that. I think I'll stay well out of this!!

Kingr


Rorty - 27/6/03 at 03:02 AM

Torque it to the recommended figure for the size and type of fastener you're using.


andrew-theasby - 28/6/03 at 06:08 AM

Where would i find this torque figure? Im not worried about overstressing the bolt, more about nipping the lugs onto the bush so its stiff to move. Or should i just not tighten it up that much and split pin/wire lock it? I just dont want the bolt turning in the lug and wearing the diameter of the hole. Thanks.


Rorty - 29/6/03 at 12:26 AM

andrew_theasby, Nothing should be percievably loose. The PU bush should be an interference fit, and all the metal to metal contacts should be tight as per the torque setting for the fastener involved.
If you check out my site, and click on "Formulas, Charts and Data" there is an online bolt and nut torque calculator.
Rorty Racing

[Edited on 29/6/03 by Rorty]


andrew-theasby - 29/6/03 at 09:55 AM

I understand how the polyeurathene bushes work, by acting like a bearing, but im using the rubber ones, and as far as i can work out the inner surface of the metal sleeve and the bolt should be the 2 bearing surfaces as there would be too much friction on the rubber thats just there to cushion the vibration and allow for any flex. If this is so then when i tighten the bolts right up, the lugs are going to nip onto the sleeve possiby stopping it from moving or at least causing a lot of wear on the ends of the sleeve and to the lug. I use a lot of interference fit bolts at work and i wondered whether to use some of these which would allow me to tighten the nut down to achieve clearance on the bushes but the interference would stop the bolt from spinning. Any thoughts on that? How has everyone else using these set them? Thanks for your pointers so far


MikeR - 29/6/03 at 10:20 AM

When i fiitted by bushes I bought some rubber and nylon lubricant from Halfords. Polished the inside of the tube my dremil and wire brush attachment. squirted the lube everywhere then pushed the bush in as far as possible. When i couldn't push the bush in any more (which was on some wishbones not very far and on some nearly all the way) I used a combination of vice and long bolt + washers to push / pull it into place.

This seems to have worked really well and all the bushes are now a tight fit - although i've only trial fitted the suspension. If someone could point the link about tightening the bolts i'd be interested.

Oh, one thing i do know is don't fully tighten the suspension till the car is fully built and on level ground - that way you set the suspension with no twist in the bushes at default & so less wear and tear.


Rorty - 30/6/03 at 04:46 AM

Andrew, OK, I'm with you now!
If you haven't got the Metalastic type rubber bushes which are vulcanised onto the steel crush tubes, then, as you point out, you'll have to press your separate crush tubes into your rubber bushes. They are an extraordinally tight fit, as they're not supposed to pivot on the crush tube; they just deform around it!
The best way to press the crush tubes in, is to keep them doused liberally with plain water (the water will evaporate, thereby virtually bonding the rubber to the steel).
When you have assembled the bushes, you'll have to go through almost the same rigmarole again to press them into the wishbone tubes.
Once assembled, and mounted in the car, insert the correct sized bolts, but don't tighten them until the car is complete, and sitting at normal ride height on the ground (ideally with driver on board too). Then tighten the bolts to the recommended torque value.


andrew-theasby - 30/6/03 at 08:17 PM

I see, so are you saying that when the wishbone moves, there should be no pivoting or movement anywherein the bush, bolt or sleeving but that all the movement will be taken by the rubber twisting and flexing? If so that would make sense then about actually tightening the bolt onto the distance tube locking it in place. Thanks for your help.