My rear bush is too small and it rattles around in my opening

Started by threepot, May 3, 2022, 00:22

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threepot

I've come across this problem a few times, hole too big, my part too small. Measure twice and cut at least trice...

Anyway front lower control arms - rear big bushing.

The hole in the original arms is 55mm give or take a stamping deformation, here is the OEM one and a copy one, the copy is tighter than the original by a nats donga.


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And I'd bought one of those whole car polybush kits, and I fitted this bush as per the documentation:-


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But it literally rattled around in the hole, these things should be tight, like force it in the hole and hope it doesn't twang tight. So I did a bit of measuring and then cut the lip off to get it back out as it was a one way street.


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54mm! Both of them two in all directions. That doesn't seem right. And not just that I don't like the idea of this bush at all. The original has a nice tapered sleeve which adds to the surface area of the compression forces. I can imagine this polybush crushing under the point loading under braking etc. Its a mickey mouse idea if ever there is one.

So I looked at the standard bushes, which are a tapered interference fit, which makes a great deal of sense, just over the 55.1mm so they squeeze in on the press and stay where they belong:-


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But after a bit of hunting for a Polyurethane bush I found these other bushes by Stongflex 211686A mostly listed for the mighty yaris:-


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And they are actually sleeved like a proper job, and the sleeve is the right size for the hole. And thus they fit OK, but I'm not really happy with the parallel tube as there is no proper interference fit. I'll run them and inspect them to see how life plays out.

I have seen these mighty nice powerflex pillow block style bushes that might fit:-

https://www.tmcmotorsport.com/products/toyota-gr-yaris-powerflex-front-wishbone-rear-bush-caster-adjust

Or potentially make something like this with some spherical tie rod ends and some welding action

https://www.hardrace.com/product_detail.asp?id=949

Anyone else come across this?

Dev

I do not like the design of that bushing. The poly bushings I have that are made by Superpro has the poly material fused to the casing. They were dimensionally accurate and just needed to be pressed in using a wood block with a soft mallet or a vice press and wood until they sat flush.
 I haven't had any problems with them and its been over 15 years since they were installed.




Call the midlife!

Maybe give BRD a try, Brookes Racing Developments (I think) he makes a lot of poly bushes for the MR2, among others and doesn't get many complaints.
60% of the time it works everytime...

Dev

Quote from: threepot on May  3, 2022, 07:55So you must be running SPF2782K
https://www.superproeurope.com/ajax/part.number.cfm?partnumber=SPF2782K&vehicleid=3775&productreferenceid=152794

Is the outer sleeve tapered?




Yes.
Its been a long time so I looked at detailed photos and it appears that the casing has a taper on the lip to make insertion of the bushing easier. As far as having a gradual taper on the body to lock it in place I don't know but its possible and cant be seen unless it is measured with a caliper.
 Superpro researches their bushings unlike some of the other brands and they are considered the best in the industry. Out of thousands of people that have replaced this bushing I never heard of an issue.
 

Carolyn

Perry Byrnes Memorial Award 2016, 2018.  Love this club. 
https://www.mr2roc.org/forum/index.php?topic=63866.0

MrT

Quote from: threepot on May  3, 2022, 00:22I've come across this problem a few times, hole too big, my part too small. Measure twice and cut at least trice...

Anyway front lower control arms - rear big bushing.

The hole in the original arms is 55mm give or take a stamping deformation, here is the OEM one and a copy one, the copy is tighter than the original by a nats donga.


You cannot view this attachment.
You cannot view this attachment.


And I'd bought one of those whole car polybush kits, and I fitted this bush as per the documentation:-


You cannot view this attachment.
You cannot view this attachment.   


But it literally rattled around in the hole, these things should be tight, like force it in the hole and hope it doesn't twang tight. So I did a bit of measuring and then cut the lip off to get it back out as it was a one way street.


You cannot view this attachment.


54mm! Both of them two in all directions. That doesn't seem right. And not just that I don't like the idea of this bush at all. The original has a nice tapered sleeve which adds to the surface area of the compression forces. I can imagine this polybush crushing under the point loading under braking etc. Its a mickey mouse idea if ever there is one.

So I looked at the standard bushes, which are a tapered interference fit, which makes a great deal of sense, just over the 55.1mm so they squeeze in on the press and stay where they belong:-


You cannot view this attachment.
You cannot view this attachment. 


But after a bit of hunting for a Polyurethane bush I found these other bushes by Stongflex 211686A mostly listed for the mighty yaris:-


You cannot view this attachment.
You cannot view this attachment. 


And they are actually sleeved like a proper job, and the sleeve is the right size for the hole. And thus they fit OK, but I'm not really happy with the parallel tube as there is no proper interference fit. I'll run them and inspect them to see how life plays out.

I have seen these mighty nice powerflex pillow block style bushes that might fit:-

https://www.tmcmotorsport.com/products/toyota-gr-yaris-powerflex-front-wishbone-rear-bush-caster-adjust

Or potentially make something like this with some spherical tie rod ends and some welding action

https://www.hardrace.com/product_detail.asp?id=949

Anyone else come across this?


I have the Polybush bushes in my 2 and had no problems with handling or geometry/deflection etc. I personally am very happy with those bushes for fast road use and mine had no slop when fitting so is completely tight and secure.

I fully agree the sleeved bushes will offer little deflection and maintain geometry so be a better performing solution. Just thought I'd give some feedback on the Polybush bushes.
Cheers
Tyler

RIPieces: Sable \'05 Roadster \'Red\' edition.
Project: MR-S import (JDM) now my toy and mule for:
SC build OR a 2AR-FXE swap (ref: Frankenstein Motorworks) OR Electric conversion
AND rebody with a fibreglass replica of Porsche 550 Spyder.

threepot

To me, either something is correct or not, a fit is a fit, and those polybushes are just a cheap quick poor solution. They didn't want to manufacture a stamped tube item as its expensive.

But neither is all well with the sleeved bushes.

After about 400 miles, 100 of which are track time, the sleeve on the left arm has moved. I made the black lines when I installed them to keep an eye.



There is a tremendous amount of force being applied to this bush under heavy braking. More than most people can conceive. Tonnes, literally. Especially running semi slicks and aggressive brake pad compounds.

They NEED a tapered interference fit, but what I am going to do is weld these tubes to my arms with a few sneaky spot welds. Christ knows how I'm going to get the bush out of the sleeve without damage.


Iain

I have the polybushes (orange/red ones) in my track car, never had an issue with them, fit a treat. Are you arms still OEM ones or aftermarket? If aftermarket that could well be the issue.

Im also fairly sure that most of the grid in the mr2 championship run those polybushes so there shouldnt be any issues with them. Always a chance you could have been unlucky and ended up with a duff set of course.

Dev

Quote from: threepot on June  8, 2022, 18:50To me, either something is correct or not, a fit is a fit, and those polybushes are just a cheap quick poor solution. They didn't want to manufacture a stamped tube item as its expensive.

But neither is all well with the sleeved bushes.

After about 400 miles, 100 of which are track time, the sleeve on the left arm has moved. I made the black lines when I installed them to keep an eye.



There is a tremendous amount of force being applied to this bush under heavy braking. More than most people can conceive. Tonnes, literally. Especially running semi slicks and aggressive brake pad compounds.

They NEED a tapered interference fit, but what I am going to do is weld these tubes to my arms with a few sneaky spot welds. Christ knows how I'm going to get the bush out of the sleeve without damage.



I would cut my losses and get the Superpro bushings. Do it right, with the right part. The hardness and the way the bushings deflect is crucial otherwise the bushings can cause behavior that can result in an accident which some have experienced trying to source their own bushings from various other applications as it has to be researched by an engineering company. 
Out of hundreds of people that I have been in touch with that have installed the Superpro over more than a decade no one had an issue like this including experienced track racers. 

MrT

@threepot just FYI I've done about 20k miles with my polybushes in all sorts of driving including practically rallying on crappy back roads on quiet mornings etc and hee. Bushes never flinched, car never twitched or squiggled like they were deflecting, hard braking on bumps was solid and sure footed. So I'm confident in mine.

But the sleeve seems a secure and stiffer option. Definitely welding the sleeve in the arm is a better solution. Press the bush out with soapy water or silicone spray then weld the bush in and press the bush back in. A small amount of heat deflection won't hurt cause the bush will accommodate it.

Good luck either way with finding a better solution though.
Cheers
Tyler

RIPieces: Sable \'05 Roadster \'Red\' edition.
Project: MR-S import (JDM) now my toy and mule for:
SC build OR a 2AR-FXE swap (ref: Frankenstein Motorworks) OR Electric conversion
AND rebody with a fibreglass replica of Porsche 550 Spyder.

threepot

I spent about 2 hours fighting trying to get those bushes out of those damn sleeves!! I even made a collar thing to try to push against them, there is not much to hold onto as there is no lip or taper etc. In the end I just slit the sleeve with the hack saw, then welded it back closed again.

I've welded the sleeves in tonight, just buzzed in some deep penetrating MIG spot welds every 10mm round the circumference. I'm not a welder though, but functional it is. Grinder and paint makes me the welder I ain't.

I'm a bit of a funny bugger with all this stuff. I draw white tipex lines on all my nuts/bolts/adjusters ect so I can see trouble before it starts. I put my cars on my ramps every few weeks or so, I actually bother to inspect these things. Most people would never notice the sleeve shifting like I have, most wouldn't look.

I emailed about the superpro bushing asking if the casing was tapered like the OEM ones, but I never got an answer. I've got what I already have and I can make this work with the welds.

threepot



I think my 3 year old daughter can probably weld better than me.

But the arms are on and they sit nice.

MrT

Cheers
Tyler

RIPieces: Sable \'05 Roadster \'Red\' edition.
Project: MR-S import (JDM) now my toy and mule for:
SC build OR a 2AR-FXE swap (ref: Frankenstein Motorworks) OR Electric conversion
AND rebody with a fibreglass replica of Porsche 550 Spyder.

ralf321

I have a set of Superpros waiting to be installed and I just measured the diameter. They are not tapered and I measured a diameter of 55.16mm.

BR
Ralf

SuperArt

I have nothing to contribute other than to say I appreciate the way you worded the title of this post.
I laughed harder than I should've.
Best regards,
Arthur
Essex - "Always happy to meet up for a weekend drive"
Making demented squirrel noises since 2014