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Frosty

Guide to wishbone bushes

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Rob55

For anyone considering nylon bushes - the factory supplied bushes and wishbones were a terrible fit in my experience. That does not mean I regret buying them, but I spent quite a lot of time making adjustments so that they would work properly. 

 

The biggest problem was that the wishbones were not reamed at the factory, which meant that the nylon was a poor fit and often too tight, which meant it deformed and then the inner crush tube would not insert without a lot of force.  The crush tube then would not rotate because it was under pressure.  In the end I sent my wishbones back to the factory, as I could not achieve a satisfactory result with a Dremel and I have no idea where to get a ream of the correct size.

 

The other problem I found, was that the inner crush tubes, were never the correct size (usually narrower than the bush, which meant the nylon was crushed by the suspension mount). With some time and patience, this was a relatively easy fix, it involved shaving tiny amouts off the face of the nylon and refitting the wishbone on the car multiple times until a satisfactory gap was achieved, which allowed the crush tube to rotate freely inside the nylon.

 

In the end I spent absolutely hours at it but got a very good result.  My wishbones now all fall under their own weight and have almost no friction.  They have the benefit of a rose joint (minus the adjustment) but with a long life span, as nylon will last a very long time.

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Ian Bunker
A couple of weeks back I started the process of re-bushing the rear suspension of my SE Narrow and opted to fit new metalastic bushes. I reckon the existing ones have been on the vehicle for 20+ years.


 


Now the question -  all the forums say not to torque tighten the bushes until the "wheels are under their own weight.


 


Does this mean the car has to be on the ground in which case i will have to get the car over a pit to gain access - or is it ok to just have the weight of the wheels acting on the suspension while the car is up on axle stands?


 


Thanks in advance for the advice. Ian Bunker 



 

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Dave Eastwood (Gadgetman) - Club Secretary

As long as the cars weight is on the road wheels, so that the wishbones will be at the same angle as when driving around, it doesn't really matter how you achieve it - I've had the car up on ramps before now to do it, though on the current build, I left the boot box out so could get from above with it just sat on the drive.

 

Once tightened up, all the rotation in the bush comes from the twisting of the rubber between the inner and outer tubes. So if you tightened them up with the wishbones drooping under their own weight, once on the ground, they'd have pre-load in them when stationary, due to the twist when the suspension compressed as you lowered the car. Add more compression, from an extreme bump, say, and you might even start to run out of stretch and twist, either damaging the bush, or reducing suspension travel.

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DamperMan

All the Bush types have there uses.  Polyurethane also comes in different material types as well as stiffness's.  As poly is usually sold as a performance upgrade they are usually stiffer than the equivalent rubber.   Rubber has typically better at noise and vibration absorption to as it has a higher hysteresis value... (it has more damping effect than poly.    Nylon is good where everything is in line and it effectively becomes a bearing surface with some flex and refinement is not an issue.   It could be argued the best performance inspired solution if your looking for a flex free low friction solution is spherical bearings or needle bearings, .     A lot is said about tightening up the bushes and getting a tighter feel and controlling the geometry..then we to fit 13" wheels and loads of rubber in the tyre!    There is not a right or wrong answer since it depends on the car, the person and the tools we have. For most Poly is the most convenient solution, I have a personal preference for rubber.       From personal experience make sure there is loads of grease between the bolt and the stainless crush tube used with stainless or nylon solutions,  since the 2 create a corrosion cell and love to corrode together.    

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CL290005

Frosty

This is a great read and perfect timing as I was only thinking about my widetrack this week which I need to fit.

Now need to decide on which bushes to use

Might get myself an adjustable reamer

Cheers

Chris

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BCF

A couple of weeks back I started the process of re-bushing the rear suspension of my SE Narrow and opted to fit new metalastic bushes. I reckon the existing ones have been on the vehicle for 20+ years.

Now the question - all the forums say not to torque tighten the bushes until the "wheels are under their own weight.

Does this mean the car has to be on the ground in which case i will have to get the car over a pit to gain access - or is it ok to just have the weight of the wheels acting on the suspension while the car is up on axle stands?

Thanks in advance for the advice. Ian Bunker

I'm guessing yours is a live (English) axle? In which case, I jacked mine up by the axle with a mate in the drivers seat, then torqued them up.

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jonjh1964

Powerflex%20bushes_zpsrpns5ido.jpg

 

The latest Westfield/Powerflex bushes seem to be a polyurethane/nylon hybrid to address the issue of the polyurethane causing stiction between the chassis mount and wishbone.

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Dave Eastwood (Gadgetman) - Club Secretary

I've not really investigated it myself, but I have to say, a few chassis/suspension experts that I've talked to over the past year or two do seem to reckon that the game has moved on considerably with what we thinking of as poly bushes, and that at least with some of them, it's a completely different story and very different conclusion to when this piece was first written.

Interesting to see those Westfield bushes, I must admit, I've never really looked at them before.

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Trevturtle

Powerflex%20bushes_zpsrpns5ido.jpg

 

The latest Westfield/Powerflex bushes seem to be a polyurethane/nylon hybrid to address the issue of the polyurethane causing stiction between the chassis mount and wishbone.

 

I have recently fitted these bushes after the bright yellow nylon? bushes in the front bottom wishbones deformed under heavy braking during my last track day... they were not worn out, they 'reshaped themselves' due the braking force...not very good  :no: .  Probably ok for the road.

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Dave Eastwood (Gadgetman) - Club Secretary

Westfields Nylon bushes are black.

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bollockybill

IMG 4005

 

IMG 4004

 

IMG 4003

 

These poly bushes are less than 3 years old and have covered about 4,000 road miles. The witness mark is where the shock absorber was hitting the top of the rear upright. Back to metallastic now.

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Rich8977

John

Did you have your torque wrench on the right setting when you fitted them ;)

Rich

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Michael Whitworth

I am requiring a full set of new bushes front and rear on my SEi.

Having read various posts on this thread, I am none the wiser. lol

 

My car is used mainly for track days but is getting a bit old now. Would fitting harsher stiffer bushes put more stress on the frame leading to cracking or twisting?

Would I be better sticking to Metalastic?

Recent experiences and opinions would be useful.

TIA,

Mike

PS suggested suppliers would be handy too.

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AdamR

If you want a direct 'fit and forget' replacement, go metalastic. Just remember that the car needs weight on it before tightening them up!

If you'd like a slightly 'tighter' car and don't mind faffing about a bit with reaming, trial fitting etc, go nylon - Plays Kool or Westfield do them.

 

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