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[terry paget]

OE03 EWW 3.2 police special manual saloon

I know this forum, and the maintenenace guide, recommends changing wishbones in pairs, but I cannot see why, any more than changing trackrods or drop links in pairs. It sounds like common sense and good practice, but it means changing a perfectly good wishbone just because its chum has one dodgy joint.

[tidla]

You can do what you want.

Drop links are usually just as worn on both sides or not far behind. I suppose the reasoning is that upon closer inspection, the other side will be not far behind in wear.

[Kevin Wood]

Also factor in that a wishbone change will require a suspension setup afterwards - could be the best part of £100. Not much point in doing half the job, as the other side won't be far behind.

[chrisgixer]

Numerous reasons.

Firstly uneven performance is to be avoided.
Especially if you have oe bushes, this doesn't apply to poly. If one oe front bush fails and is replaced tother will be softer, so given the level of toe out on the brakes designed into the bush movement you could get the car bearing off under braking or emergency braking.

Rearward bush also but less likely as there is less give in that one.


Then there's the set up issues as Kev says.
Changing bones means set up after. Changing one means set up. Then set up again when the other fails soon after. Plus you've got all the tools out, you may as well do both.

But the main reason is to give even performance across a given axle. It's the soft squidgy bits that need to be even. Bush play on bones. Spring rates and damping rates.
Oil and gas in the shocks. Etc.

Drop links don't really apply to the same level as the play just causes an annoying knock. It doesn't affect performance to have 0.05mm of play in one drop link. Only thing to consider is tother side won't be far behind on wear. There no set up either obviously.

There's owners preference to consider. Most people don't want the agro so may as well do drop links while doing bones, is one line of thinking. I wouldn't change them unless they knock personally.


But in short. Reason is, even performance across a given axle.

[terry paget]

Thank you gentlemen, for your wisdom and experience.
No-one has mentioned track rods, the one item of the three listed that is adjustable.
I struggle to see why changing a wishbone for another dimensionally identical item should affect the steering geometry; it should put it back to where it was before the old wishbone went soft. It should not change castor angle, camber angle, or toe-in.

Track rods, on the other hand, however carefully fitted, always need adjustment to make the steering feel right and avoid squeal on cornering.

[05omegav6]

The wishbones are within tolerance, not identical... the difference between ball joint position on two otherwise identical wishbones could be as much as 5mm... doesn't sound alot, but when geometry is measured in fractions of degrees, it really does matter

[chrisgixer]

Thers a pic in the guide, handling etc in FAQ iirc.

Shows loss of control of the pivot position on a failed bush (again this doesn't apply to poly. Plus variations in dimensions, slop in the bolt holes, for and aft, and left right.

 I did a test myself once, refurbished a polyed wishbone by replacing the rearward bush. Then set up. Same ball joint, same metalwork, same poly (and same car obviously )

Camber needed adjustment from 1.40 odd on one side, and a slight tweek on the other I can't remember how much.

No way I'd run a set of tyres at 1.40. (Even though that's irmschers recommendation) Plus tramlining increases with increased camber.

[terry paget]

Good points, gentlemen. Castor angle cannot be adjusted, camber angle can, but on a Mcpherson strut/wishbone system it varies with depression of suspension and roll of vehicle, so must be a compromise. Toe-in may vary slightly with change of wishbone, if out at all will cause immediate problems with feel and steering, requiring correction. Rear end geometry is not changed with change of wishbone.

On a happier note, when I changed the nearside wishbone on OE03 EWW last Saturday I came to no harm, not even a bruise. MY dear wife assisted by heaving on a pipe to lower the new wishbone to enable me to insert the pin into the hub, and seems to have pulled a muscle or bruised a rib. Oh dear, I must get a longer pipe next time. Is there a better of doing it?

[05omegav6]

Leverage is about the only way for that... weighing 17 stone invariably helps

[TheBoy]

Castor angle cannot be adjusted

/Panto mode on:

Oh yes it can

/Panto mode off

Whomever told you it couldn't is incorrect I'm afraid.

[terry paget]

How is the castor angle adjusted?

[05omegav6]

By moving the subframe there's about 10mm scope at each of the six subframe bolts...

[Darth Loo-knee]

I ain't trying to be funny but you would buy a pair of shoes not just one 

[chrisgixer]

Castor angle cannot be adjusted

/Panto mode on:

Oh yes it can

/Panto mode off

Whomever told you it couldn't is incorrect I'm afraid.

Indeed it can. ...and it was me that told wim as much as well.

Remember, the open day?

[chrisgixer]

Good points, gentlemen. Castor angle cannot be adjusted, camber angle can, but on a Mcpherson strut/wishbone system it varies with depression of suspension and roll of vehicle, so must be a compromise. Toe-in may vary slightly with change of wishbone, if out at all will cause immediate problems with feel and steering, requiring correction. Rear end geometry is not changed with change of wishbone.

On a happier note, when I changed the nearside wishbone on OE03 EWW last Saturday I came to no harm, not even a bruise. MY dear wife assisted by heaving on a pipe to lower the new wishbone to enable me to insert the pin into the hub, and seems to have pulled a muscle or bruised a rib. Oh dear, I must get a longer pipe next time. Is there a better of doing it?

Are these statements or questions Terry ?

Set up is very much a compromise.  Ride height is so important on these, as the camber changes with suspension movement. Wishbone pivots on an inboard radius and that radius pulls the wb ball joint inboard and outboard on bump and rebound. That's why the front tyres wear the edges.

Re set up. Once camber has moved, toe automatically needs adjusting due to the hub leaning in or out, the track rod then needs adjusting in or out to match. likewise, if the caster is moved, then that moves camber by default, and then toe.
 Therefore the order of adjustment is, caster, camber then toe.