New Tires Fitted - Please give advice on Castor Rod bushes

Hi Guys,

As the title states, I just got some new Pirelli's fitted to the car. They said they wont bother doing the wheel alignment yet becasue my castor rod bushes are worn. Can anyone tell me what exactly these are and where I can buy them? If someone could send me an Ebay link or anything to fit my E34? I cannot find them online.

Thanks.

Never heard of that term before. But what I can tell its a radius arm, anyone else get this?

Originally Posted by Ssuss34

Hi Guys,

As the title states, I just got some new Pirelli's fitted to the car. They said they wont bother doing the wheel alignment yet becasue my castor rod bushes are worn. Can anyone tell me what exactly these are and where I can buy them? If someone could send me an Ebay link or anything to fit my E34? I cannot find them online.

Thanks.

Sounds like they are talking about front swaybar links, although I didn't realise that they affected the car's castor.

http://www.ebay.com/itm/BMW-E24-E28-...9093a5&vxp=mtr

For the front wheels, the only thing you can change is the toe. Camber, caster and anything else is unchangeable. Nothing can be changed for the rear wheels.

The only stuff that changes these alignment areas would be adjustable camber shock mounts.

www.realoem.com has detailed diagrams and info about your car.

The link above detail HD (heavy duty) versions supplied by Meyle. Its worth paying a little extra for those. If its marked HD, its even better than Lemforder stuff, which is the oem company for our car's suspension.

They may also be talking about upper or lower control arm bushes. Extract the relevant diagram from realoem.com or the E34 Bentley manual (downloads available on google) and show them the diagrams for confirmation.

I would assume they are talking about the upper control arm bushings. We usually refer to it as the upper control arm bushing or thrust arm bushing. The upper arm has a large bushing on the body mount end. I'm not sure that you can do it with the arm on the car because the bushing needs to be pressed out/in. You can also replace the whole arm with bushing and get a new ball joint in the deal

There are lots of threads about rebuilding the front end. Use good parts, Myle or Lemforder. I would do uppers and lowers at the same time, both sides.

Or if you're on a tight budget, just do the left and right arms of the one with the damaged bushing. I believe Meyle's HD stuff comes with the bushings pre pressed into the arm, whereas Lemforder's are sold separately and require a machine shop to press them in at an additional cost at your end.

If you replace the arms, remember to have them pre-load the car before tightening down the bushes. Not doing so leads to premature failure. This is a highly important and often overlooked step. If you're not sure what pre-loading means, search these forums or consult the bentley manual.


rgds,
Roberto

Originally Posted by robertobaggio20

They may also be talking about upper or lower control arm bushes.

Originally Posted by snowsled7

I would assume they are talking about the upper control arm bushings. We usually refer to it as the upper control arm bushing or thrust arm bushing.

+3
However, the E34 uses a variation of the Macpherson strut suspension and by definition, has no "upper control arm". The only suspension arrangements that have a bona fide upper control arm are the double wishbone and multi-link.

The E34 thrust arms are technically radius rods (in suspension engineering terms), which are referred to as "castor rods" in Aussie speak.

I don't know where the best place is in Australia to get them.

A little conversation i had...

fcpgroton: Welcome to our live chat support. How may I help you today?
Joe: Shipping available to australia?
fcpgroton: Yes. USPS International.
Joe: Do you know how long it would take to ship? Guesstimate?
fcpgroton: We usually see delivery times from 5-7 business days on average to Australia.
Joe: thank you very muc for your help

Link to site, I've used FCP Brand before and was unhappy with the result. Switched to Meyle and it is much better...
FCP Groton E34 Suspension

Thanks for the advice guys. I spoke to the blokes at the workshop thismorning an they said another name for the Castor rod bushes is lower control arm rear bushes. Does this help? Please post a link to this part or an eBay auction. Thanks again.

Lamforder parts ordered, AU$35 each. Getting fitted tomorrow. Cheers for the help guys.

Originally Posted by Ssuss34

Thanks for the advice guys. I spoke to the blokes at the workshop thismorning an they said another name for the Castor rod bushes is lower control arm rear bushes. Does this help? Please post a link to this part or an eBay auction. Thanks again.

Did you speak to them about pre-loading your suspension ? Unless of course, you wish to change this out every 12-18 months.

If they have never heard of it, tell them that they can use a transmission jack to push up each front wheel until it is approximately at the position it would be when the car is naturally on the ground, and then tighten.

Don't be frightened to insist on this and take your business elsewhere if they don't get it.

If they have not heard about this but seem open to it, strip out some videos from youtube and show them. Check the Bentley manual too.

Pre loading ensures that the bushings remain largely unflexed in the typical position of the car, when it is on the ground. If it is tightened up while in the air without pre loading, the bushings get heavily flexed and remain that way when the car gets back on the ground. This greatly reduces their service life and possibly performance as well.



rgds,
Roberto

Originally Posted by robertobaggio20

If they have never heard of it, tell them that they can use a transmission jack to push up each front wheel until it is approximately at the position it would be when the car is naturally on the ground, and then tighten.

It is much easier just to drive the car up on a couple of blocks. I was able to crawl under the car easily and tighten the bolts with just 3-4 inches of wood under the wheels. Seat passengers and tighten it up perfectly loaded.

The jack under the wheel might be less precise and if overdone or, not done evenly it could cause the same issues as not properly loading the suspension before tightening (indexing) the bushing.

I'd be very hesitant to attempt jacking an individual wheel to trim height. It is a bad idea from my experience.

It assumes the vehicle is suspended either via lift or stands, and unless the struts are disconnected and removed, the springs will only compress so far before the entire body starts to shift around (usually well below the specified trim/ride height).

That's an unsafe situation with the car sitting aloft, not to mention it won't get things aligned where they need to be.

Originally Posted by snowsled7

It is much easier just to drive the car up on a couple of blocks. I was able to crawl under the car easily and tighten the bolts with just 3-4 inches of wood under the wheels. Seat passengers and tighten it up perfectly loaded.

+1 ..and you can always use a tape measure between the wheel center and fender lip to confirm that a particular wheel's suspension is compressed to the correct height before torquing things down. Of course if a shop has a pit and a couple of big dudes, then the process takes only minutes.

Originally Posted by snowsled7

It is much easier just to drive the car up on a couple of blocks. I was able to crawl under the car easily and tighten the bolts with just 3-4 inches of wood under the wheels. Seat passengers and tighten it up perfectly loaded.

The jack under the wheel might be less precise and if overdone or, not done evenly it could cause the same issues as not properly loading the suspension before tightening (indexing) the bushing.

That the transmission jack method is not a precise method is true and all the points that radian mentioned are valid (however i've not noticed any safety issues with the front springs the way he's described). However the tranny jack method is sometimes what you're stuck with.

The alignment guys would also be good fellas to do this with. For wheel alignment, the car is either driven onto a metal platform that is lifted high enough to permit tie rod adjustments, or its driven over a pit with stairs that the chap will go down to access the tie rods. These are the ideal times to do it. The car is on the ground exactly as it would be. You'll just need them to first loosen and then retighten the bushings according to the Bentley manual's torque settings if possible, when the car is in position.

Of course, if you wish to be a real stickler, you need to pre load the car with weights as well. Good luck convincing your guys to do that.


rgds,
Roberto

Using transmission jack is a waste of time your bushings wont even be aligned properly.

This is specification for pre-load, not bad at all few tools will give you 100 lb:

Each front seat 68 kg (150 Ib)
Center of rear seat 68 kg (150 Ib)
Trunk 21 kg (46 Ib)
Fuel tank full

Do it on ramps or an alignment station.

Originally Posted by Radian

+3
However, the E34 uses a variation of the Macpherson strut suspension and by definition, has no "upper control arm". The only suspension arrangements that have a bona fide upper control arm are the double wishbone and multi-link.

The E34 thrust arms are technically radius rods (in suspension engineering terms), which are referred to as "castor rods" in Aussie speak.

I don't know where the best place is in Australia to get them.

as for preloading, more or less pointless for this task. its either safe throughout the range of suspension travel or it isn't. thats reserved for other suspension tasks such as spring rates which are irrelevant to this post.
Even if it was necessary, its the same as any other car, its not BMW specific, remember, these guys are professionals your dealing with

Originally Posted by _Ethrty-Andy_

as for preloading, more or less pointless for this task. its either safe throughout the range of suspension travel or it isn't. thats reserved for other suspension tasks such as spring rates which are irrelevant to this post.
Even if it was necessary, its the same as any other car, its not BMW specific, remember, these guys are professionals your dealing with

Interesting point...

I didn't have the car wieghted to set the toe. I think the amount the angle changes on the tie rod is so miniscule as to be of no consequence. The tires continue to wear fine.

When I did my front end though, the LCA bushings had teeth in them. The clear intent is to keep it locked in place. I had a full fuel tank and a driver and passenger in the car when I clamped them down. Seemed prudent, especially with all of the tales of early failing parts.

Your point is well taken though. It really shouldn't matter. I beat myself up over it on the alignment but, I also concluded... it shouldn't matter.

Originally Posted by snowsled7

It is much easier just to drive the car up on a couple of blocks. I was able to crawl under the car easily and tighten the bolts with just 3-4 inches of wood under the wheels. Seat passengers and tighten it up perfectly loaded.

The jack under the wheel might be less precise and if overdone or, not done evenly it could cause the same issues as not properly loading the suspension before tightening (indexing) the bushing.

This is what I did, but i needed more height than a couple blocks. Ssuss is lowered (from what i understand in his thread about the spacers) but this is approx what I did. I drove the car onto ramps (a bit taller) and torqued them down. My girlfriend is sub 95 lbs so i didnt have any ballast in the car when i did it...

Originally Posted by _Ethrty-Andy_

as for preloading, more or less pointless for this task. its either safe throughout the range of suspension travel or it isn't. thats reserved for other suspension tasks such as spring rates which are irrelevant to this post.
Even if it was necessary, its the same as any other car, its not BMW specific, remember, these guys are professionals your dealing with.

It doesnt hurt to prelaod and it's been a point thats been discussed to death ever since i've been on the forum. It isnt much more difficult to torque down the bolts with the car on sturdy ground (wood blcok/ramps) than with the wheels in the air. It is described ad a process and procedure for proper installation by both BMW and bentley and many shops, just my $0.02

Bentley manual pg 310-09-11

CAUTION-
Tighten the thrust arm bushing through-bolt to its final torque only with car on the ground and the suspension normally loaded as described earlier.

^ which are the specs that 1995i540 posted about the weights.

The blokes that I get to do my alignments have a hoist that you drive the whole car onto and it raises the entire car in the air. So it is in the same position asif it were still on the ground.

Originally Posted by Ssuss34

The blokes that I get to do my alignments have a hoist that you drive the whole car onto and it raises the entire car in the air. So it is in the same position asif it were still on the ground.

wish i had one of those

Hey guys, turns out they sold me the wrong parts. I have found the part I need (see photo) I need number 7 & 8 on the diagram. Can anyone tell me the names of these parts?

In the US that would be commonly referred to as the upper control arm and bushing, or upper thrust arm. Meyle brand versions usually come with the bushing installed, Lemforder versions usually have the bushing(8) seperate.

Part Numbers are:
31121141097: Left
31121141098: Right

2-Piece Upper Thrust Arm (Meyle)

Here you are, mate