Fitting Polyurethane Wishbone Bushes

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Mike Fishwick
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  Z3 roadster 2.8
Location: Daglan, France

Fitting Polyurethane Wishbone Bushes

Post by Mike Fishwick »

I recently fitted Powerflex polyurethane bushes at the rear ends of the wishbones - an easy job which has stopped the usual 'tramlining' effect, for which Z3s fitted with seventeen-inch wheels are notorious.

I had to carve a 25mm diameter and 10 mm deep counterbore in the front side of the bush, to enable it to slide fully up the pin at the end of the wishbone. There must be a small difference between the Z3's E36 wishbones and the E30 type which is supposed to fit.

However - if you want freedom from 'tram lining' - even with new tyres - this is the answer, for only £20 a side.

Fitting is easy - insert a junior hacksaw blade through the gaps in the original bush, and saw through the rubber bits. The outer shell and bracket will then come off easily. Use a full size hacksaw to cut through the steel shell from the inside, so it can be compressed a little and pushed out.

Pull the centre of the old bush off the wishbone pin with a two-legged bearing puller.

Push the modified poly bush fully onto the pin, and coat with the supplied silicone grease.

Press the rigid outer bush shell into the iron bush carrier - making sure you get it the correct way round! A good vice is ideal for this job. Slide it over the poly bush, and insert it onto the tapered location dowels in the floor of the car. Insert the bolts and secure them fully, using blue Loctite.

Don't forget to have the toe-in checked afterwards, as it will have slightly changed.

The steering is a little sharper, but I have not found any problems such as increased road noise or harshness - no minus points at all.

I bought mine from Proven Products of Tavistock, who deliver throughout the UK.
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Last edited by Anonymous on Sat 02 Dec, 2006 16:56, edited 2 times in total.
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Robert T
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Post by Robert T »

Excellent article Mike. Would simply replacing the rubber bushes with new ones help any? I'm not going to be able to change them myself, and the carriers on mine will probably want replacing soon. I'm not really looking for a miracle cure, just to get the car feeling more like it used to again. I'd much rather fit original parts if I can, and if renewing the rubber bushes is likely to help, I'll probably get them done sooner rather than later. Many thanks, R.
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Solids

Post by Guest »

Yes - the M type solid bushes will help a lot - anything is better than the OE type, but poly bushes are even better than rubber. Don't be too carried away with the wisdom of BMW!

I think that the M Roadster bushes have a steel core - if so they will require use of the specialBMW lubricant to fit them over the wishbone pins. IT evaporates after fitting, and makes the job a lot easier.
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c_w
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Post by c_w »

The OE ///M bushes are very solid compared to the ridiculously soft bush of the standard Z3 (just waggle the wheel on the ground and you can see the arm moving around). They'll be at least as solid as the poly ones I bet (ie they don't give much at all). The wishbone is still suspended is relatively soft rubber balljoints though, but the bushes will reduce movement a lot.

You can buy either central or offset solid bushes from BMW (the offset ones were fitted to early E36 M3s and add a bit of castor, central ones are E36 EVO/Z3M). They were about £40 from BMW I think. I ran with these on my old Z3 but felt they give the steering a lot of kickback and harshness so went back to standard ones in the end. Strangely it doesn't seem to be noticeable in the M Coupe though.
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Robert T
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Post by Robert T »

Thanks guys. I will have a think about what I want to do. I am really just looking to recover the original handling if possible. After nearly 8 years, she doesn't feel quite the same, particularly on the m'way. I'll consider ///M bushes, but I'd be happy if by simply replacing like-for-like will bring the handling back to what it was when she was new. I don't want to firm the ride up to much - I don't think my back could take it! Thanks R.
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Ball Joints

Post by Guest »

Rubber ball joints? The joints are all steel - apart from the boot around the pin, is there a rubber insulating piece between the joint and the wishbone?

I don't think more castor angle is a good idea - on a powerful car with radial ply tyres. more castor angle just produces understeer - like on an MGB in days gone by. True - castor angle will help you to run straight on bumpy and rutted roads, but at a price in steering feel and response.
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c_w
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Re: Ball Joints

Post by c_w »

Mike Fishwick wrote:Rubber ball joints? The joints are all steel - apart from the boot around the pin, is there a rubber insulating piece between the joint and the wishbone?

I don't think more castor angle is a good idea - on a powerful car with radial ply tyres. more castor angle just produces understeer - like on an MGB in days gone by. True - castor angle will help you to run straight on bumpy and rutted roads, but at a price in steering feel and response.
Yea I meant the ball joint is suspended in rubber (the M has regular ball joints); use a lever/screwdriver between the ball joint and the brass cap under the ball joint and you'll see how much these move. It is possible to pack the gap with rubber to reduce the movement but probably not necesary [as most movement is from the bushes].

I'd agree excessive castor can make off centrer steering respose slightly slower but gives more feel once off centre and feels "meatier". The castor also gives the wheel better geometry in turns; it gives negative camber on the outside wheel and some positive on the inside which gives better tyre wear (particularly on track). You can really see this when the car is parked on full lock.
TimS
Joined: Mon 16 Oct, 2006 11:52
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  Z3 roadster 2.8

Post by TimS »

I recently fitted Z4 18" Ellipsoids on my 3 and I had really bad tram-lining. After reading this thread I bought a couple of eccentric Powerflex bushes from Flea Bay. I must say the difference is dramatic. Car now drives better new - unbelievable :D

Tram-lining has always been an issue for me. My home made strut helped with the stock wheels, but initially after fitting my new wheels I thought I'd made a mistake.

With the new bushes fitted I am very pleased - Thanks Mike.
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Ian_C
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  Z3 roadster 2.8
Location: Lytham St Annes

Post by Ian_C »

TimS wrote: After reading this thread I bought a couple of eccentric Powerflex bushes from Flea Bay.
What's the difference between the eccentric bushes and the standard Powerflex ones? I thought the eccentric ones were for ///Ms and the standard ones were for non M types. Any tips on which ones to buy as I will be replacing my zeds bushes soon :?
TimS
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  Z3 roadster 2.8

Post by TimS »

You are correct the eccentric ones are not normally intended to be fitted to a non ///m. However I wanted to add a little more caster as I believed this would help with the problems I had. The ///m models run with a much larger caster angle. I believe that they have done this to alleviate the issue of tram-lining, but I could be wrong?

I cannot say if the improvement would have been as good using normal bushes. All I can say is that it has certainly transformed my steering.

Note: The bushes I fitted are different to Mikes, but I still had to remove some material to make them fit.
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muppet
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Post by muppet »

spoke to my spanner man ,dave at BM Motors in Lanarkshire, and I will be ordering them tommorrow . He will fit them with me , helping, looking on ...well getting in the road . the V1LAN is also due an intermediate oil change and the engine is hunting for an idle when cold so things are getting sorted out for the good weather :)
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c_w
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Post by c_w »

TimS wrote:You are correct the eccentric ones are not normally intended to be fitted to a non ///m. However I wanted to add a little more caster as I believed this would help with the problems I had. The ///m models run with a much larger caster angle. I believe that they have done this to alleviate the issue of tram-lining, but I could be wrong?

I cannot say if the improvement would have been as good using normal bushes. All I can say is that it has certainly transformed my steering.

Note: The bushes I fitted are different to Mikes, but I still had to remove some material to make them fit.
I think you can fit whichever bush you please, but as you say the eccentric bush will give you a bit more castor and should help more. The Z3M standard bushes would be a direct fit and aren't offset/eccentric but are just much stiffer than the standard Z3 bushes. The extra castor on the ///M model is all from the repositioned top mounts. These are about £36/pair.

BMW do have an offset/eccentric bush though that will fit - off the E36 M3 (>1995, pre-EVO), these are about £50/pair.
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AndyBass
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Post by AndyBass »

Just fitted my poly bushes and taken the car for a test drive over a particularly nasty piece of road and I am amazed at the difference. Previously the car was all over the place and wouldn't hold a straight line despite a white knuckle grip on the steering wheel, but now, well, it is a vast improvement both in steering and suspension. Get some fitted to your car if you want to make a serious improvement to the way it drives. I wish I'd put some on years ago and not just before I sell it :dunce:
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muppet
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Post by muppet »

have ordered mine from Proven products they said there are 4 at the rear , does this make sense or am I being had
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Goody(UK)
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Post by Goody(UK) »

Excellent thread, thanks to everyone who has helped me with an answer to my post 'Newbie - Needs Advice' 16/02/07.
It appears that I have been worried about expensive symptoms while a cheap cure is a dealer visit away.
For absolute clarity what do I ask for ( yes I am a bit dim ).
I am not concerned about slowing down steering inputs( yes I am a bit slow in that way as well ).
The reduction in 'tramlining' is appealing.
Not bothered about a hard line asI have ample padding.
So, bushes need to be ??????
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Bushes

Post by Guest »

Yes - there are 4 bushes at the back end - two on each trailing arm, but they look a right pig to change, unless you remove the arms first. I guess it depends on physical strength.

If you want to change the bushes at the back of the wishbones, get the bushes first, then find someone to fit them - BMW dealers are not permitted to fit non-BMW parts, so a good indie will be required. Show them my write-up and pictures, so they will know what you want.
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c_w
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Post by c_w »

I wouldn't bother with the trailing arm bushes; they are fine - its the rear subframe bushes that would need upgrading first as this permit more movement of the susupension that the trailing arm brushes. And they do look a pain to change!!
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Post by Goody(UK) »

Sorry guy's I think I may have misunderstood.
I thought it was the rear bushes of the front wishbones that gave the trouble.

Item 6 of attachment (if it saved )
Is Item 4,ball joint, a problem area as it looks like the base is rubber clad ( oah missus )

Image taken from
www.realoem.com/bmw/showparts.
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Robert T
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Post by Robert T »

Goody(UK) wrote:Sorry guy's I think I may have misunderstood.
I thought it was the rear bushes of the front wishbones that gave the trouble.
No, you understood correctly - this thread is about front suspension bushes. It went rearwards with muppet's post! It is the front that causes tramlining problems.

Cheers R.
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c_w
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  M roadster S50

Post by c_w »

Yes it's the bush at the back of the front wishbone, but as it only has one bush just call it the front wishbone bush.
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Ian_C
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Post by Ian_C »

I looked under my zed at weekend and its got 2 bolts holding the wishbone bush carrier in (item 8 on the RealOEM diagram) - is this normal?
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Robert T
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Post by Robert T »

In the above diagram, the carrier (labelled #5) appears to have two holes, which would imply two bolts (labelled #8). These diagrams often only show just one bolt when several identical bolts are used, but it you look at the description table on RealOEM you should see that the quantity is 2.

When I looked at mine when the car was on a lift, I am pretty sure that I saw two bolts, so that would confirm the above. If you think about it, it would flop around if it were only held on by one.

Or have got hold of the wrong end of the stick again?

Cheers R.
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c_w
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Post by c_w »

No, two bolts (17mm IIRC) hold the bush carrier on the car; the carrier sits in two indents for extra strength.
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muppet
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Post by muppet »

argh,l I thought it was the suspension at the rear and that is what I ordered . Will talk to my spanner man about doing them all though .
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Post by Goody(UK) »

Flippin Eck !!!
I have fitted (fairly easy DIY job,good instruction from earlier posting )
a pair of Powerflex bushes (Product Code - PFF5-303) these are the E30 M3 eccentric type. Drove the car down the usual commute roads which consists of approx 6 miles of varied country roads, many corners, bumps,differing road surfaces.
There is already a noticable improvement in the way the car tracks, I still intend to get the alignment checked/adjusted but I can confirm that it is £40 very well spent.
Probably benefit from a strut brace as well just to make sure.
Thanks to all who offered advice & opinions as I was thinking that my Z3 was a pup, the trolley moniker has now been buried.
Paradise Regained..
Goody.
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Eccentric Adjustments

Post by Guest »

Contrary to general belief, the M3 type eccentric bushes do not increase castor angle, this being a function of moving the top strut mounts backwards, as on an M roadster.

The eccentricit bushes permit the back of the wishbones to be moved sideways a bit, this being handy to compensate for any error in the alignment of the front end, such as after a small crash..

The problem with theeccentric bushes is setting them correctly, as it is necessary to check if the outer ball joints are symetrically positioned, then adjusting the bushes accordingly. Failure to do this will result in a misaligned front end, though whether one would notice this is another matter.
TimS
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  Z3 roadster 2.8

Post by TimS »

Before and after fitting the eccentric type I fully jigged up the front. The only significant changes were to the toe in and the caster angle. The toe reduced from 20' to 5' and the caster angle went up by around 35%.

However with the eccentric bushes the wheel is slightly further forward in the arch.
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c_w
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Re: Eccentric Adjustments

Post by c_w »

Mike Fishwick wrote:Contrary to general belief, the M3 type eccentric bushes do not increase castor angle, this being a function of moving the top strut mounts backwards, as on an M roadster.
Yes they do, they move the balljoint [and hub] forward in relation to the top of the strut. Granted it's not as significant an increase as moving the top mount as much as the M but there would be no other reason to have an offset wishbone bush (I'm talking about OE offset bushes which are not adjustable).

On the E36 M3 EVO, BMW apparently "toned down" the suspension from the E36 M3 and altered the topmounts (now offset along with a bit more castor) with central semi-solid wishbone bushes (same as Z3M) as opposed to offset bushes.
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Castor Angle

Post by Guest »

I'm amazed that moving the outer ball joint slightly sideways, and a tiny bit forwards can make any appreciable change to the castor angle - you learn something every day!

As an old MGB owner, I hate the idea of increasing castor angle - the MGB had 7 degreees, whereas a Sprite had 3.5 degrees - the difference was that the MGB had lots of power understeer and heavy steering. Ever since then I have regarded additional castor angle as curing the symptom (lack of straight line stability) rather than the cause, and from my experience the use of extra castor angle on a Z3 is not necessary, given ordinary poly bushes.
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muppet
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Post by muppet »

now got the bits for the front suspension , will see spanner man about doing the lot front and back
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c_w
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Re: Castor Angle

Post by c_w »

Mike Fishwick wrote:I'm amazed that moving the outer ball joint slightly sideways, and a tiny bit forwards can make any appreciable change to the castor angle - you learn something every day!
The centre wishbone balljoint is a pivot so any movement at the bush results in an equivalent change in the position of the hub. Although it does affect the track width at the same time. TimS seem to have notice a visual change inthe posiiton of the wheel; the castor angle has to have been changed.

I think these references to the MGBs of the olden days were when proper tyres weren't available :P The fact is the ///M runs huge amounts more castor than the non-M Z3, which results in better steering feel, better dynamic camber change and fantastic tyre wear control if you drive on a track for example.
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djfield
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  Z3 roadster 2.2i
Location: Southend

Post by djfield »

Thanks for the great write up Mike, I have now ordered some new bushes from the nice people at Proven Products. I look forward to giving them a go.

Cheers for the info ... this is a dangerous sub forum to read !!!!
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djfield
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Post by djfield »

I'm now the proud owner of some new bushes, planning to fit them on a sat in the next couple of weeks (kids and work permitting).

Couple of questions, how do you cut out the 10mm recess ? I was thinking about using a 25mm auger bit with the bush in a vice. Does this sound ok ?

Looking under my car I saw a heat shield protecting one of the bushes and I can see this getting in the way of the puller. Do you just bend this out the way or does it need to be removed?

One last one, excuse me for being such a novice, where would I go to get the Toe in checked ? Would a normal tyre place be able to do this, I need to get my tracking checked after my wheel refurb so I thought I could get them to look at this at the same time. Will they know what I'm asking for ?

Cheers for any info

Dave

p.s. Found this which gives me a lot of info on toe-in.....
http://www.allpar.com/fix/alignment.html

This link really helped, I now know what toe in is and how to check it myself. Nice. What to do afterwards and what is an allowed amount is ....

Another great link for explaining Toe-In
http://www.aa1car.com/library/wheel_alignment.htm
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Post by Guest »

The heat shield does not get in the way, as when the bush bracket is unbolted, the wishbone pivots arounf the inner ball joint.

I used a Stanley knife and a small wood chisel to cut the recesss, but an auger bit may be ideal, if you fit a piece of wooden dowelling into the hole to act as a centre - it's a matter of trying it. I don't know why Powerflex don't make a bush to fit an E36 wishbone. I'll email them and see.

Any decent tyre place should be able to set the toe-in, if they have good equipment - I use ProTyres of Plymouth (even though I live in France!) and they are a national company.

Don't use a BMW dealer, as they will charge £lots to do a full suspension alignment, and the rear end never changes unless you hit something!
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djfield
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Post by djfield »

Thats great Mike, I kind of wondered if there was some movement in there.

Good idead about the dowel hadn't thought about centering I was going to rely on my pillar drill and vice (with padding :) ). I shall give it a go a report back.

There's loads of big tyre places around so I ring round and also see if ProTyres are near me.

Thanks again for the guide, really looking forward to giving them a go.

Cheers
Dave :cheers
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Machining

Post by Guest »

I would ideally use a lathe, running at about 2500 rpm, with plenty of lubricant, but a pillar drill at its highest speed should do a good job.
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Top Mounts

Post by Goody(UK) »

Is it possible to swap the shock top mounts for an offset pair ?
After the initial (dramatic) improvement of fitting eccentric bushes to the w/bones the car still had worn off I started to notice there is still an amount of 'slack' in the directional control of the car.
I am right on the verge of buying a strut brace but do not want to jump the gun & buy the wrong brace just in case I change the top mounts.
Though the mounting holes will remain the same I am concerned that the centre bolt will not align.
Cheers
Goody
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maurice
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I want to resurrect this topic....

Post by maurice »

...because I'm about to do it, or something similar. I spoke to my local independent garage (the mechanic was a former BMW main dealer mechanic) and explained this polyurethane bush mod to him. He advised the poly bushes would give a much harder ride, but changing to ///M solid rubber bushes would be a good compromise. My other concern is c_w's comments:- "I ran with these on my old Z3 but felt they give the steering a lot of kickback and harshness so went back to standard ones in the end."

The mechanic also said that if I used the hard poly bushes, he would recommend replacing the wishbones as the extra harshness would wear out the other bushes holding the wishbone to the car.

What are your opinions? Poly bushes or ///M bushes? Will the ride be too harsh if there are no other suspension mods? Are new wishbones needed if poly bushes are fitted? (I have a 2001 2.2 sport, if that makes a difference)

Thanks in advance for all comments.
Maurice
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icarus
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Post by icarus »

I've read this thread time and again and I'm still in the dark and totally confused, not suprising I can hear you gasp.

If you have a 1.9 then the engine is mounted very high and only a few strut braces will fit, be very cautious.
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SledgeHammer
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Post by SledgeHammer »

Maurice, every "upgrade" has its downsides. While providing a better feedback, urethane bushings don't give room for movement, so all the shocks are absorped by surrounding parts, increasing wear.

IMHO, ///M bushings will give you best of both worlds. And not as pricy.
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Poly Talk

Post by Guest »

I wonder if your mechanic has any real experience of poly bushes? His comments sound more like he is confusing them with the nylon bushes used on some real race cars.

I did not notice any harshness after fitting poly bushes, and in terms of the front end, there are NO other bushes on the wishbones to wear out - unless he is counting the small rubber bushes on the ARB drop links?

Poly bushes are fine for any road car - we also have them on our Golf TDI in every possible location, and again, in about 40,000 miles have had no problems with road noise or harshness - just better steering response and longer tyre life.

A strut brace will certainly improve initial steering response, but to remove all trace of deadness around the sraight-on position, you really need to lower the susupension a bit, to gain about one and a half degrees of negative camber.
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muppet
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Post by muppet »

I had my spannerman fit the poly bushes and the tram lining has gone but now the steering is affected by mid corner bumps , spannerman reckons this is because of lack of play in them. He thinks they are a good upgrade for track use but he personally does not like them for the road.
Still thinking about it myself
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Bumps

Post by Guest »

I have never noticed any tendancy for the car to react to mid-corner bumps since fitting poly bushes - perhaps there is something worn at the front end causing this?

My car is also lowered by 30 mm at the front, so gaining some negative camber, but that seems to have the effect of sharpening the steering response a little, which would increase any tendancy to react on bumps.

The steering is bound to feel different after fitting stiffer bushes, as the old ones would have permitted a lot of lateral wheel movement on bumps, so perhaps you should see how it feels after a month or two, and meanwhile look very hard at the other componenets of the front suspension.

After 90,000 miles the Red Zed is predictable and unfussed by even the worst road surfaces, as is our Golf TDI, so I would think your problem does not lie in the poly bushes.
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c_w
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Re: Poly Talk

Post by c_w »

Mike Fishwick wrote: I did not notice any harshness after fitting poly bushes, and in terms of the front end, there are NO other bushes on the wishbones to wear out - unless he is counting the small rubber bushes on the ARB drop links?
The hub ball joint that is fastened to the wishbone is in a rubber bush, in that the wishbone can move around slightly on this rubber independent of the hub ball joint. I think the ball joint on to the subframe is "solid" though.

On the M there is none of this movement on the hub ball joint, but bizzarely it doesn't seem to have kickback harshness that I got in the Z3 with offset M bushes.

The best compromise I found was by filling the gaps of the standard Z3 wishbone bushes with rubber strips about 4mm thick on either side. Was cheap too!! :lol:
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PhoenixCoupe
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Post by PhoenixCoupe »

I have poly bushes on my E28 and they made a world of difference to the handling, even though the bushes they replaced were basically brand new.
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maurice
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Re: Poly Talk

Post by maurice »

[/quote]


The best compromise I found was by filling the gaps of the standard Z3 wishbone bushes with rubber strips about 4mm thick on either side. Was cheap too!! :lol:[/quote]

Sounds good to me! I'll try it this weekend and report back....
Maurice
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Cw

Post by Guest »

Maybe CW's problem with harshness was due to the use of offset bushes - mine are the normal symmetrical type.

The rubber lining around the outer ball joint does not really qualify as a 'bush,' as the rubber surround is very thin - about 4 or 4 mm and seems to outlast the ball joint itself, when replacement with an M joint seems to be a good idea.
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maurice
Joined: Thu 13 Nov, 2003 13:16
Posts: 53

  Z3 roadster 2.2i
Location: Archallagan

Finally got around to doing this mod with ///M bushes...

Post by maurice »

...Also had the tyres changed for Eagle F1s, so I can't do a direct comparison. So far, all tramlining seems to have disappeared, but there are some notorious roads I haven't been on yet. At the moment I'm too busy to try those roads, as it is now TT fortnight over here -WOOO-HOOOOO!!!
Better report to follow in a few weeks (after I stop grinning!)
Maurice
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oakley6691
Joined: Tue 25 Apr, 2006 13:33
Posts: 257

  Z3 roadster 2.2i
Location: Abercrave

Post by oakley6691 »

I went and bought the complete Powerflex Polyurethane bush set for my Z3, I had them of Larkspeed in Leeds via Ebay, the complete set was £175 (inc. delivery).
I fitted the front 4 bushes at the end of last week and have only driven the car for about 30 miles and i have to say what a difference they have made, the steering into bends is much sharper and more precise and when you catch a painted line in the wet or a dip in the road at high speeds it seems to hold its line much better, no tram lining at all.
I have yet to fit the rear bushes so will post again after they are done and a test drive.
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chrig
Joined: Sun 08 Oct, 2006 21:27
Posts: 87

  Z3 roadster 1.9i

Post by chrig »

I've been having handling problems and after an MOT today the notes mentioned the "front wishbone eyelet bushes deteriorating".

Reading through this thread, are the eyelet bushes the same bushes being referred to here? I'm thinking the "Powerflex PFF5-301 BMW Front Lower Wishbone Rears"?
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