Bushes, bushes, bushes...

[Forsh]

Evening all,

I've had my little roadster about 2 months now, and it's been great, but it's obvious that things can be improved.
I dug out the MOT slip and had a look at the advisories:

• Front wishbone rear bushes deteriorated - both sides
• Rear axle carrier bushes (A.K.A rear beam bushes) deteriorated - both sides

I've had a knocking coming from passenger front since I got the car, mainly over speedbumps or small bumps at low speed, so I knew the front need addressing (possibly anti-roll bar bush?) so my plan was to overhaul all the bushes up front with Powerflex items £120 plus £80 labour. Job done. (correct me on the labour if I'm wrong please!)

What I didn't realise is that the rear job was a big one. I've come to learn that in order to change the rear beam bushes, the exhaust and rear axle need to be dropped. This isn't something I can attempt myself, and if I'm paying someone to do it for me, I'd like to make the most of the axle being dropped.

After some time reading on the forum, I've learnt that I definitely want to change the rear beam bushes to Powerflex, and the diff. mounting bush to poly/rubber.

I have a couple of questions to further expand my knowledge of this area:

• Will new rubber diff. mount bush stop the diff. clunking from 1st to 2nd? Or will I need poly?
• With the rear axle down, would it be advantageous to also replace the rear anti roll bar bushings and the trailing arm bushes? If so, poly or rubber?
• Are there any other areas, other than bushings, that should be replaced with the axle dropped?
• How much should I be looking at in labour costs to drop the rear and replace beam, diff and any other bushings?

Thanks in advance for you sterling advice!

Forsh.

Edit: I should also probably mention that this is my daily driver, doing 200-300 miles per week, including motorways.

 

[GazHyde]

Having had a full rear end rebuild I went with OE quality rubber bushes and am glad I didn't bother going with Powerflex (the one concession was the diff bush as it's considerably easier to fit). The ride is plenty good on OE bushes and with the UK roads I really wouldn't want my suspension any stiffer. If you are going on a track or are a spirited driver then I would suggest Powerflex would be worthwhile. OE quality (mine came from GSF) is obviously cheaper too

To try and answer some of your specific questions...

• The "clunk" from 1st to 2nd may or may not be related to the diff bush. A knackered diff bush of course isn't going to help, but you may want to look at the guibo bush and bearings on the prop shaft.
• While you have the rear axle down it's definitely worth replacing everything rubber in one hit.
• Other stuff while there... handbrake cables will invariably worn through and worth changing.
• Labour costs - no idea on that one.

 

[Forsh]

Thanks a lot for your insight Gaz, much appreciated.
I think you may have changed my thinking re: Powerflex bushes. I do enjoy spirited runs maybe 3 or 4 nights a week in summer, but it's only a 1.9 after all... Keeping the cost down on the rear may also allow me to overhaul the front bushes as well, and maybe even refurbish my alloys.

 

[Dino D]

For the rear beam bush I definitely reccomend Powerflex.
Takes away the steer from the rear effect these cars have had, even from new. The standard bushes allow for small movement in a place where you really could do without.
Minimal increase in NVH I've found.
The Powerflex diff bush may make the diff louder, it has in mine.
I am due a diff fluid change.
Not sure if the open diff ok a 1.9 is quieter anyways.
In any case I wouldn't have OEM again, I prefer the lack if slack and general 'mushiness' that comes standard with BMW gearshifta (if you've driven a Honda you'll understand why BMW shifts can be improved!).

Being a 1.9 the handling, gear shifting and keeping of momentum is more important than on the bigger engines (and fun) so I would want to go to that direction when refreshing.
These cars are loud already so for me a trade off of more NVH for much better handling was worth it for me.
Refresh your audio too and enjoy te driving potential the cars can offer when set up right!

Ps all that said a set of fresh dampers would probably make the biggest single difference for you.

 

[Forsh]

Thanks a lot for your reply, Dino!
I feel like I've got a Poly devil on one shoulder, and a Rubber angel on the other!
Haven't looked into dampers, and unless they're cheap as chips, I don't think I want to open that can of worms just now!

If I went for Powerflex rear beam and diff. mount bushes, would the others suffice with being rubber?

I think I'll add a diff fluid and gearbox oil change to my list whilst it's in, just to make sure everything is running as it should. Cheap to replace the guibo bush at the same time?

 

[Dino D]

Re Poweflex mixed with others I belixe that can be done but @Lee will know better than me.
In not sure if the other bushes actually make anything harsher though.

Damper can be changed easily enough later on so don't worry there.

Ps your beam bushes must be bad - I say this as mine were but never even hot picked up on the MOT. My diff bush was very bad too and also sailed through mot (and my test station is also a garage so happy to find extra work when they can!).

 

[Forsh]

Okay, thanks Dino.

Yeah, apparently so! I bought it on a bit of a whim about 8 weeks ago now, not really knowing what it was I was reading on the MOT advisories. Willing to put the money in now though to get the car up to scratch!

 

[Lee]

Morning @Forsh

I rebuilt both Dino's and Gaz's z3 rear chassis last winter. One with Powerflex one with OEM quality. I did this purely on driving style and how the owner intends to use the car. Dino wanted a sharper more track focused car apposed to Gary who just likes to have spirited drives from time to time(all the time if you ask me ). If you was to drive both cars back to back you wouldn't be able to tell the difference between what bushes were fitted. The Powerflex only come into their own when driving the car on the edge anyway.

The Powerflex bushes you can guarantee for the life of the car and they're not that much more than the OEM so I suppose its something you can tick off once fitted. The way I see it mate. The OEM bushes have lasted the last 17 years why wouldn't the next OEM pair.

Lee

 

[GazHyde]

all the time if you ask me

Cheeky...

As Lee says we all want different things, and I wanted something comfortable for the UK roads, but with the ability to handle well when needed.

Just don't mention bargain priced coil overs to me...

 

[Chazzy]

I've recently done all the bushes on mine, front and rear, all with powerflex.

It is possible to get the beam bushes out without dropping the beam completely, but it is pretty tricky.
I just dropped the whole back end, replaced the beam, trailing arm, and diff bushes, the ARB bushes and the ARB drop links. It would be worth checking that your rear top mounts are okay.

The front bushes are really easy to do, you just need the right tools!

I found that the handling on my car isn't too harsh, and that's with koni shocks, springs and H&R anti roll bars. It's night and day from what it was like before.

 

[Forsh]

Lee, Chazzy, thanks for your both your responses.
I reckon I'm going to go with OEM bushes for the bushes. Given that the current bushes were picked up on MOT, they must be in a sorry state, so just refreshing them I'm sure I'll feel a world of difference.

Thanks a lot for your insight on this - perhaps I'll see some of you at the Sunday meet?