Z3 M Roadster springs on an non ///M

[GazHyde]

This thread came out of a discussion between @Lee and myself last night.

My 2.2 Sport has shorter springs than a standard non-///M Z3. When we put these next to a set of Z3M springs we can see that the M springs are shorter and slightly thinner than the sport ones.

My questions is based around the idea of fitting the shorter Z3M front springs in place of my Sport springs, in the thought that it would lower the front ride height of Rosie. Can anyone think why fitting M springs to a standard shock absorber would be a good or bad idea? The shocks I have are slightly shorter so would cope with shorter springs.

I know when the general question of whether Z3M suspension fits a non-///M is usually answered with a solid NO. Would this be down to a difference in shock absorber?

We know already that Z3M rear springs are ok on a non-///M as Lee fitted them to his Dads 2.8 and it brought the ride height on the back down nicely.

Am I barking up the wrong tree, or does this seem a possibility for lowering my Z3.

 

[Grumps]

Interesting Gaz. I'd like to see a pic of Lees dads car to see the ride height.

 

[pgunter]

@GazHyde yes an interesting idea.. and you barking ? never... yet alone the tree...

 

[Brian H]

IMO It will not be the physical fit but will come down to spring rates, the Z3M Springs will be a stiffer spring due to the extra weight of the engine block, I know when I ordered new OEM front springs for my car the options the car had fitted were taken in to consideration.

 

[EnthuZiaZT]

I would not have thought the weight difference between the 2.2 and the Z3M would have been great enough to make a great deal of difference. Although the ride will be harsher on the Z3M springs, fitting them should still improve the stance and the handling of the car.

I have just looked on Wikipedia, the difference in weight between the two cars is 70Kg however it does not tell us how that extra weight is distributed.

Mike

 

[oldcarman]

I would think @zedonist would have some ideas re this switch! I'm sure it comes down to spring rates and whether or not they would make the ride unbearable but don't think so because of the minimal difference in the weights between the 2.2 and the 3.2. If I had all the parts to exchange I'd give it a shot, you may be onto something here guys! JIM

 

[GazHyde]

IMO It will not be the physical fit but will come down to spring rates

That's my initial thought - albeit as a complete noob to setting up cars!

Although the ride will be harsher on the Z3M springs, fitting them should still improve the stance and the handling of the car.

Again my thinking they would be stiffer than non-///M's.

Am I likely to find out what the spring rates are for the various Z3s from the Bentley manual Lee keeps in his garage? Although I'm not sure knowing them will really help with the decision, it may just be a suck it and see job!

Thanks for the replies chaps, will do some more thinking and see what happens when we get around to changing my fronts over...

 

[zedonist]

As you have access to a garage and mechanic, just swap them out and give it a try, the only issue I see is that front and rear rates won't match and you may experience bobbing, but then again it may work, go for it.

 

[GazHyde]

Thanks Rich, I would most likely keep an eye out for a set of rear springs to match so hopefully there wouldn't be any bob bob bobbing along!

 

[McZee3]

i have M rear springs on my 1.9. they are about the same spring rate as the m-tech springs i have previously had fitted but they seem to sit a little lower. i can't say about the fronts as i am running m-techs still but i would think they would be the same rate but a little lower maybe?

 

[t-tony]

Thanks Rich, I would most likely keep an eye out for a set of rear springs to match so hopefully there wouldn't be any bob bob bobbing along!

Not as if you've got a red, red robin Gaz. Suck it and see all you have to loose is some time.

Tony.

 

[5harp3y]

If there is a differences in spring rate i doubt anyone other than a race driver would tell the difference. Plus i can't see the front end of a Z3M being much heavier /lighter than a standard Z

 

[TaffZee]

Its like everything else Gaz, the stealers will tell you they are not transferable just to sell them at a premium price, I have come across a lot of parts that are transferable to other vehicles in my time, but the "computer says No" is the common reply from the techs. Don't know a lot about the M's but I am presuming that the suspension main components swinging arm turrets wishbones are the same as non M's (correct me if I am wrong) so putting springs and shocks from a M on should not be an issue. providing they fit correctly.

 

[Brian H]

The ///M uses a cast iron block, the M54 uses an aluminium block hence the difference in weight

 

[t-tony]

Parts guys at dealers will be stopped from telling you that parts are transferable between models out of fear of being sued if something went wrong. A sign of the times of the CYA world we live in. The only way you will find out is by talking to someone who has done for themselves.

Tony.

 

[oldcarman]

i have M rear springs on my 1.9. they are about the same spring rate as the m-tech springs i have previously had fitted but they seem to sit a little lower. i can't say about the fronts as i am running m-techs still but i would think they would be the same rate but a little lower maybe?

It's nice to know these can be used on a 1.9 successfully, I've been wondering what to use to lower mine, now I know these work! Thanks, JIM

 

[GazHyde]

Actually this is a forum folklore issue, something I "learnt" from another forum when I was a member there. The question comes up, and those "in the know" say Z3M suspension doesn't fit a non-///M. Now as a complete unit (shock and spring) it may be physically different (too tall etc), but I'm not sure I've seen the spring question asked before.

Being honest, I wouldn't ask a BMW parts department that question because (a) they aren't likely to know, and (b) they wouldn't say anyway because it's their butt on the line - and that's something I'm happy to respect.

The only way you will find out is by talking to someone who has done for themselves.

That's why I'm here

 

[t-tony]

Spot on Gaz, you're the ginnea pig mate. But don't keep it to yourself,

Tony.

 

[Dino D]

I would think the spring would fit and that's more about the mounting locations for the full suspension making it not interchangeable.

I would expect a higher spring rate given the performance of the M.
Just bear in mind a higher rate spring will compress less hence the drop might not be as much as you would expect.

In my experience different spring rates are very noticeable - going from 6kg to 8kg was immediately noticeable even in normal driving for me on my rear springs.

 

[swamper]

I would think the spring would fit and that's more about the mounting locations for the full suspension making it not interchangeable.

.

that's correct its the mounting on the M for the drop links that are different