Improving on M3 suspension (E36)

[handgrenade 189]

Hi All

With BMW spending countless millions with potentially hundreds of suspension engineers and racing experience advice, is there a reasonable justification to try improve on the standard setup?

I understand that a full adjustable setup properly tuned with quality parts can produce excellent results for track use but I'm thinking daily driving with the occasional spirited drive .. No track use.

With some cars putting in lower stiffer springs can do wonders for a standard suspension setup but with a very highly pretuned setup from a machine like the M3, is there any benefit from springs or other smaller modifications short of a full adjustable setup alone?

Cheers

[Michael. 2313]

Improving for performance or more comfort?

The more solid the rubber bushings generally the better maintained the geometry under harder driving.

Of course the trade off is more vibration etc, stresses, etc.

[handgrenade 189]

Thanks Michael. I understand there are always tradeoffs but are there any acceptable tradeoffs to improve performance at the minimal cost to comfort? Or has BMW got this right from factory?

[Michael. 2313]

Your M3 has got high ish ks so if the major ball joint and bushes havent been replaced start there.

A new steering arm to the rack is a good upgrade to get back that tight feel, as is getting a rebuilt or replaced steering rack.

Have you done the RTAB limiter kit? That stiffens the rear up somewhat.

Other than that, stiffer sway bars, upgraded shocks and harder spring rates will be the next avenue to get more out of the car, but I think if your using it on the road Stock new M3 stuff fits the bill better.

[m3Dakar 5]

I have just installed Bilstein shocks and custom made cobra springs from Chamberlins in ChCh. Aswell as a whiteline Adjustable sway bar in the front with all new bushes, has worked wonders for the car so far transformed its manner into something very sharp yet still not being ultra rock hard like most coil overs, probably more expensive than buying a set of coil overs but depends what your going for, i still want to be able to go away on trips with the occasional track day and a bit of daily driving, well worth it

[handgrenade 189]

I had a mechanic friend check out the suspension on a hoist and we could tell a lot of the bushings had been replaced .. New rotors and shocks on the back. All very well maintained. I'm not sure that I would push the limits of the standard suspension of course .. Would riding a little lower mess with the factory beautiful handling??

[Beeker2 69]

Unless you want a hard ride just refresh the bushes and the shocks (I would recommend Bilsteins, but there is a heap of options).

[Beeker2 69]

Two additional notes:

> try to stick with OEM bushes (or quality rubber), its more expensive fitted but you'll get a more OEM level of comfort, performance and reliability.

> Konis are great, but more people can rebuild or revalve the bilsteins.

my experience only!

Edited June 18, 2014 by Beeker2

[handgrenade 189]

My car has a full service history from new and mostly hot highway kms. From having it up on a hoist all the bushings look good and the rear suspension including shocks bushings and discs have been replaced.

I was thinking of the UUC springs for sale by mike. Plus some better shocks. But I don't want to upset the geometry even if is only a few cm drop ..

[Allanw 1071]

The bushes can look fine, but be poked, and highway is harder on them than around town. It they aren't changed already, they're probably not like new ones at all. Our E39 bushes looked fine (at 12 years and 115K, though the shocks were 100% rooted), but I rebuilt the entire front end (used powerflex bushses) and transformed the car - it's really tight and smooth now.

I've not owned an E36, and I realise the E39 is a lot more complex suspension wise, but if it were me, I'd not bother with "Goodies" until the chassis foundations were sorted. Might turn out you don't need any goodies (even though they're more interesting )

Full service histroy doesn't mean a car has had all required work done either - it just means it went in for the "recommended" oil changes/inspection etc - additional work can always be declined by the owner, though I'd hope this was less likely on a proper ///M car. If you have all the invoices, then you have a usable history and can check for the bushes etc.

[Beeker2 69]

The bushes can look fine, but be poked,

Bingo.

eg My bushes passed a BMW dealer pre inspection, yet 500km later when i replaced my RTAB the centres were completely seperated from the rubber.

[handgrenade 189]

Seems like the general consensus is to refresh the factory gear!!

Will dropping it an inch mess up the geometry?? Of course it will change the angles etc but its not that much of a change??

[MLM 57]

I have done some measurement recently based on my non m spec suspension. Using a bit of cad wizardry it shows a 40mm ride height reduction gives a roll center height decrease of approx 120mm which results in a roll couple increases of 30%. ( will check numbers later as away from cad box right now)

Unfortunately I can only measure these things out of my interest but not comment on the real world impact of these changes as I am at the same point as you looking at upgrade options. I don't want to derail your thread away from your original question but thought it would offer a viewpoint to discuss any changes you may want to make.

Edited June 21, 2014 by MLM

[handgrenade 189]

Sorry I work with planes so get stuck in imperial!! Haha

Suspension right now is 100% untouched e36 m3 sedan Evo suspension.

[handgrenade 189]

The drop is driven by aesthetics but if it is going to comprise handling then I will give it a miss.

[handgrenade 189]

Ken, M3 ride heights vary, measure the ride height from the lowest point on the wheel (lip) to the highest point vertically on the guard

looks like you have 17" contours

-- Rear measurement should be 540mm

-- Front measurement can be 560mm for sports or 585mm for "std" M3

If the front is the latter then you can drop it 25mm , yours look like it is running close to 580

Dropping the front to 560mm -570mm introduces a little rake to the chassis and as the Sedan is slightly rear biased weight wise , shifting the weight onto the front wheels improves turn in, feel and reduces wandering if you have any.

P.S. some of the things I deal with on a daily basis are also imperial sizings, but I convert them to metric when needed and only work in imperial when un-avoidable, The native language is metric, we should all use it

Hi Ron,

I went out with the trusty tape measure. made sure to use the side with metric

And here are the numbers: front, bottom lip of wheel to highest arch = ~600mm

rear bottom lip to highest arch = ~575mm

As far as I am aware the suspension is stock, and tire sizes are as specified by bmw.

seems like i'm riding high!!

Here are some images, excuse the dirty curbed rims (im saving for a refurbishment).

[handgrenade 189]

It should have evo m3 suspension in there already!

Was looking at these springs. seem cheap ..

http://www.vividracing.co.nz/h_r_sport_springs_bmw_e36_m3_3_2l_96_99_1013460297.php

[handgrenade 189]

Link is just to some sport springs by H&R. Says a 25mm drop for the m3 Evo

[handgrenade 189]

What brand springs would you recommend? Something with maybe a 25 to 35mm drop.. Thanks mate!

[_ethrty-Andy_ 2132]

before we get too carried away, don't forget to take into account the car is probably not on a completely level surface, so measurements might not be correct.

[handgrenade 189]

I will measure with a builders tape and measure both sides and average to account for any non level surface but my work carpark is pretty level .. Koni will be next on the list!! Thanks everyone for their input. Info to come

[handgrenade 189]

here are the measurements. going from FR to RR to RL to FL

[handgrenade 189]

Hahaha, Keith at GeorgeStocks can custom make/match some King Springs (which they run in their racecar) for the same price as H&R springs, the only thing is that I will need to provide to them a front spring from an evo sedan and a rear spring as well for them to match spring rates etc.

The other option is to go with the H&R springs.

It is definitely riding high if your measurements from rim bottom is correct .. Keith from George stock mentioned that usually the measurements are done from the wheel hub centre which I had also thought, however measuring from a known rim diameter would be as static as measuring from the centre hub.

Will go try find some H&R springs, or a front and rear standard evo spring for Keith to match.

If anyone has a standard e36 m3 rear spring and a front evo m3 spring, would be greatly appreciated if I could borrow them for a few days! George Stock will measure, test and find the right springs to match.

[jom 98]

With standard motorsport springs on a 328 Coupe (17' rims) I get 582/575 front (L/R), 557/553 rear. I'd suggest that that's as low as you'd want to go at the front if you want to keep the centre undertray - otherwise you'll lose it over speed bumps.

[handgrenade 189]

Yep trying to source some H&R sport springs which should put the ride at the proper height .. Maybe about 25mm under factory

Don't want to go too low but 25mm should not mess with the suspension geometry too much!!