'Solid' riding BMW models?

[Michael. 2312]

So one thing that grinds my gears about my E36 cope is the relatively flexible feeling chassis... in the sense it creaks and squeaks over our average to poor condition urban & rural roads, enough to have the interior make noises and such things - it makes me cringe!

I believe the E36 coupe chassis is the softest besides the convertible, apparently the fold down seat design in the rear bulk head reduces the overall rigidity considerably.

I went in a friends 2001 E46 330ci coupe and I was blown away just by how much smoother and quieter it was over smiliar roads than my car. No doubt this is down to the superior chassis design & torsional rigidity?

This got me thinking, what are the more 'solid' stiffer feeling BMW models out there as a good platform to work on, obviously the newer ones are, but from what I see the 4 door E46 models are the perfect option for making a car ride and handle the best..,,

Some extended input on this would be appreciated!

[roo 41]

E34 is MILES better in this regard to my E36. I thought the exact same, E36 feels soft, E34 is solid, quiet and handles surprising well for a big car.

[westy 614]

We had an E46 4 door with non fold down rear seats and solid panel in the back and no sunroof. By far the stiffest of the BMs we've had. Noticeably stiffer than the fold down seated, sunroofed 330 we have at the moment.

I know what you mean with regards the E36 coupe. Wonder if a solid panel behind the seats would help much. Wouldn't help the floppy front end though...

But hey, least it's not an E39 touring.

[BM WORLD 1261]

_{same e34 rides better , e36 bouncy etc}

_{but way more sound deadning in the e34 and e46 models etc , all adds weight though .}

_{i think the e36 chasis may be stiffer than the e34 though as a newer design}

[Eagle 1525]

Longer wheel base sure helps. Ive found E34's to have less rattles etc than E39, even rugged neglected ones usually ride smooth and quiet.

[jeffbebe 1559]

Start with a simpler strut brace front and rear - something like this:

http://www.ebay.co.uk/itm/933-motorsport-BMW-3-series-E36-front-and-rear-strut-bar-brace-kit-320-325-328-/301123117888?pt=UK_CarsParts_Vehicles_CarParts_SM&fits=Plat_Gen%3AE36&hash=item461c562340

If you notice a difference think about investing in something tougher as per Dave's pic above.

The front one I fitted in my E39 did nothing noticeable as far as handling goes but did eliminate a lot of the creaks and flex noises in the cabin.

[Young Thrash Driver 1020]

What you're hearing is probably the car protesting at being Toyota powered, Michael.

[qube 3568]

^ hahaha

[hybrid 1039]

Strut braces and have a negative effect on bumpy roads .. too much chassis stiffness sucks for open road driving. Also can amplify understeer on cars with staggered setups. The harder / more ridged and lower profile tired your car is the more it is pronounced.

I had this on my e46 and took them off as they made the car too 'darty'. This was even after mucking aorund with alignment / camber / castor etc.

They are great for roads that are flat and dont have too much articulation.

Ultra-racing under chassis brace is the first fix, then if you still arent a fan, do the strut tower linking.

http://www.pro-wholesale.co.nz/ultra-racing-strut-brace-sway-bar-chassis-bracing-products/e36/

PS. Westy forgot to mention that he cut open a e46 once ... it has a hidden plate steel 'roll bar' in the pilars which really help with stiffness. Tradeoff obviously is more weight.

[westy 614]

The e46 chassis is stiffer by all accounts, yes. But you can still stiffen up the e36 considerably.

Front x-brace and strut tower bar does wonders. If you want to go nuts then something like this apparently increases torsional rigidity. It links the rear subframe to the shock towers.

Mason Engineering...

Otherwise... a half cage?

See that ruddy great hole in front of it? I'd start with filling that in...

[Driftit 1953]

Strut braces and have a negative effect on bumpy roads .. too much chassis stiffness sucks for open road driving. Also can amplify understeer on cars with staggered setups. The harder / more ridged and lower profile tired your car is the more it is pronounced.

I had this on my e46 and took them off as they made the car too 'darty'. This was even after mucking aorund with alignment / camber / castor etc.

They are great for roads that are flat and dont have too much articulation.

Ultra-racing under chassis brace is the first fix, then if you still arent a fan, do the strut tower linking.

http://www.pro-wholesale.co.nz/ultra-racing-strut-brace-sway-bar-chassis-bracing-products/e36/

PS. Westy forgot to mention that he cut open a e46 once ... it has a hidden plate steel 'roll bar' in the pilars which really help with stiffness. Tradeoff obviously is more weight.

Strut brace on my E30 series car made it understeer badly. Gave it away to someone.

[polley 916]

 

Strut brace on my E30 series car made it understeer badly.  Gave it away to someone.

interesting. I had bad under steer issues last week. Will try removing the strut brace at the next event

[BM WORLD 1261]

have a z3 underbrace thing if someone whats to stiffen up the front of there e36

[Rgvkiwi 10]

Hi Brent will this fit the Dakar 93 m3 we visited you in on Saturday? do you want to pm me price if so.....

I have to admit being a bit disappointed in the legendary handling of the M3 BUT that is in comparison to my MX5 race car...maybe unfair...haven't decided yet!

[Eagle 1525]

May of been legendary when it first came out, 1992 is along time ago. I think Jack of all trades, master of none sums up the BMW brand.

[BM WORLD 1261]

^{they look like this}

^{pm me for a price}

[Michael. 2312]

Thanks for the responses guys. Some thought provoking feedback!

Brent, I already have a front X-brace, it sure made a difference but I think the back is where I feel the cars a bit sloppy.

I recently designed a Mason engineering style cross brace for the rear strut / subframe, still have yet to make it though! I've posted this before

I think some extra braces such as this will help dampen my qualms with the car.

But my main thought is for future projects... do I use an E36 again or move up to an E46?

The E85 Z4 roadsters also interest me, but as a convertible I suspect I'll be disappointed with how it handles the rough stuff.... that said I believe the Z4 and E36 coupe have a very similar torsional rigidity rating. Are they any good, to those that have driven them?

Edited May 22, 2014 by Michael.

[euroriffic 601]

Keen Brent

[MLM 57]

Thought this may be of interest:

Chassis stiffness values

BMW E46 Sedan (w/o folding seats) 18,000 Nm/deg
BMW E46 Sedan (w/folding seats) 13,000 Nm/deg
BMW E46 Wagon (w/folding seats) 14,000 Nm/deg
BMW E46 Coupe (w/folding seats) 12,500 Nm/deg

I cant verify the numbers any more than other data of the net but shows the deficiency of the coupe format. Possibly a reason why BTCC e36 shifted from the coupe to a sedan? It would be interesting to see comparative e36 numbers if anyone has them.

The interior build quality of my e46 is far better than my e36 which is quite frankly appalling and a step back even from the E30. The E36 certainly missed target expectation in this area. Im not surprised your e36 squeaks and rattles more than e46.

Your bracing looks hefty Michael, Have you done any calcs on this? I wonder how much value the short angled in braces are offering relative to the weight and build complexity they add.

Edited May 22, 2014 by MLM

[Michael. 2312]

Have you replaced the rear trailing arm bushes with aftermarket Urethane or similar takes out the "passive" rear steer .

also shock top mounts with Meyle HD so the shock control is more direct?

All new original bushes have been replaced when I rebuild the rear end in March.

Currently has M3 trailing bushes with the limiter kit installed. Also running the reinforced type strut mounts available through pelican parts.

[aw-krazy 45]

Also keen brent if it hasn't gone lol

[Michael. 2312]

Also keen brent if it hasn't gone lol

Caution, It might scrape fitted on you car

[Driftit 1953]

I'd think through the physics of the strut brace "inducing " understeer and discarding it because "it " is the problem.

More likely the stiffer front chassis geometry means the sway bar and all the other elements that can contribute to understeer are coming into play earlier and to a greater degree.

You might find you can back off a few other things and gain a significant improvement with the strut brace providing a more stable platform for it to hang off ?

I'd also look at what is happening at the rear - if the front is coming into play earlier and more pronounced then the back will respectively be having less influence and this will increase understeer.

Brent, what's the Z3 brace look like ? might be keen to use it in a Kevlar underbody panel.

It was an E30 Series car with a full cage through to the front and rear struts. No amount of adjustment would result in any benefit from the strut bar on the track. It was costing me up to a second at Taupo. That's a life time in an E30.

Careful when going to a harder bush in a road car. You will end up with much more road noise in cabin. (I am sure you don't have to worry about this Michael )

[hybrid 1039]

Outside of locked e30 series specs, you can easily eliminate understeer in an e30 several ways (actually any car). Simplest is front camber and toe out. All of this is based on the assumption that the mechnicals of the suspenion are up to good standard in the first place as others mention.

There is a chart I use which is quite good .. let me see if I can find it.

[Driftit 1953]

Also raising the rear end of the car slightly till you find a balance. The factory bump stops being put back in made a big difference for me and many others.