my un-5 lug swap

[hoveringuy]

Call me a heretic, crazy or just sentimental; but I swapped my 5 lugs back to 4.

No, I'm not swapping back to the m20, too...

Here's the figures I recorded from the un-swap:

Front. fully-dressed e36 M3 struts w/control arms, springs and everything ready to bolt in weighed 72 lbs.

The e30 struts with all the same stuff weighed 56 lbs. 16lb difference.

My TRM C1 15x8 with 215/50 tires weigh 35.5 lbs each. The front DS2 weighed 40.5 each.

That's 21 lbs per corner or 42 lbs off the front.

In the rear, the 318ti hubs/rotors/calipers only weighed about 4.5lbs more, but the 245/40 wheels weighed 46.5 lbs each. So, 4.5lbs in suspension and 11lbs off the wheels. 15.5 lbs per corner or 31 lbs off the rear.

The total here is 73 lbs of sprung, rotating mass.

The car feels quicker and noticeably livelier. The downside is that the m3 brakes were just plain awesome but other than that this is a much better daily driver.

Yes, I could have found lighter 17" wheels but it would have only made a small difference in the front.

[erik325i]

Front. fully-dressed M3 struts w/control arms, springs and everything ready to bolt in weighed 72 lbs.

The e30 struts with all the same stuff weighed 56 lbs. 16lb difference.

What were you using in the front? e30 m3, or e36 stuff?

[Philo]

Sounds like E36 stuff. The E36M3 rotors are massive compared to the E30 stuff. Unsprung weight is the main reason I don't want E36 5-lug. E30M3 stuff should be fairly comparable in weight to the narrow body E30 stuff.

[balooshinakus]

If I had to do it again, I would keep the 4lug and do Massive brakes (don't feel comfortable on e30 brakes with an s50 at the track) mainly so the suspension geometry would be correct in the front (right now, even with the "proper" setup my wheel sits too far back and my slightly oversized tires rub on the back of the wheel well). I'd still end up with bigger rims though to fit bigger brakes.. Thats probably what weighs the front suspension down so much is the massive e36 disks and calipers. It's always a trade off right? Less weight or more brakes? I need the brakes so I don't have much of a choice.

[Aptyp]

going from DSII with oversized tire to TRMs with undersized tire would make a difference on any vehicle, regardless of extra weight in hubs or brakes.

This comparison is very much unfair to people running lighter wheels, than DSII (the heaviest BMW wheel) and not run oversize diameter tire on them. Added to that, you're running tires that are 1/2" smaller, than stock tires.

Example:
DSII front is 22.3 lbs and DSII rear is 24.8:
K1 17x8.5 are 16.8
Right there, you've lost 31lbs.
And there's a huge difference in physics of running an oversized tire.

[Philo]

Truth.

I'd like to see the simple weight comparison between the E30 stuff and the E36 stuff without wheels.

[hoveringuy]

Truth.

I'd like to see the simple weight comparison between the E30 stuff and the E36 stuff without wheels.

I broke the suspension out separately in my original post... front difference between e36m3 and e30 was 16 lbs per side. That's primarily the rotor, caliper and spindle.

In the rear it's 4.5 lbs per side. The rotor is slighly larger in diameter and it's also wider for the extra offset.

So even without wheels the difference is 41 lbs.

I'm not here to poo-poo the 5 lug swap, but for my needs 4 lug is better.

Also, I'm running the 215's because they have the exact same treadwidth as the 225 version of the tire, with a slightly shorter sidewall.

This comparison is very much unfair to people running lighter wheels, than DSII (the heaviest BMW wheel) and not run oversize diameter tire on them. Added to that, you're running tires that are 1/2" smaller, than stock tires..

I'm not throwing rocks at anyone, I'm just documenting my example. I would have loved some Apex wheels..

[samiam3356]

Damn, you weren't kidding about wishing you had never went 5 lug. Honestly, I wish I had just went with a bbk 4 lug kit sometimes as well. BUT I plan on tracking mine a good bit so I will be keeping the setup on mine.

[MikeDE]

Function over Form, good going Hoveringuy.....this is why I am always on the lookout for a set of E30 Alpina B6 front calipers, these with 296mm rotors will be plenty. And the fact that TUV can be a PITA when the stuff isn't factory. Some MB calipers will work BUT I would still have to use a bracket.

[hoveringuy]

This is purely conjecture, but are 245's tougher on the clutch? The original 195's would spin, the 245's didn't. Now I'm on 215's...

http://r3vlimited.com/board/showthread.php?t=198094

After being back on the 4 lug suspension for a while now I still like the handling and "manners" better.

[einstein57]

I bet a BBK like massive or UUC would shave additional weight along with the increased performance. I'll weigh my kit if it ever arrives. Hell even the RX-7 kit probably saves weight considering how light that aluminum caliper is.

[hoveringuy]

I bet a BBK like massive or UUC would shave additional weight along with the increased performance. I'll weigh my kit if it ever arrives. Hell even the RX-7 kit probably saves weight considering how light that aluminum caliper is.

I think both the RX-7 and massive kits are basically the same as stock. Lighter caliper, but heavier rotors.

[2002maniac]

The main reason to go 5-lug for me would be the tougher wheel bearings. When I was doing a lot of track days I would change my front bearings every season.

That's a lot of extra weight though.

[Gruelius]

if it was just a hub setup for the front (using old e30 gear) would it be too heavy?

[rThor432]

To the OP, I appreciate your reasoning on the subject and the fact that you took the time to weigh the components and provide us all with simple, solid numbers. If I had access to a nice scale I would toss an E30 M3 strut/brake assembly on it to find where it falls in the middle. It is quite a bit heavier than a standard E30 strut/brake assembly already. I'm planning to install one of Massive's kits on the E30 M3 5-lug'd car that I have in order to [hopefully] drop the sprung corner weight back down to stock weight.