Stiffening the convertible chassis

[xLibelle]

OK, well that sums it up about the buttstrut. rubbish

[Liam]

OK, well that sums it up about the buttstrut. rubbish

Pretty much.

There is some stuff back there that could use some extra control, but like I said in an earlier post, it's an engineering nightmare and where it would have to go to make it work would mean tearing the whole world apart.

[N2MYE30]

Ive got to remember this when I upgrade the suspension.

[CorvallisBMW]

OK, well that sums it up about the buttstrut. rubbish

I'm not so sure. I noticed a difference, without a doubt. Was it as much of a difference as the mason x-brace? No, but it was a difference. I still think they are worth doing, and the testimonies on the butt-strut website from Z3 and E30 owners count for something too.

[xLibelle]

I imagine that if you have the OEM rubber subframe mounts, where the sides do not have rubber, then the frame is likely to resonate to some extent... rather as much room that the mount cylinders will allow. Much less likely if you have something solid in there like urethane mounts.

Taking a close look at that region of the car, you have a considerable amount of structure and framework. Near-by lateral motion is controlled by the base of the back seat, for the most part. As the car gets into a turn, the lateral forces will roll the cabin's walls and relocate the subframe mount points in some way, shape, or form. To say exactly how much is probably a hard thing to do. Is it enough to effect the suspensions geometry for a street vehicle with some HPDE's? NO WAY.

But then this shouldnt be a thread solely about if the butt-strut works or not and I will stop the tread shitting here. I doubt you're hurting anything and more than likely have provided for some much needed frame strengthening. Is it worth the ground clearance loss? i dunno.

Good luck with it.

[Lance Racing]

Nice job.

For those wondering why BMW didn't do this from the beginning, remember their customers back in the day. For $35k you could buy an E30 M3, for a just a few thousand less you could buy an E30 cabrio. So in those relative close price ranges, the people looking for performance were buying the M3. The original purchasers of cabrios were boulevard cruisers and were not putting the demands on the car that enthusiasts are now.

Did I see this cabrio at the Picnic last year? If so, it was stunning. White on white?

[BDK]

what I will do when I install my new subframe bushings is the same as I did with my E28's...
Stock HD Mounts filled with poly, you get the extra stiffness of the poly filling without the extra roadnoise that pure solid mounts transfer....

but with a cab, you're picking up road noise anyway, but the hardtop does make a world of difference with that too....
I'm doing big sway bars, lowering springs, good shocks (billie or koni), the Xbrace, prolly throw the buttstrut in there too boot...
I thought that I read somewhere that you should not run a front strut tower brace inconjunction with an Xbrace, anyone else read/hear that?

[CorvallisBMW]

Nice job.

Did I see this cabrio at the Picnic last year? If so, it was stunning. White on white?

Yes, it's that same cabrio. In fact, I wanted to talk to you about doing a feature at the picnic this year, kind of like what Josh did last year. I'll send you an email.

what I will do when I install my new subframe bushings is the same as I did with my E28's...
Stock HD Mounts filled with poly, you get the extra stiffness of the poly filling without the extra roadnoise that pure solid mounts transfer....

but with a cab, you're picking up road noise anyway, but the hardtop does make a world of difference with that too....
I'm doing big sway bars, lowering springs, good shocks (billie or koni), the Xbrace, prolly throw the buttstrut in there too boot...
I thought that I read somewhere that you should not run a front strut tower brace inconjunction with an Xbrace, anyone else read/hear that?

I have heard of people doing the rubber/poly hybrid and i think it's a cool idea. I know some people that have also done it with sections of PVC pipe. As far as the strut brace/x-brace, I don't know but I'm curious to know more.

I tried making another version of the rear strut today, using the same 6061 2"x0.5" aluminum that they sell online for $340. They claim there's is 'T6 Hardened', whatever that means; I don't know. Anyways, I clamped it in a vice, heated it up with the acetylene torch, and got to bending:



My first impressions are that it gave me more ground clearance, but it's not even close to being as stiff as the steel tube design. It bends and flexes with almost no force, which means it's useless when on the car. I did install it and run it, and I couldn't feel any improvement at all.

I also noticed that the stock nuts were not engaging the studs as far as they should. Instead of seeing 2 or 3 threads of the stud poking through the end of the nut, i could see 2 or 3 threads inside the nut! Not good. So I fabbed up these custom fasteners that allow me to grab on with a full 12 or so threads:





I am still convinced that the steel tube design makes a real, noticeable and worthwhile difference. The aluminum bar though is crap. I'm putting it in the dumpster.

[alpinaclone]

T6 refers to the temper of the aluminum. There are all sorts of different tempers. T6 is pretty hard and resists bending well. "O" is the opposite, dead soft, like a soda can. A general rule of thumb is that to approximate the strength of steel, you will need twice the thickness of a mid temper aluminum.

[bimmerboy12]

Corvallis- looks like you have the equipment and the skills (you have a TIG right?) why don't you make duplicates of the Mason X-brace and sell them on here? I can't justify $295 + shipping but would probably pay $150-$200... just an idea.

[xLibelle]

wow, just lay it out there that you are willing to fuck a stranger in the ass

how about a MarkD copy while youre at it?

[NC325iC]

yeah thats pretty crappy, "i cant spend $295+shipping to pay for the materials, the work put into making it, and the engineering costs that went into designing it. but if you want to make a rip off copy ill pay $200 for it."

Mason im sure has put alot of time into that brace trying different configurations and you dont think that you can afford an extra $100 to honor the mans hard work.

[bimmerboy12]

geezus sorry I retract.

[jjmtools]

Mason e30 x lower brace

ACTUALLY
I lowered the price to $275 for the steel brace plus UPS shipping

I thank you guys for your ethics
and yes the prototyping and R&D was not an easy picnic

JOHN MASON

[bimmerboy12]

ACTUALLY
I lowered the price to $275 for the steel brace plus UPS shipping

I thank you guys for your ethics
and yes the prototyping and R&D was not an easy picnic

JOHN MASON

My bad sorry for the hijack, those were not my intentions.

Are there existing holes to fasten the x brace to or do you create them, and if so is a template of some sort provided?