e30 Cabrio Chasis Stiffening

[Brezzi]

Hi folks,

Its your neighborhood idiot again back to ask more questions about track performance for cabriolets.

I'm trying to overcome the flex and shake associated with driving a lowered e30 convertible. To achieve this I plan on buying and installing:

-front cross brace, leaning towards raceskids. Talk me out of it Garagistic's is cheaper.

-eventually doing a half cage because race car

-Really want something like this "butt strut": http://www.strong-strut.com/Butt-Strut.htm

My questions are:
-The guy that runs that site still makes the strut and charges around $370 shipped. All the testimonials rave about it. Anyone have experience with a product like this?

-Would you guys reco some kind of non-stock sway bar set up or just go with poly bushings and stock bars?

-Should I be considering anything else? Non-driver wise. I know I need all the practice I can get. I just want a well set up car. From a suspension perspective the car has:
>fully adjustable coil overs still playing with spring rates
>75d poly engine and trans mounts
>front strut bar
>offset 75d poly CAB's
>New OEM Control arms

>rear bushings will eventually be all poly too


I KNOW cabbies aren't the first choice for racers but that's where I compromise - wind in my face is too fun.

[TobyB]

I can't resist-

you could always weld a ROOF onto it!

t
who would also race an open car in a heartbeat-
if it didn't have fenders.

[squidrope]

We're in the process of building a 92 vert into a Lemons track car. Our plan is to use the cage to eliminate chassis flex. Since we're trying to get the car under 2,000 lbs., most of the "vert" stiffening goodies will be removed.

The Butt Strut looks heavy(1/2"x2"). We're hoping to get the same result with Poly subframe bushings. I'd also be concerned about the BS catching if/when we go off track.

search facebook for "squidrope racing" for pics and more details.

[spike68]

I'm a little confused on the butt strut because I dont see how it would help when it attaches to the subframe bolts. It doesnt look convincing to me. If you're getting butt wobble then the sway bar needs to be adjusted appropriately.

I do reccommend poly bushings everywhere. They make different on durability and stiffness and theyll last much longer. Sways are recommended as well. I dont see why any aftermarket sway wouldnt be a good choice. Just read about them here on the forums.

[Brezzi]

I can't resist-

you could always weld a ROOF onto it!

t
who would also race an open car in a heartbeat-
if it didn't have fenders.

har har I knew someone wouldn't be able to - who says I'm keeping my fenders :devil:

We're in the process of building a 92 vert into a Lemons track car. Our plan is to use the cage to eliminate chassis flex. Since we're trying to get the car under 2,000 lbs., most of the "vert" stiffening goodies will be removed.

The Butt Strut looks heavy(1/2"x2"). We're hoping to get the same result with Poly subframe bushings. I'd also be concerned about the BS catching if/when we go off track.

search facebook for "squidrope racing" for pics and more details.

Checked you guys out - love the splitter you guys are running looks very functional.

I'm a little confused on the butt strut because I dont see how it would help when it attaches to the subframe bolts. It doesnt look convincing to me. If you're getting butt wobble then the sway bar needs to be adjusted appropriately.

I do reccommend poly bushings everywhere. They make different on durability and stiffness and theyll last much longer. Sways are recommended as well. I dont see why any aftermarket sway wouldnt be a good choice. Just read about them here on the forums.

It probably just adds extra rigidity to the overall rear subframe or something. Literally every review I've found on the internet about them raves the same way people rave about how much a front x brace helps. That being said - I did want a r3ver's a approval because they aren't cheap. Plus they kinda look like something I could throw together if I got creative enough. idk jury's still out on the BS

edit: found this on the guys site: "Although the rear Strong-Strut appears to be bolted to the sub frame/ rear axle carrier, it is actually bolted to the mounting brackets that support the sub frame assembly. The sub frame itself is above the mounting brackets and is mounted in large rubber bushings that allow considerable movement but also isolate road noise and vibration. Although the sub frame is a massive assembly, it offers no rigidity to the rear body structure since it is mounted in rubber. The rear Strong-Strut is bolted to the same brackets but below the sub frame. This placement results in direct reinforcement of the chassis since the rear Strong-Strut is effectively bolted to the chassis/body."

[squidrope]

Checked you guys out - love the splitter you guys are running looks very functional.


Thanks, but the splitter isn't done. Waiting until the car is fully lightened and suspension bits swapped out. There will be an adjustable lower portion with "deck".

[fight4life28]

Front x brace helps. less flex going over bumps and windows dont chatter has much anymore.

[Brezzi]

Front x brace helps. less flex going over bumps and windows dont chatter has much anymore.

yeah I'm def getting one of those.

Do you have the raceskids, mason, or garagistic one?

I'm leaning towards raceskids but still not 100% on it yet.



Also I've been thinking about the butt strut. The rear subframe should provide a decent amount more extra strength if its mounted to poly or solid bushings. Any thoughts on using solid aluminum subframe bushings and then some poly 75d RTB's?

[validius]

yeah I'm def getting one of those.

Do you have the raceskids, mason, or garagistic one?

I'm leaning towards raceskids but still not 100% on it yet.



Also I've been thinking about the butt strut. The rear subframe should provide a decent amount more extra strength if its mounted to poly or solid bushings. Any thoughts on using solid aluminum subframe bushings and then some poly 75d RTB's?

I have the raceskids one and i have no complaints. I have no basis for comparison with the others though.

After reading this thread, i think i'm going to replace my rear subframe bushings with some 'soft' polly ones.

[jpod999]

The Garagistic cross brace looks to be $50 off right now.

https://store.garagistic.com/e30-performance-parts/E30-reinforcement%20/garagistic-e30-x-brace-cross-brace

[decay]

on my old vert project i did:

-mason x-brace
-sparco knockoff front strut bar
-front subframe reinforcements
-rear trailing arm reinforcements
-hardtop

the hardtop was the last item that went on, but when it did it was fucking night and day. i suggest starting with finding one, and then seeing where you think there is still flex after that.

[jeffnhiscars]

I love my hardtop and while it does a great job of sound deadening I am not convinced it does much in the way of stiffing the chassis.

[decay]

well like i said- i had already reinforced lots of other stuff and done solid/urethane bushings throughout the car- so it's very likely the lack of a roof became the biggest flex point for it.

[jeffnhiscars]

well like i said- i had already reinforced lots of other stuff and done solid/urethane bushings throughout the car- so it's very likely the lack of a roof became the biggest flex point for it.

I think it's the placebo effect. Less rattle and road noise seems stiffer.

[decay]

I think it's the placebo effect. Less rattle and road noise seems stiffer.

every single person i share my experience with says that... but they are all wrong. the handling of the car noticeably changed.

i think i'm just the only nutbar out there who bothered to do a real chassis build with a vert.