Tubular rear subframe - Input needed

[snowborder714]

Why don't we take the redesigned strut tower convo to another thread?

 

[Blurred Talon]

Awesome, keeping my eyes on this.

 

[jdsoza]

So how goes the testing on this and when can we expect a price and possibly a delivery?

 

[snowborder714]

For the last time, please do not ask about price, selling info, etc. Freelancers are not to discuss this info in the forums at all. Keep checking the Freelancer section of the classifieds and if/when it is for sale, I'm sure you'll see it listed.

 

[99gst_racer]

Thanks Brian.

No info on testing yet either. I'm still waiting for John to take delivery of the first one. I imagine I'll have some updates come summer.

 

[acemas99]

Yup.


The pickup option is the inboard connection for the lower control arms and the toe arms. My kit has everything needed for installation. It uses spherical joints at every connection instead of bushings.

On a related note; I am also going to work on a bracket to raise the upper control arms. I'll hopefully have a prototype set finished and in use this spring or summer. I'd ideally like to raise the upper control arm 1" to match the lower.

Paul,

Just to clarify your post - Are you planning to incorporate an adjustment for the fore lower control arm inboard pickup on your tubluar front subframe? I'm interested in raising this pickup ~30mm, and would love to upgrade to a tubular subframe instead of modifying my current subframe.

Thanks.

 

[99gst_racer]

Paul,

Just to clarify your post - Are you planning to incorporate an adjustment for the fore lower control arm inboard pickup on your tubluar front subframe? I'm interested in raising this pickup ~30mm, and would love to upgrade to a tubular subframe instead of modifying my current subframe.

Thanks.

I did plan to raise it. I'm not quite sure by how much yet. I had originally planned to go about 25mm, but it was recently brought to my attention that due to cv shaft clearances, ~19mm (which is about how far the Robispec modification goes) may be as far as I can go.

 

[acemas99]

That answer is good enough for me. I'll plan to stick with my current subframe and take care of the LCA pivot shift with a tubular subframe.

I love reading about your builds...Keep up the great work!

 

[rhtwng2]

I went over to SIM on Saturday and test fit it on John's Talon. I'll post more about it when I'm less hungover.

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Sign me up for one...that is soooo nice...Like that fuel cell as well...

 

[bmoha7321]

I always enjoy updates on this thread. In the 11 years I've been a member on this forum I've got to say this has been one of my favorite threads.

 

[bmoha7321]

I wonder about improved airflow under the car... I mean the stock rear subframe is basically like a big air brake under the car. Air flow is forced around it. Can't get thru it. Now with these tubular subframes I'm sure there's some turbulence caused but not much to block air flow. I'm sure it's not a big deal but it's neat to think of.

I guess I mean this more for a car that has spare tire well eliminated

 

[twicks69]

I wonder about improved airflow under the car... I mean the stock rear subframe is basically like a big air brake under the car. Air flow is forced around it. Can't get thru it. Now with these tubular subframes I'm sure there's some turbulence caused but not much to block air flow. I'm sure it's not a big deal but it's neat to think of.

I guess I mean this more for a car that has spare tire well eliminated

You would be suprised, doing a fuel cell (in the stock location like Frontline Fab's) and a tube subframe, along with chopping out the spare tire well makes the rear bumper even more of a parachute. It is really shocking to see how much it takes up for space with all the rest of the crap removed from the car. I need to either make a belly pan or chop my bumper and do a diffuser with some other aero to prevent the ass-turns-into-parachute effect (AKA MC Hammer Effect).

 

[bmoha7321]

That was exactly what I was wondering about Tim. Rear bumper cover looks to be a pretty good air foil. On some cars like Andrew's and tsiawd666's car I see they have eliminated the bottom of the rear bumper cover while installing the extreme downforce body kit. Even without the bodykit I could see at the very least having to cut some air pressure relief holes Or raising the bottom lip a bit.

 

[twicks69]

That was exactly what I was wondering about Tim. Rear bumper cover looks to be a pretty good air foil. On some cars like Andrew's and tsiawd666's car I see they have eliminated the bottom of the rear bumper cover while installing the extreme downforce body kit. Even without the bodykit I could see at the very least having to cut some air pressure relief holes Or raising the bottom lip a bit.

If I had my choice, I would be cutting it as high as the license plate. Pretty much the initial aero that Andrew Brilliant did before he made the entire aero package way back in the day.

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[TSiAWD666]

Don't you have that choice?

 

[twicks69]

Don't you have that choice?

Yeah yeah, I do, , but I still have to accept the fact that I would be chopping half of my car's ass off. The bumper and paint is so damn clean on my car I have a hard time doing it currently. I would rather get the diffuser made first, then cut the ass off. Then I can integrate the exhaust into the aero with a belly pan.

 

[bmoha7321]

I like it but I'm not sure how much the police would like it I think if I'm not mistaken you still drive yours on the street every so often? Or is it now a purpose built race only since it is so heavily modified? I still have to get out to your shop to check it out

 

[97gst_spyder]

Updates!

 

[gofer]

From what Paul told me he was finishing tacking up the second (my) subframe and pulling it out of the jig this weekend to finish it up and send it off to powdercoat, hopefully soon! He's been really busy making those 1g cross members...

 

[99gst_racer]

Working on squaring away sway bar attachment soon. I have some adjustable end links for it and still need to fab up some brackets. I'll post pics soon.

The first subframe is installed under John's car now. Hopefully he's got his car track/road worthy soon. Though I think I'm more excited to see how well his compounds function.

 

[eclipsh]

Yup. Although it would be cool to develop some sort of aftermarket strut tower to weld in place of the original for the guys that want to change the angle of the front upper arm. I imagine there would be a very small amount of people interested in doing that to their cars though.

Hmmm..... *wheels turning*

Hope this isn't too tangential. What about modifying (or replacing) the knuckle to go to a McStrut upper but keeping the lower double ball joints? My buddy Pagosa DSM mentioned BMWs do something like this. It'd sure make camber/caster adjustment easier and probably shed some weight. Not sure what it'd do to the suspension dynamics though...

I wonder if you could use the front knuckle from an AWD BMW. Might be worth looking into. That or just go to a single ball joint, a longer a=arm, and longer axles for a wider stance (and wider tires). With the custom lower control arms in the rear you could do the same and get an overall wider footprint and more tire under the car.

 

[99gst_racer]

Hope this isn't too tangential. What about modifying (or replacing) the knuckle to go to a McStrut upper but keeping the lower double ball joints? My buddy Pagosa DSM mentioned BMWs do something like this. It'd sure make camber/caster adjustment easier and probably shed some weight. Not sure what it'd do to the suspension dynamics though...

I believe the double wishbone trumps the mcpherson in terms of handling. Double wishbone rolls better and affords more opportunity for fine tuning. Having an upper control arm eliminates camber gain during compression, which a mcpherson does not. A better idea for improvement to the 2G front suspension would be an adjustable upper control arm.

That or just go to a single ball joint, a longer a=arm, and longer axles for a wider stance (and wider tires). With the custom lower control arms in the rear you could do the same and get an overall wider footprint and more tire under the car.

I talked with Andrew Brilliant quite a bit about the front compression arm. In short, he says it would be a terrible idea to eliminate it being that the front corners experience both acceleration and braking loads.

Increasing track width would be nice though, provided axle length doesn't become a problem.

 

[eclipsh]

I believe the double wishbone trumps the mcpherson in terms of handling. Double wishbone rolls better and affords more opportunity for fine tuning. Having an upper control arm eliminates camber gain during compression, which a mcpherson does not. A better idea for improvement to the 2G front suspension would be an adjustable upper control arm.

In general I believe the same and have no need or intention to do anything so complex with my car. However, as my friend pointed out to me many great handling cars use a McStrut including the Evo, Porches and MBWs. Another thought is that with the spring rates and sway bars many serious people here are using there isn't a lot of compression in a corner thus not much geometry change. I do agree a good adjustable upper arm would be nice (if it didn't move around all the time).

I won't distract from this thread any further though. This is some great work and I look forward to hearing how it does in testing.

 

[99gst_racer]

Yeah, many great road race cars use a Mcpherson strut. I don't think its benefits outweigh that of the double wishbone, but nevertheless it can be made to function exceptionally well. And a McPherson does have the benefits of better packaging and reduced weight. But I still don't think I'd ever spend time/effort/money to switch from double wishbone to McPherson. Althugh a properly setup Mcherson suspension beats out a jumbled double wishbone setup any day of the week, so I'd say stick with what you have and perfect it to the best of your ability.

I plan to make an adjustable upper and lower for the front. The upper will be camber adjustable and the lower will allow for more shock travel. Both with spherical joints. I should have prototypes to share sometime this summer.

 

[Alan11]

Ah crap, i can't believe i missed out on this thread, now i have to to read the thing.. awesome job paul!!!