Tubular rear subframe - Input needed

[FLASH1970]

, beatle is accually a 69, 1500cc.. just putting the engine back in today!

I didn't know the tail lights were that big in 69. I have a 70 (hence FLASH1970) and I don't remember my tail lights being that big but it's been a while since I worked on it. I'll have to look at my car now.

Good luck getting it back together. I'll be helping a buddy rip out a 1776cc out of his Karmann Ghia to redo the pushrod tubes and other gaskets pretty soon.

To Paul, nice work on everything! I look forward to seeing finished pics of the rear subframe and the front. A smaller tube setup for drag racing would be awesome too.

 

[fjm9898]

didnt have time to read the whole thread, but what kinda of roll center implementations did you put in?

would be coll to put the sub frame higher in the chassis like the 240 guys do (lower the car and/or change roll center). but then i know we would need to change the knuckle a bit too.

 

[99gst_racer]

didnt have time to read the whole thread, but what kinda of roll center implementations did you put in?

The inboard pick-ups have an option to be raised 1". That will raise the instant centers and roll center. Also, the toe arms should greatly help reduce bump steer as they are "tunable" in length and inboard and outboard height. And having spherical bearings instead of bushings on the arms will eliminate bushing deflection and that should make the rear suspension more predictable.

I'll also probably move the sway bar end link attachment points outward on the LCAs by a small amount. That will help resist body roll and further help reduce the roll angle.

IMO, the biggest room for improvement on the rear of a 2G is the upper control arm. I wish it was easier to raise its inboard pickups and to lengthen the arm. That would yield huge improvements.

I'm hoping to get over to my car within the next couple days to dig it out enough to get some measurements of the rear suspension, and I'll plot my instant centers and roll center. My car is currently sitting too low, so my upper control arm angle is ugly. I don't expect my instant center to be in a good place.

 

[gofer]

Your posts sound like a Charlie Brown phone conversation when you start talking about suspension. Everything you've done sounds exciting and great, just wish I could give you some constructive critism and add to the thread other than the obvious, "LOOKS GREAT P!"

 

[snowborder714]

Corey, check out this link for some clarification/more info on roll/moment/instant center.
Moment Centre / Instantaneous Roll Centre - Fully Explained (anti 56k)

 

[gofer]

What scares me is once I get this rear subframe I won't know what/how to set it up properly and it will be a downgrade, besides the weight savings, once installed.

Thanks for the link Brian, I'll look through it.

 

[turbosax2]

I don't claim to know much about suspension, so forgive my ignorance.

Also, the toe arms should greatly help reduce bump steer as they are "tunable" in length and inboard and outboard height.

Is this even a concern in the rear end? Either way, adjustability is good.

IMO, the biggest room for improvement on the rear of a 2G is the upper control arm. I wish it was easier to raise its inboard pickups and to lengthen the arm. That would yield huge improvements.

I don't understand this. I can see how raising the inboard pickups would be beneficial if the car is very low, but isn't lengthening the arms essentially what a camber kit does?

 

[ViciousLord]

I've been carless for damn near a year and a half (thank god for an awesome girlfriend, it also helps that I live where I work, property management ftw!)

My biggest fear is buying all of the factory suspension pieces and within the same week, this piece gets finished and final pricing is out. Do we have a ball park figure on final cost yet? I'm willing to send partial payment if I can get an ETA.

 

[99gst_racer]

Is this even a concern in the rear end? Either way, adjustability is good.

It exists in the rearend simply because there is suspension compression and an arm locating toe. But I don't personally know how rear bump steer affects a car in motion at a track. I assume that eliminating it completely would really stiffen up the feel of the car, but I have no idea how important it is in the overall scheme of handling. Hopefully an experienced autocross or road course racer can chime in on that.

I know that most cars are set up to keep rear roll steer to a minimum. And once we start changing things like control arm angle, the amount of bump steer can also change. Hence the adjustable arms to adjust and help chase zero bump steer again. I don't know how much rear bump steer we have from the factory, but I'm hoping zero can be achieved with this subframe and arm set.

I don't understand this. I can see how raising the inboard pickups would be beneficial if the car is very low, but isn't lengthening the arms essentially what a camber kit does?

In the scheme of things, raising the pickups offers far more impact than arm length simply because it directly affects instant center and roll center. But a longer control arm will swing less during suspension movement, so it will have less of an affect on camber change while cornering. So, smoother wheel movement, but less camber gain. That should allow the car to be setup with less negative camber and still have the wheel roll to be perpendicular in a corner.

 

[99gst_racer]

What scares me is once I get this rear subframe I won't know what/how to set it up properly and it will be a downgrade, besides the weight savings, once installed.

Thanks for the link Brian, I'll look through it.

Don't be scurred! Installation will be pretty easy and straight forward. Set up the toe arms to be as parallel with the LCAs as possible (I'll probably have this figured out long before I sell one of these kits). Then take the car to the alignment shop and have them set zero toe and whatever camber specs you prefer. And it's ready to rock.

I've been carless for damn near a year and a half (thank god for an awesome girlfriend, it also helps that I live where I work, property management ftw!)

My biggest fear is buying all of the factory suspension pieces and within the same week, this piece gets finished and final pricing is out. Do we have a ball park figure on final cost yet? I'm willing to send partial payment if I can get an ETA.

I can't discuss things like pricing and availability in this thread. This thread is really only for sharing the build progress and bouncing around ideas for the build. I'll have something posted in the freelancer section as soon as these become available.

PMing you right now.

 

[snowborder714]

Then take the car to the alignment shop and have them set zero toe and whatever camber specs you prefer.

Or pay to fly me, my scales, and my SmartStrings out to you and I'll corner balance and align the car

 

[99gst_racer]

Or pay to fly me, my scales, and my SmartStrings out to you and I'll corner balance and align the car

Not to mention we could calculate center of gravity with your scales as well.

 

[Calan]

Or pay to fly me, my scales, and my SmartStrings out to you and I'll corner balance and align the car

Better yet, just load it all up in a car and drive there, swinging through OKC since it's on the way of course....sort of. We are both east of you.

 

[snowborder714]

I couldn't be emissions exempt if I drove all the way out to all you guys

Not to mention we could calculate center of gravity with your scales as well.

How would you do this?

 

[99gst_racer]

How would you do this?

I can't remember where I originally read about it, but this guy covers it pretty well here: Centre of gravity of a car - Single Post

 

[99gst_racer]

It's welded and out of the fixture. Turned out excellent. I'll weigh it tomorrow and post actual weights. I'll also be pricing out powdercoating at a local shop within the next couple days. Enjoy the pics!

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[1990AWD]

wow...

 

[99gst_racer]

A few weld pics:

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[viperlp01]

Need one of these. Quality work Paul!! When you coming out to the shop?

 

[snowborder714]

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[99gst_racer]

Need one of these. Quality work Paul!! When you coming out to the shop?

Thanks man. I was hoping we'd finish this yesterday so I could come out today, but we didn't get it done til this afternoon. I might take a half day off work sometime this week and head over there. If not, then maybe Satuday.

 

[greengoblin]

awesomeness

 

[twicks69]

giggity giggity! Awesome work man!

 

[Rob10_99]

Are you putting triangulation on the rear toe control, or do you think two tubes can handle the force? Not to nit pick just asking for safety purposes =)
Btw, those heim joints your using aren't cheapo ones are they? We get jeeps in the shop that have those same 1 1/4 or 1 1/2" balls and they get sloppy fast.

 

[ferruchnuts44]

Damn..I need to venture on this forum more often! Subframe looks fantastic Paul, I've been looking into one of these for quite some time but obviously our options have been limited before. Can't wait to see weight figures and order one up! Ive been around curt brown to long and have become a real weight nazi and anyway to save a few pounds and add strength I'm in.