Tubular rear subframe - Input needed

[rx7ttlm]

Hey Paul, If I were going to go through the trouble of building the rear subframe out of CM I would ditch the stock arms and revise the geometry that has silly amounts of toe change through compression and droop.

 

[99gst_racer]

This one turned out to be a bit heavier than I thought, but not bad though. I just weighed it in at 24.4 lbs. So, 5.8 lbs heavier than the first one and still 28 lbs lighter than the factory subframe.

Did you add that "hoop" over the diff for additional support? I couldn't pick that out in the pictures you posted of Johns. That looks pretty damn solid to me, Paul, just curious to see how these sway bar mounts play out.

It's pretty much the same design. I just had to move the three bars at the rear (including the bent one) to give clearance for the OE fuel tank. This one just has a greater bend angle in the tube around the diff than the first one did.

Hey Paul, If I were going to go through the trouble of building the rear subframe out of CM I would ditch the stock arms and revise the geometry that has silly amounts of toe change through compression and droop.

Like this?

 

[99gst_racer]

You have that much distance between the lateral arm and the axle?

Yup, that shoots that idea right out of the water. I made a trip over to see my car yesterday and took a peak at the rearend. I had forgot how close the CV shaft was above the end link. It really sucks for me to not have easy access to my car when trying to figure out things like this. I'm hoping to change that very soon though.

I'm wanting to save the twin tube arm as a last resort, so I'm still searching for an alternative idea. After seeing the clearances around the OE end link, I now see that it won't be able to be moved.

Next idea: I could weld in a mono-ball bearing mount in the center of the control arm. Then bolt in a single heim to attach to the sway bar. This would yield proper end link height and it would afford movement in all directions. Thoughts on this?

 

[eclipsh]

How about going to a generic stock car sway bar and attaching to the spindles instead of the LCA? Lots more options for bar stiffness that way. There is certainly plenty of room to work with and mounting points aren't much of an issue. My friend Pagosa DSM keeps talking about trying something like that on his 1g.

 

[greengoblin]

How about going to a generic stock car sway bar and attaching to the spindles instead of the LCA? Lots more options for bar stiffness that way. There is certainly plenty of room to work with and mounting points aren't much of an issue. My friend Pagosa DSM keeps talking about trying something like that on his 1g.

That is how my car is set up.

However Paul is trying to keep the cost of the unit reasonable so he want the option to run OEM stlye bars.

 

[greengoblin]

Yup, that shoots that idea right out of the water. I made a trip over to see my car yesterday and took a peak at the rearend. I had forgot how close the CV shaft was above the end link. It really sucks for me to not have easy access to my car when trying to figure out things like this. I'm hoping to change that very soon though.

I'm wanting to save the twin tube arm as a last resort, so I'm still searching for an alternative idea. After seeing the clearances around the OE end link, I now see that it won't be able to be moved.

Next idea: I could weld in a mono-ball bearing mount in the center of the control arm. Then bolt in a single heim to attach to the sway bar. This would yield proper end link height and it would afford movement in all directions. Thoughts on this?

How would that effect the overall arm strength? Would you cut a hole int he tube and weld the ball flush into the tube and then mount the link in single shear?
Or would the mount be welded on top of the tube?

 

[99gst_racer]

How would that effect the overall arm strength? Would you cut a hole int he tube and weld the ball flush into the tube and then mount the link in single shear?
Or would the mount be welded on top of the tube?

The bearing cup is 1.75" diameter and is a full inch thick. there wouldn't be clearance to weld the cup on top of the arm. So, I'd have to cut the arm and notch both ends and weld in the cup. I don't think strength would be an issue because of the diameter and wall thickness that I use. But even still, I can add reinforcements if I need to. I'll tack together a prototype tomorrow and post pics.

 

[StarFawkes]

I didn't read through this whole thread but I am wondering if a 1G version of this was built.

 

[99gst_racer]

I didn't read through this whole thread but I am wondering if a 1G version of this was built.

Not yet, but it will probably be a fall/winter project.

 

[StarFawkes]

Not yet, but it will probably be a fall/winter project.

That is good to hear. I am always impressed with the quality work you and the rest of the DSM community do. I'll definitely be a buyer of one of these amazing subframes whenever you have one for the 1G!

 

[99gst_racer]

Well, here's what I have in mind. My buddy Tyler made a good point today. This arm isn't under any twisting forces, and the only bending forces are from the sway bar, so that isn't much. It's primarily tension and compression. And having this bearing in the arm shouldn't compromise stength in compression and tension. .120" wall 1.25" diameter 4130 is far stronger than this application needs, so it has that going for it as well.

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[RipperXX]

All I can say is impressive, and me want.

 

[rr06rs]

Could there possibly be an option for those wanting to run a 3kgt rear diff and axles?

 

[gofer]

Paul. Any verdict on this quick change in design, did it work?

 

[greengoblin]

I like that Paul. That was a really good idea. Is that really cheaper that building a twin tube arm?

 

[RipperXX]

Got any installed pics of the rear subframe? Obviously I drive a 1g so this is useless to me, but it still looks sweet .

 

[99gst_racer]

Could there possibly be an option for those wanting to run a 3kgt rear diff and axles?

If the 3kgt rearend is larger in size than out stock one, then it would be impossible to fit into my jig. Which means I'd have to build a whole new jig to do it - which I doubt I'd ever do. But if it can fit my jig, then it's something I'd be willing to do. If you know of a place where I can get a bare rearend housing for next to nothing, I can at least look into it further.

Paul. Any verdict on this quick change in design, did it work?

I am going to run with the arm/bearing idea posted above. I'll have the arms done by the end of the week and the sway bar mounted tot he subframe by the weekend.

I like that Paul. That was a really good idea. Is that really cheaper that building a twin tube arm?

Far cheaper. The bearing and cup aren't really that expensive and it saves a boatload of fab time.

Got any installed pics of the rear subframe? Obviously I drive a 1g so this is useless to me, but it still looks sweet .

The only installed pics I have are from when we mocked it up on John's 2G before it was powdercoated.

Pics: http://www.dsmtuners.com/forums/152925271-post326.html

 

[gofer]

I am going to run with the arm/bearing idea posted above. I'll have the arms done by the end of the week and the sway bar mounted tot he subframe by the weekend.

YES! I'm glad to hear that it will be ready for powder by next week then. I'm having a surgery that will put me out for a few weeks on the 22nd, hopefully I've got this piece sitting in the garage by the time I recover.

 

[99gst_racer]

I got the sway bar attached. I had to fabricate a bolt-on addition for my jig to locate the mounts. The whole process went smoothly and the mounts are rock solid. I wish I had a prettier sway bar for these pics, but this pile of rust is all I have laying around. Oddly enough, this sway bar came off a GSX with only 60k. Gotta love MI.

I'll post up some more pics of the end link adjusters as soon as I get everything back from the powdercoater. It's a trick little set-up. Can't wait to get one of these under my own car.

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[gofer]

Looking good.

 

[StarFawkes]

Beautiful. Can't wait for you to get this done so you can start the 1G subframe.

 

[greengoblin]

Glad to see it still moving along.
Maybe instead of building a jig for the peeps that want to use a different rear end you or Andrew could come up with a diff cover that would adapt them to your current mounting set up.

Just a thought.

Keep up the good work.

Kevin

 

[99gst_racer]

Maybe instead of building a jig for the peeps that want to use a different rear end you or Andrew could come up with a diff cover that would adapt them to your current mounting set up.

The complication is how my jig holds the diff in place while I build around it. The jig simply cannot accommodate a wider rearend. If I can get my hands on a 3/S rearend, I'll see if I can make it fit though.

 

[Blurred Talon]

Can't wait to see this finished.

 

[shane90gsx]

Looks great man!!