Tubular rear subframe - Input needed

[99gst_racer]

Thanks guys!

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.

The LCAs and toe arms should be plenty strong as they sit. I used heavy wall tubing on both. Also keep in mind that each rear corner uses a trailing arm to do much of the work of keeping the wheel in place.

No economy heims here. The heims I used have heat treated bodies and balls. The body is coated for corrosion resistance, and they are also teflon lined, so no need to lubricate them. I shopped around and compared various radial load capacities of several different models before I finally landed on these. And they are a large part of why the arms cost so much.

I have used the general purpose carbon steel heims before and I know what you mean about sloppy. They're loose when they're new and they wear out very fast in a stressed environment.

 

[99gst_racer]

OE subframe (no arms, sway bar or diff housing): 52.5 lbs
OE lower control arm: 3.2 lbs
OE toe arm: 3.0 lbs

4130 (drag version) subframe: 18.6 lbs
4130 lower control arm: 2.3 lbs
4130 toe arm: 2.1 lbs


Total weight savings = 37.5 lbs!
+ sway bar deletion = 46 lbs!


EDIT:

4130 (road race version) subframe: 24.7 lbs

 

[gofer]

The rear subframe is 44.4 lbs - Bare.

My 4130 subframe: 18.6 lbs
My lower control arm: 2.3 lbs
My toe arm: 2.1 lbs

This is awesome, I can't believe that entire piece weighs less than a crank.

 

[99gst_racer]

Looks like 50 lbs with the OE pinion support attached. I'll still probably drag my OE subframe into work tomorrow to weigh it just to be sure.

I am happy with the weight that it came out to be. It's plenty light for a drag application as well. I really don't think I could pull out any more weight from it without sacrificing strength.

 

[donk]

Looks really nice ! now be a good boy and make a 1g one and i will buy it in a heartbeat!

 

[99gst_racer]

Looks really nice ! now be a good boy and make a 1g one and i will buy it in a heartbeat!

Thanks, but 1G stuff would have to come after a matching 2G front k-member.

 

[gofer]

...a matching 2G front k-member.

 

[jw4free]

Comparing your design to the 'Other Guy's' design, they are quite different in how they attach the differential to the subframe. I realize that the subframe is there to help the suspension hold up the car, and to position the rear axle under the car. Yours does this well. Realize, I have never seen a DSM rear diff post explosion. So forgive the ignorance. Do they fail from pushing the ring gear out the back, or from twisting the differential between the front half (pinion) and back (axles, viscous coupling). Your pinion mounting looks a lot stiffer than stock, and I think I like the rear lower mounts on the cover. Where do you think this subframe will flex under driveshaft twisting, and if your using long through bolts on the lower cover mounts will they snap or crack the cover?

Again, I really like the look and the welds are precision. I vote Clear coat finish.

 

[donk]

Thanks, but 1G stuff would have to come after a matching 2G front k-member.

I can wait,as long as you plan to actually make one.

/A

 

[99gst_racer]

Starting the fixture build tonight.

I can wait,as long as you plan to actually make one.

/A

I will. Or I should say, we will. My buddy Tyler and I are going to build a pair for his car. It will probably be a project for late this year.

 

[99gst_racer]

Comparing your design to the 'Other Guy's' design, they are quite different in how they attach the differential to the subframe. I realize that the subframe is there to help the suspension hold up the car, and to position the rear axle under the car. Yours does this well. Realize, I have never seen a DSM rear diff post explosion. So forgive the ignorance. Do they fail from pushing the ring gear out the back, or from twisting the differential between the front half (pinion) and back (axles, viscous coupling). Your pinion mounting looks a lot stiffer than stock, and I think I like the rear lower mounts on the cover. Where do you think this subframe will flex under driveshaft twisting, and if your using long through bolts on the lower cover mounts will they snap or crack the cover?

Again, I really like the look and the welds are precision. I vote Clear coat finish.

On the rear of a 2G, the suspension holds the weight of the car from the spindle, and the arms really only locate the wheel. And the subframe really only houses the differential and provides pivot points for the arms.

Torque kills the rear differentials by twisting them. With only one rubber mounted pinion support and two mounting points on the thin, weak cast aluminum cover, they just aren't solid mounted well enough to resist twist on a high powered car. The covers just shatter when they've had enough. Having four mounting points on the cover and bracing on both sides of the pinion will really help hold it steady and resist twist. I had a buddy that went through 3 diff covers in one season a few years back.

I don't forsee my subframe having any flex issues. It's very rigid due to the material and the multi-plane triangulation of the design. And there most definitely won't be any issues with differential twist or bolt issues. I plan to run a stock cover with this subframe on my own 2G.

 

[99gst_racer]

I weighed the stock rear subframe today on our fresly calibrated scales. It came out to 52.5 lbs without the rear diff, arms, and sway bar. So, that brings the weight savings to a total of 35.7 lbs.

I also found an awesome powdercoating shop right in my own backyard. They have an amazing 60,000 sq/ft facility and are very friendly to talk with. We decided that it would be wise and beneficial to first cathodic electro primer coat (they call it e-coat) everything before powdercoating, to give it a resistance to corrosion. For the subframe and arms and for both processes, it's only going to run $80 for black. Excellent price, IMO.

Here's a couple shots of their shop:

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[snowborder714]

Sweet shop and a really good price!!

 

[fjm9898]

sickness!

 

[FLASH1970]

giggity giggity! Awesome work man!

This.

 

[bmoha7321]

damn... still need a like button

 

[Aproductions]

didn't see the big question answered since you finished this.

Are you going to sell these?
How much?


If you do produce these please take your time! Not saying you won't or anything but I hate to see these DSM products slowly show poorer and poorer quality with welds and stuff.

Anyways let me know!

 

[fjm9898]

didn't see the big question answered since you finished this.

Are you going to sell these?
How much?

read more

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.

 

[Aproductions]

Thanks, I will be checking that section for the update when the time comes.

 

[twicks69]

didn't see the big question answered since you finished this.

Are you going to sell these?
How much?


If you do produce these please take your time! Not saying you won't or anything but I hate to see these DSM products slowly show poorer and poorer quality with welds and stuff.

Anyways let me know!

Are you intending on using this on your car as a FWD??? You do know of course that this is AWD only....

Just making sure.

 

[BoostedinSoFla]

Are you intending on using this on your car as a FWD??? You do know of course that this is AWD only....

Just making sure.

IIRC he's doing/done an AWD swap

 

[bradselph]

Looks awesome!

But i may have missed it or just not understand why you didn't add provision for a swaybar?

 

[fjm9898]

he isent done yet. sway bar setup is the last part he is working on.

 

[jdsoza]

This:

Thanks, but 1G stuff would have to come after a matching 2G front k-member.

= this

 

[dexterholland04]

Hoo boy, I can't wait for both the subframe and k-member to come out. Even if it's half of what Magnus charges, I'm there.