Im impulsive....subframes lets talk about it.

mjannusch · Post by **mjannusch** » Sun Aug 30, 2020 2:23 pm

The more I look at this, it just looks super flimsy and easy to bend/break.

DCIV · Post by **DCIV** » Sun Aug 30, 2020 5:16 pm

[quote=""mjannusch""]The more I look at this, it just looks super flimsy and easy to bend/break.[/quote]

He says its not done and will get more gussets and stuff so Im open to suggestions on where and what you would change.

Coop

mjannusch · Post by **mjannusch** » Mon Aug 31, 2020 3:32 am

Honestly, I think this whole design is flawed. He's holding up the weight of the diff using long tubes connected far outboard from the diff. Basically the diff is at the long end of two levers - those tubes are going to either break off the subframe mounts at the end, at the plate mounting them to the diff, or be bent in the middle.

Compare to the stock rear hanger, which is a really beefy part and has a lot of reinforcement bends in it to box in the structure.

He's also holding the front of the diff from the sides, instead of hanging it from the front, so this whole design is missing a major triangulation point there. There's nothing solid preventing the diff from moving fore/aft at all.

Compare to the stock front plates which are mounted straight forward and connected to the subframe to prevent fore/aft movement, as well as resist torsional stress (to some extent - though the rear mount provides much more torsional resistance):

I dunno man... Is the guy building this for you any sort of engineer?

I'd be looking for something more like this (Volk Metalcraft):

I wouldn't recommend copying Volk's idea though - he's extremely well known in the DSM community, and makes 3S parts as well.

Is this thing going to retain the anti-sway bar in the rear? Hope so - you aren't going to like it for anything other than straight-line racing if it doesn't.

DCIV · Post by **DCIV** » Mon Aug 31, 2020 12:33 pm

Yes it will have sway bar and aws mounts. That volk Deff gives some ideas. Thank you very much.

Coop

aaronatstate · Post by **aaronatstate** » Mon Aug 31, 2020 12:39 pm

I would say every mounting point of the diff needs to be triangulated, along with each mounting point for the subframe itself. Otherwise things are just going to twist/move and break.

Monochrome · Post by **Monochrome** » Mon Aug 31, 2020 2:26 pm

The 3D rendering software I use has an entire physics simulation built into it. Haven't even scratched the surface of all the features but part of me kind of wants to use it to design a subframe like this then simulate the forces it would see on it to find out how it could fail. Would be a neat project.

DCIV · Post by **DCIV** » Mon Aug 31, 2020 2:30 pm

I support this greg. Do it with what I sent and see what it says.

Coop

ChargerX3 · Post by **ChargerX3** » Mon Aug 31, 2020 3:22 pm

[quote=""mjannusch""]

I'd be looking for something more like this (Volk Metalcraft):

I wouldn't recommend copying Volk's idea though - he's extremely well known in the DSM community, and makes 3S parts as well.

Is this thing going to retain the anti-sway bar in the rear? Hope so - you aren't going to like it for anything other than straight-line racing if it doesn't.[/quote]

mjannusch · Post by **mjannusch** » Tue Sep 01, 2020 12:12 am

Yeah, hang a 100 pound rear diff on it, then subject the diff to 5000 ft/lbs of rotational torque and see what happens...

DCIV · Post by **DCIV** » Fri Apr 30, 2021 7:27 pm

Coop

mjannusch · Post by **mjannusch** » Fri Apr 30, 2021 8:52 pm

I hope that isn't the finished assembly.

DCIV · Post by **DCIV** » Fri Apr 30, 2021 9:02 pm

[quote=""mjannusch""]I hope that isn't the finished assembly.[/quote]

Not quite but please elaborate. Im out of my zone here.

Coop

mjannusch · Post by **mjannusch** » Fri Apr 30, 2021 9:18 pm

I already did a while back.

ChargerX3 · Post by **ChargerX3** » Fri Apr 30, 2021 9:58 pm

Is it me or does that pipe look thin walled? Plus some of those flanges are not thick or really attached the way I would want them. eeek.

aaronatstate · Post by **aaronatstate** » Sat May 01, 2021 4:17 am

[quote=""ChargerX3""]Is it me or does that pipe look thin walled? Plus some of those flanges are not thick or really attached the way I would want them. eeek.[/quote]

Yup. Do not want. Also there is almost no triangulation. That thing is gonna twist and bend the moment torque is applied to it. Ill stick with the stocker. Tubular subframes on a 3/S for 99.99% of owners, including everyone on this forum.

DCIV · Post by **DCIV** » Thu Jul 15, 2021 1:03 pm

Oooops.

Coop

mjannusch · Post by **mjannusch** » Thu Jul 15, 2021 1:18 pm

I hope it works for you.

Looks weak for my tastes.

DCIV · Post by **DCIV** » Thu Jul 15, 2021 1:35 pm

[quote=""mjannusch""]I hope it works for you.

Looks weak for my tastes.[/quote]

We have a couple places here in town that build cages and tube frames for real deal stuff. I know some of them. Im gonna take it to them first. Not just gonna jump into it.

I can say from holding it it feels beefy as hell. Ever heard of docol r8? Thats what he used.

Coop

aaronatstate · Post by **aaronatstate** » Thu Jul 15, 2021 1:44 pm

I still do not see the point of this, except for a dedicated track machine, which a 3/S should not ever be a dedicated track vehicle, as there are much better options for that.

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