Subframe Reinforcement?

First, the pix and this is the front subframe for an Evo. The pickup points that don't look particularly stout are the rear LCA pickup points:







And the salient service manual page so you can see how everything goes together:



I'm thinking just the rear LCA mounts need to be beefed up. We could double them, we could run reinforcing ribs to help prevent deflection, etc...

Pull out your slide rules and leave your suggestions!

How are they breaking in the field?

Already looks three fucktons better than A2 Golf.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

I think I remember ACP saying the suspension pickup points are weak points. And I assume he's talking about that rear mount, the front looks fine to me, thick metal, completely boxed.

The reason I'm replacing the subframe is I tore it up pretty good at Ojibwe last year at the opening super special stage.



The sump guard bolts to the subframe and as it got pushed back all sorts of bad things happened.

But I figured while I have a fresh one ready to go on, might as well beef it up.

Goddamn stupid specials! The landing off the same jump caused my fuel pump fuse to fall out in 2013. I'd leave as is and not land like that in the future.

The question about what breaks in the field is a good one, no sense beefing up a subframe if it's the sacrificial part vs. tearing up the chassis.

Dave

Yeah, I think I'm just going to leave it as-is. We'll weld up the damaged one and keep it as a spare.

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Nubby
Yeah, I think I'm just going to leave it as-is. We'll weld up the damaged one and keep it as a spare.

Crazy.

Strengthen arms
Strengthen mounting points for arms
Strengthen subframe mounting points

Strengthen everything..

It hit me once at Ford motorsport back in 1989 when i was there for a series of long long interviews.
In those days they were using modded OEM stuff--except the HUGE cast aluminum front uprights which were

EVEYTHING in the suspension was strengthened and double plated and double skinned..
This thought popped up:
Dayum if they doubling everything and adding weight---and thety are as weight obsessed as they are---I think I oughtta pay attention...

This "fuse" idea is ridiculous...despite the fact that self-described "heroes" keep repeating it for others to do...

I'll pay attention to what I see SERIOUS teams doing...
Strengthen everything.
Stitch weld the subframe.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Was just saying I'd rather replace a bent subframe than go find another shell and start over. Did the bent subframe in this case result in a DNF or were you able to continue and finish Tony?

I'll happily stand corrected if that's what's done on those things in the rally world, say GroupN or open class Evos with that stuff beefed up. In fact, I'd probably beef up mine if that is the case since I like to run into stuff just like everyone else. And and and...any fixes for the rear bendy aluminum arms? They look bent even when they're new!

Biggest problem with Evos is that replacement bodies still fetch $5k, while on a subaru you don't have to start with an STi...any old RS chassis will work fine and at probably 1/10th the price.

Dave

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john vanlandingham
This "fuse" idea is ridiculous...despite the fact that self-described "heroes" keep repeating it for others to do...

A fucking men.

Yeah, I know, rallycross, but I saw one of my friends throw away the Nationals because he folded a control arm on course and couldn't continue. He explained that he'd rather bend a control arm than damage the subframe.

I'm thinking, you're not going to damage a subframe hard enough to make the car immobile like a tacoed control arm will. A bent subframe isn't going to end your weekend, which especially sucks if you are in serious danger of winning the event. You can buy more subframes but you never get your weekend back. And when you do buy your new subframe, you examine the old one to see where it bent and you reinforce THAT and keep iterating fixing the weakest point until your car is an anvil.

---

Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

You lot losing sight of the real issue. John is right, reinforce all that shit. Things dont just bend from one impact. Over time all that nonsense fatigues and if reinforced you'll have a much happier life. Plus, if you hit something hard enough to bend a subframe, then wouldn't there be more serious issues than just pickup points eh?

I looked at the subframe last night, there's nothing to stitch weld, all the seams are fully welded from the factory.

The front pickup point is a box that's around 1/8" thick steel on 3 sides and only a bit thinner on the 4th so that's pretty beefy.

The rear pickup point is the thinnest metal on the thing, so that will get reinforced. That pickup point is puzzling, everything else is built like a tank, on the rear pickup points there's 2 fairly thin pieces of metal cantilevered out into space.

As far as mounting points, I'll have to take a look once we have the car in the air and see what makes sense.

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Nubby
I looked at the subframe last night, there's nothing to stitch weld, all the seams are fully welded from the factory.

That's not good enough...you must reinforce it! Everyone sayz!

Guess some of the Group eNgineerd stuff was reasonably decent off the shelf.

FWIW, I've got the caster adder kit on my car, and I had to actually bend the lower of the rear mount point slightly to allow for full droop of the front suspension. I've hit guardrails, and the side of a mountain, and as of yet, no damage to a subframe...that I've noticed.

Dave

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Nubby
The rear pickup point is the thinnest metal on the thing, so that will get reinforced. That pickup point is puzzling, everything else is built like a tank, on the rear pickup points there's 2 fairly thin pieces of metal cantilevered out into space.

Thats because the forces that rear point see's are only linear motion and in a axial orientation. Anything different than that and its crash damage.

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DaveK

Quote
Nubby
I looked at the subframe last night, there's nothing to stitch weld, all the seams are fully welded from the factory.

That's not good enough...you must reinforce it! Everyone sayz!

Guess some of the Group eNgineerd stuff was reasonably decent off the shelf.

FWIW, I've got the caster adder kit on my car, and I had to actually bend the lower of the rear mount point slightly to allow for full droop of the front suspension. I've hit guardrails, and the side of a mountain, and as of yet, no damage to a subframe...that I've noticed.

Dave

I'm glad you mentioned that, part of the re-prep is 7.8" travel Bilsteins up front so we should probably make sure the suspension can fully articulate before we start plating shit. Might need a little bendy-bendy or grindy-grindy before weldy-weldy.