Improvements to a strut brace

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Callumgw
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Improvements to a strut brace

Post by Callumgw » Wed Apr 23, 2008 9:33 am

I recently got round to putting the front and rear braces on my Exa. Just thought I'd feed back some of my thoughts. In general I think Brendan did a damn fine job and my thanks go to him for all the hard work. I made a few minor tweaks to improve on his good work and already passed these on to him so he could incorporate these ideas if he makes any more.

For the rear, mine was a 'to the floor' option. The floor panel there is very thin and so moves easily. Using a larger footing plate or using more bolts spaced out would add significantly to the stiffness without adding much to the weight. Alternately, and this is what I did so as not to mod the brace, was add a large backing plate under the floor plan to increase the clamp area.

I found the front the braces are not that stiff once installed. This is because of a very simple to remedy.
When the strut towers move in under load they compress the brace. If the brace goes straight from one tower to the other there is no bending loads (as on the MRD brace), just compression.

Image

With the raised design needed to clear the intake gear you develop bending loads within the brace. The bending loads act on the least stiff part and the pin joints to the adjuster brace reduce the stiffness further because pin joints can’t pass a bending load that acts around their axis, and allows it to act as a mechanism. In this strut brace I found the weakest point then bends at the feet of the brace where it joins the strut tower, about the line shown below.

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If you want to simulate what I’m talking about push on the elbow in the brace where the arrows are in the picture above.
In these next images you can see the result of the bend:

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And the bend lines in the paint:

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To improve this we just need to carry bending resistance out past the bolts by adding some simple vertical flanges.

Image

So first I installed the brace and made sure it sat level and how I wanted it. This way it’ll be clamped while I tack weld it and be right after I take it off and complete the welds. Then I cleaned up the paint.

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Tack welded some flanges:

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Took the brace off and then filled the rest of the welds and flanges:

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Before cleaning it up, painting it and putting it back on:

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(I know my welding ain’t as good as Brendan’s)


The only other tip is to do with getting the adjustable brace tight enough. Make sure the install is tight and that the bolts won’t come out (before the nuts go on). This is done by making sure the bolts can’t be installed in the static position without a little bit of press to move the legs. This way the brace is preloaded and will have no slop.

Happy tuning!

And thanks again the Brendan for a good pair of Strut Braces!

C

raddavey
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Post by raddavey » Wed Apr 23, 2008 10:30 am

Excellent write up. So what were the on road results?
ACL Pistons, 226/236 cam, T28 Turbo, FMIC, FJ20T Injectors, Wolf V4 ECU, NPC Clutch, VL TB, Custom High Mount Manifold, N13 Internals G/B, 3" SS Exhaust, Walbro 500hp Pump.
237hp@18psi
13.52@108.95mph (street trim, leaky hg)

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Callumgw
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Post by Callumgw » Wed Apr 23, 2008 11:39 am

Haven't actually taken it far yet :oops:

and I need to replace the old shocks at the front to get a good feel I reckon.

Soon though . . . . .

C

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thepurplepulsar
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Post by thepurplepulsar » Wed Apr 23, 2008 5:45 pm

Good thinking Callum, now to get my hands on a welder. I noticed that the brace flexed when I installed it aswell, one other thing was that I think the cross-bar could have been shorter (10-20mm) to allow more tension to be put on the thread/nut adjuster as mine is wound tight on both ends.
Number 5 on the Top Ten List - 12.39 @ 110mph

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Callumgw
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Post by Callumgw » Wed Apr 23, 2008 7:24 pm

because both are right hand threads, turning the bar doesn't tighten it, the bar just moves to one side and stay the same length. You need to set the length with it not pinned at the ends.

C

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SashET
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Post by SashET » Wed Apr 23, 2008 7:29 pm

Gasless MIG ey C?

Mines the same, try the anti splatter spray, works treat.

Gasless MIG's are fiddly as shit, but once you get it right, they work ok.

Nice work anyway C.

Cheers
Sash

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thepurplepulsar
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Post by thepurplepulsar » Wed Apr 23, 2008 8:20 pm

Yeah I'm aware of that, both my ends are tightened hard against the pin bracket. Rethinking that, it's not the bar length thats the problem it's the fact that the feet flex. The further you tighten the adjuster it just gradually lowers (shortens) the cross bar untill you run out of thread.

Welding the extra plate on the feet would fix the problem though.
Number 5 on the Top Ten List - 12.39 @ 110mph

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Callumgw
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Post by Callumgw » Wed Apr 23, 2008 8:52 pm

SashET wrote:Gasless MIG ey C?

Mines the same, try the anti splatter spray, works treat.

Gasless MIG's are fiddly as shit, but once you get it right, they work ok.

Nice work anyway C.

Cheers
Sash
I got a CIG Mig165, just had gasless wire in it. Thats the second roll of wire used so I figured it'd be worth trying gas. Was going to get the small disposables, 'cause I don't reckon I'd use enough gas to cover the bottle rental and gas in a year. Got any experience with these?

C

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SashET
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Post by SashET » Wed Apr 23, 2008 8:55 pm

Not with the disposable bottles but its the next item thing I want to try with mine. Its a gasless and gas mig so I can connect the bottle to it.

I've used gas mig before and it shits on the gasless.

Need the bottle and reg!

Cheers
Sash

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Callumgw
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Post by Callumgw » Thu Apr 24, 2008 7:29 am

The reg for the little diposables costs about $40, and the gas varies depending on the type - argon, argon-CO2, CO2. But at least then I can have a crack at Alum and stainless.......

C

raddavey
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Post by raddavey » Thu Apr 24, 2008 10:51 am

I didn't think you can weld aluminium with a MIG??? Need a DC TIG welder.

You can weld stainless with a ARC welder. Just get some stainless rods.
I did my whole exhaust with a 20 year old non adjustable amperage ARC welder and stainless rods. Came out pretty good.
ACL Pistons, 226/236 cam, T28 Turbo, FMIC, FJ20T Injectors, Wolf V4 ECU, NPC Clutch, VL TB, Custom High Mount Manifold, N13 Internals G/B, 3" SS Exhaust, Walbro 500hp Pump.
237hp@18psi
13.52@108.95mph (street trim, leaky hg)

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Callumgw
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Location: Melbourne, Australia

Post by Callumgw » Thu Apr 24, 2008 11:14 am

No, can definately do Al with a mig,

http://www.lincolnelectric.com/knowledg ... actmig.asp

C

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SashET
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Post by SashET » Thu Apr 24, 2008 11:25 am

Callumgw wrote:No, can definately do Al with a mig,

http://www.lincolnelectric.com/knowledg ... actmig.asp

C
I'll confirm that, can definitly do Al with a mig.

Cheers
Sash

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tassuperkart
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Post by tassuperkart » Fri Apr 25, 2008 9:52 am

I ROFLMAO'ed when I read this particular gem regarding the correct filler wire for ally.
.......You will not obtain good results attempting to weld on aluminum with a steel wire electrode.
Errr... nah I spose not.......ROFLMAO!!!!!!!

L8tr
E
Forcd4 wrote:Oh fuk no dude it's you a again, the oracle.

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Callumgw
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Post by Callumgw » Fri Apr 25, 2008 12:22 pm

Yeah I had to scratch my head on that and try to figure if they were seriously suggesting that some people might try......

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