OkanaganIroc

I'm wondering about fabricating a strut brace in my TPI car. I'm curious about a few things on the 2 point braces though
1) the rod ends that attach to the brackets on the towers, do they swivel freely and if not what keeps them from doing so?
2) how much room is there between a stock TPI V8 and it's closed hood? I need to know clearances so I can get bend angles right.

I already have a set of rod ends. they are scrap wing strut ends off a Piper supercub made out of high quality steel I'm just wondering about a few things before I start to finalize my plans.

hotrodln

I have an edlebrock 3 point brace on my 87. There is very little clearance from the top of the mainifold to the underside of the brace and about the same to the underside of the hood. The end points on mine are bolted up tight.... if your proposed joints swivel, will they still be strong in compression ? or just in tension? The brace needs to be stiff in both directions.......otherwise, people would just use a cable.......I'm sure you can do something with the parts you have.........just as long as it ends up stiff........

OkanaganIroc

Thanks,
From my understanding the brace is to keep the towers from compressing inward to each other even so I will be designing it to keep any flex or swiveling to a minumum.
I've also determined that I'll figure out the distance with the old play-doh compresion method between the plenum and hood. Does your LT1 equiped Iroc have the same intake dimensions? If not the distance between the two could be different.

hotrodln

Yeah the brace is to keep the sides tied together, so the brace needs to be strong in compression and in tension. I put my brace on when i had the 305 TPI. That's when it was tight. After I put the LT-1 in it, then there was lots of room under it.......like 4 inches or more if I remember right. The LT-1 intake is much shorter vertically.

OkanaganIroc

Thanks for the input.

Could you tell me the diameter of your brace tubing? and when you mean tight in the 305, how tight do you mean? how high was it off the plenum?

hotrodln

the brace has a rectangular cross section. it's 3/4" high by 1 1/2" wide. There's currently about 3 inches of clearance to the top of the intake. ON the TPI car-I could fit at least 1 piece of paper- maybe two. I still have the 305 sitting on the barn floor- it has about a 1/4" across the top where it's been rubbing against the underside of the brace.........

OkanaganIroc

Thanks for your help. I went to a pick and pull wreckers today and found a set of brackets that will work for me. They are rear door hinges (the body mount half) off a 80's ford van. I figure that is they are strong enough to hold those big heavy door on (and they are 3/8"" thick steel) mounting the brace should work for them.
I haven't decided if I'll use square or round tubing. round should be stronger and easier to weld the nuts onto.

OkanaganIroc

Well a few things I've figured out.
1) there is 2 1/2" clearance between the hood and upper plenum.
2) Don't use Ford door hinges for mounting brackets

The Ford door brackets are cast metal and the pretty much crumbled when I was trying to remove the hinge pin from them. Forunetly my Father-in-law had some 3/8" angle iron that I fabricated some new ones out of. I've managed to mount the brackets and clevises on the car so now I can determine the dimensions for the bar itself. With 2 1/2 inches I'm figuring on using 1" pipe to build the bar. that wil give me 3/4" on either side for clearance. I've also bought all the hardware, all 8 grade.

hotrodln

Now you see the problems when you build your own stuff! My Edlebrock brace fit fine the first time! It's a nice heavy duty unit. But my car also has a 6 point rollcage which also helps...........

irockid86

i did think about building my own strut tower brace but between the time and money involved i figured it would not be worth it. i have built truck bumpers and rock sliders and stuff and no matter how much planning you do you will always have to run out to the store and back again a few times. its great if you have the time and money, and is always nice to see what people come up with. sounds like you have a nice little project, good luck, and dont get discouraged, its all part of the game.

OkanaganIroc

Oh I'm not discouraged in the least. To paraphrase Thomas edison" I have not failed I have merely discouvered several way that it won't work."

Actually now that I have the brackets and clevises mounted ot will be much easier to figure the main brace dimensions.
More to come later

Spifz

What size rod ends do you have? 5/8" shank rod ends look good with 1.000 tubing, 1/2" might not look too bad, and if you don't have a lathe to turn a pair of threaded inserts to weld in, you can grind down 1/2-20 nuts (3/4 across the flats I believe) to fit half way in the tubing and then weld.
The attachment is one my Dad made, 1" solid bar drilled and tapped for the rod end. The nut in the picture is a jam nut, but it is a full size nut, not the half height ones you typically get with a rod end. The bracket is a welded together L shape out of 3/4 x 1 and 1/2 x 1. People usually get bent out of shape when they see a bolt in single shear (like my 1/2 inch bolts for the rod ends in my pushrod rear suspension, and 5/8 bolts that bolt my torque arm to my housing... ) but a 1/2 bolt torqued right is quite strong in single. The only argument I see for a double shear mount is that it might naturally spread the load into a larger area of shock tower. However, I would recommend attaching on top of and close to the inner edge of the tower (if you can make it fit there) rather than to the flat part which is pretty flimsy. The front edge might be a good choice as well.
Keep building your own stuff if you have the time, sometimes it is more expensive, but at the end of the day, when someone is checking out your STB, you can tell them that you didn't just bolt it on, you made it. And there is a lot of room for improvement over mass-produced stuff it you take the time to figure out what you really need.

OkanaganIroc

The Shank ends and the bolts are all 3/8" grade 8. It may seem rather small but as I said earlier the Strust clevises are aircraft quality and held the wing struts on. the angle brackets that they are attached to are held on but two bolts through the upper strut plat so I'm confident of the strength of construction. Of course getting the strut ends for free was another reason to use them.
I had originally thought of welding the nuts onto the ends of the bar but now that you mentioned it I might get they inserted into the ends and use a second nut for a jam nut.

OkanaganIroc

Just a quick update. I met with my welder friend and he's got all the dimensions for the main bar. It will be made out of 1" square tubing. Conveinetly the nuts slip right inside them so the job of welding them there just got easier.

Stephen

iTrader: (12)

Just like $200 SFCs. You can build like 3 wrong sets before the 4th one works, and STILL be ahead on the money game, and have the satisfaction of saying "I built them myself.". My buddy built his on his 'vert. I will too....some day!

And, you can sell your skills to others, since you have "proven" stuff, on your own car.

Build, don't buy!

gbettner

iTrader: (2)

OkanaganIroc, Did you ever complete this brace? I'm getting ready to modify a Eldebrock TBI STB to fit a TPI and wandering if your dimensions worked out on the plenum/hood clearance.

mjdavis68

iTrader: (1)

bump