toxic_d

I just pulled my engine to fix a frame rail issue and would like to know if anyone has ever done this and what guague steel to use. It feels as if there may be steel plate behind the frame to support the arm bolted to the frame.





This seems to be the worst of the camser in the car for now... there is some minor surface rust in other places...

peejay

When in doubt, overkill.

I'd personally use a huuuge section of 1/8" plate. Like, some angle iron welded to the top edge, angle iron welded to the bottom edge, and some plate welded to the middle. It won't be as light as factory but when in doubt, strong is more important than light.

My thinking is that the concern isn't for the idler arm mounting, since the idler arm mounting sees rather little stress other than bushing flex, and when the suspension is at full droop on the right side (and then then it's relatively small compared to what the steering box sees!). What concerns me is the "framerail" strength since, even though the inner fender carries the load of the car, torque forces and suspension sideloads get transferred in part via those channels.

Hell you should see how I'm doing the brackets for my rear suspension. There are 1 ton trucks with mountings less beefy.

- Pete (There's no kill like overkill. When in doubt, beef it out!)

jgrewe

iTrader: (1)

I havn't cut into that side of the frame but the reinforcment for the steering box side is in the form of sleeves the bolts slide through as well as some extra metal. That way when you tighten the bolts you don't compress the frame rail. And both sides of the rail get some of the load. You should be able to see how thick the metal is where it meets the inner fender. My guess is around 14-16 guage, at a minimum 18 guage. For the repair I'd go with 14-16 just because its easier to weld.

robs_seven

iTrader: (1)

if i were you i would grind off the major areas so it dont spread and get the paint off where you will weld the edges to the existing frame if not your welds will not hold, then lay over a piece of 1/8 sheet metal, if not 3/16. cut a piece and bend to match the frame weld a piece on top and bottom and then cut a piece to match the side of the frame and bring it all together with a good solid bead. i would use sheet metal all over i dont like mixing in angle iron, some stuff depending on its molecules dont like to stay together under stress, use one material and stick with it plus sheetmetal you can get to match the frame, make sure you get good pinitration (spelling errors sorry) even to the frame, but dont warp it or make it brittle. once your all done paint it if not you will just wreck it, welded areas rust quick cause of the heat and new materails change its moleculaur structure hope this helps good luck

toxic_d

Thanks guys I thought that the guage would have to be about 16 guage as from what I understand anything thicker than that needs to be heated before shaping. I may just go with 14 to be safe or possibly even thin plate.

Before pulling the engine the damage looked worse and I had intentions of cutting a larger portion out...



After getting a better look at things it seems that I may be able to safely cut a smaller section out and repair ithats way. I think I can just cut one plane out rather than cutting the entire rail...



BTW thanks for the responses.

Toxic_d

Gregs

wow, thats amazing, ive NEVER in 4 years of owning / parting/scrapping rx-7's have seen anything REMOTLEY close to how bad that rust is, ive personally seen probably under the hood of 60-100 first gens in my 4 years that just makes me go , around here if something like that came along we could gut the car for parts and scrap the shell and use another one as our base. lol

Gregs

oh and from seeing that frame rail does that car happen to be the same color as mine? (tender blue)

toxic_d

Yep its the same color. Strangely enough that is the worst of the rust on the car... The bins are not that bad just surface rust so far, though I plan on replacing the damaged sections there as well at the same time.

7's are rather rare in this area so make do is all I can do beside its reall not that bad.

toxic_d

After the frame repair is done I plan on Foamsealing the entire chassis... As well as some minor weight reduction ie sound deadening and eventual emissions removal and such.

Link to foamseal http://www.foamseal.com/auto_aftermarket.htm

It will stiffen up the chassis some and dampen vibrations a bit without the weight penalty.

Toxic_d

85rotarypower

Pfft, thats nothing compared to what my car had. Both sides of that frame rail were rotted pretty bad in that one area on my car. Can't think of the gauge of steel I used to fix it, but I know it was too thick to form without heating it first, not that any forming is needed there. I know I needed to heat it because I used the same steel to fix the floors and rear wheel wells too, and let me tell ya, that was a bitch. The car is probably stronger overall than stock now too since I used steel twice as thick as stock for the rails under the floors. Actually, now that I think about it, I believe the rails I used were originally made for a Mustang.

toxic_d

The reason I made mention of the 16guague is because the factory would have stamped these cars out of sheet metal rather than pouring molten steel into a mold for the frame rails. 16 guage I believe the thickes that you can go without have heat...