Info on mini-tubbing an IRS car?

[tedly]

Got a nasty surprise when I was stripping down my 97 TBird, the rear shock towers are rusted pretty bad. One of the ideas rattling around in my head is mini tubbing it but I have found very little info on doing this with an independent rear suspension. Any help pointing me in the right direction for ideas/info would be greatly appreciated, whether it's for mini-tubbing or repairing the rust damage.

[anotheridiot]

We dealt with the terrible shock towers on the camaro.

I got one of the competition engineering shock mount and rear frame stiffener, but to use it, we would need to cut the new stock fuel tank and move the spring perches on the new 4:11 posi to make it work. so new from idiot engineering, mostly 3/16ths x 3 stock





No more rusted shock towers with shocks coming thru to the speakers for this car. Its just one side, the other one is in and will have a piece of 2 - .125 square tubing welded in between the two where it forms around the rear frame rail. Should get the stiffening effects of the competition engineering one while leaving the springs in the same place and the shocks connected to something better than the sheet metal.

Dont know what you have with the T Bird frame, but wrapping something like this and sandwiching your sheet metal tower will fix your current towers.

[tedly]

Not a bad idea, I'd thought of something similar with maybe rectangular bracing between the towers. Only problem is I'm pretty sure I'm going to need bigger than 3" stock.


I am a beginner when it comes to body work and having learned to work on cars in the south rust still freaks me out. So I gotta ask, is this as bad as I think it is?

[SuperBuickGuy]

can you drive a pick (with your hand) through the rust? from the picture, it doesn't look too bad - just sheet metal repair the hole.

in any case, I'd certainly stop and treat the rust.... any more..... dunno, the answer might lie in how much you love the car?

[A/Fuel]

If you were to mini-tub it, where would you put the shocks?

[Barry Donovan]

should be laminated, stronger piece doing the work..most often the skin riding it as body color will get lost, and look worse than it is.

I had to do this for a subaru. 80kspi weld alone can take you back to factory pieces, the psi is the win.

the skin moving means something else is moving, check roots of wheel wells/subframe/ their covers. that is where the big work is needed.

my own turned into 21 feet of bead each side of the car, and a geometric hammer welding I could never replicate..all solid seamed. after this is done..you will find quirky snakes at other points in the chassis for years following. have fun..

[anotheridiot]

Not a bad idea, I'd thought of something similar with maybe rectangular bracing between the towers. Only problem is I'm pretty sure I'm going to need bigger than 3" stock.

I am a beginner when it comes to body work and having learned to work on cars in the south rust still freaks me out. So I gotta ask, is this as bad as I think it is?

Bad on shock towers is you can see the top of the shock thru the floor. you are dealing with metal that is probably .030 thick at that point. You can probably get away with a flat piece of steel bolted in a few places back where there is no rust, looks to be about 6-8 inches away. make it a foot long and drill three holes in it. The top corner is just keeping the water and mud out of the trunk, your support is the bends around the tower. So depending on what kinds of fab equipment you can get to, the easiest way to fix that tower is just bending a piece like an angle and bolt or weld it in place to get your support. If you can bend the s, then run it up the inner wheel well, flat where the shock mount is now and back down. Once you have the piece, you can decide how much you want to cut out of that rust, or just por-15 it and put your new piece on top. there are other rust treatments that basically turn the rust black and stop it from spreading.

I went around the frame rails of the unibody so there is no real weight on the trunk pan anymore, but just beefing up the three solid parts you have should keep the shock in another 15 years easy.

[milner351]

Looking at that - there's no reason to minitub if the rust repair is your concern - just reinforce as stated.

[tedly]

can you drive a pick (with your hand) through the rust? from the picture, it doesn't look too bad - just sheet metal repair the hole.

in any case, I'd certainly stop and treat the rust.... any more..... dunno, the answer might lie in how much you love the car?

I haven't had the chance to clean it up and test the extent of it yet but I think I could probably push a pick through in parts. Treating the rust on the car is my primary concern, no other parts for the build will be bought and no other work done until I at least establish the extent of it and what my best option is for getting rid of it. There is quite a bit of sentimental attachment with the Bird, it will be fixed.

If you were to mini-tub it, where would you put the shocks?

That, my friend, is exactly what I am trying to figure out. Would moving the shock mount mean I could just change the angle of the shock or will that screw up the geometry of the rest of the IRS? I'd like to gain some clearance for larger tires but have found nothing on this yet.

the skin moving means something else is moving, check roots of wheel wells/subframe/ their covers. that is where the big work is needed.
after this is done..you will find quirky snakes at other points in the chassis for years following. have fun..

I'm stripping it down to just the body shell anyway, so hopefully I'll find most of the snakes soon.

Looking at that - there's no reason to minitub if the rust repair is your concern - just reinforce as stated.

Rust repair is primary concern, but if I was going to have to cut out a big chunk of the wheel well anyway I thought I might be able to gain some clearance for wider tires.

Thanks for the input guys, it is definitely helping me!

[tedly]

Bad on shock towers is you can see the top of the shock thru the floor. you are dealing with metal that is probably .030 thick at that point. You can probably get away with a flat piece of steel bolted in a few places back where there is no rust, looks to be about 6-8 inches away. make it a foot long and drill three holes in it. The top corner is just keeping the water and mud out of the trunk, your support is the bends around the tower. So depending on what kinds of fab equipment you can get to, the easiest way to fix that tower is just bending a piece like an angle and bolt or weld it in place to get your support. If you can bend the s, then run it up the inner wheel well, flat where the shock mount is now and back down. Once you have the piece, you can decide how much you want to cut out of that rust, or just por-15 it and put your new piece on top. there are other rust treatments that basically turn the rust black and stop it from spreading.

I went around the frame rails of the unibody so there is no real weight on the trunk pan anymore, but just beefing up the three solid parts you have should keep the shock in another 15 years easy.

Cool. It's good to know I was on the right track when I was thinking about this. Is it possible to get pics of this in your Camaro?

[hauen]

You could move the shock anywhere you wanted to with these, it's strictly a dampener and doesn't locate anything. The only problem with that is how effective it is at dampening, but that's something you can easily figure out with some simple math and a little online research. How good are your fabrication skills? You could use levers and bellcranks and mount them horizontally if you really wanted, it's just a matter of what your end goal is.

[anotheridiot]

Cool. It's good to know I was on the right track when I was thinking about this. Is it possible to get pics of this in your Camaro?

I have a picture stuck in a phone, I will try to get another one that I can send to show you how it wraps around the frame rail on the bottom. But the reason I made this heavy is because we are old school and are going to be running air shocks, which puts alot more pressure on that tower.

[tedly]

You could move the shock anywhere you wanted to with these, it's strictly a dampener and doesn't locate anything. The only problem with that is how effective it is at dampening, but that's something you can easily figure out with some simple math and a little online research. How good are your fabrication skills? You could use levers and bellcranks and mount them horizontally if you really wanted, it's just a matter of what your end goal is.

Interesting food for thought. I'm going to chew on this for awhile. Thanks!

I have a picture stuck in a phone, I will try to get another one that I can send to show you how it wraps around the frame rail on the bottom. But the reason I made this heavy is because we are old school and are going to be running air shocks, which puts alot more pressure on that tower.

If you can get it, I would greatly appreciate it.