Build Thread '83 T-top Coupe - This Is Tough

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CarMichael Angelo

clearly, I’ve got something going on in that hole
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An independent rear suspension.

Are you new to this forum? If so, you should make a post in the Welcome Wagon.:kmcoff:

There is no upper front mount needed with an IRS.
You probably used too many words when originally talking about that part of the plan.....Noobz don’t like it when you use too many words.
 

90sickfox

I didn't really have an issue with the stink...
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I left my uppers intact just incase I decided to got back SRA..with meaty tires and a mini tub. If going coil over in the rear...the IRS requires a different mounting point up top. They use a bracket that is welded to the inside of the shock tower. You could weld a plate on the back side of it and run a brace across them and then kickers down to the frame rail. That would stop and movement there.

The upper arm boxes shouldn't be a stress point at all. I would think the stress point would be ahead of the lower boxes ( that are already strengthened by your welding ordeals )...or something like that.
 
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Davedacarpainter

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So, I’m finally getting off my butt to do something. I wasn’t feeling great yesterday so I did nothing worthwhile.

After joking about the hf jack stands, I thought i should check the two I have. Guess what? Lol, holy crap i did a LOT to Booger with these being a main support.
238DFD10-07BE-4361-8C4E-9A1ECFDB7F82.jpeg

I‘m off to hf to do an exchange.
 
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Davedacarpainter

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Ok, I finally got the IRS dropped, yay! That last bolt on the front left was the only one that required me to be fully under Booger again. I’ll get it stripped down tomorrow.
943CD366-3733-4BE7-BFEB-9A518D06D567.jpeg

Now, here’s the next area of modification. The upper control arm mounts. You’ll notice five different areas of concern for me. First in green are the dumbo ear mounts that normally clear the IRS by the narrowest amount, and I mean narrow, like 1/4” separation. They’ll be gone. Got to go back to hf and get a few spot weld cutter bits.
7CA6C5E3-54DD-45DB-B736-D18FD82BD0C9.jpeg

Then comes the other three that I want to keep and maybe slightly modify. In yellow is the backing plate that’s welded to the floor pan. I think it’ll stay.

The other two in red are the support plates for the rear seat belts. I need to maintain them. Though they may be slightly modified and trimmed at the top so the 2x2 tubing will fit. Then I’ll weld the trimmed part to the new tube.

Here it is higher up in the air than it’s been in a long time.
B515A25E-7C8C-42F7-9150-E6DF98FE28B1.jpeg

This final picture just seems to excite me, lol! I’ll be playing under there for a bit. I’m looking forward to making that trans tunnel all green.
DD002F57-3AC5-4531-B7DA-3C85F7967453.jpeg

I didn’t get much done this weekend, but I’m set for the next stage tomorrow!

Tomorrow’s plans are to just strip down the IRS and stop by hf to get the spot weld cutters.

This IRS is going to be costly, I’ve already added up $2500 in modifications for it. That’s OK though, it’ll be totally bitchi’ when it’s done.
 

RaggedGT

check back later..
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Fwiw-the berating comment was not directed at you Dave (my bad.), was for the few who find my suggestions unwarranted.. But I do tend to have that effect on people-I suggested back halving booger cause you where talking about all the close clearances and removing mounts etc.. I’m sure you will figure out what you wanna do with the irs etc. and make it look damn nice.
:leaving:
 

CarMichael Angelo

clearly, I’ve got something going on in that hole
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Fwiw-the berating comment was not directed at you Dave (my bad.), was for the few who find my suggestions unwarranted.. But I do tend to have that effect on people-I suggested back halving booger cause you where talking about all the close clearances and removing mounts etc.. I’m sure you will figure out what you wanna do with the irs etc. and make it look damn nice.
:leaving:
He’s talking about me.

Its not that your comments aren’t appreciated Raggedy, it’s just that they are sometimes a little too “reach for the moon”, when the problem exists here on the Earth.
 

RaggedGT

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He’s talking about me.

Its not that your comments aren’t appreciated Raggedy, it’s just that they are sometimes a little too “reach for the moon”, when the problem exists here on the Earth.
100% agree , from time to time my ideas are overly excessive. My brain outruns my common sense sometimes. So I do apologize for that. Sadly it’ll happen again :(
For real though Mike, wasn’t a jab at you or Dave, sadly I’ve agitated more than just you guys- Unfortunately it came out that way. Cutting the rear rails outta the car was definitely overkill for a suggestion-but I still kinda stick with altering the rails and floor to make room for all the irs stuff.
 

02 281 GT

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100% agree , from time to time my ideas are overly excessive. My brain outruns my common sense sometimes. So I do apologize for that. Sadly it’ll happen again :(
For real though Mike, wasn’t a jab at you or Dave, sadly I’ve agitated more than just you guys- Unfortunately it came out that way. Cutting the rear rails outta the car was definitely overkill for a suggestion-but I still kinda stick with altering the rails and floor to make room for all the irs stuff.
I really think you need not apologize nor explain yourself to anyone.
 

Davedacarpainter

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Holy smoke, lol.

You may not recall Chris, but you’ve made suggestions on my cars in the past..... :chin

I can’t remember one time you’ve offended me by those suggestions. Sometimes they’ve made me chuckle a bit even, like this time.

I like new ideas, I actually think about them most of the time. There’s nuggets to pull from most suggestions that can be useful and sometimes I even take a suggestion wholesale and do it. ie: mini-tubbing.........

This one made me chuckle simply because it’s too large for me in this environment that I have to build this car. I replied with a short answer in a way to be funny for you in particular.

But you know what I’ll be studying probably for the next few nights before new things get welded in?.........:scratch:

So, no need to be sensitive about my replies Chris. I consider it friendly banter is all.

If someone else should come along on my thread and try to bash you about your ideas, I’ll just tell them to go booger themselves :nice:
 
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Hoytster

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I was looking at that thread about the full fox frame and it got me thinking. Not about getting one of those, mind you. I just kept looking at it and the different parts.
006DCA58-702B-4A2A-997C-3F342B11381A.jpeg

I was thinking about stress areas in my coupe. Since I’ll have coil overs in the rear, I thought more about that upper shock mount.

Maybe replacing it with a new box that welds deeper into the subframe wouldn’t be a bad idea? Much heavier gauge than factory too. I‘m strongly leaning towards replacing the shock mount. Plus an additional tube between the upper mounts since the full weight of the car will rest upon those and transfer a bit of twist under hard acceleration? Since I’ll be replacing the uca mount with tubing, I don’t know if that’s really necessary. It’s just a few inches away from the shock mounts. Yet the new X-brace inside the cabin will have a strut going to the shock mounts.

I luckily came across some heavy gauge flat steel that I can make gussets, backing plates, rear upper shock mounts maybe out of.

I’m thinking the IRS adds a crapload of lateral support for the subframe as long as I do a hard tail and maybe a hard nose on it. @Hoytster didn‘t you do something with the front mounts of your IRS? It seems to me that to eliminate all bushings from the IRS to frame couldn’t be anything but good.

Help me think here guys. Tomorrow the IRS will be out and disassembled and the rear mods really begin. I’m starting by removing the factory upper control arm mount and replacing it. Speaking of that, do y’all think I need more than just a tube welded between the rear subframes? Like angle supports welding from the tube to a lower are on the subframe. Would that Just be a waste of material and add weight, or be helpful?
8CE2B97D-E90C-4664-B08D-F1C9AB4E1175.jpeg

I’m taking a hard look at those dang torque boxes too. Remember, there won’t be any movement of the lower IRS mount like there would be with a control arm. Maybe it could be redone, maybe completely?
You're correct, the IRS itself adds a fair amount of lateral support toward the back of the car. Especially with the hard tail conversion, the IRS cradle essentially becomes part of the frame when bolted in. I don't think you will need to add anything else back there. The main point of adding the bar after removing the upper control mounts was to add support to the floor since that was removed with the upper control arm mounts. The added lateral support was just a benefit of the whole setup. If I ever went back to a SRA, I was just planning on buying aftermarket upper control arm mounts and welding them in.

041591.jpg


Plug welds from the floor to the top tube for support.
20190204_191941.jpg



I did hard mount the front of my IRS cradle as well. Do know that doing this will probably add a large amount of NVH to the vehicle, especially if you are running Delrin bushings in the IRS like I am. There will be almost no isolation between the control arms, diff, ect and the body of the car. I maintained the torque box mounts and added reinforced plates on the IRS that through bolt to the frame rail right by the torque boxes. I'm replacing the bushings on the torque box mounts with aluminum ones so everything is solid. The whole point of hard mounting the front of the cradle in my situation was to reduce the amount of deflection that occurs in the IRS cradle at the point it bends to engage the torque boxes. This only seemed to occur when corner forces exceeded 1.2g's in my simulations.


In this pic you can see the front mounts added to the cradle.
707782.jpg


I am aligning the front hard mounts for the through bolts in the frame rail in this pic.
20190218_192602.jpg
 

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Hoytster

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I also stitch welded the rear shock mounts on the inside and outside, and have them boxed out and reinforced on the inside to handle the future coil over conversion. I will be running a bar between the shock mounts on the inside of the car, and the whole system will be integrated with the cage. Just stitch welding the shock mounts is usually good enough, but there is some inward deflection on the frame rail that occurs when REALLY hitting a bump that the bar between the mounts help to control. The tie into the cage helps to control the deflection of the entire rear of the car (basically the frame rail/back half bending).
 

Davedacarpainter

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The main point of adding the bar after removing the upper control mounts was to add support to the floor since that was removed with the upper control arm mounts.
Did you consider leaving the backing plate of the upper uca mount for attachment to the floor?
The whole point of hard mounting the front of the cradle in my situation was to reduce the amount of deflection that occurs in the IRS cradle at the point it bends to engage the torque boxes. This only seemed to occur when corner forces exceeded 1.2g's in my simulations.
Since my ex won’t be driving this car I don’t have to worry about the 1.2g cornering force being exceeded.

We had talked about how the irs cradle was similar to the k-member when you were considering the hard front mount. I kind of still hold to this view. The NVH would be from delrin bushings in the control arms then, I would think. I will be using urethane for my bushings. Hopefully this will make it a little more gentle.

I’m not sure if I’ll do the hard front or not yet, I’ll think on that one. I like the idea of the strength the cradle gives the rear subframe.
 
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