rsonedecker

Looking for advice or examples on best practice on notching out the outside of the rear trailing arm mount area / rear frame riser for wider tires. I'll have rear coilovers with offset arms and a custom offset (narrower) sway bar, so the main area I'm looking to prepare for is the "stick out" lip on the outside of the trailing arms pivot mount area. I'm looking to notch it out and subsequently reinforce other areas, just looking for ideas and examples on the best way to keep structural integrity.

Keep in mind in the pic below, it's upside down (frame is upside down in a rotisserie)

1971CorvetteII

Why do you have to modify that area, first time I've ever seen this attempt ?
how tall of a tire do you plan on running

rsonedecker

26"-26.5" front, 27"-27.5" rear (305+ tire)
Coil-over rear suspension with offset arms (so it will be lowered some)
Custom (narrower) rear sway bar.

I'm trying to set it up to be able to run as deep of backspace as possible, since I am reworking and welding the bare frame right now. I have everything tucked inside the frame, EXCEPT this one area that sticks out and I would just like to take care of it now. I've seen the end-result of notching this area, but not any ideas on how to make sure to reinforce when notched.

Z51JEFF

Is that bottom weld factory? Not much room to work with after you notch this area,you might look into making a plate for this entire area after the notch is made.

Mdbirk

All I picture is this lol

1971CorvetteII

That is the only reason I could imagine as to worry about that section, at least you could run 4" exhaust under the car.


If you have seen this done what did it look like ?

How is this modification going to affect getting the trailing arm in & out & shim thickness
At that point cut out the IRS & tub it & install a straight axle = will get rid of weak links in the back, custom drive shaft.

Is this mod for ? what is the drive train you are running, horse power, trans or is this more of a visual treatment / look cool with fat deep rims.
Heat it red and pound it in until you have have what you want.
Sounds like a good waste of time personally, keep the pictures coming = we want to see

rsonedecker

That monstrosity is not where I am going.

More like this (not quite THIS wide)


I'm simply thinking about it because I am doing everything else to the frame right now before I get it e-coated and powder coated. Welding, gusseting, installing grounding studs, riv-nuts, welding in the rack-and-pinion mount, etc. I have read many threads where people have gone wide and had to shave that area of the frame, so because I'm here with a bare frame on a rotisseries and plenty of MIG wire and 1/8" steel sheets, I figured I would just get it out of the way now. Why not give myself all the backspace I can?

Z51JEFF

I fully understand what you're after,ignore the stupid comments. These guys put a set of TORQ THRUST II wheels on a car and think it's the baddest thing out there. I answered this already but after a little more thought I'd make a notched plate and cover a large area for strength. I want to put as wide a wheel/tire on my 75 but the most I'm looking at is an offset T-arm. If you can try and find a picture of a frame together with a wheel on it to find the area to re-work b

Corey_68

Someone here has certainly done that frame mod because I remember seeing the pics.

1971CorvetteII

So everyone that comments in your opinion spew out stupid comments, we understand also, for you to assume we don't is as you say stupid.
Your comment isn't stupid, but it sure is funny

That is why I just suggested cutting all the factory junk out of there & installing a straight axle, tub it = problem solved, yep might be a little more work
but will solve a couple problems with the IRS suspension.
While he has it out for easy access, did you notice the 1/8" plate mentioned, seems a bit thin for me, might be ok for a filler brace = not me
You stated (plate) I don't think 1/8" as plate/structural.

As far as finding a picture of an assembled car / frame I included the red frame one, it's supposed to be a 65
To me it's just not worth the effort, go as reasonable wide as possible, then spend more money and install flares, body work, paint
Might as well go all out if your going to do it.

What is stupid is running your tires so close to the frame as the car pushes left or right, suspension movement might ( NOTE MIGHT ) cause interference.

rsonedecker

I have searched and searched. I can find LOTS of people pointing out the rubbing and seen some post-modification pics, but haven't come across a write-up. Just about any time someone talks about going over 285 in the rear (without flares) this comes up. You can find the below pics scattered around here, as this is the last place it rubs before you meet the frame.

rsonedecker

I don't believe anyone's opinions or ideas are stupid and appreciate all the feedback. There have been PLENTY of times when I was "dead set" on doing something, only to change my mind because of ideas and recommendations.

I do not have the skill, time, or desire to undertake that large of a rear suspension mod. I am simply looking at trying to remove a 3" area on the frame that sticks out almost 1" from the plane of the frame, simply so that I don't regret it later, seeing as it's a typical talking point for anyone who is trying to put wider tires back there. I don't want my tire to rub on the frame -anywhere- so your point about being so close to the frame is a good one, and kind of the reason I want to move 'this' part of the frame away from the tire - in essence, I'm moving the frame away from the tire.

My 1/8" thick gussets and reinforcements are about twice as thick as the factory stuff,

Corey_68

This is 295 x 4, I believe someone here has 305s with later C3 stock mudflap flares.

https://www.corvetteforum.com/forums...4-corners.html

rsonedecker

This is a good representation, but keep in mind that the diameter of the tire is unknown, the shape of tires vary, and the suspension is not under load. If you put a couple inches of body weight compression on that rear suspension, I bet the tire is much closer to that point than you think.

Z51JEFF

Not all but the pictures of the stupid DONKS,is this somebody's way if implying this is what the OP is looking for?

Richard454

Here you go-

https://www.corvetteforum.com/forums...clearance.html

Did I say I detest photobucket....

Mdbirk

I was just poking fun about the donk vette..I have thought about the mod you're thinking of when I inherited my dad's vette but my dad installed a set of flares he ordered from ecklers in the early 70s....I think maybe even 69ish. I have a 295 50 15 on it now....and torque thrusts....only because my dad had them on the car back in the day. I like big meats.

BigBlock77

Bee Jay had this thread going several years ago when he tucked wide tires inside his stock fenders. The photobucket watermarks are now on the pictures unfortunately, but you can still get the gist of what he did. You can probably PM him for more pointers, I think he's having too much fun with his C8 now and his 79 is resting a bit more. Check here: https://www.corvetteforum.com/forums...clearance.html

69L88

As you can see in the pic below, plenty of clearance with 28” tires running on 15x10s with a 5” backspace. This is a very late 1969 production (all stock) frame.

rsonedecker

So I called my hot rod guy and was telling him about this - he stopped over after work and we took a good hard look at it. If you want to gain at least a half inch of clearance, it's actually really easy, especially when the frame is bare and upside down.

NOTE all these pics are a frame upside down.

Inside there is a cross member / box top that is flush everywhere except the area where we need to work. There is a 0.5" (or more) gap there.


With a little heat and a couple of wacks of the hammer and this area can be flattened against that section of the cross member inside. You'll notice that the upper corner (lower left) buckles up because there is no weld there.


We then cut out the extra metal in that buckle


Then we pound the lip back over and smooth it out


Then we weld it back together, and weld the crossmember to the outside frame wall that now butts up against it.


And the results are amazing (one side compared to the other [before we did the other side] - notice the big gap on the inside of the left side)


From 2.75" to just under 2.25" in about 45 minutes. The other side took only about 30 minutes.