Rear Frame Rail Notching How To!

[Dusty Bradford]

The quarter panel wrinkle is common on cars with frame notches. I have seen several builders add a reinforcing tube to the rear of the frame between the frame and the coil spring. I think it will help but is not the answer.

When looking at how the suspension works. You have the upper arms pulling on the frame and the lower arms pushing on the frame. IMO the only way to properly brace the frame after notching is by tieing it into the roll cage. You will need to tie the roll cage into the suspension points. This will be the area on top of the coil spring. From the coil spring back the only function of the frame is to hold the bumper up. By tieing the roll cage into the coil spring cup you take the load off the frame in the coil spring and the upper control arm frame mount areas. The roll cage will help fight the powers that are pulling on the upper control arm mounts on your frame when the car launches.

 

[karolko]

Dusty i couldn't agree with you more. Well Put.

 

[Alky V6]

So you're saying I should just back half the bitch now.

 

[six shooter]

That would be my choice since you don't have to worry about class rules. If you want to keep the stock suspension pick up points, I would bend tubing rails to follow inside the stock pieces and build off of that. If you need MIG or a plasma cutter let me know. I would be happy to let use whatever I have.

 

[Alky V6]

That would be my choice since you don't have to worry about class rules. If you want to keep the stock suspension pick up points, I would bend tubing rails to follow inside the stock pieces and build off of that. If you need MIG or a plasma cutter let me know. I would be happy to let use whatever I have.

Thanks six shooter. I'm going to be looking into this carefully before I start cutting things up. I know... bracing first. :biggrin:

 

[steve hughes]

When i notched mine i added a rear driveshaft loop between the lower control arm mounts and ran two tubes up from the loop to the upper control arm box. Ther are some pics in my photo bucket site in my signature. I broke a rod end on the anti rollbar last year on the launch. Left front wheel was about 5 feet off the ground and the about one foot. No quarter panel buckle or b post crack after that and many many hi 1.2 to low 1.3 60 foot times. Simple approach but it seems to work.

 

[Quick Turbo V6]

Here is how mine is done for now.

HTH,
Scott

 

[Dusty Bradford]

So you're saying I should just back half the bitch now.

Not at all. I knew where some pics we're that showed alot of the cage work that I'm talking about. They aren't where they used to be so I have e-mailed the guy to find out where they are. The roll cage main hoop needs to be tied into the suspension points. The rear down bars should go to the top of the spring mounts. I will be away from the computer all day working on a car but I'll dig up some pics in the next few days to help explain what you need to look into.

 

[Alky V6]

I have some pics at home, I can send you, or post,
the kit I got has inner braces /plate also, one at the top of the frame,(inside) another inside at front of the frame, near where lower arm connects, also included is a cross bar that goes between the frame rails.
To help eliminate body buckling, I planned to run a bar from roll bar ro rear bumper /frame area, to trianglate the frame, eliminate flex, and possibly an X to help lateral movement.
To gain maximum area, you will need to cut the frame to almost nothing,
leaving just the inner frame rail, thats why the kit has 1/4 in plate.
org frame looks like 1/8, so by using two, 1/4 plates , you will have sufficient material to help eliminate flex.
Donnie, when you plan to attack this? I'm off the 9th thru the 15th, (other than 12th) I can drive down and give you a hand.
tools I used were plasma cutter, die grinder with cut off wheels, saws all, and a torch, and of course a mig welder.
keep in mind, you will need to modify the wheel well, to optimize the frame notch, I chose to mini tub it.
let me know!

Finally checked out Scooby Doo's link to your install. Very interesting. I'm getting some ideas.
The frame actually does a lot of work in the area of the spring perches up forward to the lower control arm mountings. The overlapping stock channel offers a lot of strength compared to a flattened member, no matter how thick. I see some boxing, channeling and bracing will be needed.

 

[Dusty Bradford]

Here's a few more pics of some bracing.

http://www.outlawradial.net/suspensionpics.htm

 

[Fat Tony]

So you're saying I should just back half the bitch now.

You might as well, less work better chassis.

 

[twin 93 svt]

nice pic's

 

[Alky V6]

nice pic's

+1. Thanks for the link Dusty. Good food for thought.

 

[Louie L.]

Don,
Something to think about. Make your notch big enough for a tire upgrade in the future. Ive seen many notch jobs that with fit a 28x10 MT and thats it, me included. We deal with the depth issue but not the leght. I just upgraded to a 295/65 MT drag radial 30 in dia. The tire was hitting the front and rear most section of the tire.

So i had to go in there and modify a 5 year old notch job and it sucked LOL

 

[Dusty Bradford]

Don,
Something to think about. Make your notch big enough for a tire upgrade in the future. Ive seen many notch jobs that with fit a 28x10 MT and thats it, me included. We deal with the depth issue but not the leght. I just upgraded to a 295/65 MT drag radial 30 in dia. The tire was hitting the front and rear most section of the tire.

So i had to go in there and modify a 5 year old notch job and it sucked LOL

I dread going back into mine. I'm good for a 30" tire but I want the 315/60 to fit inside. That will be ALOT of work.

 

[Alky V6]

Initial Frame Notching Plan

Since I'll be cutting things up and welding things in, I decided to add more stuff to the 'to do list':
Notch frame for larger tire clearance
Install TRZ anti-roll bar
Install QA1 coil-over shock conversion

This is the starting plan. If anyone sees anything whacko, please chime in.

First, a survey of available room with the suspension at ride height.

Then the car will be supported at a height so as to be comfortable to work in, around and under the car.
The car will be supported in a manner to prevent any abnormal chassis bend or twist. The chassis will sit as if the car was resting on the ground on the tires.
Preliminary support points:
Under the front tires
Just behind the front tires at the turn point of the main chassis channel
Just in front of the rear tires at the turn point of the main chassis channel
Just after the rear wheel well at the chassis channel
At the rear most point of the chassis channel

The car will be supported at all four tires while all the other supporting points are fitted.
After that, the rear suspension will be relaxed and the rear axle, shocks, springs, brake lines, fuel lines will be removed.

A crossmember with an integral driveshaft loop will be fabricated between the lower control arm mounting locations at the frame. Tie bars may be extended from just outside the driveshaft loop on both sides to the middle section of the X-frame member. The upper control arm mounting locations at the frame will be tied to this new crossmember. How it will tie in still to be determined.

The next step will be to build a new inner wall for the frame channel of the wheel well. The new inner wall will be set around 3" inboard of the old channel inner wall. The outer wall of the channel will remain intact until the new inner wall, the roll bar, the support channel for the coil over shocks and reinforcements are in place. Then the outer wall of the old channel can be removed and the old inner wall of the channel will now be the new outer wall of the channel. It may be easier to just build a whole new complete channel inboard of the old one and remove the complete old one. Sounds like I'm back halving now, doesn't it.

 

[tsm3089]

Is the coilover conversion for the front

 

[Alky V6]

Is the coilover conversion for the front

No. The coil-over conversion is for the rear. I'm going to leave the front alone until I see how the new rear suspension works.

 

[tsm3089]

I would look into a strange double adjustable or afco rear shock.

 

[Alky V6]

I would look into a strange double adjustable or afco rear shock.

Thanks. I will. Any reason why?