Cutting rear frame rails for different offset wheel????

[Chris McDade]

Ok guys,
I need some advise here. I want to cut my rear frame rails so I can put a different offset rear wheel. Im running 3-1/2" back space now. I want to put a 4-1/2 or 5" backspace so the wheel will sit in the fender a little more. Im going to drop the car a little.

I work for a machine shop and we a very good certified welder here. I ask him about doing the job for me and he said no problem. So my question is: Is there any thing special that I need to know before I get going on this? Is there anything I need to remove before he starts cutting and welding back there? ( I know to unplug the battery ) Do you re use the peace that he cuts out? Or do you have to put another peace of metal in there? If so what type of metal? ( Material ? )

Thanks in advance

 

[Louie L.]

Chris,
Im in the middle of this same project. I disconnected the battery , and unplugged the ecm.
I put mine on jacks stands suppoerted by the suspension and supported the rear most part of the frame. I have just cut just to the middle seam and as far front and back as possible. I did so with a 110v plasma cutter. Now i have to "dress" up the area by doing some grinding.

Although many advise to reuse the stock section , im going to make card board templates from each side , then im having the local welding shop cut the fill plates fron some thicker heavy steel . this will give me some streght in that area. reason is that the factory stuff is kinda flimsy.

I have a bunch of several notching jobs from several board members. if you need them let me know.

 

[Chris McDade]

Louie,
It sound like your going about it the right way. I don't know much about the cutter you have. Do you think it would be ok to cut it with a torch? Clean the metal up and weld it back in? How much and how far back do you cut out?

Do you have some pictures of those notching jobs?


Thanks

 

[clean86]

Hay Chris , stay away from the tourch. Heating the metal so much as you cut it might really screw up the whole area. The plazma cutter is the way to go. Just mark where you want to cut and follow the lines. It will go through it like butter, 30 min tops for both sides and it won't overly heat the rest of the frame rails. Good luck!!

 

[tazgn]

Measure FIRST!!!

Hey, I also recommend that you try fitting the wheels on the car before you make any cuts. I have 18x9.5" wheels on the back of my car with 5" backspacing and they fit GREAT with no cutting. Every car is different, so just because 4" backspacing rubs on one persons car doesn't mean it will even be close to rubbing on yours.. Just thought I'ld throw that out... Since i also thought I would have to notch the rails until I bolted the wheels on and was pleasantly surprised (with stock steel brake drums too).


Derrick

 

[Louie L.]

A plasma cutter is the way to go. I rented one for 35.00 a day. Some places have same day return for a discount. Although the cutter is super easy to use it wont take just 30 mins to use! You have to be very carefull as that sucker will easily cut more than necesary.

Dont forget that after youdo the frame work you still have to massage the wheel wheel above the frame as most times thiswill stick out furter than the halfed off frame. A couple of relief cuts and a BFH and you get the max clearance.

 

[Chris McDade]

Tazgn,
My wheels are real close to rubbing now. so I know that they will rub with a different offset.

Thanks anyways,

 

[Chris McDade]

Thanks Louie,
That helps. So I should cut Half the frame out?

Thanks in advance

 

[Louie L.]

Chris,
If you have a way to reinforce the frame from the rear , that is from the inside then i would take it all the way to the back side. But Thats about 3 times the work and you have to be very creative. It takes some reinforcing and guseting to get it strong enought. By this time most cars have a real ROLL CAGE which helps tie the back of the car also.

Many of us just take it out to the middle seam on the frame rail. Leaves much more material for strenght.Also be aware that the rear most part of the frame sweeps to to the outside of the car. In other words , your gain at the front of the frame rail is more than you will get out back. Im gonna try and cheat mine out back but that remains to be seen.With the job im doing i believe i will be able to fit a 28x10.5 on a 10 in wheel w/ 5in bs with no trouble.

Check the last 2 pics in my yahoo album below.

 

[Chris McDade]

Louie,
The pics of your car is that with the rear frame already done? Is that with the 5" offset and the 28x10.50. It looks nice. Thats how I want my car to sit.

Nice combo you got there. How does the car run? How much does it weigh? Look like you've been doing some cutting.

Thanks
Later

 

[1320n10]

There is some pics of my car on gnttype.org that show the notched rails. It was cut out with a plazma cutter and new metal was tig welded back in. I have 15x10 convo pros with 5" backspace And had 28x11.50 mt slicks on the car. I am now running 28x10.50s to meet tsm rules. (want to buy some slightly used 28x11.50s)

 

[Louie L.]

Originally posted by Chris McDade
Louie,
The pics of your car is that with the rear frame already done? Is that with the 5" offset and the 28x10.50. It looks nice. Thats how I want my car to sit.

Nice combo you got there. How does the car run? How much does it weigh? Look like you've been doing some cutting.

Thanks
Later

Chris,
The frame project is not done yet. The pic is of my car with an 8in rim with 4.5 in bs. Tires were 28x11.50 ET streets. Just bare fit and would spin them all day at the track. They did look real good. The pics i just put in there are of the frame with the front half removed. I just spent some time dressing up the side. Im gonna borrow my buddies 10in wheels and slicks to see if there are gonna be any issues before final welding.

Before all the cutting began, full weight with a tweaked,boost leaking head gasket and 2 broken valve springs it went 97mph in the 1/8 with 21 psi.I decided to do all the work, HGs ,lightening at the same time. Now all the problems have been fixed and the heads have been fully ported. Cant wait to go back

 

[Chris McDade]

Thanks Guys,
I will keep you updated on the project. Im going to start it in about two weeks.

How thick is the metal that your sticking back in there?


Thanks

 

[Louie L.]

Originally posted by Chris McDade

How thick is the metal that your sticking back in there?


Thanks

I just spoke to my metal shop guy. He asked me to bring him a piece of the stock stuff i cut out. he will then help me pic the best thickness for strenght. I would think at least twice as thick. The stock stuff is very thin. The slice of metal i took out can easily be bent by hand!

 

[Chris McDade]

THanks Louie,
Keep me updated on how it comes out. I would like to see some pictures of the finished job.

Thanks
Chris