Frame rail notching for wheel/tire clearance?

[turbomark]

I would like to hear from anyone who has notched the rear frame rails for wheel/tire clearance. How much can be reasonably cut away? Any photos of the finished frame cuts and reinforcements would really help. I have the body raised up off the frame for cleaning and painting, so that won't be a problem.

Thanks!

Mark
'84 GN project

 

[jim406]

frame mod

you can safely cut 3/4 of the way into the rail just plate[box it in]the section you remoed from it only holds 2 rear body mounts and bumper not much strenth needed there and after you box or plate it it will be stronger

 

[turbomark]

jim406,

I don't suppose you have any photos of the finished mod, do you ??

Mark.

 

[KendallF]

I cut everything except the rear wall of the frame rail. The rear bars of the cage come down through the trunk floor to reinforce the crossmember just above the upper control arm mounts. I thought about adding more reinforcement along the back of the notched section but the only thing it's holding up in the back is the bumper. I have a few pictures of the work in progress (see web site in my signature).

 

[turbomark]

Kendall,

Thanks for the info. I don't have a roll bar installed in the car (yet), so I will have to reinforce the frame more than you have. My car will be aimed more at the autocross-type chassis, so my target is to fit 285/40R-17's or even 315's if I can squeeze them in. Since these tires are much shorter than the 29x10.5's you installed, do you think I will need to tub the wheel wells ?

Thanks,

Mark.

 

[QWIKTURBO]

Here's some pics for you......

Just go to www.Hartlineperformance.com. Go to the area where the pics of his car are at. He's got some pics of the notching with the body off the car. You can see that he cut out quite a bit but he boxed it in. As far as safety and "integrity" of the frame rail goes...his car runs well into the 8's!!

 

[Two Lane]

wrong linkee

 

[QWIKTURBO]

OK....

How about http://hartlineperformance.com/

 

[Louie L.]

A regular notch job will likely be all you will need to fit that tire in the car.Check out the pics in the below link of the job in my car.Cals frame mods are 1st class. But i can tell u 1st hand that it took some well planed gusseting and bracketry to do the job as i was there and helped with it. Really beyond of what can be done with the body on the frame as most of us have done.

 

[turbomark]

I live about a half hour from Cal Harline. He suggested that I come by and take some photos........

Thanks, Cal !

Mark.

 

[Louie L.]

no need i got plenty ofthem here since i took them. i can email them to you in a couple of hours

 

[JeffG]

turbomark,

i just did mine two weeks ago. I didn't go crazy on the notch. I basically cut it back to the welded seam at the top of the rail. It didn't make much sense to me to cut it any further because I couldn't beat the inside fender well any further back then this line anyway. That leaves about 1/2 to 3/4 of an inch to the rear rail wall.

I just measured last night and I think I'll be going with a 315/35/17. Most of them measure 12.5-12.7 inches wide and around 25.25 to 26 inches tall. These will just barely fit with the fender lip rolled..........I mean barely. I think the perfect rim would be a 17x10.5 with a 5.5 back spacing. The 17x11 will probably be two wide without some kind of off the wall off set.

 

[turbomark]

Jeff,

315's fit......woohoooo !!! Seriously, send me a couple of photos when you get them installed. I'd love to see how that looks.

Thanks,

Mark.

 

[JeffG]

Mark,
I can do that once it's done. I have 275/35/17 Nittos on there now. They're bald so it's time to trade up anyway. I think I'll be going with a regular (non drag) radial this time. As others have stated, the 17 inch drag radial is kind of a waste of time. They would light off almost as easy as the regular tire...........but with half the wear.

Good luck!

 

[DeltaT]

Four different sets of pix of G-Body frame rail notching at:

www.maliburacing.com

in the "What's New" box

Article is titled: "TECH- Notch Your Frame Rails for Bigger Tires

Jim

 

[JCotton]

If you plan to cut any further in than the welded seam of the rail, better reinforce the back side of the rail as well as running a bar from the center bar of the hoop down to the top of the frame rail where the front of the lower control arm is attached. If you make any kind of power and launch hard, the frame rail will twist up into the floor pan, mine had twisted up almost 3" denting the floor board an 1". When this happens, your axle will not be located where it's supposed to be. I didn't run the bar down to the top of the rail, instead I installed the hotchkin supports between upper and lower control arms.

 

[KendallF]

Originally posted by KendallF
I thought about adding more reinforcement along the back of the notched section but the only thing it's holding up in the back is the bumper.

Hah...my own words come back to bite me. I trailered the car over to the painter and hooked the tie downs in the rear to the frame rails. I managed to twist one rear frame rail substantially during that 30 mile tow. I am going to add a bar between the frame rails just in front of the back bumper, and I may add a cross-brace or two as well.