Frame Notch, How Much Backspacing Gained, Info?

[gnfanatic]

I made it. Bought the end pieceS and wlesed it up.
Cost me about $100 in materials

 

[1986 Buick GX1]

Who make that brace ??

Scot has the brace or just the brackets.

Body/frame-g-body | GNSperformance

www.gnsperformance.com

 

[gnfanatic]

Yeah . Got the brackets from him. I like the square brace because I mounted my FP relays on it. Chucks idea

 

[turbocamino1]

The ss tire sidewall sucks on the street in a high torque situation with 0 prep to the road.
The 2 tires are incomparable.
The r is the tire to run if you have to run a radial on a unpreped road
What most guys dont understand is that radials really need to be on a radial prepped track to work and grab their advantage over other tires.
You would have to oversize greatly on a radial to get it to work along with an ace driver and proper boost control

ohh,,secrets,,i like it,,, on a unprepped street,,on the R radial ,,,do you prefer squat,,or separation?

 

[Chuck Leeper]

do you prefer squat,,or separation?

Girls squat, racecars don't.
Madman 2017

 

[Mr.Spool]

ohh,,secrets,,i like it,,, on a unprepped street,,on the R radial ,,,do you prefer squat,,or separation?

maximum separation that is controlled

 

[Chuck Leeper]

On the frame notch work I've done, I put a reinforcement plate against the inner side of the frame rail.
3/16" cut to fit. Drilled, plug welded, then the outer piece reinstalled.
Helps with rigidity as the cross-section of the frame is reduced with the notch.

 

[GNVYUS 1]

Photo I got like 1 week ago after they almost finished the notch. I get the car Friday, then off to suspension shop for front arms, Viking coilover with double adj and rear tire fitment (possible wheel widening).

3" room from the tire sidewall of this tire..

275/60/15 (11.1" section width)
15x10" 4.5" bs
That's 5.05" in BS tire, looks like I can easily go 2" more and have frame clearance.

Next is the coil over bracket, damn thing looks like it might need modding. I'll report back later.

 

[murphster]

Good luck with the suspension setup!

Since you are going with a 275/60 tire the only thing I would have done different is go with more backspace. 5” or 5.5”. Should still give you enough room to the frame and worse case you could use a 1/4” spacer if the 5.5” was too much. The benefit would be that with a rolled fender lip you could lower the car in the rear much more as an option and not worry about hitting the fender with the outside tire. With tall and wide tires the fender lip clearance is usually the biggest issue to ride height.

Just attaching pics of my car for future reference. 15x9.25 RTS Welds with 5.5” BS and 275/60 Mickeys. Fender height is 26.5”

 

[GNVYUS 1]

Nice looking ride Murphster.

Chuck, you think that rear frame mounting bar that runs across L to R like the bumper is a good solution to frame twist?

The 275 breakdown is the current tire in the picture, that's how much backspacing room there is with that whole setup, there's a ton of room to fit a 325/50r15.

Except with coilovers and the damn mounting bracket that gets in the way of the original frame location.

Yep, I'm custom making a bracket to move them in since it looks like the Viking UMI bracket is in the same location.

Well I'm not making it but I'll make sure to have my guy keep the dimensions and sell it to others in this position to have an easier out.

I can see the car on the lift, for a week and the brown lunch bag of hundreds I'll need to bring them now. LOL

 

[Chuck Leeper]

Chuck, you think that rear frame mounting bar that runs across L to R like the bumper is a good solution to frame twist?

The rear rails are just "swinging in the breeze" once they are past the rear spring pockets.
That's why I made the brackets. It helps tie the rails together.

 

[GNVYUS 1]

Like the GNS rear bracket setup

Body/frame-g-body | GNSperformance

www.gnsperformance.com

Ya that makes sense, tie both ends together to keep them strong, not flex and then moving as one.

 

[Chuck Leeper]

I designed and made I'd guess at least 100 sets.
I then turned the patterns over to Scot.
GNS is now the go to place for them and a lot of other great "goodies".

 

[GNVYUS 1]

Well thanks for your engineering and problem solving skills, I'll get the brackets.

Would aluminum bar be OK for the actual beam?
Weight savings you know.

 

[Chuck Leeper]

Not unless you use alum for the brkts.
It's a welded assembly.
As for wt savings... Not much, as the alum tube would need to be pretty heavy wall.
Additionally, the added wt is behind the rear axle.
There is some discussion as to the use of rd vs box tube.