Help Stiffen Me Up!

Ferf

Member
Dec 6, 2002
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Looking to get complete up my '65 Mustang coupe project here within the next month or two and I am looking for some advise on stiffening up the chassis and suspension. I will be running a 347 ci stroker with 425 HP and 425 ft/lb of torque. The rear is a Ford 9" with a Detroit Tru-Trac and 3.73 gears.

Here is what has been or will be added to the car:

- Shelby Drop
- Export Brace
- Monte Carlo Bar
- Torque Boxes
- TCP Subframe Connectors
- Shelby Under-Ride Traction Bars
- Mustangs Plus Suspension Kit that includes:
- New KYB Shocks
- New 620 lb Coils
- New 4 1/2 leafs
- New Poly Bushings
- New 1 1/8" Front Sway Bar
- New Rear Sway Bar


I read some positives and negatives about adding a rear sway bar. What are your thoughts? Do you recommend roller perches? Do you recommend a steel rear seat divider? Any other thoughts or comments?

Chris
 
all good things you are wanting to do. a few things;

add the rear seat divider, using a good one properly mounted will not only act as a firewall, but will also act as a shear panel which will also stiffen the chassis.

use jacking rails that are welded to the inner rocker panel, and tie these to the subframe connectors with cross tubes, and add a few shear panels there to cover the cross tubes as these will also stiffen the chassis.

you also want to use a center cage similar to what TCP created.

these will give you about as much stiffness as you will get without going to a full tube chassis and cage.

as for a rear sway bar, that depends on whether or not you are using a locker. if you are, then no dont use a rear bar as you will have severe oversteer. if you are going to use a traction lock diff or other non locking diff, the yes use the rear bar.
 
all good things you are wanting to do. a few things;

add the rear seat divider, using a good one properly mounted will not only act as a firewall, but will also act as a shear panel which will also stiffen the chassis.

use jacking rails that are welded to the inner rocker panel, and tie these to the subframe connectors with cross tubes, and add a few shear panels there to cover the cross tubes as these will also stiffen the chassis.

you also want to use a center cage similar to what TCP created.

these will give you about as much stiffness as you will get without going to a full tube chassis and cage.

as for a rear sway bar, that depends on whether or not you are using a locker. if you are, then no dont use a rear bar as you will have severe oversteer. if you are going to use a traction lock diff or other non locking diff, the yes use the rear bar.



+1
 
"use jacking rails that are welded to the inner rocker panel, and tie these to the subframe connectors with cross tubes, and add a few shear panels there to cover the cross tubes as these will also stiffen the chassis."


Rbohm, Do you have any pictures of of this? I looked around w/o much success.
 
What rbohm said

about the cross-connector and the jacking rails. There might be a slightly better way to do the subframe connectors and an "X" connecting the two, but the TCP combined with jacking rails and maybe shear panels is the best almost-off-the-shelf way to do it, probably.

Generally, I think you want to try to work with and tie into the unibody structure, which includes the front and rear subframes and rocker panels, and all the sheet metal in between, as much as possible. Try to augment the unibody structure and tie together the strongest parts of it, don't seek to replace the whole thing with something else . . .
 

while that will definitely give one a stiffy, it is not what works for a mustang chassis:D:D

"use jacking rails that are welded to the inner rocker panel, and tie these to the subframe connectors with cross tubes, and add a few shear panels there to cover the cross tubes as these will also stiffen the chassis."


Rbohm, Do you have any pictures of of this? I looked around w/o much success.

here you go; Mustangs Plus - Tech Articles - Chassis Strengthening Kit Installation
 
Personally I think you've got too much spring and too little sway bar, front and rear. But that's just personal taste.

IMHO you do need an adjustable rear bar without it you won't be able to tune the suspension for neutral handling.

I would also make sure that whatever you do with the springs, make sure to drop the car at least an inch front and back.

Good luck...
 
I have read that the steel rear seat divider does help out a lot and it is something that I will seriously consider. However, if I was thinking about putting a couple of subs in the trunk as I intended to upgrade the stereo. It is my understanding that this steel divider will pretty much seal off the trunk from the cabin of the car. If this is the case, then won't the sound quality of the subs be drastically reduced?
 
I have read that the steel rear seat divider does help out a lot and it is something that I will seriously consider. However, if I was thinking about putting a couple of subs in the trunk as I intended to upgrade the stereo. It is my understanding that this steel divider will pretty much seal off the trunk from the cabin of the car. If this is the case, then won't the sound quality of the subs be drastically reduced?

yes adding a rear seat divider does help, but you have to install it right. you cant just use any old pop rivits, or a few sheet metal screws. the rivits you want are going to need to be structural. there are some that you can use a standard pop rivit gun to install, i believe they are called cherry rivits. check with an aircraft supply company.
 
I'd weld the seat divider.

As far as the subs are conserned, you could vent into the trunk through the package tray or use the seat divider from a convertible which is full of holes. In either case you loose the fire protection.