Subframe Connectors and unibodies

[Rusty34]

Jack up one corner of the car and notice the difference in opening and closing the doors. Since the entire unibody flexes like a spring Chrysler could go with softer suspension for a better ride. These cars attracted a different crowd when they were new and while buyers loved the performance engines they would never have given frame strength a second thought. If the engineers had strengthened the chassis more it would have added a lot of additional cost and most new car buyers wouldn't have been willing to pay for something they didn't understand. The problem only becomes serious when you put sticky tires on that hook up.

 

[RemCharger]

Just a dumb question, but why are you planning on so much horsepower if you don’t plan on having traction as well?

A; tv shows.

 

[BigLime]

Just a dumb question, but why are you planning on so much horsepower if you don’t plan on having traction as well?

Well, to add a little detail:
(And sorry guys if I am getting off topic here. I can't find an EFI section on the Forum. Maybe I missed it. Some help there please.)

I am going with the Super Sniper EFI by Holley. The Sniper offers a simple traction control method either by RPM or by time. The ignition is retarded based on a curve you can input into the Sniper. You hit an input on the Sniper to activate this.

The time/retard option is used by some people trying to get of the line faster with some simple way to control traction (to some degree). I am not going this route since I should be able to spin the tires at will with this kind of HP and being time based, it does me no good. Hitting the pedal at, say 40 mph in 1st gear on the street is going to result in serious wheel spin and loss of control.
The time method therefore wouldn't work for me since I can floor it at any "time".

On the other hand, the RPM control of the timing could be very useful to me.
My plan would be to use something like what Davis makes. A simple ring around the driveshaft to detect wheel spin and use a sensor to see the pulses.
Drive Shaft RPM Rings & Sensors - Davis Technologies

Alight, I know guys, this will not detect individual rear wheel spin but will tell me at least one wheel, maybe both, are spinning.

This is where my electrical engineering comes in.
I am going to set up a frequency to High/Low output system using a PID (Proportional/Integral/Derivative) controller. This is basically a "math" controller that will be tuned by me to detect a certain acceleration pattern that indicates wheel spin. When the PID detects wheel spin, it will hit the Sniper with a signal that will retard the timing based on what RPM retard parameters I set up in the Sniper.
Now, I can adjust the PID controller to whatever slip I want at the rear wheels.

Since I am retarding the ignition to control the wheel spin, I am not maxing out on torque to the ground, thus I would expect a longer life on the engine, suspension, etc. than by using sticky tires and no control. I am still delivering the max torque that the tires can handle on the bumpy street, therefore, hopefully maximizing acceleration.

Some info on PID:
PID “Proportional, Integral, and Derivative” control — Sentek Dynamics - World class provider of vibration test equipment, shakers, and environmental test chambers

I know, I should use the front wheel too, since I should never be able to lift the front end on the street and then detect the difference to determine wheel spin, but, this is a cool project for me to try out.

I want to try this out this method. Old guys like me need a mile long project list.

Anybody know someone who has tried something similar?

Any input is appreciated!!!

Ooof, sorry for the long post.

Dave

 

[padam]

Well, to add a little detail:
(And sorry guys if I am getting off topic here. I can't find an EFI section on the Forum. Maybe I missed it. Some help there please.)

I am going with the Super Sniper EFI by Holley. The Sniper offers a simple traction control method either by RPM or by time. The ignition is retarded based on a curve you can input into the Sniper. You hit an input on the Sniper to activate this.

The time/retard option is used by some people trying to get of the line faster with some simple way to control traction (to some degree). I am not going this route since I should be able to spin the tires at will with this kind of HP and being time based, it does me no good. Hitting the pedal at, say 40 mph in 1st gear on the street is going to result in serious wheel spin and loss of control.
The time method therefore wouldn't work for me since I can floor it at any "time".

On the other hand, the RPM control of the timing could be very useful to me.
My plan would be to use something like what Davis makes. A simple ring around the driveshaft to detect wheel spin and use a sensor to see the pulses.
Drive Shaft RPM Rings & Sensors - Davis Technologies

Alight, I know guys, this will not detect individual rear wheel spin but will tell me at least one wheel, maybe both, are spinning.

This is where my electrical engineering comes in.
I am going to set up a frequency to High/Low output system using a PID (Proportional/Integral/Derivative) controller. This is basically a "math" controller that will be tuned by me to detect a certain acceleration pattern that indicates wheel spin. When the PID detects wheel spin, it will hit the Sniper with a signal that will retard the timing based on what RPM retard parameters I set up in the Sniper.
Now, I can adjust the PID controller to whatever slip I want at the rear wheels.

Some info on PID:
PID “Proportional, Integral, and Derivative” control — Sentek Dynamics - World class provider of vibration test equipment, shakers, and environmental test chambers

I know, I should use the front wheel too, since I should never be able to lift the front end on the street and then detect the difference to determine wheel spin, but, this is a cool project for me to try out.

I want to try this out this method. Old guys like me need a mile long project list.

Anybody know someone who has tried something similar?

Any input is appreciated!!!

Dave

Oookaayy…

 

[BigLime]

A; tv shows.

Nope, just loving wheel spin.

 

[BigLime]

Oookaayy…

Hey, you asked for an explanation but didn't say how long it could be!

 

[padam]

Hey, you asked for an explanation but didn't say how long it could be!

Just way over my caveman head.

 

[BigLime]

Just way over my caveman head.

Me to to some degree. But, need another project!

 

[RemCharger]

Me to to some degree. But, need another project!

So you're going to bog down an already overly planned/complicated project with traction control, meanwhile, every person with a new car immediately shuts it off lol.

 

[BigLime]

So you're going to bog down an already overly planned/complicated project with traction control, meanwhile, every person with a new car immediately shuts it off lol.

Yes sir!
The difference is that I have more control over the traction than just pushing the on/off button on a new car. If it works out OK, I can allow a large percentage of slip to get the car moving and the tires hot enough for more grip.
There are many out there that use the Sniper time based traction control for a more consistent launch when drag racing, so it can't be all that bad? Maybe a lazy way out, but it is a cool project.

Thanks for the input!!!

 

[Bold & Old]

in removing some of my old floors & trunk pans I discovered that at least a third of the original welds were broken.

The car (67R/t) was originally equipped with a the 440 4spd 3:54

I dont no if this is normal but this gave cause to me to install the frame connectors having near 600 hp and 555 torqued hemi.

also installed inner fender stiffeners too..

My 2 cents worth

also took two radiator supports and laminated them together to form a 9 gauge support so it looks more like stock.


I could pickup the front end to both sides of the when I installed my motor assembly.... that is 400 lbs to lift with no flexing at all.


Beefed up where they connect to the inner fenders.

 

[BigLime]

Did you use the weld holes just to tack it in place? Curious...

 

[BigLime]

I am assuming that you are taking about the lower radiator support..... if yes and I clamped it heavily in photo.... hard to see in picture below.... tack welded holes.... then....

The drilled and tap 30 4-40 button allenheaded screws zig-zagged the entire length..... this alone would have been enough to hold both pieces alone......I lock-tited the screws in and ground off the excess.

Then seem welded it slowly to prevent to much heat ......

I gusseted 2 bridges per side between the lower radiator support inside to the frame rails.

probably over kill... that's just me.

.View attachment 1393549

You certainly have a lot of clamps!

 

[70bigblockdodge]

Stiffer is always better.
Do you want you foundation to flex so your living room floor is softer to walk on?
You have **** spot welds if they are breaking with or without connectors. The very definition of welding is making 2 or more pieces of metal one.
Traction control is done by your foot.

 

[Bold & Old]

You certainly have a lot of clamps!

 

[BigLime]

BigLime - I think the bolt-ons I used way back then were Competition Engineering, or something like that.

Topside- Thanks. I was looking at their website last night.

I hate to weld anything since my welding skills are poor and I don't like anyone else doing anything on my car.
Since I am street only, I think the bolt in's would be good enough to not rip anything loose???
When you had yours bolted in back then, were you on the strip or just street?

 

[topside]

The Nova was a street car, though I ran it down the drag strip once just for grins.
The Z28 was for handling, used to run the canyons in SoCal with it, but basically a street car.
Dedicated drag strip - or street/strip cars that didn't have to be OEM-correct - got welded-in ties.
The bolt-in ties never loosened, but weren't put to an ultimate test. They may have been under more stress, as those 2 cars had front subframes and unit-body rear halves, and took cornering loads; hard for me to quantify.

 

[Curiousyellow71]

Topside- Thanks. I was looking at their website last night.

I hate to weld anything since my welding skills are poor and I don't like anyone else doing anything on my car.
Since I am street only, I think the bolt in's would be good enough to not rip anything loose???
When you had yours bolted in back then, were you on the strip or just street?

I don't think you will be ripping anything loose....
..... But if your car is made like our 69 charger(and I don't know that any two cars are exactly alike as far as spot welds). We have popped off some lead filler where the roof meets the quarter from body flex. We also have cracked the driverside door latch and had to weld it. Our doors both drag hard to open/close. Our car was a 383 4 barrel car, chassis is all original/stock. In '94 the 440 we had was dynoed at 560hp. In 95 we switched to a 510 and It's still in there. We run mickey 295/65r15 s/s radials 4.10s and 4300 stall. The Car seems to handle power pretty well but it has some scars...that perhaps it wouldn't have had w some stiffening.
We haven't run these, but they have less welding then most connectors. Hotchkis Sport Suspension 4010 Hotchkis Sport Suspension Weld-On Subframe Connectors | Summit Racing

 

[BigLime]

Thanks for the link. I like the less welding approach.

 

[70ChargerRT]

A stiffer chassis is better but to what extent do you stop at stiffening it? Unless you’re a full blown racer of some sorts a lot of people are over killing their cars with these stiffening kits and suspension. My buddy runs a level 3 car tool set up with the biggest Hotchkis T-Bars and sway bars you can put on a car and he absolutely hates it and 1 ride in it compared to mine and you’ll understand why. I’ve had the old school home made 2x3 tubular sub-frame connectors in mine for probably 20 years and what a difference they do make. If you do subframe connectors you don’t need torque boxes or anything else and the only way I’d ever stiffen the front of a car would be for a coil over set up which I hate. So along with a with my sub frame connectors I’m running PST 1.03 T-bars, 1 1/8 Hellwig SA, Qa1 upper and lower tubular arms, Qa1 strut rods, C-body tie rods and Viking shocks and the car rides awesome.