Vehicle Weight vs. Wheel/Spring Rate

[69plywgn]

I had my '62 Savoy Suburban weighed using a platform scale under each wheel in order to determine the best diameter torsion bars for my driving needs (street cruising/ride quality).

Description: 440 V8, 4-spd., 8 3/4, 3.23, dual exh., front disc/rear drum brakes, 15x7 steel wheels, 225/70R/15 front, 275/60/15 rear (Cooper Cobra), manual steering, stock interior, no opt. equip., stock/rebuilt front suspension set to FSM susp. height of 1 1/2" + or - 1/8", .88" t/bars (P/N -776 & -777, 471 date code), 6 leaf rear springs (new 4 yrs. ago from Espo Springs N' Things), Gabriel Classic shocks.

Weight: 3,890 lbs., full fuel, no driver. (Note: a friends '62 Suburban weighs 3,830 lbs.)
- Lt. front 1,060
- Rt. front 880
- Lt. rear 970
- Rt. rear 980

I reviewed the '62 to '81 "Torsion Bar Application Chart, Table 3", which shows my current t/bars were used for "most 2-bbl. V8's" and have a 95# rate. The .925" bars used for the "440, 426 Hemi" have a 108# rate.

I read the "Torsion Bar Tango" article, which said "A handy rule of thumb is to pick a bar that has a wheel rate that's 1/10th of the front-end weight" and "Mopar Performance now recommends much higher wheel rates than the factory did 30 yrs. ago."

Based on the info., my current t/bars could be too small a diameter and may be 50 yrs. old. The front-end weight is 1,940 lbs.; 1/10th would be a wheel rate of 194#. Firm Feel has .94" bars with a rate of 142# and 1.00" bars at 175#. I don't want a stiff ride.

I'd appreciate any input from other early 60's B-Body owners. If I left something out, let me know. Thanks in advance!

 

[oldbee]

Firm Feel .94 tbars. I'm still running my original bars even tho the engine went from 383 to 440. "Nice ride" is all well and good, but a little stiffer is never bad.

 

[PRND21]

I have .96 Mopar Performance bars on the front of my 65 Belvedere post car. Don’t know the weight, B engine with aluminum heads, manifold, water pump and housing, radiator. I think they work well, not real happy with the poly bushings, though. I’d be curious to know how they compare to the Firm Feel and PST bars.

 

[33 IMP]

I think you answered your own question. What you have is too soft, you dont want the ride you would get with the mondo handling bars, so..... firm feel .94 bars.

 

[Dave P]

One thing I didn't see is front anti roll bar dia. if being used.
Bar diameter will effect ride, potentially a bunch.
Dave

 

[69plywgn]

Dave P: "Bar diameter will effect ride" in what way? Handling, ride quality, or both?

I have a '62 OEM "sway eliminator", which is about 7/8" diameter. I removed it thinking (maybe mistakenly) that it affected handling more than ride quality. The rear of the bar attaches to the strut rods, not the LCA's as on later years.

 

[Nate S]

That sway bar, while not wrist thick like modern stuff will certainly help. The sway bar is essentially a second torsion bar that only works when the two sides of the car see different things. Make it super fat and it's like having big torsion bars when you hit bumps etc. Nose dive on braking, speed bumps, other symmetrical stuff excepted.

 

[Dave P]

Nate S in his reply above basically hits it. The bar will act to increase an individual
wheels spring rate vs. no bar. As you corner and the weight transfers the bar acts
to increase the spring rate on the "outside" wheel.
So yes both "ride" and handling are effected.
Dave