My dad just bought a beautiful 1931 Chevy 2 door sedan. The car has one major issue that we need to resolve. The car has a VERY sensitive steering and oversteers badly. It is pretty unstable and at highway speeds is a real white knuckler to drive. It has a Heidt Super Ride MII front end with power rack and pinion. The rear end is a Lincoln Versailles rear end. It has the original leaf springs. They are very flat and the previous owner added extra long rear spring shackles to lift the rear end along with air ride between the springs and the frame right in front of the axle. I originally thought that the problem is the rear axle not being stable. It has also been suggested that the problem is the car being too light for power rack and pinion. I am attaching a few photos. Suggestions on what we should do are desired. Thank you.
Our '38 chevy had a cobbled together power steering system on the original straight axle, very limited turning radius and way to quick. After taking off the power steering it was a lot easier to drive. Air over leaf also isn't the most reliable way to go about things. Since you have coilovers on the front, I would put some decent leaf springs in the back and rip out the air over leaf. That would leave you with a manual mustang II up front and a regular leaf rear end. Pretty basic setup that shouldn't give you any issues. FYI - Chevrolet did not have a 2 door sedan, it is technically a Coach. Someday I will have my '29 Coach on the road.
Nice car. If the engine is an sbc (I'm ***uming something here) the power steering is overpowering the Mustang rack. You need to put a restrictor into the system and that will cure the twitchy steering.
I have a '32 that has been in our family since new. It was really getting dicey so I sent the original steering gear box out to a very experienced steering repair shop. They replaced the bearings and other work. It came back and I still wasn't too comfortable. So, I bought a new Vega box and pitman arm with a bracket to allow for the proper fit of the box on my frame. I had to use two 3/4" universals and a Carrier Bearing but the steering now is vastly superior. I sold the other box and items on Ebay for $130 bucks so it was a good safe trade. Nice car by the way. Normbc9
Could be numerous things: 1. Caster angle, if not leaned back enough at the top of the spindle it will be very twitchy.2. If toe-in is insufficient it will act strange. You want about 1/8 inch in at the front vs rear of the front tires. 3. The Saginaw P/S pump makes too much pressure for the Mustang II rack, the best solution is to put a new pressure relief spring in the pump. 4. The longer shackles make any slop in the rear springs to be exaggerated.
I´d check toe in , caster but I think the long shackles and "lowering block" sheet metal is to blame for the touchy steering. I´d shorten the shackles and mount the axle direct on the leafs springs, maybe add a panhard bar. You can push the car sideways in the back and see if the axle moves in relation to the frame. I had this problem in my 34 Plymouth until I hung the rearend on hairpins and coilovers, plus a beefy panhard bar. Today it handles like a sports car although it´s on bias plys and stock front suspension...
Do you actually mean oversteer, in the sense of the tail wanting to slide out in fast corners, or rather oversensitive steering or not enough/no self-centering? If the latter, what the guys have said about the power steering; though personally I'd lose the power steering altogether. A bit more caster will give better self-centering, too. If the former, you've got too much rear roll stiffness. Try moving the air springs further inboard on the axle.
Ned, By oversteer, I mean that once you start a turn, it seems like the car wants to keep on going around. When reacting to straighten out, it wants to kepp going around the other way. I woudl say that seld centering is a problem too. Thanks.
Several people have suggested caster angle. What is the easiest way to measure this? Is it enough to put a toropedo level on the side of the coil over?
First of all find a shop that can check your alignment.If it is not correct or the suspension is installed not straight All the talk wont help.Have a great day Gary
You can buy a valve from Speedway motors the take care of that problem. Your old pump is over powering the rack. It is a simple fix it take about 30 min
usually when a car over steers the springs are too stiff compared to the frt or are mounted too low on the body causing the body to tilt inducing roll steer and a panhard may help.in the frt caster helps the the steering to center it's self and go straight at speed or it might have too much weight on the frt or springs too soft or both.check with heidt on the alignment specs and ride height
That sounds about right. Something is preventing off-lock servo feedback from registering. A pump too powerful for the valve springing seems plausible. Oversteer is something different to what you've got, by the way. Oversteer is when you're running bigger slip angles at the back than at the front. "Slip angle" is a bit of a counter-intuitive term. "Squelch angle" would be better, as what it means is the angle between the direction a wheel is pointing and the direction the patch of tyre tread at the bottom of it is pointing. The more the tyre is twisting, the greater the slip angle. Incidentally, a drift didn't always mean a controlled slide, like the way people use the term nowadays. It used to mean travelling with the tyres twisting so the car is pointing in a slightly different direction to the direction it's going, without the tyres actually breaking traction. An oversteer drift was when that causes the car to adopt a slightly tail-out at***ude.
Heavy rear springs and a high ride height will both make the rear loose. a front roll bar will help over steer, and a rear one, under steer. Drag cars were raked to clear large tires and straighten the drive shaft angle, but the increased rear height actually takes weight off the rear end. Heavy rear springs and a light rear weight will make the back end skate all over the place; the bags are extra springs and will have the effect of changing to a larger spring. An old rule of thumb for road (not drag) racing was the softer the spring the better, and if it doesn't bottom out, it's hard enough.
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