I'm new to this forum and classic Olds.

Just picked up a '69 98 and it wanders badly at anything above 45.
What is the main cause of this? The arm from the box to the tie rod has a little play, and not really much steering wheel play.

I'm thinking bad tires but would like some opinions on the matter.

Tires are 235/75/15 and about 15 years old

 

You need new tires and probably an alignment.

 

Thanks!
I figured. The door jam label says 8.55-15.
Do you have a recommendation on size?
Are the 235/75/15 appropriate?

 

8.55-15 is between letter size H and J. A J is 225-75-15, The 235-75-15 is an L and is a bit too tall in the sidewall which can contribute to wandering.

Wait for others to chime in but I'd look for 225-75-15 or 235-70-15.

The loose center link as will any loose component will contribute to wandering. On a car of that age go over it thoroughly looking for worn bushings and joints. Also confirm all of the wheels are correct, straight, true and match before mounting tires.

Post pics!
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... and the only drive you should be contemplating in that car is the one to the tire and alignment shop. Those tires are a catastrophe waitng to happen.

 

Just checked the 1969 Oldsmobile Chassis Service Manual, 8.55-15 is for Deltas, 8.85-15 is for 98.

Here is a progressive conversion listing recommendation from left to right. Tire Rack, 1949 to present.

8.00-15 8.85-15 J 225R15 P225/75R15 235/70R15 265/60R15
https://www.tirerack.com/upgrade-gar...old-tire-sizes

Just scroll to bottom of that page and then come back up slightly.

 

There are about a bazillion possible causes for wandering. Unless you have too much money and need to get rid of some, stop buying anything and first figure out where the problem is first. Start by checking for wear or looseness in the steering linkage and front suspension. Verify that the steering box does not have excessive play. Verify that the alignment is set correctly. THEN worry about tires. Putting new tires on a worn suspension and steering is a great way to trash expensive new tires.

 

Just a quick addition for anyone following along.

Over the past month I replaced rag joints in both of my Olds ‘66 big cars and the steering tightened up noticeably. Road feel is up substantially too.

I never knew how important a fresh rag joint was to good steering feel.

A new rag joint won’t fix wandering, but should be considered when you’re going through the rest of the front suspension.

Chris

 

Quick easy check is turn the steering wheel side to side while parked. If its moving more than an inch or so side to side start looking at whats moving. My center link was bad and you could see things moving while the wheels stayed still. I had it rebuilt and along with adjusting the gear box tension, tightened up the steering a lot, especially the wondering affect on the freeway.

 

There are a few problems with that approach. First, the OP's full size has rear steer, so checking the slop in components like the idler arm or inner tie rod ends can be difficult with the car on the ground. More importantly, this doesn't check the ball joints, which require the car to have the springs compressed but weight off the wheels.

 

Old tires can change sizes