Power steering and wheel/tire size

dotcentral · Post by **dotcentral** » September 7, 2011, 10:52 am

This is on my 71 F100, but could relate to any Slick retrofitted with the Ford or non-Bendix power steering. In fact I wanted to install P/S on my 66, but this has me reconsidering that.

I am running 8" chrome cragars, and 25560r15 Firestone tires all around. They are not balanced. 30 PSI in all tires. Ford power steering with the correct p/s column.

At speeds over say 25 mph, seems like it is overly sensitive. I used to have 21570r15 on the front, and thought those were a bit twitchy, but eventually got used to it. I thought a wider tire would reduce some of that floating, over-assisted feel, but seems like it is worse now. Granted, I need to get the tires balanced, but not sure that is the whole problem. I could have got 70 or 75 series 255, but thought that a shorter tire would behave better.

Any ideas? Maybe the pump needs checked? Or the steering gear?

They way it is now, I am thinking about swapping back to manual steering and putting 215's back on the front - except I figure 8" rims will be to wide for the tires. And not sure if I still have the original 17" steering wheel, I swapped a cheap 15" grant wheel when I did the p/s.

tomrooster · Post by **tomrooster** » September 7, 2011, 8:17 pm

Mine is kind of twitchy to ( when you steer a little it sometimes goes to much) but I don't know the answer to the problem . I was thinking the tires are to big. I have a rebuilt box and new tie rods but I still have to check the king pins. Tom

MadMaxetc · Post by **MadMaxetc** » September 7, 2011, 8:56 pm

I have almost the same setup on my 67 and I don't find it sesitive at all.

One thought could be the caster. If you don't have enough then it ciuld be ti easy to tun at speed. When I got my frontend aligned after I rebuilt everything, they had to put 2* more back into the beams to get them back to stock.

loosrp · Post by **loosrp** » September 7, 2011, 8:57 pm

Maybe an alignment issue.... Ackerman angle is off or possibly not enogh caster? Either of the two will wear tires but cause drivability issues.

realisticretiredone · September 7, 2011, 9:26 pm

King pins that are installed too tight or not greased good will cause that problem. james

dotcentral · Post by **dotcentral** » September 9, 2011, 9:06 pm

Thanks for the replies.

Hard to find places in my area that will even touch an old twin I-beam truck. In the past I have gotten lots of replies like, "We don't have it in our computer, so we don't know what to do."

loosrp · Post by **loosrp** » September 9, 2011, 9:39 pm

Have you tried a shop that primarily deals with trucks? We have a shop here in Dayton that does everything from cars to heavy trucks, their main customer base is heavy trucks.