48 F-1 Alignment Problems

[48bill]

I don't seem to have any luck getting my F-1 to go down the road with ease.  

It has a 3" MorDrop axle, all new suspension parts (springs, kingpins, Bushings, etc.l), rebuilt steering box and it is tight with no play .  It has a power steering kit from Classic Performance, 15" 205 radial tires and a 78 425ci Caddy engine.  

It alledgedly has been aligned to the 48 F-1 "factory spec's.  Over 40 miles per hour it is a bear to drive.  It has what seems to be bump steer and it also seems to over steer on turns at speed.

Does anyone have any suggestions as to spec's or what I should look for?

Thanks in advance for you help.

[enjenjo]

Check the caster. Most alignment shops don't check it on straight axle cars and trucks.You can go up to about 9 degrees with power steering, I would want at least 5. I had similar problems with a 52 F1, more caster fixed it.

[av8]

It alledgedly has been aligned to the 48 F-1 "factory spec's . . .

That may very well be. Factory specs in the '48 Operator's Manual show 1 to 3-1/2 degrees caster. I like Frank's specs better!

I'm going to be dropping my F-1 in a couple of weeks -- early 3-inch Mor-Drop, reveresed-eye leaf springs front and rear. I will continue to use the original steering, serviced and adjusted, with new drag-link and tie-rod ends, and new kingpins and bushings.

[48bill]

Frank & Mike,

Thanks for the help.  I will try the greater caster. Any suggestions on toe in settings other than stock?

Mike,

I have a set of  "Posies - Super slide" front springs that you are welcome to if you want them.  I used on my F-1 for a few thousand miles and have replaced them with a set of original style replacement springs.  The Posies's springs lowered my truck too much and I scraped going in and out of my driveway.  If you want them send me an e-mail and I'll send them off to you.

[enjenjo]

Toe in depends on the tires. If Bias, factory specs work good. If radials, 1/32" to 1/16" toe in works good most of the time. I have even set some up with a little toe  out to get them to drive good.

[48bill]

Enjenjo & Mike,

Thanks to you both.  I finally got to changing the castor.   I now have 6 to 7 1/2 degrees of castor and the drivability has improved drastically.  

The front end shop I was dealing with in May and June struck out big time.  A real nice bunch of knuckleheads.  At one point they told me I needed longer U-bolts for the thicker shims.  After I got those they told me that in order to get another 4 degrees of castor I needed spring center bolts with a longer head in order to go thru the shims and locate in the axle.  I figured I'd have to make them so I asked them to sell me the shims so I could install them when I put the new bolts in.  They did not have any.  When I went to our local spring supplier to buy the shims I asked about the bolts and they gave me bushings to use which effectively increase the length of the spring bolt head.  

The last couple of months have been a blur enjoying summer and I just had the chance to make the change today.  The truck now steers like a dream and goes straight on down the road.  I was OK before under 40 mph but now it is great up to 75 mph.

Thanks again.

[Dave]

Enjenjo & Mike,

Thanks to you both.  I finally got to changing the castor.   I now have 6 to 7 1/2 degrees of castor and the drivability has improved drastically.  

The front end shop I was dealing with in May and June struck out big time.  A real nice bunch of knuckleheads.  At one point they told me I needed longer U-bolts for the increase for the shims.  The next time I was there they told me that in order to get another 4 degrees of castor I needed spring center bolts with a longer head in order to go thru the shims and locate in the axle.  I figured I'd have to make them so I asked them to sell me the shims so I could install them when I put the new bolts in and they did not have any.  When I went to our local spring supplier to buy the shims I asked about the bolts and they gave me bushings to use which increase the length of the head.  

The last couple of months have been a blur and I just had the chance to make the change today.  The truck now steers like a dream and goes straight on down the road.  I was OK under 40 mph but know it is great up to 75 mph.

Thanks again.

My 2 cents.. I like 7 degrees of caster and 1/8 toe in........
Dave

[av8]

Enjenjo & Mike,

Thanks to you both.  I finally got to changing the castor.   I now have 6 to 7 1/2 degrees of castor and the drivability has improved drastically. . . The truck now steers like a dream and goes straight on down the road.  I was OK before under 40 mph but now it is great up to 75 mph.

Thanks again.

Bill -- Thanks for the good-news update!

I still have not gotten to mine, but I have a ton of work scheduled for this Winter, including the drop, the T5, and the new motor.

Looking forward to getting those Posis in place. Again, thanks a bunch for them.

Mike