Hi Folks,

While my Truck is down for a few months getting some creature-comforts, I thought I'd describe a problem I have. Perhaps I can check out a few things before taking it to a Pro Shop.

My F-1 has the stock Suspension. Engine weighs 525 lbs. I have the oft-mentioned darting around a bit when going over uneven patches in the road. The bigger concern however, is tracking under hard acceleration and deceleration. I drive like a Grandma 99% of the time but I can't / won't romp on it. To do so initiates a "pucker-fest".

"Tru-Trac" Diff, a loose Torque Converter, and a wide Rear Tire. All to say, from a dead stop when nailed, the Engine is fully "at-HP", distribution to the Axles is hopefully even, traction is excellent, and the Front-End is nearly unloaded. The Truck launches hard with minimal wheel-spin trying its level-best to take me into the next left lane toward my demise. When I lift, it wants to head in the other direction though not as hard. In normal traffic cruising around town it seems fine except for the occasional wander. A friend driving behind saw no indication of "Crabbing". I have noticed it will dip right for a second if I hit the Brakes suddenly.

Tires, new, footprint 8" front / 10" rear
Wheels, new 15" Steelies
Front Axle, Sid's 2" drop - new King Pins / Bushings
Caster Shims - 4 degrees - thick side facing rear
Tall Head Center Bolts for thicker Caster Shim
Front Springs, new, no Leafs removed
Pins and Bushings, new
Shackles, not excessively worn
Rear Axle Housing, '60's 9" "Bolt-In" (no mods)
Rear Springs - Original, (new Bushings), 3 leafs removed - (Too soft for my liking)
Front/Rear U-Bolts, new, torqued to Spec. Jam Nuts / Blue Loctite
Shocks, HD new
Toyota Power Box, shaft play OK
Pitman Arm for Toyota Box Swap, new (not fully perp to street when wheels are straight)
Drag Link, new
Tie Rod, HD new
Dropped Tie Rod Ends
Drum Brakes, everything new and adjusted properly.
Tow-In professionally set @ 3/16"

Suggestions / Comments always welcome

Thanks,

E

 

radial tires, or bias ply?

 

Dawg Ol' Buddy,


I'm suffering from the same type scenario. If I'm at the drags or something and just nail it and keep it nailed its all pretty good. Its when I nail it and its pulling pretty hard and then I back out of it, it will want to jump to the left.


I attribute it to the twisting of the frame. I boxed my frame from the center x-member forward but the poor old thing still twists pretty good on a hard acceleration.
Try to visualize what's happening to the suspension, steering linkage, and geometry when the torque of the engine tries to twist the frame. The right front spring compresses while the left front unloads...and then when you back off of it everything reverses.


Bobby

 

Darting over uneven terrain sounds like excessive bump steer. You may want to check it. Curt

 

T/A Radials all around.

 

Mister T, I do well enough trying to Visualize where I left my Glasses. What's annoying, is I had a '49 back in the '80's with a lousy stock suspension that made a jillion 1/4 mile passes in the high 90's straight as an arrow..... Them Thar fancy Boutique Chassis Companies do have some awfully nice Assemblies that I could Visualize.

E

 

With the drop axle, how level is your link from steering box to axle? If this is at an angle it will dart as the suspension travels up and down.

 

Your "darting around" problem could be several things. I'm assuming that you checked all the normal loose steering component issues on flat ground? Turn the steering wheel and how much free play when you turn the wheel back and forth?

Tire pressure should be even side to side.

I have a similar tire/wheel setup. But I'm not a big fan of removing leaves from springs. And the fact that you took some leaves out of the rear and did nothing to the front seems strange to me. Springs are designed to work as a system.

Many of us have used Posie's Dual flex in the front and SuperSlide springs in the rear. I also have Bilstein shocks on the front per their recommendation.

Driving is certainly a pleasure now vs. the stock setup.


Posies springs give you about a 2 ½" drop.

 

I’m no rocket scientist but I believe your shims are installed providing negative caster.


Fig 2 negative caster; Fig 3 positive caster

With the thick end of your shim in the back that drops (negative) the front of the axle like fig 2. Negative caster will cause wandering and erratic steering.

 

Dawgaroo


Uh Oh, did I just enable you to go out and spend big bucks on a fancy chassis?? LOL


For the darting around on regular driving a few degrees of caster would probably help a bit. You can buy caster shims in 2 degree increments. I think 4 degrees should be plenty


Bobby

 

I put 4 in it when I installed the axle Bobby. Thick side facing rear. I believe orientation is correct?

 

Thanks - Good Stuff - Makes a lot of sense.

I'll try and shoot some pics tomorrow but from what I can see, the Link appears to be a lot lower at the Pitman Arm.