CPP / Speedway PS conversion pics?

[yossarian19]

Does anyone have pictures of the Classic Performance PS kit installed?
I'm confused from reading instructions / looking at grainy pictures... does the tie rod wind up in front of the axle? I hadn't thought so, then I thought so... now unsure.
Trying to determine whether my tie rod can / should be removed while I fit the engine in place, or whether I need to navigate around it.

[yossarian19]

Nevermind: found the pics online after a while.

[spinned]

Originally Posted by yossarian19

Nevermind: found the pics online after a while.

Well where are they? How about some links?

[NEWFISHER]

It never happened unless there are pics lol
Posted via Mobile Device

[Old Crow]

Tie rod stays where it's at. Top bracket of the left front shock has to relocate behind the axle because the steering box mounts where it was. Get the steering linkage in place first, because there's a very small window of space to mount that bracket so it'll clear the new steering shaft.
We did that kit on the '58 we're building. Instructions on it were not that great as I remember. I'm looking elsewhere next time.

[Russell Ashley]

If you are talking about the kit that uses a later model Chevy steering box that mounts outside of the frame, I would not recommend it. I have that kit on my truck and I'm not completely satisfied with it. It also limits you on tire size although that is not a problem for me. If you are set on using it I suggest that you mount the box as far forward as you can and use a longer drag link than the one that comes with the kit to lessen bump steer. I got some six degree axle shims from Summit that I am going to install to see if increased caster will improve the drive. Knowing what I know now, if I were at the point in my build where you are I'd go with an independent suspension. The cost of the p/s kit added to the cost of adding disc brakes to the straight axle will cost half as much as an after market suspension.

[yossarian19]

I want to keep the stock ride height, travel & weight capacity, so for me it is one solid axle or another (barring any heavy fab, that is)

I might not keep the stock front axle, but I think I'll need / want to mount a power steering box regardless.

Interesting to hear the comments on the PS kit, though.

[yossarian19]

You can't see the steering arm in this one, but...

[mknittle]

I still say they are not well thought out. You will always have bump steer with the box and shackle on the same end! the shackle is there to allow the spring to move, as the spring flattens and returns to an arc it linghtens and shortens . In this cycle the axle moves back and forth. yet the drag link from the steering box dosent move! somthing has to give. that would be the steering knuckle/spindle. So as the spring compresses the axle moves forward the drag link pushes the s arm on the spindle back and the wheels turn left then returns or goes the other way depending on the next bump in the road!!

The best way to correct this is to mount the solid end of the spring in front and the steering box pitman arm as close to the spring pivot as possable.this keeps the drag link parrellal as posable.{think 4link} this also makes the front ride better. The reason is now you are pulling the axle instead of pushing it. I have done this in the pastand it is well worth it!
It changes from herding your truck to driving it.

[Russell Ashley]

What he said... If you are set on keeping the straight axle maybe you should consider the kit that uses a Toyota box that mounts in the stock location.

[Coach529]

Originally Posted by Russell Ashley

What he said... If you are set on keeping the straight axle maybe you should consider the kit that uses a Toyota box that mounts in the stock location.

What model Toyota would be a good donor?

[mknittle]

Originally Posted by Russell Ashley

What he said... If you are set on keeping the straight axle maybe you should consider the kit that uses a Toyota box that mounts in the stock location.

Yes that is also a good option. that is how big trucks are peterbilt etc.

[1project2many]

The axle "moves" no matter which end the box is attached to. On our trucks the axle moves forward every time the spring is compressed. In order to reduce bump steer you'll need to position the front mounted box so the drag link angle increases away from parallel as the spring compresses, effectively shortening the length of the drag link as the axle moves forward. For a rear mounted box the drag link should move closer to parallel as the spring compresses, making the drag link effective length greater. To really get it right requires a bit of planning and probably some math as well.

A better approach if it can be implemented is to incorporate a cross-steer tie rod / drag link arrangement that moves parallel to the axle instead of the frame. These can be found on many solid axle 4X4 vehicles including Dodge, Jeep, and Toyota trucks. The axle may move with spring length changes but as long as you keep the drag link angle low you'll find there are minimal effects from bump steer.

Yes, front mounting the fixed end will improve ride quality. So can angling the shock absorbers. And replacing the leaf springs with coils and a track bar can do wonders as well. It's a great lesson IMO to drive a late model solid axle 4X4 then look underneath to see what small changes can be made to a solid axle vehicle to make it ride and drive so much better than our trucks do in original form.

The Toyota box commonly used is from 79-84 trucks. Although this article is for F*rd trucks, it is good reading if thinking about improving a Chevy as well. Scroll about 1/2 way down the page to see the Toyota swap. http://www.ford-trucks.com/article/i...60_Trucks.html

[yossarian19]

Does anyone know if the 70s Chevy PS box pitman arm can be turned 90* to run the drag link parallel to the axle, or is it keyed ?

[Old Crow]

I'm pretty sure it's like most of them, keyed in 4 places, so you could turn it 90*,but I think you'd run into problems with the shock if you turned the pitman arm. You could move the box back, but then you'd run into problems with the geometry of the steering shaft.
The one we did is mounted per the instructions and we almost had to add a 3rd U-joint to the steering shaft.
We don't have the fenders on the truck we're doing, so I'll take a look at it when I get to work and see.

[Russell Ashley]

"The axle "moves" no matter which end the box is attached to. On our trucks the axle moves forward every time the spring is compressed."

That's correct, but you will never see a straight axle truck with the factory steering box located on the shackle end of the spring.

The CPP instructions for the kit we are discussing says to make the drag link as level as possible. The drag link is only about one foot or less in length which means that it swings in a tight arc that contributes to bump steer. The reason I suggested mounting the steering box as far forward as possible is so you would have room for a longer drag link.

[mknittle]

Angle has less effect than being on the wrong end of the spring and the drag link being too short. draw a 2foot circle on the floor now draw a 4 foot circle on the floor around the smaller one. now move the smaller circle to the left untill it touches the large circle. notice the gap at the right.The large circle represents the axle movement {up and down} the small circle represents a draglink that is too short.the gap is what causes bump steer. what you want is the drag link to be the length to be the same as the distance between the pivot end of the spring and the center bolt. and parallel to the line between the spring eye and the center bolt. not the ground.

If you or I angle the shocks and ride improves the shocks are too stiff cantilevering {angeling} gives the axle leverage aginst the shock makeing its dampening less effective the more angle the less effective the shock. I know that it is often impossable to put the shocks or anything for that matter where we would like but knowing the effects of the compromises helps.

20years as a CNC machinist building most ly one off scintific testing machines.

[yossarian19]

Great tech here, guys.
I'm going to see what all would be involved in a crossover steering setup, with the drag link moving parallel to the axle. That would be my preferred solution. Failing that, I'll try and make the drag link as long as I can manage. I may flip the shackles to the rear, as well.
The steering tie rod will almost definitely get flipped to the front, too.
Depending how much meat is on the steering arms (don't have it in front of me) I think drilling through them to 1/2 or 5/8 and using heim joint steering with a beefier steering rod might be the way to go...
too many ideas this AM and not enough coffee.
Thanks gents!

[mknittle]

Originally Posted by yossarian19

Does anyone know if the 70s Chevy PS box pitman arm can be turned 90* to run the drag link parallel to the axle, or is it keyed ?

Yes that is a common modifacation on older four wheel drives. often for clearance issues of bigger tires. or like my jeep there is just no where else it will fit.

if you take your pitman arm off the steering box you will notice that it has 4wide splines at 45 degrees from each other these Saginaw boxes were used by most american car manufactuers with the pitman arms in different posisions. Makes it nice fo those of us that modify everything.

[mknittle]

Originally Posted by yossarian19

Great tech here, guys.
I'm going to see what all would be involved in a crossover steering setup, with the drag link moving parallel to the axle. That would be my preferred solution. Failing that, I'll try and make the drag link as long as I can manage. I may flip the shackles to the rear, as well.
The steering tie rod will almost definitely get flipped to the front, too.
Depending how much meat is on the steering arms (don't have it in front of me) I think drilling through them to 1/2 or 5/8 and using heim joint steering with a beefier steering rod might be the way to go...
too many ideas this AM and not enough coffee.
Thanks gents!

If you do the crossover keep the drag link as parallel to the tie rod as possable. If you use the circle example I mentioed earlyer and get the centers as close as possable. just think of one end of the tie rodo drag link as the center of the circle and the other end as the side.

[gab50]

For the same reasons in the previous posts about the arc of the draglink and the forward move of the spring center on compression. After some drawings of movement, I ended up with my draglink about 3\4" up at the back from level. Now when the axle moves forward on compression the shortening arc of the draglink is about equal. The truck drives pretty good with this set up but I have now put in a 4" dropped axle with 2 leaves out so all bets are off now as I haven't got to test drive yet and will probably go to cross steer at some point.

[gab50]

I should have also added that the last thing you want with this setup is to have the rear of the draglink lower than the front. Really bad.

[mknittle]

Simply put "DON"T put the box on the shackle end of the spring !no matter how it looks on paper you will get bump steer.Goofy angles only mask the problem.

[mknittle]

I have done 2 jeeps a 3/4 ton and a 1ton and 2 Pterbilts all retro fits NO kits all have no bump steer. there is no reason to make it more complicated than it is.

[Russell Ashley]

I looked into a cross steer setup also but with the truck at stock height I'm not sure it can be done, at least not reasonably. Here's a look at how one person did it but the truck is raised considerably higher than stock..
http://67-72chevytrucks.com/vboard/s...=gasser&page=6

"The steering tie rod will almost definitely get flipped to the front, too."

If you are thinking that you can just reverse the steering arms and put the tie rod on the front be aware that you can't do that. Your ackerman would be crazy.