The Stovebolt Site Forums The Shop Area Driveline Steering opinion?

Trying to figure what is the best way to go with power steering conversion.
Who is using what and good and the bad of your setup?

Looking at ones with solid front axle not ones swapped to independent.

Should I use the factory location conversion or the swap using newer style front mounted box?

One of the easiest and most popular is the mid 80's Toyota 4wd box. Fits in the same place as the factory box with simple modification. Do a search.

If you give us your truck layout, engine, etc., size, it would help.

Ed

My truck is 55.2 GMC 150
2002 GMC 5.3 LM7
4L80E
Stock front suspension
Stock rear suspension with 9.5 in 14 bolt semi float rear 3.73 gears

I've got plenty of clearance for either setup I just wanted some opinions on how everyone likes the setup they have before spending the money to swap mine out.

I used a power steering kit from CPP for my 51 panel.
Also, upgraded the brakes to discs at that time.

No drama on the install and steered like a Cadillac. And, stopped on a dime.

I'm up for the disk brake swap but still working out details. Since mine is 8 lug its more of a challenge. Looking at probably using 88 up rotors on modified factory spindles. That will be my next challenge. At the moment steering needs to be decided on to determine which headers I use for clearance.
I like the looks of the CPP kit but I have access to 2wd truck steering box for the other swap.

I did Disc front. I did the power steering that uses an owner purchased Saginaw box on a 1956 GMC.

I'm using an 86' C10 Saginaw box with a kit from Brothers Truck. So far the only draw back I see is that you need to reinforce the frame at the mounting position. I am still working that out. The drag link and pitman arm were straight forward, just adjust the length and your good to go.

If you choose to use a CPP kit, make sure that your kingpins aren't worn out. The power steering gets swimmy if they are worn. This is annoying because it adds to the lack of road-feel inherent to driving with the Saginaw p/s box.
I removed the original caster shims and replaced them with 6 degree caster shims. This greatly improved the feel of the road. Now when I come out of a turn, the wheels return toward the straight ahead position just like the stock manual steering box does.

I can see reinforcing the mounting point. The GMC I'm working on has a much larger front cross brace engine mount than what is on a comparable chevy. But if going that route I will definitely beef it up , thanks.



I was told about the degree shims to help out with caster. But I seem to remember that only 4 degrees was recommended.

jmlloar: I concur w 52Carl....I’ve got a 48 with a Saginaw PS box. The 6 degree shim fixed my wander and steering return. And yes I beefed up the frame w some 1/4” angle iron.
Dave

What is the factory spec on caster?

Remember shims will add to or take away from what is built into the axle from the factory.

https://www.hotrod.com/articles/0902sr-science-of-straight-axles/

I'm not saying 6 degrees is wrong I just wanted to know the reason behind so much and didn't want to end up adding to large of a shim. My thinking is if the factory spec is 2 degrees and I add a 6 degree shim that makes it 8 degrees total one way and shim flipped 4 degrees the other way. Since I'm pretty sure these trucks have some caster from the factory I just wanted to be sure before I order my shims.

My 59' has shims from the factory, not sure what degree they are. I don't believe the axle it's self has any added caster. I haven't found anything in the assembly manual that states having caster made into the axle.

With no shims you have zero caster...and you really don't want that. The factory (non-power steering obviously) spec can be found in the manual but ought to be a max of 2 degrees (+/- a small fraction). If you don't have enough caster, your truck will steer much more easily but will wander all over the place and it will not straighten after a turn very well at all. Some people who think taller back tires are the answer and who never change their caster to adjust for this create trucks which are unsafe. Raising the rear lowers the caster angle every doggone time. The same thing will happen if you use smaller tires on the front. If you increase the caster to 4 degrees with manual steering, your truck will drive straighter but will be harder to turn...especially in town. The reason why is caster tilts your axle back (or front if your vehicle was built with negative caster) and so to turn it, you literally have to lift your truck up. If you want a nice visual example of caster, just look at a motorcycle from the side. 6 degrees might work just fine with power steering, but very few people anywhere will be strong enough to steer a vehicle as front heavy as a truck like this with that much caster with manual steering. And the greater the caster degree, the more wear on your kingpins, kingpin bushings, bearings, etc. That part is a given. There is a good balance which must be established. Worn out springs (leaf springs of course in this case) can also cause caster angle changes if the arch has been bastardized with time. And it can change with age, rust, use, etc. So just sticking some shims in there is only a start. Get the truck to a front end man who has some gray hair and knows what he's doing. Remember the engineers at GM didn't make it this way because they were stupid. They did this because they saw it as the best balance...and they probably never thought anyone would be driving these trucks at freeway speeds.

Also. VERY IMPORTANT. You have to be totally cognizant that there is a pin on your spring which mates with a hole in your axle. That pin is the end of a bolt which holds your spring leaves together. It is imperative that pin mates very well and very securely with that hole. If you don't pay attention to this and if your shims are not correct, they can raise the pin to the point where it just barely or worse doesn't connect with that hole. The best of all worlds is the new shims you use have the same diameter hole as your spring pin's bolt, are held in place (screwed down to the springs) with new spring pin bolts and therefore the bottom of the shim has 100% of that pin available to fit into the hole in the axle. NOT ALL SHIMS ARE MADE LIKE THIS. Some are made with a hole large enough for your pin to slip through (meaning you don't have to change pins when you change shims), and this obviously lifts the pin off the axle more as you increase shim thickness and at some point you can have wall to wall trouble. If this is in any way confusing to you, STOP and study it and ask for help.

How about electric power steering? I seen something on this and it fits under dash on column...

Ask anyone who owned a 2008 Ford Escape or Mercury Mariner or Mazda Tribute. Those were prone to fail at any time...literally any time. Driving up in your driveway or going 70 in a curve. Big recall...as I remember over 1,000,000 vehicles. I'd have to be convinced the bugs had been corrected on those.

There is an existing thread on electric power steering. As Jon suggests, I wouldn't trust a Ford unit. A Toyota one would be my preference.

1) Do not stack additional shims on top of existing shims. Buy 6 degree shims.
2) Heed Jon G's warning about securing the new shims in place. Since they are tapered, they will walk out of position if not secured.
3) Using 6 degree shims in the truck with power steering is not equal to trying to out-think GM engineers. Adding power steering to these trucks already changes the engineering.
With two degrees of castor with power steering, the wheels will not come back to the straight ahead position after coming out of a turn like a stock manual steering box does.
Six degree shims will correct that, as well as give you much better feel of the road. The truck will naturally tend to go in the straight ahead position while driving.

Please take a look at this. It is a shim I removed from a wrecked truck about 40 years ago. There were 2 but one was lost along the way. Obviously it was homemade. It is tapered (which you can't really tell from this image) and was installed under the stock shim. There was no contact between the spring pin and the axle with this shim installed. Whether axle movement caused the wreck or contributed to it is an egg I couldn't unscramble because there was very little of the truck left, but in order to always remind myself of this situation, this has been in one of my tool boxes since then. I'm fairly certain the driver didn't survive. Or if he did it was a miracle.

Ok, sounds reasonable.
6 degree shims it is.
I will be rebuilding the springs anyway so no prob with running the center pin through the shims.

Thanks for the input.

I have seen many straight axle vehicles with shims already on them. but pretty sure mine has none. I would figure it was built in and the spec was just for "if its not correct add shims to adjust it"
I will look more closely at my truck and see if there is any caster already.

If you are going to replace the shims with new pieces why not go one step further and replace the spring pins as well, after all if original they are 65 years old. Just my thoughts.

That's a given. Even IF they would come loose without breaking or stripping threads, the old ones would be to short.
I always replace the bolt when separating leaves.

I found these after doing a quick search, this kit comes with new center bolts
https://www.sdtrucksprings.com/inde...NwuO15wIVCr3ACh1-JQJcEAQYAyABEgLlivD_BwE

All in one shot is always nice.

Just an fyi
I did the box swap to 70's 2wd box and when you flip the lower shock mounts and cut the steering arm, you MUST flip the tie rod from behind the axle to in front of the axle. (very easy just put it on backwards) If not the tie rod hits the lower mount before the steering stops touch.

I found that out as well. What I did was to move the lower shock mount the top of the axle, between the axle and spring pack. It required me to fab a plate to weld to the shock mount and the use of a longer center pin. The plate is only 5/16" inch thick so it didn't add to much space under the shim. Please keep in mind that I did remove 3 leafs from the spring, so the extra 5/16" was not really an issue as I will be using shocks designed for a lowered truck. As a side note, I had thought that I would require shorter u bolts after removing the additional leafs, adding the extra 5/16" plate allowed me to use the factory length u bolts with no problems.

link for shocks: https://www.brotherstrucks.com/1955-59-CHEVY_GMC-TRUCK-FRONT-GAS-SHOCK/productinfo/FGS5559/

flipping it front to rear worked best for me. had to pull the drivers side arm off to cut it anyway. 2 bolts on each side and put the right on the left and left to the right. I did king pins so I had it apart anyway.
The down side is that its more exposed to road debris, the plus side is a ton more oil pan clearance.

PS box installed

Got a good deal on a hydroboost from a chevy van motorhome alond with the steering column

Also purchased new 2 piston calipers and brackets to go with the rotors

I purchased the 6 degree shim kit I posted, the kit came with new hardware and a shoulder washer to make up for the thickness of the shim and still allow the pin to fit deeply into the axle hole. The pin were larger diameter, 3/8 in instead of the factory 5/16 in, had to do some drilling but didn't mind using a larger pin.

I'm also doing the hydroboost swap. I got an assembly off a 01' GMC Safari 3/4 ton van. I'm just now fabbing up the mounts for that. I would like to see what you come up with.