HF542996 Power Steering conversion geometry questions, not run of the mill

[gentrysgarage]

HF542996 Power Steering conversion geometry questions, 1943 G-7123

Ok folks I am calling on the collective wisdom here to help me do this conversion right the first time.
Why not run of the mill, It's not an M35, but a G-7123 NN WWII Chevrolet cabover.

Criteria of the build in general to get us on the same page:

The whole plan for this truck is to first become my daily driver then eventually build a removable WWII military looking box on the back for family expeditions.
It must exteriorly look WWII motorpool mechanic hot rodded stock Think any thing a motorpool mechanic could get his hands on from the wrecks..it was already modded with a Federal 2 1/2 ton hoist/dump setup.
It must also be safe for my family and be able to be driven by my wife who is under 5' (ok she's 4' 11" and 105# wet) Thus the need for power steering.
It is also getting a Cummins 6BTA and an Eaton 6 speed.
I have gotten a Ford remanufactured 4 port HF542996 (for $350 Ford remanufactured and NO core charge!) to replace the small manual gearbox...thus the start of the problems. Simple physics states 2 solid objects can't occupy the same space with out explosive consequences and living in Lost Angels means I need extra cooling for the freeway parking lot commute

Question 1) I know I need to make the drag link as level as possible to minimize bumpsteer, but how long or short can it be?

Question 2) Also how far inboard or outboard of the frame rails can I place it with yet unsourced pitman arm? How much angle can I get away with in the horizontal plane can I have tho minimize contact on full right turns?

Question 3) I think the pitman arm should rest straight down at steering gearbox center position, right? I say this as the angle on the box is around 60* instead of the normal 30* of the M35 conversions.

Here is a pic showing what we are up against



Thanks in Advance

 

[wreckerman893]

The first thing I would do is try to make the cab raise up like a cab over road tractor. IMHO that would make most of the other mods a lot easier than working in tight quarters with the original configuration. It would also look a lot cooler at shows.....again IMHO. Your mileage may vary.

 

[gentrysgarage]

Hi Wreckerman,
I hope to actually, Haven't figured it out as the front grill with a winch added to the front would have to go straight up atleast 4-6 inches before it tilts over or continues to go straight up. I want to place the "heavy metal first so I can see what I need to clear
Thanks for the reply we are on the same wavelength

 

[rustystud]

First off you need to post those pictures here on this site. I could not view them without downloading some extra program which I won't do. Plus it is Steel Soldiers policy.

 

[gentrysgarage]

I had been able to post pictures, but last night it was giving invalid URL, that is a direct link to the photobucket picture. I ckecked it on2 other computers that I don't use for photobucket and it didn't need to run a special program to view them. So no linking pictures?

OK I tried again, I will research how to make it work, it wouldn't let me attach a 480kb picture (too big) So if the Mods want, please delete my thread

On a last note I enjoy and learn from every one of your threads RustyStud!

Thanks

 

[brianp454]

Welcome gentry!

That cabover truck is really cool and I’m sure it will be one sweet ride one of these days.

I did not have any trouble looking at your pics. I have had lots of trouble uploading pics to this site though. It can be very picky and I often copy the pics and make a “lowrez” batch of files just to upload.

On the M35A2 the steering box attaches to the full frame rail with 3+ bolts and has a substantial reinforcing bracket on top of that. Your frame rails neck down significantly and turn down. It looks to me like you will have to add 1-2 reinforcing brackets to beef up the area. I’d also like to see a cross brace that ties into it and would be leery of counting on the bumper to stiffen the front of the frame.

You may want to start mocking it up ASAP with a look at say 2-3 possible ways to mount it and what the geometry impact are. Then you can make decisions based on those constraints.

Better yet, the choice of the HF54 for the deuce is largely based on minimizing the necessary modifications. I’m not convinced that is the best option for you. I just happened to be at a scrap yard the other day (having just looked at the HF54 thread) and spotted a complete steering axle from a commercial truck with power steering. In your case, wouldn’t I be easier to swap in a complete 6 lug 5,000-12,000 pound rated steering axle from a commercial truck?
I’m at work now, or would upload a couple pics. I can later if you like.

 

[gentrysgarage]

Alright, I loaded extra small pictures into photobucket...here goes nothing...

 

[rustystud]

OK for question one. The drag link can be as long as needed. Now I've seen drag links up to 5ft long. Is that a good idea ? I don't think so. To much weight and resistance. I would say a good drag link will not go over 2ft on a truck this size.
Question two: Keep the drag link as close as possible to the outside frame without it coming into contact with the frame. You can be lower then the frame itself as long as your away from the spring pack. By keeping it close to the frame you minimize the possibility of hitting it with the tires.
Question three: The angle of the pitman arm will be determined by the steering gear itself. If you can mount the steering gear in such a way that the pitman arm in neutral position is vertical that would be great, but in reality you must make allowances for how the gear can be mounted. You just must be able to have a full swing of the arm pulling the drag link along without the drag link coming into contact with the arm in any way. Manufacturers spend a lot of time and energy coming up with the correct geometry for their steering systems. When you go into the realm of "one-off fabrication" then all bets are off. It basically comes down to trial and error. A lot of error ! Take heart though, it can be done ! Just be willing to except the idea that your system that you designed and built will have to be totally scrapped and you will have to start over from scratch. Not many people get it right on the first try.

 

[59apache]

As far as i can see it, the problem is that your HF has a single groove and not a full grove. There are versions with full groove available. With full groove you can mount your pitmanarm in any way you want.
With a custom made pitmanarm it is possible to mill a second groove in the shaft.....been there, done that.

greetings Juergen

PS:great projekt

 

[rustystud]

As far as i can see it, the problem is that your HF has a single groove and not a full grove. There are versions with full groove available. With full groove you can mount your pitmanarm in any way you want.
With a custom made pitmanarm it is possible to mill a second groove in the shaft.....been there, done that.

greetings Juergen

PS:great projekt

Making up your own pitman arm works too, just going to cost a whole lot more. I would go with Brian's suggestion and get a complete front axle out of a modern truck.

 

[59apache]

if you think so...

To retain the correct steering geometry you'll need the whole front end...in this case it would be easier & saver to use a complete frame, with drivetrain and just swap the cab.

 

[gentrysgarage]

Thanks for the replies guys,
You guys have answered most of my questions, the biggest one left is how short the drag link can be made. Which seems to be a try and see situation. If I can mount the box a little (even just 2 inches) more rearward the radiator and intercooler would fit nicer and could be made bigger. I am going to mount it on a plate and clamp it to the frame to check geometry and action. Also plan on using "Johnnie Joint" rebuildable sperical rod end to help alleviate any binding I might encounter.
Brian et al, let me explain my position on the axle, I fully understand I am going to spend extra on it as it is a dinosaur. To be honest my research had led me to another axle(s) when I first started this oddessy. If I would just use a Rockwell FDS 75 and 109 rear combo life would be easier for me, wide range of gears, drop out center, lighter, disc brakes on later models, was almost sold on it. Drew a picture of the axles and truck from the front, the squashed oval center just looked odd to me. I even drew a waffle iron pattern on it to no avail. While I am upgrading the safety and drivability of the truck (I dream big in that I want to use it as a daily driver!) I have made a rule to not change the exterior from what specials the factory put out but most especially what a WWII motorpool mechanic would do if he field modded it. That beast of an axle is just to prominent. This build is my oddball way of honoring all veterans and helping a wounded steel soldier .
Thanks again you have all helped alot!

 

[brianp454]

Ahh, I thought that might be your concern. I’d likely do the same thing in your shoes.

Is your existing steering shaft & box at a 30 degree (M35 reference) or 45 degree angle (cab over?) from the frame rail?

I wonder if it might also be easier for you to mount the Saginaw box outside of the frame rail. Have you seen that thread?

I would think the drag link needs to be a few inches (say 10 or so?) to minimize the effect of axle vertical movement in steering. How short are you thinking of?

There’s a guy here local that has an F650 project (full dual cab and painted metallic green with the full old school full front metal grill, lookin' good) that seems to have the same or very similar open u-joint (or the old ball dealies) front axle you have. He’s hasn’t gotten it on the road but he’s the 2[SUP]nd[/SUP] user of my 3053A transmission bearing retainer with added seal. Anyway, I’m curious about when and for how long that axle style was used.

 

[rustystud]

Thanks for the replies guys,
You guys have answered most of my questions, the biggest one left is how short the drag link can be made. Which seems to be a try and see situation. If I can mount the box a little (even just 2 inches) more rearward the radiator and intercooler would fit nicer and could be made bigger. I am going to mount it on a plate and clamp it to the frame to check geometry and action. Also plan on using "Johnnie Joint" rebuildable sperical rod end to help alleviate any binding I might encounter.
Brian et al, let me explain my position on the axle, I fully understand I am going to spend extra on it as it is a dinosaur. To be honest my research had led me to another axle(s) when I first started this oddessy. If I would just use a Rockwell FDS 75 and 109 rear combo life would be easier for me, wide range of gears, drop out center, lighter, disc brakes on later models, was almost sold on it. Drew a picture of the axles and truck from the front, the squashed oval center just looked odd to me. I even drew a waffle iron pattern on it to no avail. While I am upgrading the safety and drivability of the truck (I dream big in that I want to use it as a daily driver!) I have made a rule to not change the exterior from what specials the factory put out but most especially what a WWII motorpool mechanic would do if he field modded it. That beast of an axle is just to prominent. This build is my oddball way of honoring all veterans and helping a wounded steel soldier .
Thanks again you have all helped alot!

Just a word of warning about using those old differentials. They had special bearings that are no longer made. I rebuilt these units and other military differentials for a Seattle company years ago. They specialized in this market as many companies had bought used military surplus and where using them in the logging industry here and up in Alaska.
Any of you Washington members might remember "Ben's Truck Parts" . They went out of business years ago. The business was started by a guy just after WWI who bought a butt load of surplus. They continued this practice of buying military surplus through WWII, Korea, and Vietnam. I used to go through the large crates of NOS parts at lunch time. I still remember this box of Half-Track wire looms. Complete, still in the sealed pouches. They had a whole warehouse of just differentials stacked 10 high on large racks. But even they started to run out of the bearings for these old differentials.
So the first thing I would do would be inspect these differentials to be sure they will hold up to what you have planned.

 

[gentrysgarage]

Rustystud I wished I had run into you before I spent hours and hours researching these axles..probably should start another thread, but I want to run this by you as these axles are the weak link.

I am building the rear only at first. It's a lack of enough money thing. The worst problem is the metualurgy of the axle shafts and in my case the 10 splines also. I plan to get axle shafts splined on both ends (later 27 spline or whatever the shop recommends) made out of 4340 (would love 300M can't afford it) and run drive pucks like the 60's H110. I have a set of 5.38's heading my way already. The pinion bearing is the bear. They are around, but not at any price It would not hurt to pay. Does this sound like a good plan? Anything else I should look out for?

I have an answer for the front but as it's over 2000 for the shafts, I will be 2WD for awhile. I have to get this thing moving under its own power first.

Thanks Again!

 

[rustystud]

Rustystud I wished I had run into you before I spent hours and hours researching these axles..probably should start another thread, but I want to run this by you as these axles are the weak link.

I am building the rear only at first. It's a lack of enough money thing. The worst problem is the metualurgy of the axle shafts and in my case the 10 splines also. I plan to get axle shafts splined on both ends (later 27 spline or whatever the shop recommends) made out of 4340 (would love 300M can't afford it) and run drive pucks like the 60's H110. I have a set of 5.38's heading my way already. The pinion bearing is the bear. They are around, but not at any price It would not hurt to pay. Does this sound like a good plan? Anything else I should look out for?

I have an answer for the front but as it's over 2000 for the shafts, I will be 2WD for awhile. I have to get this thing moving under its own power first.

Thanks Again!

If you are determined to keep these axles, then I would strengthen the axle tubes. You can have gussets welded to them or have new tubes made from stronger thicker steel. You are having new axles made and I assume side gears, but what about the spyder gears ? Also the housing itself needs to be checked out. Now we are at the ring and pinion gears. How are they ? Remember they are "old" gears and probably seen a lot of service. Can you source new ones ? The last thing is of course the bearings. You really need to replace them. Can you still find them ? Before you even have a single part made (axles) I would make sure you will be able to get ALL the parts needed for a rebuild. Once you have that done then go ahead and have any special parts made up. It's easy to have custom axles made. Not so easy to have custom ring and pinion gears made. Like I said in my earlier post when I was at old "Bens" we had tons of NOS parts to use, but even then it was getting hard to find these early WWII differential parts. You don't have access to a warehouse full of NOS parts do you ?