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Converting to Rack and Pinion Power Steering

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Hey everyone,

I'm starting this thread now as I'm on my way to converting my 1950 (originally 1 ton) truck over to power rack and pinion steering, but maintaing the solid front axle. I have gone through a lot of the needs, and looked at other steering box options without much success, so I've come to the final point of using a Dodge Omni rear steer power steering rack, and a new Ididit plain hot rod column, a Ididit u-joint and I will build the new crossmember to mount the rack to myself, as nothing is available for these trucks.

I'm going to have to have my inner tie rods cut a bit shorter for sure and possibly threaded just a bit more at a machine shop if needed, and I plan to build a sleeve to use the stock tie rod ends with the Omni inner tie rods, as it looks like no other matching end to the dodge PH ends.

I haven't done anything with the pump side of things, but at this point its the easiest part of the job and I will update on that as I get to that point.

What I need some help with today is that I have all the front sheet metal off my truck, so I need to get a rough idea what the measurement is on a complete 1/2 ton (my front axle and springs have been changed to 1/2) from the top of the steering arm where the ball joint mounts, on the back of the spindle to the bottom of the frame. If I could get a few different measurements and somewhat average them out to what mine measures as is, I can set the height of the rack mount so that I don't incur bump steer with it being too high or low.

Any help is appreciated and I will take as many pictures as I can during the process! Here's hoping this is an end to strong arm steering, without the use of a complete front clip or IFS add on

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Hey everyone,

I'm starting this thread now as I'm on my way to converting my 1950 (originally 1 ton) truck over to power rack and pinion steering, but maintaing the solid front axle. I have gone through a lot of the needs, and looked at other steering box options without much success, so I've come to the final point of using a Dodge Omni rear steer power steering rack, and a new Ididit plain hot rod column, a Ididit u-joint and I will build the new crossmember to mount the rack to myself, as nothing is available for these trucks.

I'm going to have to have my inner tie rods cut a bit shorter for sure and possibly threaded just a bit more at a machine shop if needed, and I plan to build a sleeve to use the stock tie rod ends with the Omni inner tie rods, as it looks like no other matching end to the dodge PH ends.

I haven't done anything with the pump side of things, but at this point its the easiest part of the job and I will update on that as I get to that point.

What I need some help with today is that I have all the front sheet metal off my truck, so I need to get a rough idea what the measurement is on a complete 1/2 ton (my front axle and springs have been changed to 1/2) from the top of the steering arm where the ball joint mounts, on the back of the spindle to the bottom of the frame. If I could get a few different measurements and somewhat average them out to what mine measures as is, I can set the height of the rack mount so that I don't incur bump steer with it being too high or low.

Any help is appreciated and I will take as many pictures as I can during the process! Here's hoping this is an end to strong arm steering, without the use of a complete front clip or IFS add on

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My complete front frame section is sitting on a pallet with the steering box still on it if you want to take measurements .

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I need a complete truck with all of its metal on so that I can get the sitting height between those two points correct. I may have to just lay my parts on top to get a rough idea if everyone has stored their rides.

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The only cheap way to add r&p steering with a solid front axle on springs is to mount the rack to the axle which is not hard to do if you can fab the mounting system. You must have a slip joint in the shaft connection to the steer column. I've seen it done on a 33 Ply. axle using an used collapsible shaft from a 70's-80's vechicle.

A newer way to do this is using a specialty built power r&p that hooks to a bracket on driver side of frame doesn't move at that end but is long enough to reach the pass. side steer arm that also has a steer rod to the driver side that ties both sides to one another.

 

The co. that makes them  have an online catalog at unisteer.com They do make custom widths And other r&p systems for a more traditional Racks and does front & rear steer type racks to your specs.

Not the cheapest way but well done and the sell Slip joint type steering shafts and most likely can be  made to custom lengths also.

Maybe at least a call to discuss with them your plans??

 

Just thought I'd throw that info out there.

 

They also make systems for 70-80's Mopars complete with mounts to add r&p steer to older cars. ;)

 

DJ

Edited by DJ194950

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Most of the systems I've seen to add to a front sold axle vehicle DO NOT mount to the axle, and I can't see in any way that mounting to the axle is safe, and or wouldn't cause constant steering issues, as you want the rack to be stable and the tie rods to move the up and down, not only would you need a slip joint steering shaft, you would need PS lines that would allow for full travel with an axle mount.

I'm going to build a crossmember that goes from frame rail to rail and mounts the rack at a static point in line with the steering arms, this way you only have the amount of travel of the up and down motion of the axle, and the steering shaft stays solid and safe, as well as the hydraulic lines. Nobody makes anything for the Dodge trucks, went down that route already...

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I would listen to DJ. The reason a rack and pinion is mounted solidly to the frame /crossmember on an ifs is it sends one tie rod to each suspension system. Since there is only one suspension up front with a solid axle, you should use only one tie rod if you are going to mount it to the frame, or mount it on the axle so that suspension movement doesn't affect steering angles and/or toe in.

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Most semis use a frame mounted steering box with a pitman arm / draglink setup.  I'm not aware of any r/p steering for big trucks with straight axles.  I'm trying to understand how an axle mounted r/p setup would work given all the movement that goes on with the axle.  Not saying it can't be done, just trying to figure out how it would work safely.   Mike

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actually a straight axle mounted on leaf springs is very well fixed position in relation to all things suspension...while the body may sway on the spring hangers..the suspension is always fixed..there would be no stressors between the steering mounted on the frame and the suspension hung on hangers as is the stock set up...most all modern R&P is affixed to the engine cradle/suspension support member...

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I do still run my flathead and it's not going anywhere, and I'll never be convinced mounting the rack to the axle is a good idea, the bump steer issues would be endless, not to mention steering shaft issues and line issues. I don't feel this is all that huge an undertaking, at least not when you have a plasma cutter and can cut 1/4" plate without issue. I plan to build a mount roughly like these in the picture. The Dodge Omni rack is rear steer like I need, and my stock tie rod is roughly 50" end to end, the Omni is 45" without tie rod ends....just some fabrication work and trial and error on mounting, but seems to be ample room

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actually with the steering moving in harmony with the axle and all fixed rigid...properly mounted bump steer cannot be an issue as the geometry will not change except for a tad of an arc...only the suspension to the body is moving and to that end it is independent and limited by the hangers....steering column to the rear rack may be a slight clallenge..one would want the later short column copied as best one can with its dual universals and sliding shaft....this will allow for the minor shift in terrain while driving..

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I'll stick to how 99% of the steering companies recommended, the motion I'm incurring with a frame mounted rack is what most are designed for, not to mention I won't drill or weld my axle, so that makes mounting safely pretty darn tough.

Parts all hit the border this Friday, so hopefully the week after next I will start digging into the job! Got a smoking deal on UltraMat for the interior on Black Friday... Regular $40, on sale for $13.99.... Got 6 rolls, that should help the interior after the DynaMat

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I've never done this kind of fabrication, so I'm only commenting from the perspective of my understanding of how the front suspension and steering works.  If you take a measurement from any fixed point on the frame (your new rack) to the end of each tie rod at the spindle you'll get a different measurement with every bump in the road, with every sway of the cab on the springs, and with every rise and fall of the front end under acceleration and braking.  For the life of me I can't figure out how you're going to keep the front wheels in proper toe-in alignment through all this relative motion.

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Just make sure that you measure toe in as you raise and lower the truck by jacking on the frame before you drive it. One more try for me to convince you. Think about this, your tie rod doesn't mount to the frame, what happens when you replace it with something that does?

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the point above as written is keeping the solid axle..there are no a-arms for up and down movement thus no elevation change of steering in relationship to the body/chassis as the steering is affixed to the axle.....there is but the pivot of the knuckle in the steering arc..as all is to be fixed on the axle there is but the slight attention to detail of double u-joint and sliding shaft for connecting the  column to the R&P

Edited by Plymouthy Adams

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If an R&P is fastened to the solid axle it all moves up/down together and any side to side as if replace a cross tie rod and aligned with the old tie rod. Therefore no changes in bumps/load changes up/down/ & side movements, but will require a slip type joint and at least 1 u-joint in the steering column  to the rack to allow these movements without steer effect at the wheel.

 

Some previous posts assumed a power R&P not all are.

I have a friend that solid mounted to the axle W/slip joint, a manuel R&P to a 33 dodge axle in his 34 plymouth Hi-boy back in the 70's. Been there ever since. Now only uses it to race about twice a year in CA. with the same 340 w/small blower on gas to 120's and occasional 130MPH in the quarter with the same solid axle R&P setup. NO changes!

A power (not required) just needs hoses with room to move some.

 

Seems maybe only me? that a frame mounted rack even if put just in line with the wheel end steer knuckle height and fore/aft and aligned with the other knuckle will change toe in and out upon bumps/load changes with a fixed steer unit. Not  considering changes when wheels turn and camber moves the steer knuckles- this may or not have an effect, just not sure myself, just toe in/out is enough to doubt the usability of this setup.

 

It's his truck.ideas.money I have no problem if he wants to do it. :)

 

DJ

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You can't mount the rack to the axle without creating poor tie rod angle,which creates all the issues you feel the solid mounting to the frame does, the only way to properly mount the rack in a static position is with a frame mount. This IS a power rack, and I've had a manual Omni rack already in place quickly to see how things will work. There is way less movement on a solid axle spring design then a IFS, and a lot more equal movement as it's tied together.

I seen the article in one of the truck magazines mounting to the axle, and it looks like a nightmare of slip joints and things to go horribly wrong. I'm not saying I'm 1000% this will work, but not one other member I'm aware of has attempted this on a truck or a power steering box conversion either.... There is more then one way to skin a cat

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My personal opinion is the r & p setup will work fine mounted to the frame. IFS and leaf spring systems BOTH have movement up and down, forward and back as the suspension moves, at the end of the steering arm. As long as the rack is setup parallel to the axle, straight and level with the steering arm at it's connecting point when tires are straight ahead and the truck is at ride height, there shouldn't be a problem.

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I plan to have the rack directly centred to the axle L to R and at the exact height of the steering arms. If this was front steer and I could use a Mustang II rack then mounting wouldn't be such an issue, but the Omni rack mounts are quite a bit different.

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Doing a web search for: solid axle with r&p, gave many post on many differant truck and old car forums and it always came up that the r&p must be attached to the axle (not the frame) or use one that uses a cross steer type r&p.

 

Tried to attach the  install info from one Co. that makes axle mount r&p for early Ford and Chev. trucks. Nice but pricey! Maybe someone here can talk them into starting to build for early Mopar trucks.

Seems they recently moved from So. Cal. to Dandridge, TN. Close Tim??

File to big to attach but part # is ps-sa and install under tech. info to check if interested.

 

nolimit.net

 

DJ

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Talked to a cutom Rod builder today, said Im just fine going the route I am, but instead of mounting the rack exactly straight with the axle, Allow for it to be at a slight angle where when the wheels go up, it creates a straight line to avoid any steer issues. He's seen it done both ways, and both ways work and fail...all trial and error

I'm sticking with my plans, I'll post updates once I get back to work on it

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You axle fans won, after doing my initial quick set up with a manual Omni rack, then receiving the power rack to find out they mount in a bit different way, I went to mounting the rack to the axle, which isn't real fun with the Dodge axle curving both up and down but a curve inward too, killing the idea of just mounting something to the inside of the rack. I also wanted to be able to try dropping a few front springs at some point, and that also would change where the rack mount needed to be, one way or the other.

As this is a highway only cruiser and not a back roads truck, I built 5" wide x 10" long 1/4" thick plates that mount to the front face of the axle and make a 90 to come out flat under the bottom and stick past about 6"s. On the drivers side I did have to weld in a 1/4" plate to get my spacing I needed, you wouldn't have to do that if you made the upright piece longer, but I failed to allow for how close the rack bellows is to the leaf spring, and at exact axle height it would rub. The pass side is just mounted flush to the bottom with the exception or a very slight bend in the plate downwards to make sure the bellows stays away from the spring. I took a few pictures, but don't mind the mis match hardware etc, I didn't want to mess up the threads on all the grade 8 stuff pegged to go in..... Took a lot of mock up to figure everything out

I'll keep you posted how the rest goes

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