Roll your own EPS question

EastMT

EastMT

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I have seen pictures of EPS installations. Most had a u-joint on both sides of the EPS unit. Is there any reason a straight coupler could not be used on the forward steering shaft connection (to reduce u-joint shaft play), if the EPS unit is pointed  in line with the rack steering shaft?

IMG_1658.jpeg

 
Most would have one on the rack side because of the allowable angle the EPS can be installed at.  Not a straight shot.

 
Just remember that u joints move in an eclipse when angle is added. You would think that it wouldn't matter in a steering shaft because it rotates at a slow speed and not much more than a full rotation if even that much but...I had a guy that either replaced his own steering shaft u-joints or had someone do it for him on a semi. His steering wheel when turning it would get easy then hard and back and forth depending on the position. He replaced his steering box at cost of something like $1500 trying to correct it. There was, IIRC, a hex slip yolk in the shaft that got clocked incorrectly. I pulled the slip apart and reclocked it and the problem went away. He couldn't get his around what I did but was happy it was fixed. This is a pretty good video that helps you to understand how u-joints work 

https://youtu.be/Idk3BVDVHq4?si=hsIUKPUU8-Iv6-Lr

 
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this is great info above, so to add more to the idea, the left picture above can only work if the shaft could extend or contract (like slip yoke on a driveshaft)

and that's not really easy to do in the sand environment .  because the single u-joint travels in an elliptical motion the second phased u joint cancels it out.  with only 1 u joint and no slip coupler the rack and EPS unit will be sucking themselves together and then apart so set screws will be getting loose and damage to eps and rack over time

 
Would it work better to get the EPS unit in line with the shaft going to the steering wheel and have both u-joints on the output between the EPS and the rack? While I do understand the way u-joints work the rest of this is not my area of expertise (if I even have one). Here's a pic of one of my little buggies that doesn't have power steering but a good example of how to manage the back and forth movement in the shaft without a slip yoke

IMG20240711110519.jpg

 
i might add that if the eps unit was practically straight with the pinion, then one u joint and straight coupler could work but any more then a few degrees the issue will start

 
Thank you to all for saving me from wasting time and creating a frustrating problem! I now see the light of the shaft moving forwards and backwards with the straight coupler, eventually braking the EPS mount or the rack.

 
Advantage of u-joints on both sides of unit, forbid that anything happens to cause miss alignment of shaft. Have seen a car wrecked once where shaft then wobbled as it turned. To drive it back to camp, by the time car got there, the shaft had flexed enough to shear off.

 
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richard h said:
Advantage of u-joints on both sides of unit, forbid that anything happens to cause miss alignment of shaft. Have seen a car wrecked once where shaft then wobbled as it turned. To drive it back to camp, by the time car got there, the shaft had flexed enough to shear off.
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Thanks. Another good reason for u-joints. U-joints on both sides of the EPS unit it is.

 
I also don't think once behind the wheel and hitting the dunes you will notice any play in your steering wheel. Go have fun!

 
I have gathered all the parts and an EPS unit to start planning the install. Is there a recommended location or distance from the steering rack to mount the EPS unit? The frame is a 2 seat Squirt. Does anyone have a picture of an EPS mounted in a Squirt by chance?

 
EPS installs vary quite a bit  - but you want to brace the unit very well  - so that will partially determine where you put it. 

when you say you have all the pieces  and its RYO,  be careful using e-bay electronics  (potentiometer based boards) 

 
Fullthrottleguy said:
EPS installs vary quite a bit  - but you want to brace the unit very well  - so that will partially determine where you put it. 

when you say you have all the pieces  and its RYO,  be careful using e-bay electronics  (potentiometer based boards) 
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 I to was skeptical of the egay electronics and bought the controller and bracket from epowersteering.com . The bracket looks well made and better than I would have rigged at home. It has four mounting holes for the eps unit.

IMG_1883.jpegIMG_1885.jpeg

 
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Is there any issues (too short) with having the front EPS to rack shaft only 5" center of u-joint to center of u-joint? Or is a 5" shaft (no jokes Mac) OK?
 
Follow up question. Is it better to have the EPS unit as close to the steering rack or as close to the steering wheel as possible?
 
Picture of how mine ended up. Worked great and never any issues.
 

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I cut down the input shaft of the Vue EPS unit and welded on this stud shaft.
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