Adding Power Steering

[wg4t50]

Any steering gear with the high point adjustment can have the free play adjusted and agree on the positice caster, would recommend about 2.5 degree Pos, for handling with firm feel.  there is lots more to good steering than just caster and toe in.  Proper drag link, tie rod, radius rod bushings, king pins and a good steering gear box will bring it all together nicely. If you do a nice / correct job on the front end, you will not need nor want a safety steering  spring setup, they are used to cover up the slop in the system.
dave M

[gus]

Somewhere, I think on the Sheppard website, I read that the old types had about an inch or two normal slack - which mine does and it is a very old model. I decided to live with it after I found out the price of an update!

I do need to check the rest of the linkage for slack though, I expect the shafts, U-joints and slip joints are all loose a bit which adds up.

[Bryan]

Hey guys! As you may have seen on my other post, I haven't been on the forum in a couple days so I'm catching up. You guys have been so kind to help me as a newbie. Thank you for your PMs and emails! We are remodeling the inside right now which is taking a lot of my time. This part is pretty easy for me. But the mechanical end of it, I'm a total NEWBIE (in ALL CAPS lol), but I'm definitely becoming a bus nut. I can feel it haha. This is my first experience with one!

Anyway, with all that being said. A lot of this about power steering is kind of going over my head. Although I do want to understand it, I won't be doing the install myself. So I'm wondering if I just need to take it to someone that knows like a few shops or individuals and show them what I have and let them assess the bus and what it needs to have power steering and also less play in the steering wheel. I know some of you have spoke of power assist. I'm not sure if I have that or not either. As you can see I'm in NorthEast Georgia, do you guys have any recommendations of people that could look at it and give me an estimate of what I need, and costs of parts, and installing? Thank you guys!

[luvrbus]

How far is the Nashville area from you ? Ken (Hardheadken here) may have time to do it for you if not he will know of someone you can trust

[wildbob24]

Clifford,

To answer your question, I don't know the difference between a AP-1 and an AP-1-2. First I heard of that number was when you posted it here.

I do know that early 4922 used bushings and later ones used roller bearings. Maybe that's the difference?

Bob

[uncle ned]

Another person to check with if Ken doesn't have time to do It.

Gene Russell at Russells diesel.

Millsprings NC

Don't have his number handy but someone will check in.
He did Boomer's coach for him

[Bryan]

I'm about 5 hours from Nashville, 2 hours from MillSprings (I was actually in MillSprings not to long ago)

[Hard Headed Ken]

Gene is close to you an should be able to do the job. He put a Ross chassis mount gear on Boomer's Silversides and his. A chassis mount would be the best thing for any bus that an axle mount gear but it would require a major re-engineering. Probably not worth it, but if I had to do over again that's probably what I would do. The Sliversides already has a chassis mount gear so it's not such a big job on that bus.

Just about everything has been covered in this thread except this. I mentioned how to check for return to center. Here's the usual overlooked cause when it doesn't, but don't overlook king pins and ball joints. Most power steering gears only require 6 inch pounds of force to activate the internal valving which provides the hydraulic assist.  Remove the input shaft from the steering gear. You'll have to put something in the input shaft with 1/4 or 3/8 female drive (I think I used a socket that was the correct OD) it doesn't have be really tight you're only measuring inch pounds. Now measure the torque required to rotate the steering wheel. If it's much more than 6 inch pounds then the caster can't do it's job because the excess drag results in steering gear holding the tires pointed some direction other than straight (it's the same thing as the driver holding the steering wheel not straight ahead). Then you correct by steering the other direction, then it's pointed the other direction and the process repeats. Eventually you become accustom to this and learn not to over correct too much, but you're still fighting it all the time. Again, if you want to know, let someone else drive and watch them, let's say your wife (that's how I found out how terrible my coach drove but I had learned to put up with it). The steering geometry can't make the vehicle track straight driving down the highway and not require constant corrections if the steering gear won't let it.

It's nearly impossible to get below 6 inch pounds on a coach with an axle mount gear. All the u joints slip yokes, the 90 degree gear box and bulk head bearing contribute to the problem. I used a 90 degree gearbox from a transit bus, light weight synthetic oil in it and synthetic grease everywhere else. About 6 inch pounds was as good as I could get it. A chassis mount gear does not have all those parts, that's why a chassis mount gear will just about always drive better than a an axle mount gear.

Try the return to center test on what you drive every day and try it on your coach. The steering wheel probably won't return to the exact center but the closer the better. Going slow across the parking lot steer to the left or right let go of the steering wheel, it should return to near center. If it keeps heading the direction you turned it with no hands on the wheel that's why it's so hard to drive in a gusting side wind and why it darts around so bad in the truck pavement ruts.

Ken

[Bryan]

Ken, thanks so much for the info!

I think my best bet is going to be to call some shops like Gene at "Russells Diesel" and "Choo Choo Express". Thru out this thread I have learned that some think the Shepard is sloppy and some and have had good experiences with it. I've also learned that there are adjustments that can be made to help the slop. Some of these adjustments I would not know how to do, but would both of these shops know the best ways to not only install the power steering but make it as tight as possible? I guess since I'm new at this, I don't know exactly who to trust.

And last question, does this mean that parts I originally posted on this post will not work? Thanks so much! 

[wg4t50]

Ken is so correct about the darting.  Just remember, wonder and weave is loose, worn parts, while dart and diving is too tight as in rust, lack of lube.
From the old school (Bear Front End Alignment days)
Bad steering makes for unhappy long trip.
Dave M

[luvrbus]

Everyone with power steering on a bus needs to add to their arsenal  Chart Your Way To Easy Steering a manual by TRW while it is for the Ross it applies to all steering makes life so simple it is a free download from TRW  JMO  

? for the Sheppard users did any other highway coach manufacture ever use the Sheppard besides GM

[Hard Headed Ken]

Bryan,
Looking at the pictures, I think you have an axle mount gear. I don't think there's a method to determine how the gear will perform until you install it. You can clamp some pliers on the input shaft and get a rough ideal on the free play, remember that small free play will be multiplied by the steering wheel size and slop in the system. It will be a little different once installed and under load.

Ken

[luvrbus]

I have a chart that says 1/8 free play at the box will translate into 2+ inches on a 20" steering wheel fwiw for a 20" wheel the DOT gives 5-1/4 inches before red tagging how would you like 5-1/4  inches of play for 2000 miles not me lol I am guessing that would keep a driver alert and on his toes

[eagle19952]

Everyone with power steering on a bus needs to add to their arsenal  Chart Your Way To Easy Steering a manual by TRW while it is for the Ross it applies to all steering, makes life so simple, it is a free download from TRW.  JMO.  

http://trucksteering.trw.com/Service%20Manuals

This one is the: Chart Your Way To Easy Steering  a manual by TRW
http://trucksteering.trw.com/sites/trucksteering.trw.com/files/pdf/TRW1250.pdf