Sheppard steering for my 4106

Darkspeed · December 21, 2014, 04:52:04 PM

My 4106 has the hydraulic assist cylinder and I would like to upgrade to the sheppard steering setup.

Where would I find one?

Do I need to change the ratio in the steering bevel gear as well?

Thanks!

Are there better options? Like a Ross?

Barn Owl · December 21, 2014, 06:25:59 PM

Used to be able to find used take-offs from Nimco (Pump, power steering box, arm). Not sure if they still do that. Gear change is not necessary but makes the changeover even better. Look for a 4905 with OEM power steering, it should have the 1:1 gearbox you would like to have. The pump that operates your hyd. cyl. will have to be changed because the Sheppard system requires a higher psi. I have run a Sheppard with the smaller pump but it did not turn the wheels while stopped. Was not a big deal for me, but when my old pump gave out, I was amazed at how with the correct size pump I could turn the wheel with just a finger while stopped on asphalt.

OneLapper · December 21, 2014, 08:34:32 PM

Ok, I just spent 30 minutes replying to this and somehow lost it......

I'll add to what Barn Owl said by recommending just replacing the 1000psi pressure relief valve in the Vickers pump with a 1500psi unit. That what I did when going from the power assist to the Sheppard. One finger steering as Owl states!

The power assist is nearly as good as a Sheppard box. BUT, the cylinder MUST be in perfect condition and the manual box (which is used with the PA cylinder) MUST also be in perfect condition, and the steering propeller shaft MUST be in perfect condition, too. You will not steer with one finger at a stop on pavement with the power assist, but going down the road you'll note about 1" additional play in the wheel vs the Sheppard. I have had manual, power assist and the Sheppard systems in my 4106. I have spent much time and money on this subject.

Recently I spent some hours talking to a forum member about his plans to upgrade from power assist to Sheppard. His spouse drives the bus and, after several calls I determined the driving motive was two fold; remove steering wheel slop of about 8" and reduce steering effort in parking lots (for her comfort). In the end, I donated a perfect manual steering box which Luke installed, and then Luke had the power assist cylinder rebuilt, replaced the tie rods and steering propeller shaft. The end was result was HUGE improvement, less than 2" slop in the wheel, tracked perfectly while going down the road now. Granted, the steering effort in parking lots was not improved, but she agreed to let him take over the driving for the slow driving. The cost of the repairs were much less than a new Sheppard box.

I'm pro power assist and Sheppard. I'm not convinced the Sheppard is worth the extra cost. But, if you must steer with one finger in a parking lot for comfort or medical reasons, then you'll need the Sheppard.

Oh, one other thing. The Sheppard system cost me 1 mpg vs. the factory power assist.

Hope this helps.

TomC · December 21, 2014, 10:30:35 PM

I converted my bus from air assist to Sheppard. I changed the 90º bevel gear from the slow 1.5:1 to 1:1. Went from 8 turns lock to lock to 4.5. And from having to roll to turn the steering wheel to finger tip when stopped. I park my bus in a warehouse that is very tight to get in. Before with the air assist, I would have to go back and forth several times. With the Sheppard steering, I can do it in one shot. I did not notice a difference in fuel mileage. The directness, fastness, ease of steering with the Sheppard, is 180º different from air assist. Highly recommend changing. Good Luck, TomC

wg4t50 · December 22, 2014, 03:48:38 AM

Did the same on the MC7 from the assist to the Sheppard, a biggie improvement.
Dave M

bevans6 · December 22, 2014, 05:21:25 AM

"Oh, one other thing. The Sheppard system cost me 1 mpg vs. the factory power assist."

Why? I can't imagine what could have caused that? FWIW I changed from a 1,000 psi pump to a 2,000 psi pump and noticed absolutely no difference in anything except the steering worked better.

Brian

olebusman · December 22, 2014, 06:24:10 AM

I used a sheppard steering gear off a grumman flxible transit, 1982 thru 1987 at least, on my 4106. It already had a hole for the drag link in the steering arm on the left side. I had to modify the steering shaft and the air tank was too long. I used the ps pump off the 6V92. Actually I used the motor and V730 also. I have not changed the angle drive gears yet. When I find some I will try the 1 to 1 system. Mine drives good. I set the caster more positive.

Darkspeed · December 22, 2014, 07:34:35 AM

Thank you! That is a lot of good information.

So the parts i am looking for are

Sheppard 492 box, part #???
Pitman arm, part #

1:1 miter box, part#

Drag Link, part#

Mounting Plates / U bolts part#

Where would I find this information?

OneLapper · December 22, 2014, 09:30:32 PM

Quote from: bevans6 on December 22, 2014, 05:21:25 AM
"Oh, one other thing. The Sheppard system cost me 1 mpg vs. the factory power assist."

Why? I can't imagine what could have caused that? FWIW I changed from a 1,000 psi pump to a 2,000 psi pump and noticed absolutely no difference in anything except the steering worked better.

Brian

Good question. I changed nothing else when I upgraded to the Shepprd box, but ever since I've gotten lower fuel mileage. I assume the pump is working at higher pressures even when going straight. The power assist system is an open center hydraulic loop so pressure is only needed when the wheel is turned.

I'll say that the Vickers will groan for an hour until the oil is hot. In the winter it's loud.

mung · December 23, 2014, 05:40:27 AM

So the OEM power assist doesn't do anything for steering in parking lots? Is there anything that can make that easier?

OneLapper · December 23, 2014, 06:01:28 AM

Quote from: mung on December 23, 2014, 05:40:27 AM
So the OEM power assist doesn't do anything for steering in parking lots? Is there anything that can make that easier?

It most certainly does! You can still steer when not moving with the power assist system, it just take more effort that the Sheppard system.

Level of effort to turn the wheel when stopped:

Sheppard system; one finger, literally.
Power Assist; hand over hand without much trouble.
Manual steering; Two grown men and one draft horse.

mung · December 23, 2014, 06:45:04 AM

OK. That makes me feel better about spending the effort to try to get my power assist working again.

Bill Gerrie · December 23, 2014, 06:52:49 AM

I know of a Sheppard 492 box in Grand Rapids MI and one here in Ontario. They are both from a 4107 bus but I am not sure of the difference in the 4106. I would assume they re the same. Shipping is very expensive on them as they weight probably in excess of 150 lbs.

wildbob24 · December 23, 2014, 07:42:37 AM

Todd,

I have the manual for converting GMs to Sheppard steering in .pdf form. If you'll PM me your email address, I'll send it to you. It has all the information you need, except current sources for parts.

Bob

OneLapper · December 23, 2014, 10:30:12 AM

Quote from: Darkspeed on December 22, 2014, 07:34:35 AM
Thank you! That is a lot of good information.

So the parts i am looking for are

Sheppard 492 box, part #???
Pitman arm, part #
1:1 miter box, part#
Drag Link, part#
Mounting Plates / U bolts part#

Where would I find this information?

Sheppard 492 box, part 492SDW5AR Last known price 3/17/11 was $1263.23 reman, includes $350 core charge
Pitman arm, part # 2584733 From Sheppard, last known price was $138.52 new, 4905 and RTS application
1:1 miter box, part# NLA as far as I know, you'll need to find a scrapped 4905 or RTS that had factory Sheppard steering. I'm still looking.
Drag Link, part# Use the original and cut new threads. I'm looking for the die I bought to do this... can't seem to find it.
Mounting Plates / U bolts part I bought the U bolts from Luke