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?
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.
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.
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
Did the same on the MC7 from the assist to the Sheppard, a biggie improvement.
Dave M
"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
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.
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?
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.
So the OEM power assist doesn't do anything for steering in parking lots? Is there anything that can make that easier?
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.
OK. That makes me feel better about spending the effort to try to get my power assist working again.
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.
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
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
Thank you OneLapper!
Did you have to change the length of the steering prop shaft between the miter box and the steering box?
Quote from: Darkspeed on December 23, 2014, 05:22:20 PM
Thank you OneLapper!
Did you have to change the length of the steering prop shaft between the miter box and the steering box?
Yes, the prop shaft needed to be shortened by approx 3/4".
QuoteI'll say that the Vickers will groan for an hour until the oil is hot. In the winter it's loud.
Mine is very loud cold, my father's bus is quiet. Not sure why.
Well after talking to Ken about the inability to get the play out of a Sheppard I may look at doing a custom mount for a Ross/TRW HFB70 series gear.
The Ross/TRW gear that was used in the in the MCI is apparently hard to come by but making a custom mount for a more common HFB70 series should not be that big of a deal and this would give me a gear with lash adjustment.
If I was super ambitious I would replace the miter box with the power steering gear and run a drag link back to the steering knuckle but im not sure it would be worth the effort.
Kirby 4104 used the Ross from a MCI on his bus
I mentioned that gear to Todd. As far as I know they were only used on the MCI 102A2 and they are hard to find. If anyone knows where one can be found send Todd a PM.
Thanks,
Ken
Thanks Ken!
Im starting to think more about the idea of a frame mounted gear as it would simplify a lot of the system.
It would require some reinforcement but it would allow me to use a nice flaming river tilt steering column.
It may require custom bending a draglink between the pitman and the knuckle.
I am going to start doing some measuring.
If you are ever through Roanoke I can show you a 4106 with 1" play in the wheel. It takes effort and money to dial it in like that but I would think it would still be easier and cheaper than re-engineering something new.
Quotetilt steering column
That would be very nice to have. Can that be done with the OEM column?
A frame mount is the way to go JMO
Well you could replace the miter box with a frame mounted power steering gear and retain the factory steering column or use a more modern tilt / telescoping steering column. It would be more comfortable to move from a giant steering wheel at a fixed angle to a modern heated steering wheel with an adjustable angle.
This would remove the need for the axle mounted gear / cylinder, miter box , steering drive shaft, u joints, etc...
Mounting the new frame mounted gear would require reinforcing the structure of the spare tire compartment which is easy to do.
The 4106 has an empty steering drag link receiver on the drivers side but it faces 180 deg rather than 90 deg so I would need to fabricate a 90 deg mounting point for a tapered ball joint or rod end. This would be the most difficult part but is doable.
If i was going to convert the factory column to tilt I would cut the column at the bend and weld in one of these > http://www.polyperformance.com/shop/product.php?productid=1844&cat=557&page=1 (http://www.polyperformance.com/shop/product.php?productid=1844&cat=557&page=1)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.polyperformance.com%2Fshop%2Fimages%2FD%2Fd_4842-01-400.jpg&hash=50c840316818b2a7dd063f1e6145db7f9783e8cf)
Todd,
This is the critical area that needs gussets. It was weak from the factory. With a frame mount gear you'll be adding many times the force to that bulkhead it was designed for. Add large triangle gussets to both sides of the beam and to both sides of the coach. Yeah, I know the picture is from a 4104, it's all I could find. Clifford is correct, a frame mount gear will drive much better.
Ken
Looking at the picture it probably would be a good idea to add gussets to the rear of the beam and 2nd bulkhead also
Thanks Ken!
As part of my rebuild on this bus I am adding some driver / copilot protection in the form of some moly tubing in the area where the dash was and this is tied back to the two steel box sections above the front suspension and the steel ribs above the front roof. My goal was to have a better chance of surviving a front end collision. After removing the 4106 dash / rivets to do some bodywork I was amazed that the only protection was an aluminum doubler plate on the drivers side. The good news is I can stub down and have a rock solid mount for a frame mounted gear.
Looking at the top of the drivers side steering knuckle there is a tapered blank (no arm) that is only being used to mount the service brake hanger. Im thinking of making a replacement with a 90deg arm to mount the drag link to. Because the drag link will be so long (front of bus to centerline of front axel) it looks like there will not be a lot of change in length when the suspension moves through its arc.
Todd,
It seems you know what needs to done. I'm sure you'll end up with a very nice driving coach. You probably know this already but add some caster for a better return to center. I don't remember for sure but I think a total of 4 degrees positive. Hopefully someone else can confirm that number.
Ken