Home » Public Forums » GMCnet » Setting the front ride height procedure
| Setting the front ride height procedure [message #292808] |
Wed, 23 December 2015 12:46  |
Scott Nutter
Messages: 782
Registered: January 2015
Location: Houston/San Diego
Karma: 4
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Hello all
This is the first time I've ever set the front ride height. After searching out old post and going through the shop manual I have put together a guideline/procedure I plan on using.
I am posting this in hope of getting input to improve this procedure or to stop me from doing something stupid before I go in. All heights are based on a 1978 Royale, and I have not weighed the coach. That will come later next year. The coach must be on a level surface to properly adjust. The front end will Not be up on jacks. to adjust the front ride height I haven't found any references in the manual to lift the front end to unload the weight to adjust the front ride height. Once the unloader tool is in place, I will probably remove the adjustment bolt, clean it, and apply a layer of anti seize on it.
1. Set all tire pressures. I'm going 65psi in front, 60psi in the rears. Tires are 225-75r-16
2. Cut 2 blocks of a 4x4 to 8 5/8 inches in length and place under each frame rail in the rear under the height set oval cutouts. The correct height in the rear at the top of the oval is 11 11/16" +/- 1/4" from the ground. When the frame is resting on the pre cut 4x4's then you will have the 11 11/16" rear ride height that you will need to correctly set the front ride height.
3. Release air from both airbags until the bottom of the frame rails are just touching the top of the 4x4 blocks. Make sure the air system is off so the airbags won't inadvertently inflate while adjusting the front height. ( I was originally thinking of completely deflating the airbags but that would put a lot of weight on a small footprint on the frame. Possibly damaging the frame).
4. place torsion bar unloader tool onto the front crossmember with center bolt screwed into the dimple of the torsion bar adjusting arm (porkchop). On my situation, my front height is about a inch too low.
5. Tighten the bolt on the unloader tool until you have reached the correct front ride height by measuring from the ground to the top of the oval cutout on the front frame rail of 13 1/8" +/- 1/4". Once front height is set, tighten the adjustment bolt till its snug on the adjusting arm then release and remove the unloader tool. Now repeat on the other side.
6. If the front ride height is too high, tighten the bolt on the unloader tool to take weight off the adjusting arm. Unscrew adjustment screw. Slowly unscrew the bolt on the unloading tool until you have achieved the correct front ride height. Retighten the adjusting screw until it is snug on the adjusting arm. Remove unloader tool.
7. Drive for a day, while it settles, then recheck.
Any advice, input, suggestions, or ideas to make this more efficient please speak up before I get started. Thanks again, Scott
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI
Houston, Texas
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| Re: Setting the front ride height procedure [message #292820 is a reply to message #292808] |
Wed, 23 December 2015 16:54  |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Harry -
If you don't unload the pressure on the adjustment screws for the torsion bars, you will almost certainly strip them - they'll hold the bars in place but they aren't intended to move them. Buy, beg, borrow, steal, or fabricate an unloader if you're going to play with the front ride height.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
[Updated on: Wed, 23 December 2015 16:54] Report message to a moderator |
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| Re: Setting the front ride height procedure [message #292825 is a reply to message #292808] |
Wed, 23 December 2015 17:38 |
Scott Nutter
Messages: 782
Registered: January 2015
Location: Houston/San Diego
Karma: 4
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As far as lifting up the front end........and once again, I haven't done this before...........
If the wheels are on the ground, not jacked up, with the unloader tool in place and the bolt tightened up to take the tension off the adjustment bolt. Shouldn't the adjustment bolt be able to be unscrewed with a socket? I don't see where any thing would be blocking it from being loosened....
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI
Houston, Texas
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| Re: Setting the front ride height procedure [message #292826 is a reply to message #292825] |
Wed, 23 December 2015 17:43 |
Scott Nutter
Messages: 782
Registered: January 2015
Location: Houston/San Diego
Karma: 4
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Senior Member |
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And would anyone know how many full turns of the adjustment bolt it takes to raise the front ride height one inch?
So far it sounds like the weight needs to be off the front tires to adjust..
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI
Houston, Texas
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| Re: Setting the front ride height procedure [message #292834 is a reply to message #292832] |
Wed, 23 December 2015 19:51 |
Scott Nutter
Messages: 782
Registered: January 2015
Location: Houston/San Diego
Karma: 4
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OhOk. Thanks Larry! Now it makes sense. The bolt in guestion that will strip is the bolt on the tool. Why doesn't the shop manual mention this in their step by step instructions?
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI
Houston, Texas
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| Re: [GMCnet] Setting the front ride height procedure [message #292840 is a reply to message #292834] |
Wed, 23 December 2015 20:33 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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It is not the bolt on the tool. It will be the pork chop adjusting bolt and
nut that lives in the cross member where the pork chop is located. I
personally have replaced too many of them to count. No doubt stripped by
well intentioned but misinformed or uninformed people who were not using a
torsion bar unloader tool. Yes, lift the coach, install the unloader tool,
tension the center bolt until the bolt in the cross member can be moved
freely with the nut. Then, and only after you have soaked them in your
favorite perpetrating medium, remove the bolt and nut, clean up the
threads, coat the entire length of the bolt with never-seez, and replace
the nut and bolt. Take 3 turns on the center bolt of the unloader tool,
then tighten the adjusting bolt. Remove the unloader tool, lower the coach,
drive it for 8 or 10 miles, then check ride heights front and rear. Repeat
as needed.
Jim Hupy
Salem, Or
On Dec 23, 2015 5:52 PM, "Scott Nutter" wrote:
> OhOk. Thanks Larry! Now it makes sense. The bolt in guestion that will
> strip is the bolt on the tool. Why doesn't the shop manual mention this in
> their step by step instructions?
> --
> Scott Nutter
> 1978 455 Royale Center Kitchen, Quad bags.
> Houston, Texas
>
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| Re: [GMCnet] Setting the front ride height procedure [message #292845 is a reply to message #292840] |
Wed, 23 December 2015 22:36 |
Scott Nutter
Messages: 782
Registered: January 2015
Location: Houston/San Diego
Karma: 4
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Thanks Jim, I was wondering if there might be some type of nut associated with the adjustment bolt. Once again, not mentioned in the shop manual that I saw. After Christmas I will be in it!! And thanks everyone for the help. Merry Christmas, Scott.
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI
Houston, Texas
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| Re: [GMCnet] Setting the front ride height procedure [message #292850 is a reply to message #292819] |
Thu, 24 December 2015 06:02 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I am going to disagree with Larry. I have adjusted the ride height on many coaches with my un-loader tool and we ALWAYS do it with the weight on the wheels. If you do it with the wheels hanging you have no input as to how much the coach has raised or lowered when you turn the adjustment tool screw. Doing it by dropping the wheels means you will have a very long procedure because you will have to drop the coach, drive it around, and then measure see what your adjustment results are over and over again for each correction. For each correction you will have to set it up again.
The 6 turn per inch is just a guideline. As you start to turn one side the weight transfers to that side and the first few turns usually just twist the bar without raising the coach. So if you turn the screw on the light side of the coach you will get more than 1" for 6 turns and simultaneously will get some lift on the opposite side. If you are turning on the heavy side you will initially get no lift followed by less than 1" on the heavy side.
So my recommendation is to LUBRICATE the screw on the adjustment tool liberally. I use anti-seize but oil will do. Then adjust the bars on both sides with the weight on the wheels. After adjusting the second side, recheck the first side, and change it as necessary. Go back and forth between the two sides until no change is required on either side. Then drive the coach for a few miles and recheck your measurements / adjustments.
It is imperative that the REAR END be blocked in place at EXACTLY EQUAL height during the front height adjustment. We have found that a 1/4" difference in side to side height in the rear will transfer 125 pounds from side to side in the front (with a corresponding change in front ride height).
One other comment on your procedure. You can also cut some blocks for the front height measurement to the bottom of the frame rather than tape measure to the top of the holes. I do not remember the dimension of the blocks at the moment and my measurement stuff is not at home for me to look at right now.
I cut up a bunch of scrap lumber and handed out the pre-cut blocks at several of the GMCMI rallies. The blocks make adjustment much easier. I use 1x2's for the front blocks and 2x4's for the rear blocks so we do not get them confused while using them. Front and rear are different lengths.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Setting the front ride height procedure [message #292851 is a reply to message #292850] |
Thu, 24 December 2015 06:22 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Read here
http://gmcmotorhome.info/TORSION.html
On Thursday, December 24, 2015, Ken Burton wrote:
> I am going to disagree with Larry. I have adjusted the ride height on
> many coaches with my un-loader tool and we ALWAYS do it with the weight on
> the
> wheels. If you do it with the wheels hanging you have no input as to how
> much the coach has raised or lowered when you turn the adjustment tool
> screw. Doing it by dropping the wheels means you will have a very long
> procedure because you will have to drop the coach, drive it around, and then
> measure see what your adjustment results are over and over again for each
> correction. For each correction you will have to set it up again.
>
> The 6 turn per inch is just a guideline. As you start to turn one side
> the weight transfers to that side and the first few turns usually just twist
> the bar without raising the coach. So if you turn the screw on the light
> side of the coach you will get more than 1" for 6 turns and simultaneously
> will get some lift on the opposite side. If you are turning on the heavy
> side you will initially get no lift followed by less than 1" on the heavy
> side.
>
> So my recommendation is to LUBRICATE the screw on the adjustment tool
> liberally. I use anti-seize but oil will do. Then adjust the bars on both
> sides with the weight on the wheels. After adjusting the second side,
> recheck the first side, and change it as necessary. Go back and forth
> between
> the two sides until no change is required on either side. Then drive the
> coach for a few miles and recheck your measurements / adjustments.
>
> It is imperative that the REAR END be blocked in place at EXACTLY EQUAL
> height during the front height adjustment. We have found that a 1/4"
> difference in side to side height in the rear will transfer 125 pounds
> from side to side in the front (with a corresponding change in front ride
> height).
>
> One other comment on your procedure. You can also cut some blocks for the
> front height measurement to the bottom of the frame rather than tape
> measure to the top of the holes. I do not remember the dimension of the
> blocks at the moment and my measurement stuff is not at home for me to look
> at right now.
>
> I cut up a bunch of scrap lumber and handed out the pre-cut blocks at
> several of the GMCMI rallies. The blocks make adjustment much easier. I
> use
> 1x2's for the front blocks and 2x4's for the rear blocks so we do not get
> them confused while using them. Front and rear are different lengths.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] Setting the front ride height procedure [message #292860 is a reply to message #292851] |
Thu, 24 December 2015 11:15 |
Scott Nutter
Messages: 782
Registered: January 2015
Location: Houston/San Diego
Karma: 4
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Ken Burton's technique sounds more like the way the manual describes the procedure. The shop manual does not mention any steps of raising the front end. Also, all the informational videos on YouTube show the wheels on the ground during adjustments. Although the videos were all GMC trucks.
So, being my first time, I am going to err on the safe side. I will set the front ride height with the wheels OFF the ground. Once I'm under the coach I can actually get a better idea of what's going down there and the amount of force actually on the unloader tool. Then after the first test drive, I will fine tune the front height with the wheels ON the ground if I think I can do it safely. I will also try to post the end results with pictures. Scott
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI
Houston, Texas
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| Re: [GMCnet] Setting the front ride height procedure [message #292864 is a reply to message #292860] |
Thu, 24 December 2015 12:14 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I have done about 20 GMCs over the years. The last one was about 6 or 7 weeks ago. If you are going to do it jacked up in the air, be sure to park the coach when you return each time from your driving trip, straight with no turning bind on either the front or rear wheels. Drive it straight in and take your hands off of the steering wheel for the last 10 feet or so.
We do it slightly different here because we have the luxury of independent wheel scales. We still block the rears but we adjust the fronts for equal weight on each wheel. Then after removing the scales we adjust the front height. Almost always the fronts are equal in height when the weight is equal and the rears blocked. Then we can crank the bars up or down equally to the the front heights exact. We consider anything less than 100 pounds difference acceptable but we shoot for a 50 pound difference with no occupants. Almost always the left rear is heavier that the right rear, so if there is a difference in the front we go for 0 to 50 pounds heavier on the left side.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Setting the front ride height procedure [message #292865 is a reply to message #292860] |
Thu, 24 December 2015 12:17 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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I do ride height adjustments on GMC MOTORHOMES all the time. Jerry Work
knows as much about alignment and ride height adjustments as anyone. He has
a procedure on his website, thedovetailjoint.com We do them exactly as he
describes it. Seldom have issues. But, feel free to learn for yourself.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Dec 24, 2015 9:16 AM, "Scott Nutter" wrote:
> Ken Burton's technique sounds more like the way the manual describes the
> procedure. The shop manual does not mention any steps of raising the front
> end. Also, all the informational videos on YouTube show the wheels on the
> ground during adjustments. Although the videos were all GMC trucks.
>
> So, being my first time, I am going to err on the safe side. I will set
> the front ride height with the wheels OFF the ground. Once I'm under the
> coach
> I can actually get a better idea of what's going down there and the amount
> of force actually on the unloader tool. Then after the first test drive, I
> will fine tune the front height with the wheels ON the ground if I think I
> can do it safely. I will also try to post the end results with pictures.
> Scott
> --
> Scott Nutter
> 1978 455 Royale Center Kitchen, Quad bags.
> Houston, Texas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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