| Handling vs. ride height [message #182986] |
Mon, 03 September 2012 09:13  |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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Senior Member |
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Hi,
Recently got a complete front end and steering rebuild and quad bags installed by Kanomota & Co. Very happy with the work and communication links and response in aftermath, but here's the problem. Handling on trip home to Oregon was very poor, worse than before. JimK suggested I check the ride height, and indeed it is way off - front about 7/8" too low, though rears are about right. When I lowered the rears and ran in manual, handling miraculously improved, confirming JK's diagnosis.
Not practical for me to take it back to CA for JimK to fix it, so the plan for long term solution is for Jim Hupy to take a look at it around the end of September when he's done with Canada and another trip to CA, and in his exceptional and legendary customer service, JimK will make everything right if there was a problem in his install, but meanwhile I'm just looking for some answers.
1) How could front end be so low after a rebuild? Offset bushings were installed, alignment came in good with 4 deg caster.
2) What is it about the geometry of the front-back suspension that so destroys handling if the rear is too high in relation to the front?
Thanks for my continuing education,
Jay Rabe
76 PB
Portland, OR
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| Re: [GMCnet] Handling vs. ride height [message #182992 is a reply to message #182986] |
Mon, 03 September 2012 10:36  |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Jay,
The answer to your question #1 is a term called "Settling". Every
time that you make an adjustment on the front or rear suspension you
need to drive the coach for several miles for the ride height to
settle for the point it was adjusted to then check for ride height
before making another adjustment! It may settle higher or lower than
the point that you set it for and may take several adjustment to reach
what you want. I am sure that Jim's shop does this every time they
adjust ride height on a coach and it was within spec's when they
finished. What may have happened to you is that during the trip home
the new part that were installed may have caused additional settling
after several hundred miles that caused the coach ride height to
change after it left the shop.
As for #2 the castor changes with rear ride height. The first coach I
owned when it was set right the rear end appears to be slightly lower
than the front going down the road. That coach drove with two finger
steering all the years that I own it. If your coach had settle in the
front then the rear was higher and the castor change. When Jim told
you to lower the back the castor returned to where the coach drove
better. Jerry Work's says when aligning the coach "It"s ride height,
right height, right height!' You guys up in the Northwest had a rally
last year where they checked ride height on the coaches that attended
the rally and only 2 coaches out of the 50+ coaches that attended the
rally had correct ride height.
I am sure that Jim Hupy will be able to help you get your ride height
worked out!
JR Wright
78 Buskirk Stretch
Michigan
On Sep 3, 2012, at 10:13 AM, Jay Rabe wrote:
>
>
> Hi,
>
> Recently got a complete front end and steering rebuild and quad bags
> installed by Kanomota & Co. Very happy with the work and
> communication links and response in aftermath, but here's the
> problem. Handling on trip home to Oregon was very poor, worse than
> before. JimK suggested I check the ride height, and indeed it is way
> off - front about 7/8" too low, though rears are about right. When I
> lowered the rears and ran in manual, handling miraculously improved,
> confirming JK's diagnosis.
>
> Not practical for me to take it back to CA for JimK to fix it, so
> the plan for long term solution is for Jim Hupy to take a look at it
> around the end of September when he's done with Canada and another
> trip to CA, and in his exceptional and legendary customer service,
> JimK will make everything right if there was a problem in his
> install, but meanwhile I'm just looking for some answers.
>
> 1) How could front end be so low after a rebuild? Offset bushings
> were installed, alignment came in good with 4 deg caster.
>
> 2) What is it about the geometry of the front-back suspension that
> so destroys handling if the rear is too high in relation to the front?
>
> Thanks for my continuing education,
>
> :)
>
> Jay Rabe
> 76 PB
> Portland, OR
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: Handling vs. ride height [message #182994 is a reply to message #182986] |
Mon, 03 September 2012 11:07 |
PettyVTX
Messages: 363
Registered: April 2011
Location: Winder Ga.
Karma: 1
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Senior Member |
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I just put the 1 ton conversion on my coach while the front frame was out so i had no reference points to go by. When I put everything back in and set the porkchop adjusters back to original position everything looked OK untill i drove it down the driveway and back. When you look at the front end of the coach now you would have thought someone dropped it here from 100 feet in the air my caster is so far off i couldnt belive that it was the same setting i had put on it. So driving it is a must. Luckily for me I have the GURU of frontends coming over to help me set it up today. Before the steering was a 1 finger proposition Im hoping for the same results. I have the new bag setup finished and that shouldnt change rear height but we will see.
Ex Avion now looking for a 23'
Jeep Wrangler Towd
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| Re: Handling vs. ride height [message #183003 is a reply to message #182986] |
Mon, 03 September 2012 14:04 |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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Senior Member |
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Though I'm sure it doesn't make near the difference in our coaches that it does in a small sportscars, we used to corner balance the car with a simulated driver's weight in the front seat before doing the alignments, and it certainly seemed to help the feel and lap times on the track. Ideally, I imagine you should have the coach ride height set with the anticipated weight in the front seats.
As we all have seen, everything affects everything when it comes to alignments. I wonder if the driver's of the diesel pushers worry so much about these sort of things? I have never driven one of those, and don't have any great desire to do that.
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: Handling vs. ride height [message #183006 is a reply to message #182986] |
Mon, 03 September 2012 14:30 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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I plan to to put 150 in dummy weight in the drivers seat prior to my height and allignment work. Insert dummy joke here.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Handling vs. ride height [message #183007 is a reply to message #183003] |
Mon, 03 September 2012 14:29 |
Dolph Santorine
Messages: 1236
Registered: April 2011
Location: Wheeling, WV
Karma: -41
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Senior Member |
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I would hope we don't put that much side force (and pull that many G's).
I have a set of corner balancing scales for our Spec Miata, and we fine tune the suspension with it quite often (this has been a year of dialing it in).
I could not imagine doing it "old school" Digital makes it so much easier, and the software tells me exactly how many turns to put in to get close.
Dolph Santorine
DE N8JPC
Wheeling, West Virginia
dolph@dolphsantorine.com
1977 GMC 26' Palm Beach
TZE167V100820
1976 GMC 26' Donor Coach
TZE166V101610
On Sep 3, 2012, at 3:04 PM, George Rudawsky wrote:
>
>
> Though I'm sure it doesn't make near the difference in our coaches that it does in a small sportscars, we used to corner balance the car with a simulated driver's weight in the front seat before doing the alignments, and it certainly seemed to help the feel and lap times on the track. Ideally, I imagine you should have the coach ride height set with the anticipated weight in the front seats.
>
> As we all have seen, everything affects everything when it comes to alignments. I wonder if the driver's of the diesel pushers worry so much about these sort of things? I have never driven one of those, and don't have any great desire to do that.
> --
> George Rudawsky
> Chicago, IL
> 75 Palm Beach
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Handling vs. ride height [message #183027 is a reply to message #183007] |
Mon, 03 September 2012 19:05 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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John,, Your dummy weights are out driving on the streets of America and do not have the time for comments. LOL
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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