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02-17-2025, 12:19 AM
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#1
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Junior Member
Join Date: Feb 2025
Posts: 6
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Wheel hop on a Unicorn 1991 Starcraft Motorhome class A 37'
Just turned over 40k miles, this unicorn motorhome is a flawless work of art. Bought at 17k miles with like new tires that were 12 years old. Used the old tires for one season with no issues and probably could had ran them all the way down without a failure. Rig is 20,000# fully loaded so not even near tires load capacity so we felt safe. Next season we did replace with Michelins because we were getting front-end hopping at 60mph thought it was the tires, didn't fix it. What could be the issue, the shocks look visually good no leaks? We also had the tires re-balanced. If I give it throttle at speed or let off the hopping stops. Help!
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02-17-2025, 07:27 AM
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#2
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Senior Member
Join Date: Apr 2021
Location: Annapolis
Posts: 753
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Hopping when on the throttle sounds like a bad driveshaft U joint, bad transmission mounts or bad engine mounts.
__________________
2018 Thor Freedom Elite 24
on 2016 Sprinter Chassis
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02-17-2025, 07:44 AM
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#3
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Senior Member
Join Date: Feb 2022
Posts: 419
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Quote:
Originally Posted by MH Mr.fix it
If I give it throttle at speed or let off the hopping stops.
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Not sure you're feeling "wheel hopping" or just feeling vibration.
Sound to me like a driveshaft U-joint as well. Need to get this fixed ASAP or you could end up stranded or worse.
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02-17-2025, 08:07 AM
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#4
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Senior Member
Winnebago Owners Club Workhorse Chassis Owner
Join Date: May 2016
Location: Kamloops, BC, 60 miles from the Center of the Universe according to the Rinpoche, of the SF monks.
Posts: 8,170
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Is it wheel speed or faster? Knowing the frequency/speed will point you in the right direction.
__________________
Happy Glamping, Norman & Elna. 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand! 
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02-17-2025, 12:20 PM
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#5
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Senior Member
Fleetwood Owners Club Workhorse Chassis Owner
Join Date: Jun 2016
Location: On the continental divide
Posts: 3,433
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MH,
IF it has a 2 piece drive shaft, look at the center carrier bearing. At that age the rubber is probably shot. That will give you drive shaft hop. Ask me how I know.
Mike in Colorado
__________________
2004 Fleetwood Pace Arrow 37c, 8.1 gasser, (Jezebel) Ultra RV ECM / TCM, plugs wires, and rear track bar, PPE deep Tx pan w/ temp gage, Bilstein's, Sailun's & Sumo's all round, pushed by a 2002 Grand Caravan, on a Master Tow Dolly OR a WR-250 on a rail.
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02-17-2025, 01:44 PM
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#6
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Senior Member
Join Date: Oct 2014
Posts: 8,901
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Check front tires for RUN-OUT. Even if balanced, an egg shaped tire will hop.
Hard to determine effectiveness of shocks visually. What brand/model? Pull it off and verify resistance, particularly on extension.
__________________
Brett Wolfe
Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
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02-17-2025, 02:55 PM
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#7
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Senior Member
Join Date: Feb 2022
Posts: 419
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Quote:
Originally Posted by wolfe10
Check front tires for RUN-OUT. Even if balanced, an egg shaped tire will hop.
Hard to determine effectiveness of shocks visually. What brand/model? Pull it off and verify resistance, particularly on extension.
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I'm willing to bet that this is not a "tire" problem since he's changed the tires with new Michelin tires and both sets, old and new, had the same problem. The fact that the "hopping" goes away when acceleration and decelerating.
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02-18-2025, 01:17 PM
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#8
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Senior Member
Join Date: Oct 2014
Posts: 8,901
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Quote:
Originally Posted by 92LandYacht
I'm willing to bet that this is not a "tire" problem since he's changed the tires with new Michelin tires and both sets, old and new, had the same problem. The fact that the "hopping" goes away when acceleration and decelerating.
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I agree!
I was just giving a "how to check tires and shocks".
With that age coach, I would start by checking all the suspension bushings, king pins, etc.
__________________
Brett Wolfe
Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
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02-20-2025, 03:01 PM
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#9
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Junior Member
Join Date: Feb 2025
Posts: 6
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1991 Starcraft Hop
Not transmission or driveshaft, bought with 17K miles and now has 40k. The same issue at 17k, now the shocks are just old though, will remove one and give it a test. Front-end is a tight as new, greased every 5k probably not the issue.
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02-20-2025, 03:08 PM
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#10
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Senior Member
Join Date: Nov 2018
Location: Fulda, MN
Posts: 2,056
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I vote for a drivetrain problem. So, you've put up with it for 23k miles?
__________________
2000 Winnebago Adventurer 32v, P32 Workhorse
2005 Winnebago Adventurer 38J W24 Workhorse 8.1l, 5 Speed Allison MH2000
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02-20-2025, 06:18 PM
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#11
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Senior Member
Join Date: Jul 2014
Posts: 37,179
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Quote:
Originally Posted by David 70
I vote for a drivetrain problem. So, you've put up with it for 23k miles?
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Agree with above. Check slip joint for play, with transmission in neutral and wheels chocked. You don't want and strain on the drive train while checking.
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02-20-2025, 08:17 PM
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#12
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Senior Member
Join Date: Apr 2024
Location: WI Driftlesser
Posts: 2,822
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Check the driveshaft U joint "phasing" or "timing". Shouldn't be able to be messed up, but this is not your average bear.
__________________
"Bringing third world electrical work to first world luxury." RV makers of Murica!
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02-21-2025, 06:44 AM
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#13
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Senior Member
Join Date: Dec 2003
Location: Motor City, Mich
Posts: 3,435
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Just to be clear, it is a diesel pusher, correct? Seems like a driveline vibration 30' behind you would feel different than a wheel hop. But if it comes and goes with driveline torque, that does point to the driveline.
What chassis is it? Maybe someone with the same chassis has fixed an issue like yours. Not many with Starcraft boxes on top!
__________________
Tim.
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02-21-2025, 08:20 AM
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#14
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Senior Member
Winnebago Owners Club Workhorse Chassis Owner
Join Date: May 2016
Location: Kamloops, BC, 60 miles from the Center of the Universe according to the Rinpoche, of the SF monks.
Posts: 8,170
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Quote:
Originally Posted by MH Mr.fix it
Not transmission or driveshaft, bought with 17K miles and now has 40k. The same issue at 17k, now the shocks are just old though, will remove one and give it a test. Front-end is a tight as new, greased every 5k probably not the issue.
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So if it did it when you bought it at 17k, how do you know it's not drive line related?
It could be something as simple as a balance weight has come off the driveshaft.
Is it worse at 30 and 60 mph, and less at 45 mph? If so, it's a drive line problem. Been there, done that.  Bad u-joint.
__________________
Happy Glamping, Norman & Elna. 2008 Winnebago Adventurer 38J, W24, dozens of small thirsty ponies. Retired after 40 years wrenching on trucks! 2010 Ford Ranger toad with bicycles or KLR 650 in the back. Easy to spot an RVer, they always walk around with a screwdriver or wrench in one hand!
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Tags
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8.3l, alison, class a, cummins, diesel pusher, flat tow, michelin, motor, motorhome, rare, spartan, starcraft  |
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