Front Ride Height with Motorcycle on Bumper Hitch?

[Rob]

I *finally* got around to adjusting my (VERY low) front ride height...

I’ve got it reasonably close now - but was thinking I often carry a ~350 lb scooter on a rear bumper hitch rack and it likely affects the front ride height... Perhaps when I was low - it was affecting the front height to a larger degree?

Has anyone ever measured the difference in front ride height - with & without a load like that on the rear bumper? We’ve got a trip coming up I’m not sure I’ll be able to adjust it again before we leave...

Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath

 

[sgltrac]

I wouldn’t worry too much about 350 pounds on the rear bumper. The air
system will compensate for it.

Sully
Bellevue wa

> I *finally* got around to adjusting my (VERY low) front ride height...
>
> I’ve got it reasonably close now - but was thinking I often carry a ~350
> lb scooter on a rear bumper hitch rack and it likely affects the front ride
> height... Perhaps when I was low - it was affecting the front height to a
> larger degree?
>
> Has anyone ever measured the difference in front ride height - with &
> without a load like that on the rear bumper? We’ve got a trip coming up I’m
> not sure I’ll be able to adjust it again before we leave...
>
> Rob
> Victoria, BC
> 76 Royale - Rear Twins/Dry Bath
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[jim kanomata1]

I sort of agree with Todd.
The front of every coach we get in our shop is low.
Notice it more on the 77-78 and on the Coachman units.
350lbs if not more than One foot behind the bumper should not raise the
front much more than 3/8 " on a 26' coach.

> I wouldn’t worry too much about 350 pounds on the rear bumper. The air
> system will compensate for it.
>
> Sully
> Bellevue wa
>

>
> > I *finally* got around to adjusting my (VERY low) front ride height...
> >
> > I’ve got it reasonably close now - but was thinking I often carry a ~350
> > lb scooter on a rear bumper hitch rack and it likely affects the front
> ride
> > height... Perhaps when I was low - it was affecting the front height to a
> > larger degree?
> >
> > Has anyone ever measured the difference in front ride height - with &
> > without a load like that on the rear bumper? We’ve got a trip coming up
> I’m
> > not sure I’ll be able to adjust it again before we leave...
> >
> > Rob
> > Victoria, BC
> > 76 Royale - Rear Twins/Dry Bath
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502

 

[Rob]

Thanks to you both!

I was just over 2” low when I checked it! When I raised the front - I now have a good “shake” when accelerating moderately. I’ve noticed a similar shake, when I was low in the front and added the scooter to the bumper. So it made me think that it might be worse now that it’s correct up front and I add the scooter...

Manny suggested it likely needs some alignment changes to deal with the huge difference in height... But - over a month to get into a shop...

Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath

> I sort of agree with Todd.
> The front of every coach we get in our shop is low.
> Notice it more on the 77-78 and on the Coachman units.
> 350lbs if not more than One foot behind the bumper should not raise the
> front much more than 3/8 " on a 26' coach.
>

>
>> I wouldn’t worry too much about 350 pounds on the rear bumper. The air
>> system will compensate for it.
>>
>> Sully
>> Bellevue wa
>>

>>
>>> I *finally* got around to adjusting my (VERY low) front ride height...
>>> I’ve got it reasonably close now - but was thinking I often carry a ~350
>>> lb scooter on a rear bumper hitch rack and it likely affects the front
>> ride
>>> height... Perhaps when I was low - it was affecting the front height to a
>>> larger degree?
>>> Has anyone ever measured the difference in front ride height - with &
>>> without a load like that on the rear bumper? We’ve got a trip coming up
>> I’m
>>> not sure I’ll be able to adjust it again before we leave...
>>> Rob
>>> Victoria, BC
>>> 76 Royale - Rear Twins/Dry Bath
>>> _______________________________________________
>>> GMCnet mailing list
>>> Unsubscribe or Change List Options:
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>
>
> --
> Jim Kanomata ASE
> Applied/GMC, Newark,CA
> jimk
> http://www.gmcrvparts.com
> 1-800-752-7502
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:

 

[Carl Stouffer]

I sometimes tow a ~4000# trailer with my coach, The tongue weight is approx 400 I've never measured it, but if the front end height changes when I
add that load to the hitch, I don't notice it
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member

 

[Rob]

Yes - I was thinking that some of the tongue weights must be a similar load!

Thanks for the reply.

Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath

>
> I sometimes tow a ~4000# trailer with my coach, The tongue weight is approx 400 I've never measured it, but if the front end height changes when I
> add that load to the hitch, I don't notice it
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
> Solar battery charging. GMCSJ and GMCMI member

 

[boybach]

Why not get the front wheels (re?) balanced Rob and see if that sorts it out?

Larry
--
Larry - Victoria BC -

1977 Palm Beach 40,000 miles, PO said everything working but forgot the word NOT. New Atwood fridge, water heater & furnace. New SS exhaust system,
6000w Onan, Iota Converter, R134A A/C, New fuel lines & heat exchange hoses

 

[Rob]

Thanks, but I don't think it's at all related to wheel balance. The
shake is not there at all at the lower height, or when accelerating more
slowly, or at speed.

Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath

> Why not get the front wheels (re?) balanced Rob and see if that sorts it out?
>
> Larry

 

[jim kanomata1]

If the shake comes in under acceleration, it is not the balance, but
possible drive line issue.
How many miles on them???

> Thanks, but I don't think it's at all related to wheel balance. The
> shake is not there at all at the lower height, or when accelerating more
> slowly, or at speed.
>
> Rob
> Victoria, BC
> 76 Royale - Rear Twins/Dry Bath
>

> > Why not get the front wheels (re?) balanced Rob and see if that sorts it
> out?
> >
> > Larry
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502

 

[Ken B]

Go back and readjust your torsion bars again for EQUAL WEIGHT within 100 pounds side to side on the front wheels. Then check the ride heights again.
If the heights are not equal, then you have a rear airbag imbalance and maybe a height imbalance there too.

I had one guy stop by here with that problem. We fixed it by doing the above.

When setting the front ride heights you need the rears blocked at an exact equal height so they can not move as you make changes to the front.

I have a pair of 2x4's cut to the correct rear height. They are usually used for measuring rear heights but when adjusting the front, I set the 2x4's
under the frame and drop the rear air until the frame touches them and I put a little weight on them maybe 150 to 200 pounds each. Just enough weight
so they can not move while making changes to the front.

With the rears blocked we go to the front wheels sitting on scales and adjust the t-bars for EQUAL weight between the sides. OnCe that is done we
find the the heights are also equal. Now remove the scales and adjust both sides the same amount up or down until you get the desired heights
correct.

What you are experiencing is torque steering if it varies a little on heavy acceleration. The torque is switching between the wheels as you
accelerate. The wheels do not need to slip or spin to feel the problem and it is usually more pronounced at slower speeds. Worn lower a-frame
bushings exacerbates the problem.

A comment on motorcycles on the rear. I have two motorcycles that I switch between. One is around 350 pounds and the other 450 pounds plus the 40 -
50 pound carrier they ride on. I have never had a problem hauling either of them and at times I forget they are even back there. I have to look in
the center mirror occasionally just see if the handle bars are still there to confirm they are still attached. Since I have never had a problem, I
have never checked the front weight or ride height with them back there. If I remember I will get out the measuring blocks and slide them under the
front to see next time I haul one of them to a rally. The rears will not change due to the automatic air bags. I do not expect the fronts to change,
but I could be wrong on that.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Rob]

Thanks for the details.

Yes - I cut blocks and lowered the rear when performing the
measurements. I did not measure/balance weights - I'll have to see if I
can do that.

Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath

> Go back and readjust your torsion bars again for EQUAL WEIGHT within 100 pounds side to side on the front wheels. Then check the ride heights again.
> If the heights are not equal, then you have a rear airbag imbalance and maybe a height imbalance there too.
>
> I had one guy stop by here with that problem. We fixed it by doing the above.
>
> When setting the front ride heights you need the rears blocked at an exact equal height so they can not move as you make changes to the front.
>
> I have a pair of 2x4's cut to the correct rear height. They are usually used for measuring rear heights but when adjusting the front, I set the 2x4's
> under the frame and drop the rear air until the frame touches them and I put a little weight on them maybe 150 to 200 pounds each. Just enough weight
> so they can not move while making changes to the front.
>
> With the rears blocked we go to the front wheels sitting on scales and adjust the t-bars for EQUAL weight between the sides. OnCe that is done we
> find the the heights are also equal. Now remove the scales and adjust both sides the same amount up or down until you get the desired heights
> correct.
>
> What you are experiencing is torque steering if it varies a little on heavy acceleration. The torque is switching between the wheels as you
> accelerate. The wheels do not need to slip or spin to feel the problem and it is usually more pronounced at slower speeds. Worn lower a-frame
> bushings exacerbates the problem.
>
> A comment on motorcycles on the rear. I have two motorcycles that I switch between. One is around 350 pounds and the other 450 pounds plus the 40 -
> 50 pound carrier they ride on. I have never had a problem hauling either of them and at times I forget they are even back there. I have to look in
> the center mirror occasionally just see if the handle bars are still there to confirm they are still attached. Since I have never had a problem, I
> have never checked the front weight or ride height with them back there. If I remember I will get out the measuring blocks and slide them under the
> front to see next time I haul one of them to a rally. The rears will not change due to the automatic air bags. I do not expect the fronts to change,
> but I could be wrong on that.
>