PLEASE HELP! IDEAS FOR SOFTENING SUSPENSION

[Mex-Busnut]

Dear Friends,

I am new to the list. I hope this is the right place to ask a question.

We have a 1992 Ford B700 school bus, with a Thomas body that is designed to seat 28 people, powered by a Cummins 5.9L ISB engine. The suspension seems very hard. In fact, a friend renamed it the "Bioshaker"! It has Michelins, which are set at 90 pounds PSI. It has leaf-springs, front and back.

Any ideas are appreciated!

Thanks in advance!

Dr. Steve, central old Mexico

[PP]

Hey Doc, Welcome to the board. We had an old Skoolie way back when and it rode like a truck. In fact, I think it rode like a truck because it was basically a truck suspension. It softened out after the conversion because of all the weight we added to her. Solid and dependable--gotta love that! FWIW-while lowering the air pressure in the tires will help with the stiff ride, it will also cause your tires to get overly warm and increase fuel consumption. That's my interpretration from experience. Good luck, Will

[zubzub]

yep....they ride like trucks cause they are trucks....and the ride is a little better when fully loaded.  I don't know if anyone has tried converting to air ride but it would be complicated as I'm pretty sure the leaf springs also locate the axle, so you can't just get rid of them....maybe taking out a few leafs and adding air bags is simpler,  then you can tune the ride.  I know there are overload bags that work with spring set ups, so reducing the leaf springs a little and adding the bags might be a simple solution. 
Please Note:  I'm just theorizing  I have no experience in this.

[Tom Y]

What size are the tires? 90 PSI may be to much. What does the tag on the bus say for pressure? How heavy is it?  Tom Y

[wrench]

  Here the way I did it.   #15 PSI up front,   #40 PSI rear.
          1972 bluebird.

[Eagle Andy]

Hey Steve back in the day when I was building roadster's and the like we would try putting teflon between the leaf springs might be a little out dated today I don't know . But removing a couple of springs and adding air bags might work as was mention earlier . anyway good luck .

[Eagle Andy]

I new there would be an answer here , looks good  Wrench

[HB of CJ]

Possibly the bus chassis was ordered, converted and employeed as a schoolie and now motorhome-to-be with the wrong suspension...from the factory.  Leaf springs can ride nice.  My Crown Supercoach ex-schoolie had leaf springs front and rear and had a very nice firm but easy ride, even when empty.

If all else fails, check out your local, friendly, inexpensive wrecking yard and look for some one to two ton front and rear springs.  Might be cheaper than having your spring shop remove every other leaf on your existing springs.  Also a good set of HD truck Monroe shocks helps too.  HB of CJ (old coot)

[Iceni John]

Hi, Wrench:

I'm very interested in what you did.   I may need to add supplemental air springs to my bus, because Crown used different numbers of leaves in the rear springs to compensate for the two 8D batteries on the left side, but I will eventually have more weight on the right side (where the rear spring now is two leaves softer).   Even now my bus leans slightly to the right because I have all my heavy stuff on the right side, so when I also get up to eight golf cart batteries on the right side it will make it worse.   (If I add air bags I'll have to change my tag line . . .)
Are those Firestone air bags?   Do you feed them off the accessories air tank through regulators, or do they have their own independent air supply?   Do their pressures vary according to how loaded the bus is, or are their pressures fixed?

I've also heard of folk taking out almost all their springs' leaves, leaving just enough to still locate the axle, then adding air bags as the primary means of suspension.   If one did that, would one also have to change shocks?   (I don't intend to go that far!)   My bus rides really well, especially now that I made a spare tire mount under the nose that adds 200-plus pounds to the front, so I don't need to soften the ride per se, just reduce my right-leaning proclivities.

Eagle Andy:  I heard that Rolls Royce used to oil their leaf springs and then protect them in leather gaiters, I guess for the same reason as roadster folk using PTFE.   Maybe a dry graphite lubricant that wouldn't attract road dirt could work instead?

Dr.Steve:  Are you anywhere near Aguascalientes by any chance?   I would love to take my bus deep into Mexico when it's finished (the bus, not Mexico).   Having a Mexican GF helps!   Have you had any issues with the authorities anywhere?   How easy is it returning to USA?

Thanks, John

[BG6]

We have a 1992 Ford B700 school bus, with a Thomas body that is designed to seat 28 people, powered by a Cummins 5.9L ISB engine. The suspension seems very hard. In fact, a friend renamed it the "Bioshaker"! It has Michelins, which are set at 90 pounds PSI. It has leaf-springs, front and back.

The one piece of information we really need is to know what stage of conversion you're at.

The skoolie is a truck chassis with a metal box on it.  It has to handle not only that weight, but the weight of an adult passenger in every seat, plus all the stuff they might bring on board.  So, fully loaded, you are looking at THREE TONS of payload.  If you have an empty shell, with the seats out, not only do you not have that three tons, you have even less weight.

Until you have the conversion done, you won't know what the real weight on the springs will be.  If the conversion IS done, you have two possible issues -- too much spring or NOT ENOUGH.  Someone will need to get under there and verify that the springs are still arched.  If they are, and if there is too much spring, have a suspension shop take the smallest one out on each side and see what that does for you.  However, it's possible that you have too much weight on the springs, in which case they have inverted.  This is dangerous, and you will need to either reduce weight or add spring.

[robertglines1]

Got to share when we used to lower cars in the front....4 fat guys on hood and cutting torch to heat springs---- ::)really once your done enough to have a operational weight..your local spring shop can adjust you spring weight rate..