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Info on Upgrading 93 Prevost 10K hitch to 25K-30K
I a looking for information on upgrading my existing 8V92 hitch/motor cradel or installing a separate support framework to tow a stacker.
Thank you in advance
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14 Replies
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You might want to look for a bus with a series 60 in it.
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Thanks, but already own the bus. Really looking for someone/Company to design the new frame extension.
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I have an 8V92 and I tow a 6,000 lb Ford Ranger. I am not sure how much towing you have done with your 8V but that is a lot of weight for that engine.
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Yes, it will be a lot of weight and I have never seen even an estimated GCWR for my bus, but I’m assuming the drive train will be OK.
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Cooling will be one of your hurdles. The 8V runs warmer than the S60
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At one time Prevost had a means to upgrade a 10,000 pound hitch to 20,000 (1,500 tongue weight)
If it is not a Prevost designed upgrade do yourself a favor and get a coach specifically designed for the weight you want to tow.
Over the years a lot of Prevost coaches have had structural failure (hidden) because the owners did not comply with the limits which going by memory were the stated hitch weight limit at about 8″ out from the bumper. The typical issue was the CG of the hitch weight was often further out, such as on a motorcycle carrier with the CG as much as 24″ out and a bike weight of 500 lbs, making the limit exceeded by 50% or more.
The Prevost structure that typically experiences broken welds is that which extends downward, sandwiched between the outer skin and the coach interior. First evidence of that will be cracks across the bottom of the rear cap or cracks around the rear cap rivets. The ultimate outcome is the probability the engine cradle will fail.
Prevost will NEVER EVER repair that type of structural failure because they want to stay away from the liability and rightfully so. A Prevost is a bus, was designed for use as a bus and was never designed to be used to pull a trailer.
Clint & Tammy Summers
2000 XL 45 Country Coach (rivets)
1977 FC31 Bluebird Wanderlodge (more rivets)
Vonore TN -
Thank you for your response.
Yes, Prevost offers an upgrade to 20K, but only for the S60 engine.
If you have more information about the structure – diagram or schematic – of where the frame has failed that would certainly be of interest.
Sometimes is isn’t what you do, but how you do it. The bus is a very capable vehicle, my plan is to attach new structure to the frame and eliminate any additional load on the engine cradle.
Thanks again
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Maybe you can find someone who is experienced in designing and installing roll cages to adapt that skill for what you need.
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If Prevost wanted it to tow that much, they would have designed it that way. Take the advice you already got and forget about trying to do it. If you really need to tow up to 20k, then get a newer coach that has been designed to do that. You will be far better off doing that, and safer too.
1999 XLV X-6872, liberty #440 -
To see the bus structure the Prevost website provides access to the service manuals and the detailed views of the structure.
Big mistake to try it, but it is your bus.
1999 XLV X-6872, liberty #440 -
Thank you
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I regularly towed about 11000# with my 8V92 making gross weight about 55000#. Drivetrain was ok but you had to be careful about coolant temp (gear down, slow down, and keep revs up) and diff temp. Run full synthetic in all. I had no fan clutch on cooling fan and had installed the 9 blade series 60 fan.
I regularly tow 20000# with my series 60 grossing at about 70000#. Cooling is not an issue on the series 60 as the computer handles it but diff temp still is even though it is a larger axle. Slowing to 60-65 handles diff temp. Make sure you install a gauge if you don’t have one.
I tried to post a photo of rig. Note the front axle on the trailer…virtually no tongue weight. Competitive built about a dozen of these.
All the above said, I push the envelope all the time but I agree with most that you’d probably be better off with a series 60 coach and the larger diff. Not sure when it was phased in but my 1989 took 3 gallons on a diff oil change and my 1999 chassis takes 5 gallons.
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My 97 and my 06 took 5 gallons. Extra volume really helps with cooling.
The key to towing apart from cooling issues is low tongue weight. Towing forces in a straight line back are easily handled. A typical tow bar puts little more than the weight of the bar on the bus hitch since it pivots at both ends. A trailer does not pivot up and down so what ever weight sits on the bus hitch is what it carries on smooth roads. But that is not a static weight.
We all have driven over the whoopdee type road irregularities that bottom the front suspension and the air seat so as the rear of the bus is thrust upward as the steer axle does when the rear suspension is bottomed out the increase in weight on the hitch ramps up to a considerable degree. The bus hitch is cantilevered from the structure carrying the rear axles so the weight of the engine and transmission is hanging out there like a 10 pound weight in your hand with your arm extended.
To add support Prevost extends some stressed members down and to the rear from the upper bus structure. Keep in mind however that structure was only intended to carry the engine to an extent so adding an increased percentage of weight exposes those welds and members to far more weight than a bus is expected to carry.
A trailer, especially a heavy one needs tongue weight for stability otherwise it becomes the tail wagging the dog so addressing the structural issue becomes complex and if by now with all other factors not an issue, such as cooling, Prevost can certainly do a redesign but it is a cost versus rewards problem. Add in the difficulty cooling an 8V92 in perfect condition but with a much greater heat load it does not seem ideal.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
David:
I agree, concur, and second all the cautionary comments. Make sure you completely understand the necessary engineering.
I’d like to dwell on the differential. Our coaches are a single screw. You’re going to be putting a significant amount of torque and horsepower through that single differential. Possibly more than it was designed for. I would try to locate the manufacturer and determine if synthetic lube can be run in it and get the best synthetic you can find.
I would also install a differential temp gauge. Whatever diff lube you use, know its operating range and stay within that; which might limit your cruising speed and add challenges climbing long grades.
I would also consider replacing the axles. Unless you’ve owned the coach from new, you don’t know if a previous owner has abused the differential or axles. Last year a friend had an axle on his Prevost break. It was a very expensive experience which entailed a tow, complete breakdown of the differential and hubs to thoroughly clean everything out. I had an axle in the race car’s Ford 9″ break once and it took us hours before the mechanic was satisfied everything was clean enough.
Keep us posted as to what you do.
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