Towing with a Gas engine

[dylanking50]

Im wondering if it would be possible to tow a vehicle behind a bus with 8.1L gas engine and Allison transmission? Any thoughts are appreciated.

[magnakansas]

yes you can..........now go find the specifications and limitations of your bus/transmission in dont over load it.

william

[CHEESE_WAGON]

Originally Posted by magnakansas

yes you can..........now go find the specifications and limitations of your bus/transmission in dont over load it.

william

THIS!

Some more info on the bus in particular would be useful in helping to determine this. A simple GVWR on a body plate does not help if you don't know the empty weight (or total weight as converted) or what the trans is rated for. And the trans is usually the weak link in such situations. I would highly recommend an auxiliary transmission fluid cooler if not already equipped, if it is doable.

OP's 8.1 / Allison combo sounds a lot like a late-90s / early 00s Chevy / GMC Class 7 chassis, or MAYBE a similar vintage Savana/Express van chassis minibus. On the latter, a GM dealer should be able to find this info for you if there are no postings of it on the vehicle anywhere. If nothing else, identifying the trans model you have can get you some info from the trans manufacturer (in this case, Allison).

In theory, you should be able to, but for instance, the P30 motorhome I live in is only rated for 2,000 lbs towing capacity. Granted, it is likely a TH400, being powered by a 454 big-block Chevy (the 8.1 Vortec's older brother -- the 8.1 is a 496, the stroker version of a 454), but the vehicle's empty and loaded weight count towards the transmission's rated capacity. Point being, you can have all the engine in the world, but if the trans can't take it, it is what it is. This is the reason that most commercial trucks are manuals. An Alllison unit should be able to handle quite a bit more than a typical light-duty automatic, however.

[Sehnsucht]

As you've already read, the weakness isn't the gas engine but most likely to be the transmission. Saying it's an Allison doesn't help - Allison is just a manufacturer brand name, not a specific product. The model will help us offer better advice. For one thing, if this is a full size bus you're talking about and it's a gas engine it is probably fairly old and it's possible the transmission it's paired with doesn't have a lockup torque converter which will considerably impact it's suitability for towing. I'm just speculating until more detailed information can be shared but that'll be my first potential red flag. Following that will be GVWR as has also already been mentioned because in no circumstance should the vehicle or combination of vehicle and towed unit exceed the manufacturer's specifications. Besides being foolhardy it's also an enormous liability and can result in insurance default if you're in an accident (regardless of fault) and it's revealed that your vehicle was overloaded. I only mention this because I wouldn't expect a gas engine bus to be rated much beyond its own loaded weight much less the added weight of any kind of towed unit.