I saw a hitch somewhere for an MC-8 or -9 that didn't bolt to the engine cradle. Instead, the bumper cover was removed and this hitch bolted to the framework behind, then the cover was replaced. The receiver extended down below the bumper for the hitch. Is this design any better or worse than the more common bolt-on types? I imagine one could cut a hole in the bumper so the receiver can extend outand avoid the downward section completely. It would be a bit higher this way, which I imagine would be better. Any thoughts / ideas about this?
David
When I built my hitch I did essentially what you describe. However, I opted to not mount the receiver in the bumper for safety reasons. I was worried that if I ever got rear-ended the first thing that would happen is the receiver would be pushed back first and the only place it could go is right into the crank shaft! At least without the receiver there the bumper could spread the load out more and there would be a greater chance of not damaging the crankshaft.
That's a good point about the hitch being pushed into the engine. Perhaps an offset hitch would take care of that. I imagine the hitch frame itself, being behind the bumper, would actually help in the case of an accident, but who the hell would or could rear-end something as big as a bus? You'd have to either be blind or just not paying attention! ::)
David (edited to add a couple missing words)
Quote from: DavidInWilmNC on August 15, 2007, 07:47:07 AM
That's a good point about the hitch being pushed into the engine. Perhaps an offset hitch would take care of that. I imagine the hitch itself, being behind the bumper, would actually help in the case of an accident, but (I'm sure who was supposed to be here) the the hell would or could rear-end something as big as a bus? You'd have to either be blind or just not paying attention! ::)David
Or stupid! and in that case with the three options we've just about narrowed it down to say 75% of the drivers out there on the road today! They don't avoid accidents because of SKILL but rather LUCK! FWIW! ;D BK ;D
Sooooo TRUE!
David: Don't get confused with terminology. The engine cradle is the frame that the engine is fastened to and is pulled out with the engine mounted to it on an engine change.
The engine cradle is fastened to a framework that hangs of the rear bulkhead and gets some support from the rear shell framework, that is connected to the roof framing. Old GM buses had large hanger rods from the engine level to the frame under the rear window. MCI buses just use heavier square tubing in this area.
In theory, on T drives, the rear motor mounts almost balanced the engine and transmission and they were very close to the bulkhead. Many people who do mods and put in heavier engines and radiators don't make allowance for this. The simple fact is that these older model busses were not designed to add weight on the rear bumper. What you can do and what you can get away with is more good luck than good management.
Nobody connects a hitch to the cradle, but it is connected to the framework under the cradle. Since the rear bumper is connected to the back end of this framework you would make the loading worse than if connected to the same framework closer to the bulkhead.
Stan,
That's true about the frame vs. engine cradle. What I should have said was the frame where the engine cradle attaches. Are you talking about vertical loading when you say "... you would make the loading worse than if connected to the same framework closer to the bulkhead"? Several hitches I've seen clamp to the frame rails in a couple of places... similar to how the engine cradle is attached right under the area where the engine attaches. I was thinking that since the rear section of the bus, where the hitch would attach, has more framework in general above and beside in addition to the rails where the cradle sits would distribute the push and pull of the toad better. Of course, I could be wrong!
David
David:
Yes, the vertical loading increases the further you move out on the lever. Within reason, the busses seem to be quite forgiving to a straight pull or push, which is one reason for people towing 4 down instead of trailering.
If you fasten to the plate behind the bumper, I would make the hitch tube long enough to also support it under the engine rails so that you don't put a twisting motion on the plate.