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jasle 01-19-2012 05:30 PM

Flxible bus transmission
I am looking at buying a conversion done on a 1974 Flxible platform. Engine is 8V71. Transmission appears to be single speed forward, single speed revers. it was a transit bus formerly. My concern is about the health of the trans/engine running at highway speeds. Governer is removed and it will do highway speeds from what I am told.

am I overly concerned or will I need to change the trans/gearing?

Other than that price is right and bus seems decent.

chev49 01-19-2012 11:57 PM

Re: Flxible bus transmission
most flex transit busses of that era had vs2-8 or the vs2 transmission. some had 6v71 engines and the vs-2 transmission. I have owned both kinds, with the 8v71 with the vs2-8 transmission able to go around 70mph. The speed depends on which rear gear it has also, as many top out at 60 or less. My friends probably bought over 60 at the auction, some were the gm transits, and others were flex's with a few being the am generals. so if your bus will do freeway speeds it's probably the vs2-8 tranny.

I have never had transmission problems with mine, although not only do you have the engine and transmission, you have the planitary gear set which can go out. They are also a lot of work to fix. Other things to be aware of is oil leak in back of engine, air compresser back there and alternator... and the torlastic fan which i assume yours probably has... so you done want high gear noise either on the front or back of the engine...

another thing to check is the ujoints and the drive shaft yokes, as these will cause vibration and you might think its something else.

just thinking... but have had to deal with the above stuff...

jasle 01-20-2012 05:54 AM

Re: Flxible bus transmission
Thanks for the tips. The PO says it will cruise the highway all day along side any big rig so I am guessing 65 is no problem. I was just concerned about it being a former transit bus. i will travel regularly from Austin to Houston, austin to Dallas etc for some motorcycle races. Not exactly long haul driving but don't want big trouble. I'm reasonably competent at fixing things. Spent a good bit of time as a motorcycle mechanic. i will def make your suggested checks. I will fly out and check it out with plans on probably buying unless something is incredibly crazy.

Jarlaxle 01-21-2012 07:33 AM

Re: Flxible bus transmission
Waitwaitwait---how does it run highway speeds?! Was the GEARING changed? If not, RUN AWAY! It could easily be running 1000RPM higher than it is designed to if the governor was simply turned up! Does it have a tachometer?

chev49 01-22-2012 04:45 PM

Re: Flxible bus transmission
Yeah, they are not a 2600 rpm engine like the cat 3208. And besides they should be run in the best torque rpm.. I think the cat engine is 2400 for that and the detroit maybe 1800 rpm, but i always ran all my detroits against the governor.

Jarlaxle 01-22-2012 05:55 PM

Re: Flxible bus transmission
I recall an 8V71 maxes out at 2200RPM for short bursts, 2000RPM sustained. A Detroit WANTS to run oin the governor...but 2000RPM is all.

Jarlaxle 01-23-2012 07:13 PM

Re: Flxible bus transmission
I have seen some SCARY governor settings. Craziest was probably a little 3-53 running an irrigation pump...someone had hooked it to a pump WAY too big for it (replacing a 4-71), so they turned it up. It was set to run (sometimes for a day at a time!) at 3800RPM. :shock:

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