V drive or T drive?

[Jerry Liebler]

I'd like to have a 4 stroke diesel but My bus is a 'V' drive.  I recently saw a series 50, that was transverse mounted coupled to a ZF transmission (of unknown model), on Ebay.  It came from a 'New Flyer' transit bus.  So my question is what is the drive arangement of the New Flyer buses from the 93 to 95 era?  If one could be found, a 60 degree V drive ZF 5 speed would almost keep my top speed and even beter would be the 6 speed which would give me 82MPH at 1600 RPM.  Just dreaming.
Regards
Jerry 4107 1120 

[RJ]

That S-50 & ZF would work in your 4107, Jerry. . .

BUT

You'd better secure everything, because at idle, that 50 series shakes and vibrates like no engine you've ever worked with before.

Once it gets over 1200 rpm it smooths out, and it puts out a LOT of torque, but until then. . .

IIRC, the top of the engine will move over 7" side-to-side at idle - a lot for motor mounts to overcome.

New Flyer found a way to limit it somewhat, but it'll never be as smooth as your 8V71.

The ZF used in V-drives, IIRC, is a four-speed, but 4th is still 1:1, it's not an OD.

Keep Dreamin'   

[TomC]

Jerry- Russ is stretching the vibration of the 50 a bit.  If you are using the soft engine mounts to achieve the side to side movement of 7", then you'll feel a bit of vibration at idle.  Once above idle, it is just as smooth as any engine (I know this since Freightliner put the Diesel version in trucks for awhile.  Diesels will vibrate more than the natural gas versions that are in may transits still).  Since you have a 4107, unless you extend the rear bumper backwards for more space, a T drive won't work.  Here are the engines that will work with your V drive setup.  Obviously the 8V-71, also the 6V-92TA, Series 50, Cummins ISM, Cummins ISL.  Both the 8V-71 and 6V-92 can be used as mechanically injected engines so minimal modification will be necessary.  The 6V-92 can be electronic-also the Series 50, ISM, ISL are electronic which would mean using the V731 (for the 6V-92) and the VR731 for the others with the right handed converter gear.  Using electronic engines/transmissions means you'd have to have the electronic shifter, electric accelerator, and all the necessary wiring harnesses to make everything work.  While it has been done, not worth the time, in my opinion.  As to using the ZF, the angle of the drive is wrong for your bus.  Newer buses have a longer overhang in the back to facilitate the different angle of the ZF. 
Personally- I'd stick to what you got, and if you want more power, rebuild your engine into a turbo'ed and air to air intercooled engine that can easily put out 400hp and 1,200lb/ft torque (compared to 300hp and 800lb/ft).  But, I'd be careful adding to much more horsepower since the GM's are prone to cracking of the engine bulkhead.  Good Luck, TomC

[Jerry Liebler]

Tom,
     The ZF website lists several diffrent angle drives.  One is 60 degree, sort of like the V730.  Somewhere else I picked up that both the 4 and 5 speed were made with angle drives ( I'm not sure of the six speed but the speed limit of the angle drive makes it not useful anyway).  The 5 speed has a top gear of 0.83 and the angle drive is 0.97  so combined they are 0.805 which is very close to the 0.808 of the manual transmission which gives 77.5 Mph with 2100 engine RPM unfortunately this is above the speed rating of the angle drive but 73.5 MPH would be within the rating and give 1992 engine RPM.  So my real question is what transit busses used a modern 4 stroke diesel and a 5 speed 60 degree angle drive ZF?  It seems to me that this is as good as one can get in a 'slushbox' transplant at least in terms of fuel economy.  I'd want to start with a complete donor bus to get all the controls and senders etc.  The ZF trannys have torque ratings of 922 ft lb or 1033 ft lb and they use rh engines and do the reversal in the angle drive.  Transit sales intl has a few Flx 870s that have both the series 50 and ZF angle drive but they are awfully proud of them and will no doubt keep them a long time.
Another question is what angle did the New Flyers use?
Regards
Jerry 4107 1120

[Sammy]

Jerry, to repower your bus with a Series 50 and any electronic trans will be a huge project.
I have repowered Orion and Nova transit buses. We removed 6V92TA's and V731 and HT748's and installed Series 50's with B500's into the Orions and Series 50's with VR731 into the Nova's.
Installation was a challenge, welding, burning,etc & making it function is where the real technical stuff comes in.
Wiring for DDEC,WTEC, etc.
Cooling and exhaust and A/C system plumbing another challenge.
Tom makes a great suggestion - make the most of what you have.
Best of luck with whatever you choose to do.

[RJ]

Jerry -

The Flxible Metro 870 is the closest "clone" to the GMC powertrain, so the S-50/ZF would work.

Buy the whole bus.

That way you also get two modern axles with BIG brakes, a much tighter "cut" angle on the front, and you can swap out the pumpkin gears for 4:10s, to get back that lost top speed that 4:56 or 5:38s commonly found in transits do not have.  Rockwell/Meritor makes the axles, and the parts are available - the RTS guys frequently make this swap.

TomC was right when he said I was stretching the S-50's vibration issue a bit, but the point I was trying to make is that at idle, you'll definitely know it's a big four-banger back there, not the smooth eight two-stroke.

HTH. . .

[TomC]

Just make sure you get a 96" wide bus since most of the modern transits are 102" wide which makes for no go on the axles. I know GM, AMGeneral, early Flexibles had 96'ers.  Believe that the Flexible 870 was 102" wide.  Good Luck, TomC