Unlocking 6th Gear for Allison 2500 Transmission, Is It Worth It?

[sportyrick]

Yes it was a shoehorn job, removed belt drive fan and am using 4 electric 1500 cfm fans, alternator clears by 1/4", had to extend grill 16" to get radiator and intercooler in. The old busses had the front axle a foot or more closer to front than newer busses designed for long 6 cylinders and long transmissions. That is the reason I had to extend frontend, front axle is way closer to front of bus. I have 2 fingers between the trans pan and axle, close close close. The open holes above the engine are where the intercooler lines run so no room there. I had to get an engine where the air compressor is installed alongside the block like DT466, C7 cat and I think 8.3, couldn't be an addition to the top side of engine like earlier DT466, no room.

[cadillackid]

wow!! now thats a shoehorn job!! the factory position for an A/C compressor would be on top.. as also would be wherew bracketry systems would put it.. i cant tell but im assuming from the pic you used an NGD with Serp belt to limit the required distance out front to one flat belt vs 4 V belts?.. someone on one of the swap forums is oputting a 466 in an IH travelette and actually had so little room up front the radiator is going to be remote behind the cab.. and i think they are using an air / water Charge air cooler..



building a PTO drive for an A/C actually sounds pretty cool.. if you look at how the old GMC Busses from the 1960's drove their A/C was from a driveshaft that came off of a gearbox for the engine fan mounted on the Detroit 2 stroke.. that driveshaft went to a clutch (im told the pressure plate and disc are exact match for an isuzu Pickup truck)..



a properly built TxV based air conditioner should really never need to cycle its compressor.. a full sump compressor like a York / tecumseh style can run with 0 freon flow and not die.. (they have a true oil sump in the crankcase).. so you could set your TxV to have a true near zero flow rate, engage the PTO when you want A/C and turn it off when you dont. you can mount a gear to the front of an A/C compressor instead of the magnetic clutch..



what im not sure of is when the vehicle is in gear but stopped does the PTO spin or not? for some reason I like to think it does not when stopped unless the trans is in Neutral.. simply because when stopped in gear the input shaft is at 0 RPM. in enutral the input shaft speed matches the engine RPM and I believe when PTO is engaged you can lock the converter in Neutral for direct drive PTO and take converter stall out of the mix.

[RolesvilleMarina]

Originally Posted by sportyrick

The fifth gen Allison has got to be an electronic nightmare. Since we are off in Allison la la land how about this idea. There is no way I have room for an air conditioner compressor up front with the usual belt drive stuff on this DT466. How about this idea, this 3060 came with a full time PTO soe's how about I put my compressor back there? I think I have room and then I could have air conditioning running down the road? Yuk that means another space eater the condenser. By the way I looked into the telma and a used one goes for $2-3000 on ebay so I suspect a new one is $10,000. Jay Leno has a nice youtube about installing one on his fire truck, if he can afford it I know I can't.

I don't think you can run the PTO in gear at all if it is transmission driven

I have a Hino, and the transmission is an Allison, like a 1000 series but I have never actually looked (has a manual gearshift) and the PTO runs the hydraulic pump for the hook lift (dumpsters)

You cannot use the PTO in gear, huge warning saying no no... which being a dump lorry is sometimes a major pain in the ass unloading a skip on a hill. Engine driven

I can idle speed in gear and still use the controls, but that's it.... it has to be in neutral to spin up the motor to get good pressure and do it's work

[bapos]

Raising wheels

I am not super far from you and my brother lives not too far from the waco area so I maybe of help. I have a few lengthy replies on getting a 3060 unlocked in the forum. The guy that did mine is a bmf. Someone close to him fwd this thread to him so he hit me up..... yes lots of work but.... im pretty sure he can get you unlocked.

Hit me with a pm and chat and see if we can get you taken care of.....

[Rwnielsen]

Charlie Ball on Facebook...around $400
It's on my list of eventualities

[bapos]

Not sure who that is but the allison master wants you to contact Me so I can put you two together. If you can pm your email address so I can get you two connected.

[lcm0027]

I’ve been looking into this. A transmission shop close to me wants me to get BB to sign off on the work but I haven’t found any luck getting someone from BB to contact me. I’ve sent emails to all kinds of people asking for help but no response. I’m in north Alabama

[Rwnielsen]

Bluebird has historically denied authorization due to "liability" issues. I've not heard of any exceptions. That's why there's all these workarounds