Which Allison is this? (photos)

[Scott & Heather]

I know this has been asked before. I am an avid user of the search function on the board...someone even posted a photo of their own tranny for identification, but the photo has long since been removed...so I have to rehash an old one here. I appear to have a 4speed floor shifter so I'm assuming a 4speed automatic but is it a 700 series? 740? And TranSynd has been discussed...would my tranny be a good candidate or what is your recommendation for fluid? Also, just one filter to change correct? (spin-on type?). Thanks again gents for your expertise. Been a great help to this 29 year old green-behind-the-ears kid. Btw, just so you can be proud of me, I fixed a non-working turn signal...wiring issue, also fixed the turn signal mechanism not working for right signaling (microswitch activator lever slipped out of place in stalk assembly). 

[buswarrior]

There is a plate affixed to the side of the transmission case with the nitty gritty.

However, I expect you will find an HT740 lurking in there.

Over the years, on both bus boards, BCM and BNO, every busnut who has installed proper temperature probes on their transmission at some point in the past, and then changed to synthetic transmission fluid, consistently reports somewhere close to 10 degree Fahrenheit reduction in operating temperature.

Keep the "gain" in perspective, the transmission runs up there close to engine temperature, so 10 degrees up or down from 200 is what it is.

When changing the fluid, same as your automobile, you can't get it all out of the torque converter by just dumping the pan.

As for the choice of fluid, there are other, less expensive synthetic choices besides Transynd.

There is a bit of controversy as the test rig to prove a fluid suitable has never been made available to other lube manufacturers. Exclusive rating makes for exclusive pricing.

Others will chime in with the brand they chose.

If an auxiliary transmission cooler is also in your plan, the expense for synthetic might not be worth it for a busnut?

happy coaching!
buswarrior

[Scott & Heather]

Thanks BW. Looked all over for the plate. I'm sure it's there...under about 3 inches of crud. What is the standard operating procedure for checking the fluid level? Same as a car? Coach on...warmed up, shift through the gears (including reverse) then put in "N" and check the level? And again, just one filter (the one in the pic?)

Interesting info on the TranSynd...if it is a 740 and I don't want to use synthetic, my options are? There's a ton of talk about 40wt oil, Dextron III, and I just don't know what to use...

[buswarrior]

The plate is fastened on a sort of boss just above the pan on one side or the other.

I just run mine with boring old style pink dexron, same as what the first line fleet that ran it did.

Yes, the big external filter does the job.

happy coaching!
buswarrior

[Mike in GA]

Looks like a 740 to me.
The 750 and its cousins have a somewhat longer case, and the rear section has a Gatling Gun/bandolier look to it.
F.W.I.W.
Mike in GA

[hargreaves]

A 750 would also have fifth on the shifter.

[TomC]

When I changed my truck from the 13spd manual (I've driven 1.3 million miles-don't have anything to prove, and REALLY enjoy automatics) to an automatic, I hashed over which automatic to choose. I ultimately chose the HT740-they're readily available, are reliable as dirt, very rugged (most Boneville big rig race trucks use the HT740 behind 3,000hp engines), and have enough gears for what you need.  I have 11R-24.5 tires with 3.55 gears that will get me a nice cruise of 65mph at 1800rpm.  Just use Dextron rated oil-synthetic like Castrol transynd is nice, but very expensive.  Maybe after you're all converted you could change once you start using the bus.  Keep the trans.  Good Luck, TomC

[Dreamscape]

This is what the tag looks like on ours.



Before we installed it.



Looks like a 740 to me.

[luvrbus]

If you start with a fresh rebuilt 740 with the right clutches synthetic is good but you guys want to spend a 1000 bucks for oil on a transmission ( needs to be changed twice) you can buy for 1000 have  it make no sense to me but it's not my money 1000 bucks will buy you 250 gals of fuel lol

[Scott & Heather]

Great...thanks. Your pic of the nicely painted trans was pretty cool...but I can't locate your tag on the zoomed out photo? Trying to find it to see where mine would be. Good to know these are good tranny's. Ours was rebuilt in 2001...and shifts nice and crisp (i little too crisp...) so we're happy. Some have suggested manually shifting this thing? Is that serious?? Should I manually change gears?

[buswarrior]

Yes, the smoothest operation and best performance from a 740 is had by taking command of the transmission yourself.

Shifter is placed into 2nd for around town.

You choose the 2-3-4 and 4-3-2 shifts both up and down. Leave it to take care of 1-2 and 2-1, it can manage that by itself.

The trouble in town is the transmission wants to up shift too early on part throttle and then downshifts with a mighty bang when you squeeze the throttle or otherwise require more motive power.

The transmission will wait too long to downshift as you are climbing big grades, missing some of the available power at the top of the next lower gear by allowing too great a drop of speed. And, again, downshift with a mighty bang.

Downshifting on a grade requires a bit of technique and timing for a smooth shift. As the speedometer is dropping towards the max speed capable in the next gear down, lift throttle, select the next gear down, and somewhat concurrently but slightly behind the shifter movement, squeeze the throttle back to full fuel with some authority.

With some experience, you will know at what points the transmission will shift on its own, and whether you want that to happen or not. Your passengers will thank you for figuring out how to prevent the mighty bang.

Try the other side of the transmission for the plate, in the photo, you can see the goober from the gasket between the pan and the case.

happy coaching!
buswarrior

[Seayfam]

Scott,
Look on the right hand side of the transmission (the drivers side) right behind the bell housing. I shift my 740 manually all the time. Ofcourse I have a Bennett shifter lol! a nice little toggle right next to my arm rest.

Sent from my GT-I9100 using Xparent Green Tapatalk

[Scott & Heather]

Thanks for the clear instructions BW. As for the banging shift you can say that again! Ours shifts like that and I've never manually shifted it...so I'm glad to know I can start to get a little more intimate with my Allison...those occasional (not so occasional actually) banging shifts were a bit disturbing. Amazing that they can lurch a 30,000 lb bus so easily. I've always noticed that the tranny shifts at the worst times or doesn't shift when I really really need it too (climbing mountains in PA) and I just thought it was normal.    Thanks for rehashing the shifting procedure with me. As for the stone bennett...i envy you.  

btw, TomC, we are using the bus. Living aboard full-time...drove from Michigan to Pennsylvania last summer...then from PA to Florida last fall, and now we're leaving here in a month and headed up to Wisconsin for the summer.    Bus is definitely getting some miles. From there, we head to Ohio in August...we'll chill there until December. Thanks for the advice on the fluid (you too Cliff). Going to stick with regular stuff.

[TomC]

It's interesting about my HT740 in my truck.  They (Pedco) installed an RV transmission.  And what that does is at every shift, the torque converter lockup disengages momentarily to allow a smooth shift then reengage again.  This takes only about 3 seconds.  And it also does it on down shifts-thus eliminating all the clunking hard shifts the HT740 is known for.  Good Luck, TomC

[luvrbus]

Strictly adjustments make a 740 shift hard they are not all that way fwiw United Transmission build most of those for Pedco and is not a rocket science to make a 740 shift smooth

good luck