trans help

[skihor]

I may have to replace our trans. I assume it was taken from the same doner as the 6v92. All I really know is the engine was MFG.May '81 and is a "green block" It is a 5 speed allison auto. Any ideas on what model it is or what to look for to I.D. it ?
The issue is... when shifting, 1st, second, lock-up, 3rd, sliiiiiides into 4th, 5th. If I release the throttle when going to 4th and instantly push the gas down it's fine. Or down shift into 4th it's fine. No sign of slipping besides the shift.

Thanks,
Don & Sheila

[buswarrior]

call Luke 888-262-2434.

he'll have an idea or two.

happy coaching!
buswarrior

[RickB]

I had trouble with my 754 Allison. I had a minimal amount of slippage with my 2nd gear start transmission and I went with Rotella 15/40 in the transmission and no slippage for 3 years now. I'd give it a try before making the change. You'll know right away if it worked. Also, use an IR gun to make sure your tranny isn't pouring a bunch of heat into your motor's cooling system as that's a sign of major slippage and the oil will probably not help.

Just a thought maybe you'll get lucky like I did.

In regards to your model transmission question most of the 9's came with the 740 allison I believe.There is a plate on the side of the transmission that has the info but block up your coach as you'l have to get way under the bus to read it.

I believe I had to use my camera on my phone to get the numbers off of mine. Good luck with this.

Rick

[Low Class]

I would like to know what you find is causing this.  My 1985 Bluebird has a MT654 CR.  Shifting into fourth, up or down, is slow and lets the engine race a little.  Like yours, if I help it with the throttle it shifts okay.  Once the shift completes, it pulls fine at wot with no apparent slippage.

Searching on the net, I found that a weak or wrong "trimmer" spring can cause this.

[hargreaves]

Take it to an Allison dealer. Chances are the 3rd to 4th trimmer spring is broken . They will be able to road test it and determine what to do. It doesnt sound to be to serious. Make sure the trans fluid is at the proper level. To high or to low will cause slippng / erratic shifting.    I don,t know what kind of modulator you have but make sure it is adjusted properly.    Gerry

[chev49]

Does allison recommend that you run 15/40 motor oil in them? I think i put whatever they had on their web page on mine... maybe c4, but cant remember.. if the multivis fluid is better, then i would change mine when i change filters again.

[luvrbus]

You could have bad trimmer springs but I lean towards a bad stator, bushings,rollers or stator springs 

good luck

[Brassman]

This post from yesterday's Escapees forum is about Allison fluid requirements:

For many years, Allison specified C4 (TES-228) fluids. In fact, the original "C" (for Construction) specification goes back to 1955. I personally approved hundreds of them. C4 approved fluids included such oil types as SAE 10W, SAE 30 and SAE 15W-40 Heavy Duty Diesel engine oils, DEXRON-III Automatic Transmission Fluids, and Tractor Hydraulic Fluids (THFs). What we later determined was that, in some severe applications like transit bus and refuse (garbage) trucks, these oils had various problems. This was further exacerbated by the fact that the EPA caused engines to runner hotter and engine compartments became more insulated and enclosed. This all led to higher transmission temperatures. Some oils worked "OK" and gave acceptable drain intervals but all had problems of some sort. Example: engine oils did not stand up to heat very well and the ZDDP (zinc dialkyl-dithiophosphate) used for engine valve train wear agents tended to plate out on clutches causing them to slip, some engine oils caused clutch reaction plates to wear, DEXRON-IIIs lost viscosity too quickly (although they tended to have good oxidation resistance) and Tractor Hydraulic Fluids were found to sometimes cause "Stick Slip" which is a phenomena that causes clutches to lock and unlock at a high frequency causing a "shuddering" effect in the driveline that you could both feel and hear. Lastly, came DEXRON-VI which had seal issues in older Allison products. So, to make a long story short ..... TranSynd fixed all of these problems. I recommend you use it and not one of these older fluids.


Thomas L. (Tom) Johnson
Former Transmission Fluids Engineer, Allison Transmission, Inc.
JG Lubricant Services, LLC
Website: www.jglubricantservices.com
Email: tjohnson@jglubricantservices.com

[Busted Knuckle]

Well I have to say that we have a straight forward answer from a resident expert on the subject!

I must say that before reading his post I'd suggested the 40W  rte.
We used it quite successfully in 740 transmissions many times. But when we got newer buses that ran B500's we were warned "Sure if you want to change transmissions in 100,000 miles go ahead and run 40W, but if you want them to last run TranSynd in them."
We have followed that advice and been very happy with the results!
  BK 

[wg4t50]

Have been following Tom Johnson's articles on other forums and have gained great info for my Allison 4060R transmission, my big concerns were centered around max tempatures when using the built in hydraulic retarder (max temp when using the TranSynd oil) and Mr Johnson got me all cleared up,  Many thanks.
Cheers
Dave

[Bussman84]

Not trying to steal this thread or get off the subject at hand but what exactly is TranSynd and where does one get it? I have been considering a filter-fluid change on my 740 and maybe this is something I should check into?

              Thanks Billy

[hargreaves]

We switched to Trandsynd fluid on our transits (b400) (B500)  Gained another 200,000 kms before rebuild. Screwed up all the preventative maintenance schedules lol. I use it in my B400  lowers the trans temp approx. 15 degrees.   Allison dealers sell the fluid about  $50 bucks a gallon.

[Busted Knuckle]

Not trying to steal this thread or get off the subject at hand but what exactly is TranSynd and where does one get it? I have been considering a filter-fluid change on my 740 and maybe this is something I should check into?

              Thanks Billy

Billy TranSynd is a synthetic transmission fluid developed primarily for Allison transmissions.
Only place I've found to buy it is from an Allison Dealer.

But if you shop around different dealers price it different or run sales on it! (I like catching it on sale. Sometimes I score it buy one get on free. When they have that one running and see me coming they know what I'm after. I usually buy 2-3 cases an get the same free!)

As hargreaves pointed out it makes a world of difference, but it ain't cheap. (but neither are those tranny's!)
  BK 

[luvrbus]

Me I wouldn't rush out to spend 500 bucks for Transynd for a 700 series Allison those transmission run a million miles on different oils now a B series I would not run anything else they need all the help you can give one lol.

The 700 series did have a problem with the new Dexron when it got above Dexron III  but they run forever on plain ATF from AutoZone and others and Transynd cost me a FS740 it didn't like it,2 filters and ATF way to go on a 700 series IMO unless you just want the synthetic  

fwiw I always ran Cat oil in mine good enough for $30,000 to $50,000 Cat power shift transmission it was good enough for me lol

[junkman42]

Just for the record a shop foreman at a  Allison dealer told Me the fastest way to a disaster with My old HT70 was modern synthetic fluids.  He told Me that the glue in the clutches would not stand the modern fluids.  I doubt that many here have a HT70 but a word to the wise!  Regards John L