Allison shifting between 1-2

[Stuff]

consult a trusted transmission place for a checkup.

[GreyEagle]

Sounds like you might be ready for a service, at least a fluid and filter change..... around $200.00

[bus-bro]

I agree with GreyEagle. Fluid and filters. Done right--can't hurt, might work.

What kind of fluid?

[GreyEagle]

Originally Posted by bus-bro

I agree with GreyEagle. Fluid and filters. Done right--can't hurt, might work.

What kind of fluid?

Any will work but Allison recommends TranSynd™ heavy-duty automatic transmission fluid, ..... see links


http://www.allisontransmission.com/publ ... onType=All

http://www.allisontransmission.com/service/autoapp/172/

or http://www.allisontransmission.com/service/transynd.jsp

[Jive Turkey]

I would inspect the vacuum modulator. Look for trans fluid in the vacuum line. Check the vacuum lines and vacuum source. replace any questionable hoses with new and put clamps on them if they do not have any. I would toss in a new vacuum modulator for ha ha's to see if that fixed the problem before taking it to a trans shop.

[Jive Turkey]

I would check the trans fluid condition first before any of the above. Use a clean white paper towel, rag , cloth etc. if the color is good or reasonably good and the fluid smells ok I wouldn't bother changing the fluid proceed with mentioned above.

[GreyEagle]

Allison (AT545) Shallow Pan

Use DEXRON® III Fluid or Allison TransSyndTM Full Synthetic Fluid

14.2 liters

15 quarts

Allison (AT545) Standard Pan

Use DEXRON® III Fluid or Allison TransSyndTM Full Synthetic Fluid

18.9 liters

20 quarts

Do the Shallow pan and then check and double check your fluid level.
If it's not full then add the additional fluid for the Standard pan......

INFO SOURCE http://www.justanswer.com/car/18fid-flu ... ssion.html

[Stuff]

so buy a 5 gallon pail of it and pay bulk cost rather then quart cost lol

[GreyEagle]

Allison link .... http://www.allisontransmission.com/publ ... onType=All

goto bus series under vocational at bottom of page... click on bus series

Item 1 is for the ALLISON 500 SERIES ........LINK http://www.allisontransmission.com/site ... +modulator

Before you order any parts get the serial number and double ck all your carburetor vacuum lines...

The modulator should only be used after appropriate troubleshooting has been completed,
such as verifying that the carburetor is performing properly, vacuum lines are in good
condition (no leaks or splits), etc.
The new kit, P/N 29501199, is purple in color and can be purchased through the ATD




http://www.allisontransmission.com/serv ... wnloadID=9

[GreyEagle]

Pretty sure all ALLISON AT545's have the vacum modulator.

Get the serial number of the tranny, you will need it if you contact Allison, it's on the tag attached to the tranny, then check with Allison and/or one or more of the diesel forums to gather info. There are hundreds of diesel forums out there with way more info than I can give.
If you google Allison AT545 you can get alot of links to additional info. good luck

[chev49]

first, transynd is expensive, and something like the c-4 or atf (ford) would be better for checking on suspect tranny. (I will not use dexron when i rebuild trannys)
Second, there are tons of used and many low mileage 545's out there as a huge number of skoolies in the northwest have them in the junkyards.. even 643's, etc.. like the truck junkyard in sheridan, oregon. They frequently sell them for $500 or so for a good one.
You can also purchase 545's cheaply for a rebuilt one, from at least two rebuilders in california.. Probably around 1800 or so when you send core back. I know 643's are around that price, and some parts that you may need that aren't included in a rebuild kit are kinda expensive.
you can also pressure test them.
If it were me, and i was having something other than a clogged filter or misc easily fixable problem, i would just buy a rebuilt one from a good rebuilder... cause they are cheap, and even though i can rebuild one, the parts could easily eat up $1000 or more depending on what extra parts are needed.