V730 Shifting Problems

[richard5933]

Seems like it's my turn to have one problem after another...been one of those weeks.

Allison V730 has been working well and shifting as expected, at least until Wednesday. Slowed down on the freeway to negotiate a somewhat hairy interchange, and when I tried to accelerate again to freeway speeds something was wrong. Seemed like I was hitting the governor at about 45 mph and no more shifting in sight. Prior to this I was easily able to get to 70mph or a bit more.

I feel one smooth shift about 20 mph, another in the mid-to-upper 30s (a bit harsher than the first), and then that's it. My tach is still not working well so I really don't know the exact engine speed when all this happens. When I get to the mid 40s the tach shows 2500 (but I think it's reading a bit higher than actual). I'm guessing that either my torque converter is not locking OR I'm missing a shift somewhere.

Any thoughts on what's going on? If nothing else, perhaps someone could tell me what the 'proper' shifting pattern of the V730 should be.

Thanks.
Richard

[luvrbus]

The governor will prevent a up shift, have you checked the fluid level the V730 will not up shift if the fluid is low start there 

[richard5933]

Best I can tell the fluid is at the correct level. Engine idling on level ground fluid at at the mark. Although I was somewhat confused - there are three marks. There is a mark with the word 'cold' next to it, one with the word 'hot' next to it, and then a few inches further up another mark. The first two I figured were for the engine cold/hot. Can't figure out what the third mark further up the dipstick are.

Governor? Are we talking about the engine governor here? Or, is there another one in the transmission somewhere? If it's the engine governor, how is it connected to transmission shifting?

Thanks!

[Utahclaimjumper]

Plugged fuel filters ( or any power loss) can also cause shifting problems.>>>Dan

[luvrbus]

The transmission has a governor all older Allison's use the same governor,there is a cover with 4 bolts and the governor is inside there the plastic gets old a brittle then breaks they cost around $150.00 for a replacement ,a bad modulator or adjustment can cause shifting problems also.If you have a air throttle check the 1/4 inch line going to the modulator for breaks     

[Geoff]

I always tell people to add a gallon of ATF and take the bus for a ride and see if the third gear shift returns.  If not, then do what Cliff suggests.

--Geoff

[TomC]

On a manual V730, 1st, 2nd, and 2nd lockup are controlled by the throttle modulator-and that sounds like it is still working well. You get 1st converter, shift to 2nd converter, then the bump is the torque converter locking up in 2nd. 3rd is strickly a speed shift-no matter what the throttle position is. This is contolled by the governor-so I agree with trying extra trans fluid, then if nothing, the governor is bad. Good Luck, TomC

[richard5933]

Thanks guys for the advice. Glad to hear that the problem might not require a transmission rebuild.

I'll run through the list and see what happens.

[chessie4905]

Not much to go bad on governor,look for stripped teeth. If they look ok, hold governor with teeth up in air. Move weights together while watching if spool valve moves up and returns down when you release weights. The movement of the spool valve can be seen through the slots. If it does not move, clean it in solvent till it moves up and down without sticking.Basically it is a larger version of a GM car governor. When this symtom happened in the cars, it wouldn't shift out of second into third and you would find that nylon gear stripped.

[beatsworkin]

I had the same problem and it was a tiny air leak in the air line that went to the trans.

[wildbob24]

You might want to check the governor filter(screen) while you're at it. It's behind a plug in the valve body almost directly below the flange that the driveshaft attaches to. It's an often overlooked item.

Bob

[eagle19952]

i would never add a gallon at a time...even if i knew it said it needed it...1 quart and check...at operating temp. i am never in a  hurry

[TomC]

On big rig engines and transmissions, when indicated that it is at the low mark, that means to add a gallon, not a quart. Good Luck, TomC

[richard5933]

Quart or gallon, my dipstick is actually showing the level to be spot on. Any way that a dipstick can be out of calibration? If so, how does one know how much to add?

Also, I don't seem to be able to get the dipstick out of the tube with a totally clean reading - always seems to be a bit of fluid up and down the length.

Richard

[chessie4905]

We always read the lower fluid reading, looking at both sides. Wipe it off and then insert and check. You can do this 2 or three times and reading should be consistent. Me, I'd remove and check gov first, so I wouldn't have to remove a gallon of fluid after the problem was governor. Does your trans. drip or leak any oil causing it to be too low?