Allison VS2 transmission work needed: Anyone in the South East to recommend?

[Jack Ashore]

I'm sorta broke down in Charleston, SC with an Allison VS2-8 tranny that is acting up, i.e., occasionally failing to downshift from direct into turbo when I approach a stop, and then stalling. The Allison specialists here, W.W. Williams, say the transmission fluid is burnt, and someone needs to get inside to see the damage.  They don't want to do it.  They will, with great reluctance, give it a go but are clearly uncomfortable and they think I should have them remove it and send the tranny to someone that knows this stuff.  Of course, they don't know who that would be.  Any recommendations?  I am half tempted to have them drain and fill it with fresh tranny fluid and take my chances getting back to Florida where I at least have relatives and friends I can stay with if need be.

Thanks,
Jack

[daddysgirl]

Try General Diesel:

http://www.allisontransmission.com/sales-service-locator

See if they can help you. It's odd that the Allison site has Williams listed as a service facility. But we used General Diesel a long while ago...they were great.

[lukeatuscoach]

Hi Jack & Folks:

The burnt fluid doesn't sound good.  You might start with the governor, as if it hangs up, the result can be the problem you are having.

If you think it might help, give us a call.

LUKE at US COACH
1-888-262-2434

[Jack Ashore]

Thanks for the General Diesel recommendation, I spoke to Aaron and he expressed no hesitation at getting into it. Says he worked on 60's era stuff before.  I am confident I can nurse the bus the 4.9 miles from WW Williams to his General Diesel.

Luke, thanks for the offer, and I will pass on the bit about the governor to the General Diesel people.  I have had occasion to connect "younger" mechanics with Ted out at Coach Maintenance Company for phone tech assists on this old bus, is that something you or your people would do as well?  Or are you mainly parts?  I know your company provided the guts to our Voltage Regulator when when we got it fixed at Interstate Power Systems in Omaha last month, so thanks for that.

[Brandon]

A quick pressure gauge test would show if the problem is with the governor or the valves that do the switching. Fortunately the converter lockup valve is the easiest to access (right at the passenger rear corner of the trans up top).

These transmissions do NOT like running low or too full. I run wet-clutch tractor hydraulic oil in mine and it's been pretty happy (other than a leaker).

I have the manual posted online https://brandon314.wordpress.com/2011/08/12/vh-vs-series-service-manual/

I would not open up the transmission without first checking the condition of the oil (maybe drop the pan and see if any solids in there). Since you're not getting slipping, I'd suspect valves or the governor sticking due to contamination or messed up pressures. Good luck!

Video of governor pressure across speed range (bus was blocked so wheels could spin)
https://www.youtube.com/watch?v=JaeyZekXpG4

My transmission has weak main pressure...so some of the other videos are not good reference material.

[Jack Ashore]

Brandon, Thanks! I will pass this along to General Diesel as well.  Great to have such specific information to provide.  I tend to agree that it is something sticking in the governor or valve body given that everything else works so well.  The transmission, aside from this new problem, works a lot better overall since the clutch replacement, particularly the transition between direct and overdrive.  The one bit of oddness is the transition from turbo to direct going up in speed: I think the mechanic set the thing up to wait too long to transfer, up near 35 MPH instead of 28 or so.  Not sure if this has anything to do with the problem coming down the gear train.

[Brandon]

The one bit of oddness is the transition from turbo to direct going up in speed: I think the mechanic set the thing up to wait too long to transfer, up near 35 MPH instead of 28 or so.  Not sure if this has anything to do with the problem coming down the gear train.

Mine moves in/out of lockup around 27-29MPH (though my rear differential is ~55MPH during lockup at 2250RPM). That is easily adjusted with shims on the particular valve. A 'high' setting would usually make it drop out sooner as you slow down. There is some overlap there to make sure it doesn't flap back-forth wildly trying to decide (hysteresis)....but if it is sticking.

My splitter overdrive changeover is really crappy because of my low main pressure. I've changed the main pump, futzed with the pressure relief valves, and pressure hasn't moved an inch. I need to do some more elaborate testing to see if I can get it up closer to 95-100psi. I have a manual override to select direct drive (for hill climbs, decent, etc.) so I usually hold that until I hit 50MPH+ then do the changeover to O/D while letting off the accelerator. I set the clutch up pretty tight but not tight enough for that crap pressure apparently. :-)

Cheers!

[Jack Ashore]

Brandon, You're speaking beyond my mechanical knowledge level, but I appreciate the info.  Dang it why didn't I know about you when I spent a month in Portland this summer!?

[Brandon]

Brandon, You're speaking beyond my mechanical knowledge level, but I appreciate the info.  Dang it why didn't I know about you when I spent a month in Portland this summer!?

Download that manual and start reading. It's written surprisingly well. Thanks to Bill Gerrie for loaning it to me so I could scan into digital! Cheers!

[daddysgirl]

You are most welcome Jack. My father used to say it's the unwritten bus nut code that if you can help a fellow nut, you do 

Luke: Where are you all located? I'm going to put your number in my bus contact list, if that's OK.

Brandon: Great blog!

[Brandon]

Brandon: Great blog!

www.theghostbus.org is where the bus project/driving blog lives. It's pretty quiet lately as I haven't had time to update with the work I've done. But it has the basics :-)

[Jack Ashore]

Brandon, Regarding fluid for the VS2, I had on old bus mechanic (Ted from Coach Maintenance Company) tell me that even though the manuals call for Dexron II, the industry learned that 40 wt was better for some reason.  I see you are using wet clutch tractor hydraulic oil, so I guess you don't like the modern Dexron option either.  In the absence of tractor hydraulic oil, would you recommend 40 wt or something else?

[Brandon]

Brandon, Regarding fluid for the VS2, I had on old bus mechanic (Ted from Coach Maintenance Company) tell me that even though the manuals call for Dexron II, the industry learned that 40 wt was better for some reason.  I see you are using wet clutch tractor hydraulic oil, so I guess you don't like the modern Dexron option either.  In the absence of tractor hydraulic oil, would you recommend 40 wt or something else?

My bus had Dexron in it before...I changed it out for the tractor wet clutch transmission oil (which is cheaper and available at almost every farm store/Napa/etc). I can get a part number tonight if you like. I've heard folks run all sorts of stuff. I chose this fluid because my father (a heavy equipment mechanic) recommended it. They run it in dozers/etc. which have remarkably similar style transmissions and far more difficult working loads/environments.

I was low on fluid and we were out in some little touristy town in WA doing a vintage 4x4 meetup so I hit up the local NAPA and even they had 5-gal pails of it and it was very cheap. I dropped the pan recently to re-gasket and didn't find any alarming levels of nasty in the oil. It stays the same golden brown color and AFAIK exceeds the vintage Allison fluid requirements.

[Jack Ashore]

Great thanks.  If you have the time the part number would be helpful. 

As an update, this morning I drove the bus over to General Diesel, staying in low gear the whole time to avoid a stalling scenario.  The assigned mechanic and his supervisor do not claim experience on this model, but seem game to figure it out.  I have forwarded them all of your comments on this blog, which he read immediately, and I just sent him Brandon's ghostbus.org blog, so hopefully he gets the time to look at all the Allison transmission posts.   Right now they are dropping the pan to inspect.  They have already found some tiny metal flakes, a bad sign, but I am hoping the damage is limited.  They felt there was no point in going at the governor until they had at least checked for any obvious damage from the pan.

[Brandon]

Post a picture if you can of what was found in the pan.