Is this allison transmission working right?

Mechanicfingers

Registered User
Joined
Dec 25, 2016
Posts
34
Reaction score
1
Location
Sacramento ca
I just bought this truck . F250 1992 IDI motor no turbo. It has a gear vendor setup but Im not sure its working right . Truck shifts hard but down shifts are wicked. I believe it has a Allison transmission installed. Need to look tomorrow and see if I can get a model number off transmission. I have transmission programmer for all trucks and transmissions at my work. So if I can lower pressure for first gear would be great. I don't tow anything heavy . Thanks guys chat tomorrow Merry Christmas ..
 

FarmerFrank

Full Access Member
Joined
Sep 5, 2013
Posts
1,364
Reaction score
59
Location
Blairsville, Pa
Are you sure it's a gear vendor and not a US gear overdrive unit?
Gear vendors aren't normally hard shifting. US gear boxes can hit extremely hard because they are gear drive.

Try getting it into a steady gear going down the road. Hit the button for the aftermarket overdrive for 3-4 seconds while still lightly accelerating. Let off the skinny peddle and see if it shifts. Do the same for down shifts. See if that helps.

Take pictures of under the truck.


Sent from my iPhone using Tapatalk
 

OLDBULL8

Good Morning Ya'll.
Supporting Member
Joined
Feb 12, 2009
Posts
9,923
Reaction score
338
Location
Delphos , Ohio
Useless to reply to your thread until we know what you have.

If it is in fact a US Gear, did you get the control modules?
 

Macrobb

Full Access Member
Joined
Jun 12, 2016
Posts
2,380
Reaction score
1,234
Location
North Idaho
I just want to point out that with my own gearvendor(note that I have a zf manual in front of it), upshifts are relatively smooth, but downshifts CLUNK, when it disengages the conical clutch. It's done that since this GV unit was brand new; as such, I always shift it with the clutch in(up or down).

I'm not sure how this works with an automatic(and the lockup clutch therein), but if it /is/ in lockup when the GV disengages, I'd bet it would make a pretty loud clunk.

One thing you can play with is just unplugging the GV unit wires - there's only a single solenoid to drive it. Unplugged, it will simply be in direct-drive mode, and you can test out your automatic transmission /without/ worrying about up/downshifts from the GV unit.
 

icanfixall

Official GMM hand model
Joined
Apr 10, 2005
Posts
25,858
Reaction score
672
Location
West coast
Welcome to the forum. Its unlikely you have an Allison trans in the truck. that would be a major modification. Are you getting 4 shifts without using the gear vendors. If so and they are hard shifts then it sounds like your tps needs attention. The tps is located on the drivers side of the injection pump.It has 3 wires feeding it. the center wire is green. That wire needs to show .96 to 1.2 volts at key on engine off setting of the throttle. Make sure the engine is warmed up so the fast idle is off. then turn on the key and measure the voltage. Generally these switches last 75,000 miles. Care must be taken if you replace them. Look at the drive on the used switch and see how the throttle dog engages it. you then set it and twist the tps till you can get a screw in it. I use a digital voltmeter and ground directly from either battery. Then use a pointed probe to get thru the wire coating and see what the voltage is . Hope this helps.
 

Mechanicfingers

Registered User
Joined
Dec 25, 2016
Posts
34
Reaction score
1
Location
Sacramento ca
Thank you for all the comments. I will get pictures posted of my equipment on the truck. I had to help a friend buy a car today and was not home all day. Tomorrow after work I will check out those items. Thanks again everyone glad to be here you guys have lots of knowledge . Also very helpful. Thanks again
 

Mechanicfingers

Registered User
Joined
Dec 25, 2016
Posts
34
Reaction score
1
Location
Sacramento ca
You must be registered for see images


You must be registered for see images attach


You must be registered for see images attach
 

Mechanicfingers

Registered User
Joined
Dec 25, 2016
Posts
34
Reaction score
1
Location
Sacramento ca
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
 

Mechanicfingers

Registered User
Joined
Dec 25, 2016
Posts
34
Reaction score
1
Location
Sacramento ca
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
 

Mechanicfingers

Registered User
Joined
Dec 25, 2016
Posts
34
Reaction score
1
Location
Sacramento ca
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
 

Latest posts

Forum statistics

Threads
91,217
Posts
1,128,504
Members
24,045
Latest member
Ramtough01

Members online

Top