allison performance ???

[mad6mac2000]

Hello all I am looking for some help with a allison 643 transmision, I
am very peticular and it is starting to bother me a bit. We are getting
some weird shifts on our bird right now, 1st to second is fine and
firm, 3rd to 4th is some what troubling on the climb through the rpm
range, I get a rpm change 2 times before shifting into 4th gear. It is
almost acting like it has 5 gears, is this the torque converter locking
up in the 3rd gear range? then shifting to 4th? I guess I think it
should just shift 1..2...3....4. I have checked the shift points
compared to rpm to speed and they are right on.

this trans is the allison MT643 not 640

Mac and Carrie Good
1978 31' FC NA

[dthollis1961]

Mac,

Sounds like mine. 1, 2, 3, lock-up, 4.

David Hollis 78 FC33 Springfield,IL


--- In WanderlodgeForum@yahoogroups.com, "mad6mac2000"
wrote:
> Hello all I am looking for some help with a allison 643
transmision, I
> am very peticular and it is starting to bother me a bit. We are
getting
> some weird shifts on our bird right now, 1st to second is fine and
> firm, 3rd to 4th is some what troubling on the climb through the
rpm
> range, I get a rpm change 2 times before shifting into 4th gear.
It is
> almost acting like it has 5 gears, is this the torque converter
locking
> up in the 3rd gear range? then shifting to 4th? I guess I think it
> should just shift 1..2...3....4. I have checked the shift points
> compared to rpm to speed and they are right on.
>
> this trans is the allison MT643 not 640
>
> Mac and Carrie Good
> 1978 31' FC NA

[Mike Hohnstein]

Converter lock up will result in an RPM drop, like a shift but softer. The
biggest RPM drop will occur at the 3/4 shift.
The transmission cable should be totally stroked at wide open throttle. It is
imperative that the injector pump lever is totally stroked, then adjust the
trans cable stroke. It is very possible to have a misadjusted transmission
cable prevent full throttle.
The age of your vehicle would suggest the transmission would benefit from
operator sensitivity. When accelerating, backing off the throttle or releasing
the throttle momentarily can effect an earlier up shift and help keep engine
speed down. You wouldn't be happy with the cost of a new transmission. A
Wanderlodge is the LAST vehicle to try to save money on a drive line repair.
The oil cooler lines are the most vulnerable components, they should be like
new. If not, replace them with the appropriate hydraulic lines.
Mike Hohnstein
----- Original Message -----
From: mad6mac2000
To: WanderlodgeForum@yahoogroups.com
Sent: Wednesday, September 07, 2005 9:48 AM
Subject: [WanderlodgeForum] allison performance ???


Hello all I am looking for some help with a allison 643 transmision, I
am very peticular and it is starting to bother me a bit. We are getting
some weird shifts on our bird right now, 1st to second is fine and
firm, 3rd to 4th is some what troubling on the climb through the rpm
range, I get a rpm change 2 times before shifting into 4th gear. It is
almost acting like it has 5 gears, is this the torque converter locking
up in the 3rd gear range? then shifting to 4th? I guess I think it
should just shift 1..2...3....4. I have checked the shift points
compared to rpm to speed and they are right on.

this trans is the allison MT643 not 640

Mac and Carrie Good
1978 31' FC NA





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