Allison 1000 Upgrade
Including
Transgo shift kit
Transgo converter flow valve 190psi
& YANK SSDuramax Converter
We started with the removal of the trans form the truck.  For the most part this is a strait forward process.   The one thing to keep
in mind is that this thing is not light, (aprox 320lbs Dry with converter)  make sure you have a good tranny jack and some one to
help out.  To give you a little help you can get the converter bolts buy removing the Passenger side wheel well shroud and the starter.
To make the job a bit easier I made a
mount for my engine stand to mount to
the P.T.O. cover
Removing the bell housing as per the Transgo
instructions. The instructions are very strait
forward and vary easy to understand
Not part of the normal installation of this kit but I
decided to replace my C1’s though C3’s  the kit
only recommends the C2’s.  In My case the C2â
€™s were in great shape but my C3’s were
toasted.  I had limped the trans aprox 6-7 times at
freeway speeds in overdrive..
Here you can see the burn C3 clutches and the burn
marks on the steels
This is the C1 & C2 Drum disassembled; it looks
more complicated than it is.  If you fallow the
instructions and take you time you should have no
problems.  It’s also a good Idea to pick up an
Allison 1000 service manual to help you along
New C1 and C2 Clutches and Steels
New YANK Converter Side by Side with the stock converter.  You will notice that this thing is about 15-20 lbs heavier than
the stock one.  Also it has a billet machined cover vs. the stock stamped steel and welded on tabs.

The YANK  SSDURAMAX Converter has a Multi plate lock up clutch that gives you three times the lockup surface area that
a stock Duramax has. It also has a heavy duty one piece billet cover and custom machined stator
After all is said and done, the time comes to reinstall the Allison.  This project can be done in a weekend with a little help from
some friends.  I would guess from start to finish it took about 10-12 hours.  Keep in mind this is the first one I have ever done.  
I have never rebuilt a transmission in my life but, I have done my share of Mechanic work.
Now comes the time to test it….  My truck puts out aprox 425 RWHP and 750 RWTQ.  Well above stock numbers.  I can
easily hit the gas at 50 mph and be at 110mph is seconds with out limping the Allison now, before it took little to Limp it.   I had
a chance to test it pulling a 40,000lb Mixer up a hill for fun (who would pass that up) The truck did great, the lack of traction
was my only problem. The Transgo kit gives me firm but not harsh shifts and the YANK converter give you a strong lock up
feel along with a little faster of the line feel to it.   Overall I am vary happy with this setup.
By Chris Finstad
All SJRC Logos are Trade marks of San Juan Rock Crawlers © 2003 of sanjuanrockcrawlers.com
Transgo shift kit
Transgo shift kit includes new trim valves,
new  C2 return springs, drilling some larger
holes in the valve body, and modifications to
the C2 clutch piston. Claims to hold  up to
600 hp with a new converter

Transgo converter flow valve
The Allison runs at 250 psi and drops to 150
psi anytime the converter clutch comes on.
The Transgo converter flow valve allows you
to raise the pressure to 170 or 190 psi.

Yank SSDuramax Converter
SSDURAMAX has a Multi plate lock up
clutch that gives you three times the lockup
surface area that a stock Duramax has. It also
has a heavy duty one piece billet cover and
custom machined stator.