WEISMANN TRANSMISSIONS
TRACTION PRODUCTS
TRANS AM
"Imsa Box" or "Shuttle Box"
In the mid 70's Mark Donahue and Pete Weismann disscussed what would be the ideal transmission for front engine cars with rear wheel drive. Mark Donohue thought it would be nice to have a quick change ratio similar to a Halibrand in the back of the box. In the early 80's Pete got an opportunity to create the "Imsa Box" with the rear quick change for Electromotive's Nissan and in the hands of Don Devendorf, it won the championship in it's very first year.
The first modification was gate to the
shifter for Paul Newman who needed to know the shift was in the 2/3 gate.
Third box went to Les Lindley who used it for a full
season between rebuilds for many years.
Andy Porterfield's winning SCCA Trans-Am
CarThere
are several features that make this gearbox special. The main
feature is the set of quick change gears at the back of the trans
that enables the car to have a simple final drive live-axle with
no quick change gearset -less sprung weight, while also bringing
the power flow back on vehicle center and rotating in the right
direction. The quick change gears can be installed to either underdrive
or overdrive the output. This enables the car designer/builder
to pick any engine, tire and final drive ratio they want. Quickchange ratios can
be changed while the trans is still in the car. In fact all the gears can be
changed in less than 15 minutes.
The
next main feature is the shift mechanism itself. We call it the
"Shuttle Shift" or as the trans is now called -"Shuttle Box".
Basically the driver has a "W" pattern shift instead of the universal "H"
pattern. In other words,
on a cross gate shift from say 3rd to 4th, the driver just aims
for the gear position and slips it in, there is no distinct jog
up-right-up movement to the shift handle, just a straight shot.
Another main feature is the dog gears
are all on the pinion shaft- so the inertia is cut down tremedously with only
the input shaft, layshaft and the 3 dogrings having to be accelerated or
deccerated during shifts.
Several other key features: Low CG. The transmission is dry-sumped. There are 39 gear ratios available ranging
from a 2.74 1st to a .94 5th. The gears are all staight-cut with
dogs for quick engagement. The weight is 95 lbs, yet it can handle
1000+ hp with 1000 lbft of torque at 8000 rpm.
It won the 24 hours
of Daytona an amazing 10 times out of 11 years with Roush Racing, a couple of
those times those cars were the winners overall!
This transmission is extremely
versatile. It was repacked to sit vertically in the
Oreca Vipers that won the 1997 FIA GT2 World Championships in the hands of
Justin Bell and Tommy Archer.
It featured a revised drysump system and a novel shift
linkage to get to the bottom of the trans. Later we adapted a sequential shifter
to the Imsa Trans.
It was redesigned
into a 4 wheel drive trans, on two different occasions, in two
completely different vehicles, and won the
Pikes Peak Hill Climb
3 out of 4 times. Once in Rod Millen's Toyota Tacoma Truck and
twice in his all conquering Toyota Celica.
Currently the 4wd Imsa trans has found a
home in CORR Pro-4 and WSORR Pro-4 race trucks, and in Thunder Trucks in New
Zealand.
It has also set a few World Records at
Bonneville
in Gale Banks "Cyclone" truck and in several
other cars, check out the bonneville site.
Andy Porterfield's winning SCCA Trans-Am Car
There are several features that make this gearbox special. The main feature is the set of quick change gears at the back of the trans that enables the car to have a simple final drive live-axle with no quick change gearset -less sprung weight, while also bringing the power flow back on vehicle center and rotating in the right direction. The quick change gears can be installed to either underdrive or overdrive the output. This enables the car designer/builder to pick any engine, tire and final drive ratio they want. Quickchange ratios can be changed while the trans is still in the car. In fact all the gears can be changed in less than 15 minutes.
The next main feature is the shift mechanism itself. We call it the "Shuttle Shift" or as the trans is now called -"Shuttle Box". Basically the driver has a "W" pattern shift instead of the universal "H" pattern. In other words, on a cross gate shift from say 3rd to 4th, the driver just aims for the gear position and slips it in, there is no distinct jog up-right-up movement to the shift handle, just a straight shot.
Another main feature is the dog gears are all on the pinion shaft- so the inertia is cut down tremedously with only the input shaft, layshaft and the 3 dogrings having to be accelerated or deccerated during shifts.
Several other key features: Low CG. The transmission is dry-sumped. There are 39 gear ratios available ranging from a 2.74 1st to a .94 5th. The gears are all staight-cut with dogs for quick engagement. The weight is 95 lbs, yet it can handle 1000+ hp with 1000 lbft of torque at 8000 rpm.
It won the 24 hours
of Daytona an amazing 10 times out of 11 years with Roush Racing, a couple of
those times those cars were the winners overall!
This transmission is extremely versatile. It was repacked to sit vertically in the Oreca Vipers that won the 1997 FIA GT2 World Championships in the hands of Justin Bell and Tommy Archer.
It featured a revised drysump system and a novel shift linkage to get to the bottom of the trans. Later we adapted a sequential shifter to the Imsa Trans.
It was redesigned into a 4 wheel drive trans, on two different occasions, in two completely different vehicles, and won the Pikes Peak Hill Climb 3 out of 4 times. Once in Rod Millen's Toyota Tacoma Truck and twice in his all conquering Toyota Celica.
Currently the 4wd Imsa trans has found a home in CORR Pro-4 and WSORR Pro-4 race trucks, and in Thunder Trucks in New Zealand.
It has also set a few World Records at Bonneville in Gale Banks "Cyclone" truck and in several other cars, check out the bonneville site.
Traction Products, Inc. & Weismann Marine, LLC.
1728 Monrovia St. Costa Mesa, Ca. 92627
Tel: 949-645-4064 Fax: 949-645-2424