BW 4404 AWD transfer case "How it performs" B5000 Race Reports

[Starkman]

I finally got my truck out on the ice. I wanted to start a discussion about the BW 4404 AWD transfer case and how it performs in a race situation.

Link to the truck
98 Mazda B5000 race report

Link to a good writeup on the 4404
School Me (and you?!) On Viscous Couplings (BW4404)

 

[Starkman]

When I started the build I wanted a V8 and found a Mountaineer with 108,000 miles for the donor. After reading some write ups about the 4404 I took away that it has a torque split of maybe as much as 70/30 split. That's what the bad ass rallycars have to get them to oversteer and that is ideal for ice racing.

So, I decided to use the 4404 because it's lighter, less complicated to install (the only real option is a 4406 swap that means finding a case and driveshafts and cutting a hole for the shifter), and I have it.

 

[Starkman]

What I found

I raced my V8 Explorer on the ice and know how it performs on the ice. It has a 4406 swap so 50/50 torque split and a wore out factory limited slip. I had the suspension set up for ice with 10 psi in the front tires and 30 psi in the rear, no front swaybar stock rear swaybar. The Ex would rotate on decelerate and oversteer pretty well on acceleration.

Last spring I raced a Rallycross with the Truck. The suspension is set up with stock B3000 front and rear swaybars. I added Rancho XL9000 shocks with the fronts set at full hard settings and the rears at full soft. The rear shocks are over dampened and very stiff even at full soft settings (remember I took all the weight I could off the rear of the Truck). Open rear diff.

There was lots of traction and the Truck didn't spin the tires that much so there was understeer on acceleration. But it did oversteer during deceleration.

 

[Starkman]

Fast forward to 1/13/2019 Ice races

Set up
Same as the Rallycross, stock B3000 front and rear swaybars, Rancho XL9000 shocks in front set at full hard but swapped out the Ranchos for cheap non-adjustables in the rear (much softer). Open rear diff.

Tires
I'm running two classes. What the club calls "Comp studs" and "Comp bare".
The Comp studs are Goodyear tractor tires with normal street studs installed with a 1/4" extended out from the rubber. Comp bare are "studless" of the shelf tires I'm running Michelin X-Ice.

 

[Starkman]

OK, back to the original topic. How does the 4404 work?

The Truck will rotate on decel into the turns but I'm finding as soon as I return to power it understeers. I adjusted tire pressures (lowered fronts) with an improvement with less understeer.

The most telling thing to if the transfer case has a 70/30 torque split is in larger sweeping turns. In the beginning of the turn I'm hard on the gas and have wheel spin. The rear of the Truck comes out indicating more power going to the rear. And, as the spin diminishes the Truck goes into understeer. My guess is that once the rear wheel spin catches up with the front the torque split is 50/50 which induces understeer. Here are some pics of it.

What do you guys think?

 

[Mbrooks420]

The more wheel spin, and hotter the t case in general will cause more bias to front. It can bias more than 50% to the front.

I’m a huge fan of the 4404 on snow and ice.