Shift Management/ Dedenbear Powerglide
By Lance Clifford


When building a new competition rock buggy for my wife, I wanted all the best hardware. Shaffer's Offroad was building the vehicle, and they recommended I call up Shift Management in Rancho Cordova, CA, to discuss transmission options. So I gave them a call and talked with Bob Herr. I told Bob I wanted the smallest, lightest tranny that could still handle severe abuse. I had a 2002 Vortec 4.3 Chevy V6 as a donor motor, so I wanted it to be able to directly bolt to the motor without the use of any adaptors. Shift Management builds and sells all types of transmissions, but there was one tranny in particular that Bob felt fit the bill perfectly. He recommended I get their Dedenbear cased 2 speed Powerglide. At only 16 1/2" long and 90lbs. complete, the Powerglide is a perfect choice. The Powerglide has a standard GM V8 bolt pattern that will bolt directly to my 4.3.


Shift Management/Dedenbear Powerglide (left) next to a 700r4.

The Powerglide transmission was used in GM cars from 1962 to 1973 and is widely known as one of the most compact and indestructable transmissions for its size. It is the transmission of choice for many drag racers. Powerglides are not only the transmission of choice in the drag racing community, but in the monster truck community as well. But how will a drag racing tranny work in a rock crawler?
Shaffer's Offroad ordered an Atlas 5.0:1 transfer case for the new Diablo. With 5.13:1 gears in the axles and the 1.82:1 first gear in the new Shift Management tranny, that puts the rig at 46.68:1 in first gear. This is just about right for an automatic transmission'd rig. Remember, the torque converter multiplies the torque by almost double, so you do not need the low gearing required in a manual transmission rig.

We decided that since we were going with the best of the best, and did not want to DNF an obstacle for broken tranny parts, it was cheap insurance to buy a Dedenbear case for the transmission. This case is incredible quality! It is not only well built, but also has a high bling factor to it. It is rated to handle massive drag racing horsepower - over 2000 horsepower! I think it can handle the 220hp the little Chevy V6 can churn out without even breaking a sweat.

Dedenbear case features -

  • 100% bolt-in parts.
  • Bellhousing is part of the case just like the Powerglide so all machining alignment remains perfect.
  • Made by a permanent mold process from heat treated aircraft grade aluminum. This process is stronger, more ductile and more accurate than brittle sand castings.
  • Oil pan flanges are thickened to stiffen case. Beefed up oil pump area prevents front case distortion under high horsepower. Minimizes flexing which causes gear misalignment and breakage. This case does not leak!
  • Oil pump mounting bolt holes heli coiled to prevent thread failures.
  • Redesigned oil passages radically improves release time of the transbrake and allows instant application.
  • Reverse piston bleed hole vents air from piston area.
  • SFI approved for flywheel and clutch drum explosions, so there is no need for external shields or bottom straps.


The adapter wouldn't quite bolt up.


The notch we made in the adapter to clear the bolt

We recieved the tranny from Shift Management in less than a week after ordering, and they even shipped it right to our door! We did have an issue with the Advance Adapters adapter plate that bolts the 'Glide to the Atlas, however. It seems that the transbrake plug (yes, this tranny is capable of having a transbrake - got launch?) was interfering with the plate. We had to make a notch in the adapter plate to get it to fit properly. I believe AA has made revisions to their adapter plate to take care of this problem now.

Driving impressions
Once the rig was finished, we took it for it's maiden voyage - straight onto a trailer, and to competition! The transmission worked flawlessly, and never even heated up. We elected to use a tranny cooler with a thermostatically controlled fan, and the only time I've ever noticed the fan come on was when I had to tow another rig that was completely dead off a trail in Moab. Even then, the fan only cycled on every now and then.

Now what don't I like? I don't like the torque converter stall I picked. We went with a stockish 1800 stall. While it works nicely while crawling, it doesn't quite get the little 4.3 motivated enough when launching up the most extreme walls during competition. Last week in Cedar City I was able to drive the vehicle in the UROC West event, and could not make a climb up a 60 degree 27 foot tall climb. Yes, you read that right - 60 degrees, and 27 feet tall! The rig just didn't have the UMMPPHHH to get up the wall. We determined that it wasn't nescessarily the lack of power, but possibly too low of a stall in the torque converter. So after the competition, we went back to the wall for some redemption...

** Now kids, don't try this at home, because you'll most likely grenade your tranny into a million pieces! This manuver is only recommended for Shift Management/Dedenbear Powerglides and rental cars!!! **

I inched up to the base of the wall, put the tranny into neutral, revved it till it was bouncing off the rev limiter, and "neutral dropped" it into 1st. The vehicle launched at neck breaking force, and literally caught air over the top of the climb. We definitely are going to be swapping out the converter for a higher stall. How much higher is still up in the air. Possibly 2500-3000. We'll keep you posted.

UPDATE - 9/14/04

We decided to try replacing the torque converter before the St. George event. The tranny was yanked out of the rig, and a TCI 3,500 stall torque converter was installed. First impressions in the parking lot were immediate - the rig launched in a smoky burnout that would make John Force proud! But how would it crawl? We'd have to find out on our first obstacle in St. George...

The rig was definitely different, and took some getting used to. One very noticeable difference was the increased braking power it now had. The rig didn't overpower the brakes any longer.The transfer case also seems to shift a little easier with the higher stall not loading up the drivetrain. Of course our first obstacle of the weekend would be the test of all tests - a verticle, off camber wall that required a full thottle launch to get the belly of the rig up and over the breakover at the top. I lined up at the bottom, looked down to Mike for the nod of approval, and he yelled "GET IT!!!!" I stalled the rig up hard, and let off the brakes and put the pedal to the metal, and the rig launched every bit as hard as when I did the neutral drop in Cedar City! I rocketed up and over the climb (doing a spotter ride, mind you!) with one of the cleanest runs on the day on that obstacle. I was impressed...

As for the crawlability of the high stall, it works fairly well. Don't get me wrong, it is considerably different. The motor wants to wind up in high bind situations such as crawling up a 4' ledge. You need to drag the brakes to have control. Looking back, I think I would opt for about a 3000 stall over the 3500 if I were to do it again. However I will keep the 3500 for now, and we will learn to get used to it, and enjoy the nitrous-like lauching. One thing has remained constant through our torque converter experimentation - we LOVE our Shift Management Dedenbear Powerglide!

Shift Management, Inc.
6200 Warehouse Way
Sacramento, CA
(916) 381-4700

Dedenbear Products, Inc.
1917 Oak Park Blvd.
Pleasant Hill, CA 94523