Friday, August 08, 2008

The '71 can hang!

As it turns out, the AW71 is stronger then a lot of us have been led to believe. This part has been known for some time actually. The easiest way to cut the soft clutch killing nature out of the AW71 is to modify the accumulator pistons.

Here is a short and simple on how to do it. And I suggest that you do it with the tranny out and upside down (as in pan facing up)!


  1. Remove pan
  2. Remove VB
  3. Pop the accumulator pistons out of their cylinders. This will most likely require a little compressed air. To find where you need to apply that air is simple. Push down on the piston (not too violently either) and watch for bubbling or a stream of ATF coming out near the base of the cylinder. Use shop rags over the piston to keep parts from flying all over dodge and the old ATF spray.
  4. Once they are all unseated, compare the springs from each of the pistons. Take the spring with the smallest internal diameter and head to Home Depot. They sell round metal stock (rods). Find the largest size that will fit in there easily.
  5. Back at the pad, cut a length of the rod that is just slightly shorter then the overall length of the spring. Put a chamfer on the ends of the rod (if you have the tools), place inside the spring, then place those in the piston and re-seat the piston in it's cylinder.
  6. Repeat until finished.


I will say that if any of the pistons come out real easy, it would be a good idea to replace the o-rings that go around the pistons.

The above completed, you have a transmission that can handle enough power to make your Volvo a hell of a fun beast to pilot on the street. Kenny Howard told me this morning he put 350 wheel through his during dyno testing last night.

The crazy thing about the above testing is the RPM he ran the unit up to. It's been common belief that these units start to self destruct above 5200 RPM, but Kenny ran his up to 7400 RPM! That really managed to blow some common beliefs out of the water.

Ultimately Kenny Howard has gone a long ways towards researching other options for these transmissions. He and I are both on track to build AW71/372 hyrbrids using high performance clutches but the vast majority of work, effort and credit go to Kenny.

For me, I don't plan on needing the ability to rev the motor that high. I'm trying to build a motor with killer mid-range and torque and an HP number north of 300hp at the wheels. The idea is to do this within the 0-6200 RPM rev range that LH 2.4 allows.

On other car related fronts, the grooves continue to impress. I'm know knocking over 10psi on 89 octane gas with no detonation. Now, I'm prolly going to stop right there until I get Knocksense from Boris and make absolutely sure of what I'm already pretty damn sure about. But whatever the case, it's awesome. Cheap gas on a boosted motor equals nice!

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