W30 trans question about shifts
August 8th, 2021, 01:25 PM
#1
W30 trans question about shifts
Hi I have a 70 w30 that the origanal trans was rebuilt.
since owning the car I always questioned how it shifts.
Tough to describe, but say light throttle 1, 2, 3 shifts are a possitive / crisp
Full throttle shifts, the 1,2,3 do shift but seems slippish
Driving down the road normally, floor it and same thing sounds not normal.
I've checked filter and pan 2 times past 3 years and found nothing although rarely driven.
My 442 acts differently......so is it the extra band in the w30trans that makes a smooth full throttle shift?
since owning the car I always questioned how it shifts.
Tough to describe, but say light throttle 1, 2, 3 shifts are a possitive / crisp
Full throttle shifts, the 1,2,3 do shift but seems slippish
Driving down the road normally, floor it and same thing sounds not normal.
I've checked filter and pan 2 times past 3 years and found nothing although rarely driven.
My 442 acts differently......so is it the extra band in the w30trans that makes a smooth full throttle shift?
August 8th, 2021, 04:09 PM
#2
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Join Date: Jan 2010
Location: central Indiana
Posts: 5,341
The OW and BB calibration of the valve body, and the addition of one extra clutch plate (which requires a unique direct drum with relocated snap ring groove) the TH400 has been basically the same since it ceased production in 1988.
You say you have checked the fluid and filter, have you actually REPLACED the filter? Do the shift points become later as the throttle is increased? If not, take a look at the vacuum line to the modulator. As engine load increases, engine vacuum decreases. The modulator pressure inside the trans increases, driving up line pressure to match. If the modulator line is restricted or partially clogged with carbon, the modulator will be slow to react. There should be a noticeable change in the way the engine idles if your unhook the modulator line at the modulator.
The W-30 trans was supposed to be the performance trans, with a matching converter to work with the rowdy camshaft. I would expect it to have a fairly firm shift. If it doesn’t, I’d suggest putting a line pressure gauge on it and see what the pressure does under various throttle positions.
You say you have checked the fluid and filter, have you actually REPLACED the filter? Do the shift points become later as the throttle is increased? If not, take a look at the vacuum line to the modulator. As engine load increases, engine vacuum decreases. The modulator pressure inside the trans increases, driving up line pressure to match. If the modulator line is restricted or partially clogged with carbon, the modulator will be slow to react. There should be a noticeable change in the way the engine idles if your unhook the modulator line at the modulator.
The W-30 trans was supposed to be the performance trans, with a matching converter to work with the rowdy camshaft. I would expect it to have a fairly firm shift. If it doesn’t, I’d suggest putting a line pressure gauge on it and see what the pressure does under various throttle positions.
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