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200 4R, VERY hard 1-2 shift with normal acceleration

9K views 5 replies 2 participants last post by  SSedan64 
#1 ·
The car pounds into 2nd around 15 mph even with very mild acceleration. Shift points are within spec. I read this is caused by the 1-2 accumulator spring - is this true or could there be something else? Trans fluid pressure is within spec, and TV cable is adjusted fine.
 
#3 ·
Does a stiffer spring make it shift harder or viceversa? Could something be stuck or is that unlikely?

A shift kit was on the rebuild invoice (I didn't get it done) - may be previous owner wanted hard shift or something messed up since I got it (I didn't drive it much, but don't remember it being like this).
 
#5 ·
I read related links and saw broken 1-2 accumulator springs are common. Would that cause hard shifts? I assume it's like having no spring, but still not sure if a stiffer or softer spring causes hard shifts.

The trans invoice says "HS convertor" so it's not stock, but from what I read, that should make it shift softer.

This describes it well
"If you have a stock or close to stock tight converter using the stiffer springs/deleting accumulators will cause very harsh shifting even at minimum throttle angles."

I don't understand stall convertor theory - if they don't grab until 2500-3000 rpm, it seems the car would sit there until that engine speed - mine doesn't, it moves as soon as throttle is opened, and even at 1800 rpm will bang into second.
 
#6 ·
60smotorhead said:
I read related links and saw broken 1-2 accumulator springs are common. Would that cause hard shifts? I assume it's like having no spring, but still not sure if a stiffer or softer spring causes hard shifts.

The trans invoice says "HS convertor" so it's not stock, but from what I read, that should make it shift softer.

This describes it well
"If you have a stock or close to stock tight converter using the stiffer springs/deleting accumulators will cause very harsh shifting even at minimum throttle angles."

I don't understand stall convertor theory - if they don't grab until 2500-3000 rpm, it seems the car would sit there until that engine speed - mine doesn't, it moves as soon as throttle is opened, and even at 1800 rpm will bang into second.
The HS or H/S usually refers to a stock Hi stall converter which came in the SSMonteCarlo, Buick GN - T-Type, Olds H/O 442. Most have D5 stamped on the outer circumference of the converter. Example>> http://www.makcotransmissionparts.com/B15-HS.html
These have about 2025rpm stall rating.
A converter with 3000rpm or above stall doesn't couple as efficiently as a stock converter. The higher stall allows more slippage and therefore can act like a cushion to firmer springs and blocked accumulators.
Torque Converter Info>
Bottom of page >> http://www.carbibles.com/transmission_bible.html
http://rodcustom.automotive.com/79866/0808rc-torque-converters/index.html
 
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