200 4R, VERY hard 1-2 shift with normal acceleration - Hot Rod Forum : Hotrodders Bulletin Board
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Old 08-14-2009, 07:52 AM
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200 4R, VERY hard 1-2 shift with normal acceleration

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.

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Old 08-14-2009, 08:04 AM
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Some shift kits and aftermarket Servo's recommend removing the accumulator spring and Servo Cushion spring. Not a good idea especially if a stock converter or mildly modified stall converter is used.

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Old 08-14-2009, 12:25 PM
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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).
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Old 08-14-2009, 02:53 PM
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Good Accumulator Info here. >> http://www.turbobuick.com/forums/tra...umulators.html
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Old 08-14-2009, 03:29 PM
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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.
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Old 08-15-2009, 10:49 AM
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Quote:
Originally Posted by 60smotorhead
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/7986...ers/index.html
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