Hi all,
72 Scamp, /6, 3 speed auto, 36k miles, runs great.

Tranny shifts perfectly while under hard, medium, or light acceleration. The problem is that I live in a city, and when I'm going streetlight to streetlight and only getting up to 10-15 miles an hour it clunks into 3rd during the coast before braking. So far this is only annoying but I don't want to trash an otherwise good tranny if something is wrong.

I've tried to adjust the kickdown linkage towards the back slightly (1/4 inch or so) there is no play if you push it towards the rear. Think I should move it back further? Under hard acceleration it shifts to 3rd at about 50, under light at about 25.

WTS

I get "zinged" about it all the time, but I've always taken advantage of frequently manually shifting my automatics. For example, in city driving, I leave it in "2" range until I get going good enough to warrant Direct. I also use the same feature to downshift to second at a certain point while braking to save/assist those marginal drum brakes. I never really manual shift into first, I find it is unecessary and the l/r band apply is pretty abrupt.

You could try adjusting your kickdown (front) band, that could possibly cut down on your clunkiness, although "third" is a clutch apply. Did you try going the other way with the KD linkage? It will shift sooner, but perhaps not as harshly.

"DW"

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If it ain't broke, fix it!

I think lengthening the KD rod will make it shift harder for a given throttle opening. This will show up on your light throttle and "lift foot" shifts.
Try shortening it.

If it is not a KD adjustment problem, me thinks somebody has installed a shift kit in the trans. The 'shuttle' valve controls that lift foot acceleration situation. If somebody has irreversibly modified the valve body, you made need a stock replacement.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

May as well try adjusting the linkage the other way as suggested. As far as the shuttle valve modification possibility I doubt it cause this was a 'little old lady car' (really) but who knows what mechanic has lurked under her hood? (Nor do I know what a shuttle value is)

So you guys are saying that this is not normal and should not be happening to a healthy vehicle, right?

Thanks

Personally, I doubt you have a major issue here. Perhaps some slop in other driveline components, i.e. u-joints, spider gears, is making the direct drive coast clunk seem worse than it is. Check for excessive slop in the driveshaft, and if it's really worrying you, change the fluid and filter in the trans also, probably won't help, but it certainly can't hurt.

"DW"

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If it ain't broke, fix it!

I've had that problem in my '76 W200. When it did that lift foot upshift, it sounded like somebody hit the driveline with a 10# sledge! Very annoying! It never broke anything, but something that sounds that bad cannot be good. I removed the shift kit parts from the case and replaced the v. body, & it took about 50% of it away.
If the tranny was ever serviced, many mechanics would try and sell a shift improver with the job.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd