727 transmission - I'll try to describe my problem

[MrJLR]

318 engine, 3:55 gears brand new from Dr. Diff, 727 transmission.

When I accelerate real slow, first gear takes a long time to shift to second. ....then when it does, it slams into second. Very harsh.

If i accelerate harder, if shifts normal and great.

As I come to a stop, it down shifts from second to first very hard...

Any idea what these symptoms are caused by?

Thanks for any help in advance!

Jeff

 

[440Ken]

Throttle pressure needs to be adjusted so that when you are driving normal it will shift into third at approx. 30-32 mph. Your upshifts are happening at a higher speed, therefore decrease the pressure. This is done with the linkage that goes from the carb, to the transmission.
One adjustment takes care of the upshift as well as the off throttle downshift.

 

[krazykuda]

Do you have the transmission kick-down linkage installed?

Is it adjusted properly?

 

[AJ/FormS]

Or do you have the KD lever tied back.

If you cant get good results with a KD adjustment, I fear the governor will need to be changed. I bet its the original 2.76 slug. The new driveshaft speed with 3.55s is running up the pressure pretty quick. A lighter slug will help a lot.It solved my issues, under same circumstances.

 

[MrJLR]

So most likely I need to adjust the kick down linkage?
I'll read up on it and try first thing in the morning. ....I'm on vacation this week!


Thanks.....I'll report back with my results!

 

[MrJLR]

Ok....here are pics of my linkage setup. .....doesn't look anything like the pictures I found on the internet......

How do I adjust it?

 

[MrJLR]

Ok - I got it!
MUCH better! !!!!!!!!

The previous owner just threw it on without even trying or giving a damn.
moved the screw to the front, added the screw on the right....a little adjusting and it's WAY better now. ......!

All temporary. ...looks like hell but now I know how it works. I'll be putting a new carb and manifold soon and redo it all nice.

Thank you all for the help! Now I can drive it a little!

 

[mguner]

The factory linkage had a return spring to help keep the weight of the linkage from being interpreted by the trans as throttle position. Your front bolt improvisation emulates that function to degree. Does your linkage have an adjustment on the transmission end or is it the solid rod?

 

[MrJLR]

The factory linkage had a return spring to help keep the weight of the linkage from being interpreted by the trans as throttle position. Your front bolt improvisation emulates that function to degree. Does your linkage have an adjustment on the transmission end or is it the solid rod?

Hmmmmm... I don't know.
I'll have to check!

 

[AJ/FormS]

Well I see 3 things;
1) that wire laying across the heat cross-over is wanting to catch fire, and
2) The KD link appears to park too far to the rear. You see that [-shaped pivot link? It usually parks nearer to vertical.It may not be a big deal as somebody may have adjusted the internal stop, say as part of a shift-kit procedure. If in fact that's true, it may be partly responsible for the closed-throttle shift harshness.
3) Thats a clever cable extension, to convert a 2bbl throttle cable for use with a 4bbl . Unfortunately its not very safe. If one of those links should happen to get caught on something, the carb throttle could hang open.If it happens in traffic it could get expensive. That link should be one-piece, and free to rotate on the front pivot pin. But the best solution is to obtain a 4bbl cable. I would not drive it like that. Clever tho...

But I read that you're getting rid of that Chebby carb, so, the sooner the better. And when you switch, try to get a proper A-body 4-bbl KD system, and a Mopar specific carb.

 

[mguner]

Hmmmmm... I don't know.
I'll have to check!

That little outer groove on the shaft is where the linkage return spring usually hooks. The solid rod versions are not very friendly to A-body applications and usually bind up on the firewall floorboard area. If you can find a dual bell crank version, they use a pivot shaft that screws into the bell housing and one on the back of the throttle linkage bracket so the only movement of linkage along the firewall is vertical.