Chevy Nova Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
1,908 Posts
Discussion Starter #1
For your trans gurus out there.....

Running a TH350 with a manual valve body. The 1-2 shift is somewhat inconsistent. Sometimes it is immediate, but most times about 6000 rpm or greater there is a slight delay. The 2-3 shift is always instant.

Anything obvious that could be wrong, ie governor? Anything here I can fix myself?
 

·
Registered
Joined
·
4,760 Posts
may want to check the fluid and see what it looks like i know this sucks but you may need to drop the pan and see if there is a lot of varnish or metal shavings or red particles in the bottom your clutches may be fried ( burnt ) causing the slipping also look to see if youve got a stuck valve in the valve body or misaligned valvebody plates
 

·
Registered
Joined
·
1,908 Posts
Discussion Starter #4 (Edited)
The fluid was fine and hardly anything in the pan, nothing abnormal. The trans is on the floor so it is easy to do anything I want to it right now.

Sorry, let me clarify. The trans isn't slipping there is just a slight delay on the 1-2 upshift at the race track. For example, if I move the shifter at 5800 RPM it will shift somewhere between 6000 and 6200 RPM. Never the same point but close. Adjusting the shifter cable doesn't seem to change anything.
 

·
Registered
Joined
·
51 Posts
I am also having the same problem with my TH350. Under heavy load the 1-2 shift hesitates but 2-3 is always instant.
This has happened since the trans was rebuilt 2 summers ago.
 

·
Premium Member
Joined
·
15,966 Posts
Wear or incorrect clutch pack spacing.

The 1-2 shift clutch drum in most TH350's is only a 4 disc drum.

A true performance TH350 should be upgraded to a 6 disc drum and have what is known as "WAFFLE" clutches installed. And should be set to a tight tolerance.

Wear and excessive clearance causes the slow shift.
(what I call pause and bump)

The variable pressure valve on a stock transmission with the kick-down cable can cause this, the kick down cable controls the pressure valve that controls intermediate clutch pressure.

If you have a manual valve body the kick down cable system is eliminated.

AL
 

·
Registered
Joined
·
4,760 Posts
Wear or incorrect clutch pack spacing.

The 1-2 shift clutch drum in most TH350's is only a 4 disc drum.

A true performance TH350 should be upgraded to a 6 disc drum and have what is known as "WAFFLE" clutches installed. And should be set to a tight tolerance.

Wear and excessive clearance causes the slow shift.
(what I call pause and bump)

The variable pressure valve on a stock transmission with the kick-down cable can cause this, the kick down cable controls the pressure valve that controls intermediate clutch pressure.

If you have a manual valve body the kick down cable system is eliminated.

AL
hes correct im running the 6 disc drum in my th350 but im running a modified stock valve body i have eliminated my kick down so if i want to down shift ill do it manually :yes: :D
 

·
Registered
Joined
·
1,908 Posts
Discussion Starter #8
Thanks Guys. There is no kick down, full manual....right to the track and back. This was a rebuild from a local shop and I've changed the oil a few times and never much in the pan so wear should be minimal. Manual valve body, hardened sprag, but don't know how many discs. I can take it down to the shop and have them fix it but I'd like to learn more about these contraptions. They build quite a few winning transmissions at PRP so I'm not concerned about the quality of the rebuild but then again we are all human...
 

·
Premium Member
Joined
·
15,966 Posts
it may be the governor
Governor has no effect on a manual valve body

Thanks Guys. There is no kick down, full manual....right to the track and back. This was a rebuild from a local shop and I've changed the oil a few times and never much in the pan so wear should be minimal. Manual valve body, hardened sprag, but don't know how many discs. I can take it down to the shop and have them fix it but I'd like to learn more about these contraptions. They build quite a few winning transmissions at PRP so I'm not concerned about the quality of the rebuild but then again we are all human...
They just need to tighten up the clearance in the 1-2 clutch.

Al
 

·
Registered
Joined
·
1,908 Posts
Discussion Starter #11
They just need to tighten up the clearance in the 1-2 clutch.

Al
Thanks again Al. I'm going to have to read up and tear into the thing over the winter or start rebuilding a spare I got to learn how this contraption works.
 

·
Premium Member
Joined
·
15,966 Posts
Thanks again Al. I'm going to have to read up and tear into the thing over the winter or start rebuilding a spare I got to learn how this contraption works.
I am doing the same thing myself!

just need to get some other projects done before I start.

I have the table mount and some tools.

I believe I am smart enough to figure them out!:rolleyes::rolleyes:

Al
 
1 - 13 of 13 Posts
Top