Turbo 400 stuck in first gear - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

 7Likes
Reply
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 18 (permalink) Old Jul 12th, 18, 10:43 PM Thread Starter
Tech Team
Terry
 
Join Date: Apr 2012
Location: Australia
Posts: 243
Turbo 400 stuck in first gear

Hi all
Be great to get some opinion of what has happened here and what needs to be done to fix.

I have a 1970 Ss396 with Turbo 400. It has always driven perfectly so this is the first issue I have ever had with the car since buying it in 2012.
It doesnít get driven much but took it out yesterday and ended up limping it home in first gear. Hereís how it happened.
I opened it up with almost WOT to blow the cobwebs out and then eased off. The next touch of the accelerator got nothing. It revved like it was in neutral. I continued to slow down and it still revved like it was in neutral until it started to engage into first. So whether in D, 1 or 2 it stays in first and wonít shift now. It will go in reverse.
I checked vacuum hoses, trans fluid there are no leaks it all looks good. No burning smell or noises.
I had the fluid and filter changed just a few thousand miles ago it was all good very clean. From my understanding the trans was rebuilt but who knows? It always changed smoothly and was tight.

Any opinion on what has happened here? Where do I start.
Thanks Terry
Aus SS396 is offline  
Sponsored Links
Advertisement
 
post #2 of 18 (permalink) Old Jul 12th, 18, 11:01 PM
Senior Tech Team
Jon N.
 
Join Date: Jan 2003
Location: back in the "Hew-Hess-Hay"
Posts: 4,252
Re: Turbo 400 stuck in first gear

Disconnect the kick down switch wire from the side of the transmission and try it again. I have had switches internally short and cause the same problem.
VinceS427bb likes this.

Jon N.

The only reason someone would want insurance is if they want to pay someone elses bills or want someone else to pay their bills.

BIGOT is a word used by people that can't use logical reasoning to prove that you are wrong when you don't agree with them.
dyno jonn is online now  
post #3 of 18 (permalink) Old Jul 13th, 18, 12:02 AM
Lifetime Premium Member
Tom
 
Join Date: Oct 2006
Location: Firestone, CO
Posts: 1,436
Re: Turbo 400 stuck in first gear

If that doesn't work pull the governor out and spay it with brake cleaner.
VinceS427bb likes this.

70 Camino...Roller

69 Malibu Stock 307, Reverse Manual TH350, 4,500 Stall Edge Converter, 4.56 Spool 35 Spline 12 Bolt

76 C20 VortecPro 496 628HP 655 lb/ft TH400 Edge Converter, 4.10 14 bolt
Tommy the Cat is offline  
 
post #4 of 18 (permalink) Old Jul 13th, 18, 9:15 AM
Lifetime Premium Member
 
Join Date: May 1999
Location: Under the hood of some musclecar
Posts: 28,336
Re: Turbo 400 stuck in first gear

double check the hose at the modulator and at the intake.
Alan F and 71350SS like this.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.




To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
mr 4 speed is offline  
post #5 of 18 (permalink) Old Jul 13th, 18, 9:48 AM
Tech Team
 
Join Date: Feb 2013
Location: Hudson Valley, NY
Posts: 300
I had the same problem on my th400 recently. Turned out the intake manifold gaskets were leaking so there must have been a vacuum loss. I didn't even hear any hissing. After I changed those gaskets the car was fine.

70 Chevelle SS454
454, 3964291 Heads, Manley Race Flo valves, Crane Valvetrain, 226/236 dur, 534/553 lift
Holley 750, Edelbrock RPM Air Gap, Accel ignition,
TCI TH400 B&M 3000 stall, 3.73 posi, Lakewood traction bars.
budsthe3 is offline  
post #6 of 18 (permalink) Old Jul 13th, 18, 11:46 AM
Senior Tech Team
Eric
 
Join Date: Aug 2011
Location: Poteau, Ok
Posts: 4,830
Re: Turbo 400 stuck in first gear

Also check the line to the modulator, if there is fluid in it its bad. When checking the governor, you have remove it and check the gear on the rear of the unit.

You're just jealous because you can't hear the voices!

1967 Olds Cutlass 468 BBC/T400
1963 Plymouth Fury 440/Torqueflite
2007 Ford Mustang GT (momma's car)
oldcutlass is offline  
post #7 of 18 (permalink) Old Jul 13th, 18, 11:08 PM Thread Starter
Tech Team
Terry
 
Join Date: Apr 2012
Location: Australia
Posts: 243
Re: Turbo 400 stuck in first gear

Thanks will try all of that. The car has always had low vacuum and the brakes are pretty hard. It has a lumpy cam so gonna have low vacuum.
Canít see that the trans would suddenly be affected by that though. I might try changing the hose on the modulator it does seem a little soft in parts. Should it be connected to carb or intake?
Thanks
Aus SS396 is offline  
post #8 of 18 (permalink) Old Jul 13th, 18, 11:16 PM
Senior Tech Team
 
Join Date: Dec 2004
Location: tucson az
Posts: 14,314
Send a message via AIM to Jim Mac
Re: Turbo 400 stuck in first gear

I had the same problem years ago in my camaro, turned out the governor got stuck. pulledthe cover, slipped the Gov out and moved the weights until it clicked free. installed it and its been fine. jim

Jim

70 chevelle, SS clone 454 4 speed
71 camaro. (owned since 1978!) 6-71 blown small block 400
66 chevelle 350 4 speed 3.55 12 bolt
66 el camino 350 th350 parts hauler
Jim Mac is offline  
post #9 of 18 (permalink) Old Jul 14th, 18, 3:25 AM Thread Starter
Tech Team
Terry
 
Join Date: Apr 2012
Location: Australia
Posts: 243
Re: Turbo 400 stuck in first gear

Ok is the governor behind the plate with 4 bolts on the right rear of trans?
If I unbolt it and pull it out will I loose fluid? Also will I need a gasket to refit? Can I use auto silicone?

Jim did your issue happen like mine as I described..just curious.
Thanks

Last edited by Aus SS396; Jul 14th, 18 at 3:28 AM. Reason: Add a thought
Aus SS396 is offline  
post #10 of 18 (permalink) Old Jul 20th, 18, 1:40 AM Thread Starter
Tech Team
Terry
 
Join Date: Apr 2012
Location: Australia
Posts: 243
Re: Turbo 400 stuck in first gear

Hi
See last post in thread with questions. Any advise appreciated before I start pulling apart.
Aus SS396 is offline  
post #11 of 18 (permalink) Old Jul 20th, 18, 7:13 AM
Senior Tech Team
Jon N.
 
Join Date: Jan 2003
Location: back in the "Hew-Hess-Hay"
Posts: 4,252
Re: Turbo 400 stuck in first gear

You shouldn't lose a lot of fluid, just a little. I wouldn't use silicone. If necessary, make a new gasket. Many auto parts stores, at least they used to, carry gasket paper of several different thicknesses. Go for the thinnest.

Jon N.

The only reason someone would want insurance is if they want to pay someone elses bills or want someone else to pay their bills.

BIGOT is a word used by people that can't use logical reasoning to prove that you are wrong when you don't agree with them.
dyno jonn is online now  
post #12 of 18 (permalink) Old Jul 20th, 18, 7:59 AM
Senior Tech Team
 
Join Date: Dec 2004
Location: tucson az
Posts: 14,314
Send a message via AIM to Jim Mac
Re: Turbo 400 stuck in first gear

my wife used to drive the car to work as a daily driver, I get a call after work the car is acting up. I go to swap cars with her and drove it home in 1st. would not shift. called a couple granny shops the next day and they all told me it needs a rebuild over the phone. finally talked to 1 that said try pulling the governor and see if its stuck. crawled under the car and pulled the cover after lowering the back of the trans (71 camaro no clearance) sure enough the piston was stuck. jim

Jim

70 chevelle, SS clone 454 4 speed
71 camaro. (owned since 1978!) 6-71 blown small block 400
66 chevelle 350 4 speed 3.55 12 bolt
66 el camino 350 th350 parts hauler
Jim Mac is offline  
post #13 of 18 (permalink) Old Jul 20th, 18, 3:31 PM
Lifetime Premium Member
Harold
 
Join Date: Feb 2006
Location: Bonham , N.E.Texas
Posts: 1,445
Re: Turbo 400 stuck in first gear

governor cover gasket was cork originally, buy thick gasket material if they don't have cork. Jack up rear of car to avoid fluid loss but you will still lose some.. Hold the weights in and tap on a block of wood each way and watch for spool to move in the slots. Clean with solvent and air dry until free movement occurs without tapping. Worse case,pull gear off and spool will come out the end, then clean it well. You may need a new gear . I will send you one if needed- $5 plus postage

New paint -near complete
66 SS 396. now 427
4sp w/GV, AC,PS,3.31 Posi,ft disc,11" r drum
86 Buick Grand National
89 K25 Suburban that I bought new,is new again
And a bunch of other junk.
driveshaft-texas is online now  
post #14 of 18 (permalink) Old Jul 27th, 18, 2:24 AM Thread Starter
Tech Team
Terry
 
Join Date: Apr 2012
Location: Australia
Posts: 243
Re: Turbo 400 stuck in first gear

Hi everyone

Thanks for the replies much appreciated. So an update.

I pulled off vacuum hose and made sure clear. Blew some compressed air through. I was concerned that it is just a hose and not the metal pipe with hose ends. I tweaked the screw in the modulator to check if free it seemed ok.

I then disconnected the wiring for the kick down switch.

I took for a drive and the car changed gears beautifully. So either I did something to the modulator or the kick down switch is fried. Anyway car changes gear now so all good.
What would you suggest the issue is with the kick down switch. Would it be the part under the accelerator or the part on the transmission? Just so I know what to replace.
Thanks
Aus SS396 is offline  
post #15 of 18 (permalink) Old Jul 27th, 18, 8:05 AM
Senior Tech Team
Jon N.
 
Join Date: Jan 2003
Location: back in the "Hew-Hess-Hay"
Posts: 4,252
Re: Turbo 400 stuck in first gear

Transmission kickdown works by applying 12 volts to a solenoid that is located in the transmission, mounted to the valve body. When it gets 12v, the solenoid opens and dumps pressure, making the transmission go into kickdown mode. If it shifts ok when disconnected, the solenoid isn't the problem. Time to check to see if there is 12 volts full time with the ignition switch turned on, feeding the solenoid. If there is, problem is upstream from there.

Jon N.

The only reason someone would want insurance is if they want to pay someone elses bills or want someone else to pay their bills.

BIGOT is a word used by people that can't use logical reasoning to prove that you are wrong when you don't agree with them.
dyno jonn is online now  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome