8T1-7T9 BIONIC VETTE

What causes chugging with 700R4......
I can be in third gear and it chugs. :confused:
This has to be hard on the drive line components.
No clanking sounds yet....however if this keeps up.....I imagine the U-joints are going to start clanking.
:confused:

Russ Bellinis

I don't know enough about automatic trans to tell you what to fix, but it sounds like it is hanging up in a higher gear when it should downshift, or the torque converter has locked up and isn't unlocking when you slow down.

dman535

part throttle ? full throttle ?

Have you changed or inspected the TV cable setting ?

Does the fluid look ok ? shift ok in other gears ?

8T1-7T9 BIONIC VETTE

Not full throttle......cruising about 30-40 mph.
It stops when I drop her into second gear....however third and fourth it chugs.
Trans was set up to up shift into fourth gear at 50 mph.
Seems like it does not down shift and lingers in higher gear.....Like a standard when the driver forgets to down shift from higher gear.....the car chugs. :confused:

Jack71

Is your tranny wired to lock up the Torque Convertor in 3rd & 4th?

Larry B.

Never ever us OD at speeds less than 65mph.. Not ony is it hard on drivelline components, it is a real killer of transmissions. Thats on of the reason 700R4's eat 3-4 clutches. Anyway the Torque converter should be tied to 4th gear oil pressure so it will only lock in 4th.


[Modified by bluevetteman, 5:29 PM 3/28/2004]

8T1-7T9 BIONIC VETTE

Jack71,
I think only 4th gear......I'm not sure...
I'll take her back to the tranny shop see if they know how she's hooked up and let you guys know later.
I'll also check to see if the lock up is hooked to the 4th gear oil pressure.
What about 3rd gear?.....why does it chug in 3rd?
Looks like have some questions for the trans shop tomorrow. :confused:

wombvette

Most Corvettes lock up in both third and fourth. This is the first thing that I changed with my conversion. You should check your brake switch to make sure that the disengage function is working. The shift points can be changed with the governor. The downshift dropout from fourth should be about 35 mph. You do have a disengage switch on it dont you?


[Modified by wombvette, 11:01 PM 3/28/2004]

8T1-7T9 BIONIC VETTE

I have no clue where to find the brake disconnect switch or the downshift dropout switch.....
I'm giving it to the trans shop.....let them figure out what's the problem.....If I start tampering with this.....I could mess it up.
Thanks for the suggestions on where to look......I'll look like I know what I'm talking about when I take the car in :D

American Boy

My Cadillac with 700r4 does the same in 3rd and 4th sometimes. The lock-up don't disengaged. I didn't find why for now because it happend only 2 or 3 times. But I think that the lock-up soleinoid must be sticking. If you want to be sure, when it does it, step on the gas a little and look at the RPM. It should be following the speedo gage directly as a manual tranny.

Stephan

mrvette

Assuming the 700 is in a C3 vette similar to my '72, I think your problems are in the brake pedal setup....in that the orange wire is live, and the switch passes current to the white wire and then to the rear lights....problem is, that is just the opposite of what you need for the lockup, you want the feed voltage to disappear when the brakes are pressed....so you want to include a relay in there to open the contacts to remove 12 volts from the tranny line, when the coil is actuated by the brake switch.....

otherwise you have 12 volts allways on the tranny, and any controll on the ground side is allways boss over that lockup solenoid....the tranny gear select switches, the computer if you have one, or anything else.....

I have a switch on my console to go from manual...meaning allways locked in 2-3-4 gears, OR computer lockup at 50 mph....no matter what gear....

plus of course the brake light relay....

now the solenoid inside the tranny may have a hangup and not releasing...that is possible also....

GENE

markdtn

Use a brake switch from an 89 F-body. It has regular terminals for brake light (normally closed) and another set that can be used for lockup (normally open). Terminals are slightly different, so try to get a plug from the junkyard.

mrvette

There you go, I knew Gm had one of those switches on some car or other, but I had relays, so that's the route I used.....

GENE

The Money Pit

You're not running a singleplane intake are you?At that low a speed I wonder if lack of torque is why it chugs.I run the RPM and if I get too slow it'll chug slightly.Feels like a stick car in the wrong gear when you're first learning. :yesnod:
Mind you the same engine with the TH350 did not chug........go figure.


[Modified by The Money Pit, 5:57 PM 3/29/2004]

8T1-7T9 BIONIC VETTE

Yes.....That's exactly what it chugs like.....Like a stick shift in the wrong gear when we first learned to drive.
And yes I have a single plane intake....It's the new Motown intake.