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Topic: 700R4 dilemna

in Forum: C3 Driveline Components


700R4 dilemna

Posted: 11/4/07 8:39am Message 11 of 28
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Old Hickory, TN - USA
Joined: 5/26/2003
Posts: 599
Vette(s): 1978 L-82 Silver Anniversary hotrod. /////////////
Joel,

I understand the valve installation may prevent downshifts when I want them, like from 30 -40 MPH at part throttle. It doesn't drop all the way to second unless I shower down on it under 40 MPH. I'm talking about running 90 - 100 MPH in 4th then trying for a top end run. I don't need a downshift there.

Do you know anyone with experience in the new valve. I had looked into the valve some time ago but forgot the source. I have been waiting to get 'lectric to my new garage so I could operate my lift.

Dave


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700R4 dilemna

Posted: 11/4/07 9:38am Message 12 of 28
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20219
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Dave, check this out... I use these all the time.

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btw...this is the same set-up GM installed in the later Corvette 700s('87>), to solve the same problem.Adams' Apple2007-11-04 15:10:54


Joel Adams
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700R4 dilemna

Posted: 11/4/07 12:44pm Message 13 of 28
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Charleston AFB, SC - USA
Joined: 10/31/2007
Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
I'm having a similar problem with my 700R4. Mine has a kit that control everything hydraulically, so no electrical connections. I can't figure out how to get the TV cable adjusted so it will lock up the torque converter.
 
It seems to be shifting fine, and in the right places, but no TC lockup that I can tell. Should i try adjusting the slider forwards/aft or any other suggestions?
 
Thanks
-Josh



700R4 dilemna

Posted: 11/4/07 2:49pm Message 14 of 28
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20219
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
If the trans is set-up for a hydraulic LU, it will ONLY go into LU at a specific road speed(mph)...the TV cable adjustment will have no effect on it.
In your case, you may need to have the spring changed in the LU valve to a lighter one, so it will lock-up earlier. The kits for this normally come with at least three different springs, so the LU apply can be tailored to work at different speeds.
You should be able to feel when it goes into lu, just after the shift into 4th(around 45mph). Depending on what spring tension was used, it may not lock-up until later. There is also a check-ball that must be installed into the snout of the lu solenoid for this to work. If the ball was not installed, the trans will never go into lu.
One way to determine if the lu is working, is to watch the tach. After the shift to 4th, you should be able to see the tach drop down a couple hundred RPM once the converter does go into lu. Once the converter locks up, applying small amounts of throttle should not raise/jump the rpms. If there is no lu, the rpms will raise considerably with just slight throttle.

That being said, there are some folks that will install the ball in the lu solenoid, without using the correct lu valve line-up. This creates lu from 2nd gear up, regardless of throttle, or road speed. It also makes the shifts a little "lunge-y", or rubbery. There are some valve bodies, the late '86 and ups, that do not have a place for the lu valves. These vbs are strictly computer controlled, as far as lu. These should not be used for this application, for this reason.

                                                        More info on lu valveAdams' Apple2007-11-04 15:09:54


Joel Adams
C3VR Lifetime Member #56    

My Link


(click for Texas-sized view!)
             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

700R4 dilemna

Posted: 11/4/07 3:43pm Message 15 of 28
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Charleston AFB, SC - USA
Joined: 10/31/2007
Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
[QUOTE=Adams' Apple]If the trans is set-up for a hydraulic LU, it will ONLY go into LU at a specific road speed(mph)...the TV cable adjustment will have no effect on it.
In your case, you may need to have the spring changed in the LU valve to a lighter one, so it will lock-up earlier. The kits for this normally come with at least three different springs, so the LU apply can be tailored to work at different speeds.
You should be able to feel when it goes into lu, just after the shift into 4th(around 45mph). Depending on what spring tension was used, it may not lock-up until later. There is also a check-ball that must be installed into the snout of the lu solenoid for this to work. If the ball was not installed, the trans will never go into lu.
One way to determine if the lu is working, is to watch the tach. After the shift to 4th, you should be able to see the tach drop down a couple hundred RPM once the converter does go into lu. Once the converter locks up, applying small amounts of throttle should not raise/jump the rpms. If there is no lu, the rpms will raise considerably with just slight throttle.

That being said, there are some folks that will install the ball in the lu solenoid, without using the correct lu valve line-up. This creates lu from 2nd gear up, regardless of throttle, or road speed. It also makes the shifts a little "lunge-y", or rubbery. There are some valve bodies, the late '86 and ups, that do not have a place for the lu valves. These vbs are strictly computer controlled, as far as lu. These should not be used for this application, for this reason.

                                                        More info on lu valve[/QUOTE]
 
Hrm. Well I guess I might have to take it to a tranny shop one day then and have it looked at. I dont know nearly enough about that stuff to dive in to it. I just know it's not locking up, period. Thanks for the info.



700R4 dilemna

Posted: 11/5/07 7:15am Message 16 of 28
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Old Hickory, TN - USA
Joined: 5/26/2003
Posts: 599
Vette(s): 1978 L-82 Silver Anniversary hotrod. /////////////
Hey Josh!

Do you have it WIRED to lock up? In my case I have a vacuum switch piped to my intake that closes @ 8" hg Vacuum in series with a switch that is closed with no brake application, then in series with the transmissions 4th cog pressure switch. If all the above switches are closed the trans will lock up. If you're not in top gear or are accelerating or braking, the converter unlocks....

Joel,

That's the valve I had researched, but a different mfgr. When I get 'lectric in my garage to run my lift I'm gonna get one.

DaveAutom8r2007-11-05 07:20:03


700R4 dilemna

Posted: 11/5/07 9:27am Message 17 of 28
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Charleston AFB, SC - USA
Joined: 10/31/2007
Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
[QUOTE=Autom8r]Hey Josh!

Do you have it WIRED to lock up? In my case I have a vacuum switch piped to my intake that closes @ 8" hg Vacuum in series with a switch that is closed with no brake application, then in series with the transmissions 4th cog pressure switch. If all the above switches are closed the trans will lock up. If you're not in top gear or are accelerating or braking, the converter unlocks....

Joel,

That's the valve I had researched, but a different mfgr. When I get 'lectric in my garage to run my lift I'm gonna get one.

Dave[/QUOTE]
 
According to the previous owner, he had the tranny set up to be all hydraulic, including the lock up. Of all the things on a car I know the least about, it's an automatic transmission, so I'm taking his word for it :)



700R4 dilemna

Posted: 11/5/07 4:24pm Message 18 of 28
Former Member
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Old Hickory, TN - USA
Joined: 5/26/2003
Posts: 599
Vette(s): 1978 L-82 Silver Anniversary hotrod. /////////////
Josh,

Everything about the transmission IS hydraulic..... except the lockup, which uses an electrical signal to a lockup clutch soleniod.

Hang around here long enough and you'll be a whiz kid!

Dave


700R4 dilemna

Posted: 11/5/07 7:02pm Message 19 of 28
Former Member
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Charleston AFB, SC - USA
Joined: 10/31/2007
Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
He said even that was controlled hydraulically by a kit. So I dunno. I havent had it on a lift yet, but I dont remember seeing any electrical cables going to the tranny Dead


700R4 dilemna

Posted: 11/6/07 7:08am Message 20 of 28
Former Member
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Old Hickory, TN - USA
Joined: 5/26/2003
Posts: 599
Vette(s): 1978 L-82 Silver Anniversary hotrod. /////////////
It's just one wire. A lot of guys use a toggle switch to lock it up, but then they forget to unlock it when they hit the brakes and stall the engine. It's a fairly simple hookup to have it autom8d...

Dave


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