Please look. I have problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72chevyLWB · 05-30-2002, 01:37 PM

Okay, my tranny still isn't right (700R4 with fresh rebuild). I hooked up a light to the lockup wire going into the tranny. It seems like there is power going to the lockup. When ever I hit the brakes the light goes off and same when I get on it hard. I am still not getting 4th gear it seems. Any other ideas you guys have? This crap is really getting old, I just want to drive the truck and forget about it.

Brian19692 · 05-30-2002, 03:05 PM

I read somewhere that the converter is suppose to unlock when you hit the brakes. I don't know about getting on it .

Blue68 · 05-30-2002, 03:19 PM

It sounds like it's wired correctly. THere are usually two ways to disengage the lockup. One is with a brake switch (mounts in place of the brake light switch and operates both) and the other is usually a vacuum switch. When you get on the engine the vacuum drops and will break the connection, allowing the torque converter to unlock. Another feature of some wiring setups (Painless wiring for example) is that the converter will only lock up in 4th gear. This can only be noted inside the transmission though. So you can get a signal to the converter in any gear, but the transmission has to say 4th before the lockup will occur.

It sounds like your question may be why is the tranny not going into 4th?

How are your shifts between the other gears? Do they seem late or early? This could be an indication the TV is not adjusted correctly. I can get into 4th with lockup around 40-45 mph if just easily cruising.

bigvinnie · 05-30-2002, 04:00 PM

sounds like the wiring is doing what it's supposed to do.... as far as 4th is concerned, you should be able to feel the gears change.... Have you double checked the shifting to make sure you're really in 4th?....have you counted the gear changes from a dead stop to verify that you're only getting to 3rd gear? ..... a good ballpark method for setting the tv cable is to have the cable at max extension when the carb is at WOT.... then take it somewhere and have it dialed in...

if you've done these checks and you're not getting into 4th, you've got internal issues and I suspect it will have to be pulled to correct the problem... I got good at pulliing my 700 when I was having problems.... I could have it sitting on the tailgate in 35 minutes... good luck

*Fast68Chevy* · 05-30-2002, 04:15 PM

yeah have you carefully listened and counted number of shifts from dead stop to make sure tere are three of them ?

Mixup · 05-30-2002, 04:22 PM

The converter is not the problem and neither is the cable. It sounds like an internal problem. You said it's a fresh rebuild who did it ? Take it back to them.

snow man · 05-30-2002, 04:22 PM

you might want to check the valve body it only take a small piece of dirt to hang it up to keep it from shifting.i went trough this problem when i rebuilt the 700 r 4 for the boys blazer. snow man

72chevyLWB · 05-30-2002, 07:55 PM

we put it up on a hoist tonight and ran it. It is getting 4th gear perfect. The linkage was a little messed up though. The lockup must not be working. I can't feel or hear it unlocking or locking. I am running 2,500 rpm at 55 in 4th and 3,500 rpm at 55 in 3rd. I heard and counted the shifts. but no lockup rpm drop. It should drop from 2-400 rpm when it locks up. I have 27" tires and 3.73 gears in the truck. At 75 I am running 3,500 rpm.

Will this ruin my tranny if its not locking up?

bigvinnie · 05-30-2002, 08:43 PM

it's not a problem to run in 4th without lockup, you just don't get the benefit of less rpms on the hiway... 3500@75 seems kinda high even without lockup however... I would have expected it to be closer to 3000, then about 2750 with lockup... someone posted a link to a site a while back that had good stats showing rpms for various gear and tire combos for a 700.... wish I would've saved it......????

*racedvl* · 05-30-2002, 08:46 PM

They sell non-lockup converters. So I don't think you are hurting the tranny.

Blue68 · 05-31-2002, 03:45 PM

http://www.700r4.com/SpeedOCalc/?calc=1 is where the calculator is. You should be turning about 2500 rpm at 75mph in 4th and about 3500 in 3rd (1:1). Put it up on the hoist again and touch your brake and see if it drops. You may be getting lockup in 3rd but never attaining 4th gear. It will sound/feel similar. Since it sounds like your wiring is correct, touching your brakes will result in an increase in rpms, even in 3rd.

I still think you are not getting to 4th gear. As for ruining your tranny without locking up... it is possible due to heat buildup. But since I don't think you are getting to 4th anyway, you will be as okay as anyone running a th350 with 1:1 ratio.

72chevyLWB · 05-31-2002, 07:47 PM

when I touch the brakes in 3rd or 4th gear the rpm's decrease. They do not increase at all. I cannot feel lockup at all. I can hold the shifter in 3rd gear and when I put it in 4th it shifts. At 700R4.com they don't ask for the gear ratio though right? Is the stall maybe large enough just to slip to give me higher rpms?

**Smitty** · 06-01-2002, 02:43 PM

It makes a difference which pin you have your hot wire going to at the plug in the transmission. I think fourth is the front one closest to the trans body.

05-30-2002, 01:37 PM	#1
72chevyLWB Got 20's???? Join Date: Oct 2001 Location: Aberdeen SD Posts: 1,451	Please look. I have problem Okay, my tranny still isn't right (700R4 with fresh rebuild). I hooked up a light to the lockup wire going into the tranny. It seems like there is power going to the lockup. When ever I hit the brakes the light goes off and same when I get on it hard. I am still not getting 4th gear it seems. Any other ideas you guys have? This crap is really getting old, I just want to drive the truck and forget about it. __________________ 99 Silverado Ex-Cab 2wd, Bagged&WhippleCharged 02 Sierra Ex-Cab 4wd 2500 HD The 72 went down the road.

05-30-2002, 03:05 PM	#2
Brian19692 Registered User Join Date: Feb 2001 Location: Des Moines, IA. Posts: 188	I read somewhere that the converter is suppose to unlock when you hit the brakes. I don't know about getting on it . __________________ 67 short 2wd. FOR SALE 69 long box w/72 grill 69 Camaro 327 4-speed Des Moines, Iowa

05-30-2002, 03:19 PM	#3
Blue68 Registered User Join Date: Apr 2000 Location: Frisco, Tx, USA Posts: 606	It sounds like it's wired correctly. THere are usually two ways to disengage the lockup. One is with a brake switch (mounts in place of the brake light switch and operates both) and the other is usually a vacuum switch. When you get on the engine the vacuum drops and will break the connection, allowing the torque converter to unlock. Another feature of some wiring setups (Painless wiring for example) is that the converter will only lock up in 4th gear. This can only be noted inside the transmission though. So you can get a signal to the converter in any gear, but the transmission has to say 4th before the lockup will occur. It sounds like your question may be why is the tranny not going into 4th? How are your shifts between the other gears? Do they seem late or early? This could be an indication the TV is not adjusted correctly. I can get into 4th with lockup around 40-45 mph if just easily cruising. __________________ http://home.comcast.net/~r.landrum/w...tos.html-.html '68 C-10 LWB, '98 Z-71 350 w/accessories (Serpentine), Edelbrock Performer, Edelbrock 1405 (600cfm) carb, GM HEI, CompCam Extreme 4x4 roller cam, Thorley Headers, Carter Electric Fuel Pump, Vintage Air, 700r4, 3.73, disc brakes and power steering upgrades.

05-30-2002, 04:00 PM	#4
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	sounds like the wiring is doing what it's supposed to do.... as far as 4th is concerned, you should be able to feel the gears change.... Have you double checked the shifting to make sure you're really in 4th?....have you counted the gear changes from a dead stop to verify that you're only getting to 3rd gear? ..... a good ballpark method for setting the tv cable is to have the cable at max extension when the carb is at WOT.... then take it somewhere and have it dialed in... if you've done these checks and you're not getting into 4th, you've got internal issues and I suspect it will have to be pulled to correct the problem... I got good at pulliing my 700 when I was having problems.... I could have it sitting on the tailgate in 35 minutes... good luck __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

05-30-2002, 04:22 PM	#6
Mixup Registered User Join Date: Jan 2002 Location: Henderson, NV Posts: 358	The converter is not the problem and neither is the cable. It sounds like an internal problem. You said it's a fresh rebuild who did it ? Take it back to them. __________________ 1980 Chevy Shortbed Pickup 1969 Z28 engine Turbo 350

05-30-2002, 04:15 PM	#5
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	yeah have you carefully listened and counted number of shifts from dead stop to make sure tere are three of them ?

05-30-2002, 04:22 PM	#7
snow man Registered User Join Date: Mar 2002 Location: mt. zion illinois Posts: 276	tranny you might want to check the valve body it only take a small piece of dirt to hang it up to keep it from shifting.i went trough this problem when i rebuilt the 700 r 4 for the boys blazer. snow man

05-30-2002, 07:55 PM	#8
72chevyLWB Got 20's???? Join Date: Oct 2001 Location: Aberdeen SD Posts: 1,451	we put it up on a hoist tonight and ran it. It is getting 4th gear perfect. The linkage was a little messed up though. The lockup must not be working. I can't feel or hear it unlocking or locking. I am running 2,500 rpm at 55 in 4th and 3,500 rpm at 55 in 3rd. I heard and counted the shifts. but no lockup rpm drop. It should drop from 2-400 rpm when it locks up. I have 27" tires and 3.73 gears in the truck. At 75 I am running 3,500 rpm. Will this ruin my tranny if its not locking up? __________________ 99 Silverado Ex-Cab 2wd, Bagged&WhippleCharged 02 Sierra Ex-Cab 4wd 2500 HD The 72 went down the road. Last edited by 72chevyLWB; 05-30-2002 at 08:04 PM.

05-30-2002, 08:43 PM	#9
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	it's not a problem to run in 4th without lockup, you just don't get the benefit of less rpms on the hiway... 3500@75 seems kinda high even without lockup however... I would have expected it to be closer to 3000, then about 2750 with lockup... someone posted a link to a site a while back that had good stats showing rpms for various gear and tire combos for a 700.... wish I would've saved it......???? __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

05-30-2002, 08:46 PM	#10
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	They sell non-lockup converters. So I don't think you are hurting the tranny.

05-31-2002, 03:45 PM	#11
Blue68 Registered User Join Date: Apr 2000 Location: Frisco, Tx, USA Posts: 606	http://www.700r4.com/SpeedOCalc/?calc=1 is where the calculator is. You should be turning about 2500 rpm at 75mph in 4th and about 3500 in 3rd (1:1). Put it up on the hoist again and touch your brake and see if it drops. You may be getting lockup in 3rd but never attaining 4th gear. It will sound/feel similar. Since it sounds like your wiring is correct, touching your brakes will result in an increase in rpms, even in 3rd. I still think you are not getting to 4th gear. As for ruining your tranny without locking up... it is possible due to heat buildup. But since I don't think you are getting to 4th anyway, you will be as okay as anyone running a th350 with 1:1 ratio. __________________ http://home.comcast.net/~r.landrum/w...tos.html-.html '68 C-10 LWB, '98 Z-71 350 w/accessories (Serpentine), Edelbrock Performer, Edelbrock 1405 (600cfm) carb, GM HEI, CompCam Extreme 4x4 roller cam, Thorley Headers, Carter Electric Fuel Pump, Vintage Air, 700r4, 3.73, disc brakes and power steering upgrades.

05-31-2002, 07:47 PM	#12
72chevyLWB Got 20's???? Join Date: Oct 2001 Location: Aberdeen SD Posts: 1,451	when I touch the brakes in 3rd or 4th gear the rpm's decrease. They do not increase at all. I cannot feel lockup at all. I can hold the shifter in 3rd gear and when I put it in 4th it shifts. At 700R4.com they don't ask for the gear ratio though right? Is the stall maybe large enough just to slip to give me higher rpms? __________________ 99 Silverado Ex-Cab 2wd, Bagged&WhippleCharged 02 Sierra Ex-Cab 4wd 2500 HD The 72 went down the road.

06-01-2002, 02:43 PM	#13
Smitty Senior Member Join Date: Dec 1999 Location: Spring Valley, Ca. Posts: 1,136	It makes a difference which pin you have your hot wire going to at the plug in the transmission. I think fourth is the front one closest to the trans body. __________________ Smitty '71 Short Fleetside Spring Valley, Ca.



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