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72 K5 Blazer 700r4 upgrade

6872xtc said:
Yes, OD is mainly for the highway.

Looks like a great truck to dive into building into what you will have fun with!

If my memory is correct, one of my trucks is just switched ignition power going through the rocker switch, directly to the TCC solenoid. It's internally grounded. I believe that the other has power going into the transmission and the manual switch is on the ground wire for the TCC.
Both trucks are not using the internal pressure switch, so that I can lock it in 2nd, D and OD. I wanted to be able to lock it in drive. I have used the lock-up in 2nd in my K10 to cool the transmission down. (I had been running it slightly aggressively up Imogene Pass to catch up to another truck.) :waytogo:

I haven't ever bothered to install a brake switch in either of them. Laziness, mainly, but it keeps engine braking this way. Lol!
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She's a great base for a build. I live in the rust belt and Newfoundland uses road salt in the winter time. So to find a truck with a perfect chassis and for the frame not to be cracked at the steering box is a rare find around here.

All that makes sense and sounds simple enough. If you lock the torque converter in say 3rd gear. Does it stay in 3rd till u unlock it? Potentially causing you to stall the engine? Still new to these old auto trans. Always had a manual lol.
 
My truck will go into od at 40 something. In town I use D or 3rd since top speed is 35.
On the trails this weekend in moab I used 2nd all weekend, good to about 20mph in my rig.
I do have the full auto lock up in 4th, no delay. Brake switch unlocks the torque converter. I can also lock up 2 and 3rd. I don't do this much any more. Couple reasons, I don't like it when shifts while locked up,
I worry the engine torque might be to much fir the clutch in those lower gear ranges, and the torque multiplier from an unlocked converter is way better. I can do 65mph in 3rd, up hills at 3500-3600 rpm and not add a lot of heat. Hotest I got on I70 Monday was 190°
 
Wes Harden said:
My truck will go into od at 40 something. In town I use D or 3rd since top speed is 35.
On the trails this weekend in moab I used 2nd all weekend, good to about 20mph in my rig.
I do have the full auto lock up in 4th, no delay. Brake switch unlocks the torque converter. I can also lock up 2 and 3rd. I don't do this much any more. Couple reasons, I don't like it when shifts while locked up,
I worry the engine torque might be to much fir the clutch in those lower gear ranges, and the torque multiplier from an unlocked converter is way better. I can do 65mph in 3rd, up hills at 3500-3600 rpm and not add a lot of heat. Hotest I got on I70 Monday was 190°
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It's safe to say everyone's truck is alittle different and have to do what works best for the conditions you're in.

would it also be safe to say everyone's using a trans temp gauage as well? Or just using the regular water gauge to keep an eye on temps?
 
Keep in mind, there were several variations of the lock-up configuration in the 700. Many have a hydraulic valve that allows/blocks lockup based on governor pressure and current gear. Some are simpler. The information has been posted here before if you search for it.
 
Blue85 said:
Keep in mind, there were several variations of the lock-up configuration in the 700. Many have a hydraulic valve that allows/blocks lockup based on governor pressure and current gear. Some are simpler. The information has been posted here before if you search for it.
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Good to know. Thanks.
 
Yep ea truck will be a little different. I do keep an eye on trans temp with a dedicated temp guage. After the TV cable adjustment, keeping them cool is important.
Might not be as hard for as it is for us further south
 
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Wes Harden said:
Yep ea truck will a little different. I do keep an eye on trans temp with a dedicated temp guage. After the TV cable adjustment, keeping them coil is important.
Might not be as hard for as it is for us further south
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Yeah I'm Definitely going to get a gauge to keep an eye on it. It's pretty cold up this way lol. We even run 195 thermostats lol.

I'm still going to get a trans cooler for when I'm on the trails or in the city. I'm having a hard time finding a radiator shroud for it Which is the next step.
 
Wes Harden said:
keeping them cool is important.
Might not be as hard for as it is for us further south
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Up here, we worry about getting the trans warm enough to drive condensation out and the engine warm enough to give good heat. Overheating just means you're low on coolant. :dunno:
 
If I leave the convertor locked, it stays locked until it downshifts to 1st. It never kills the engine, but it isn't smooth acting!
:rotfl:
I may put a more automatic system in eventually. Time will tell if it gets high enough up on my list.

I only have a gauge in my big block truck. My C10 doesn't need one, and I haven't put one in my offroad truck yet because my list of projects is too long!! It has the biggest cooler of all of my trucks and the fluid still looks great after 4 years.
 
6872xtc said:
If I leave the convertor locked, it stays locked until it downshifts to 1st. It never kills the engine, but it isn't smooth acting!
:rotfl:
I may put a more automatic system in eventually. Time will tell if it gets high enough up on my list.

I only have a gauge in my big block truck. My C10 doesn't need one, and I haven't put one in my offroad truck yet because my list of projects is too long!! It has the biggest cooler of all of my trucks and the fluid still looks great after 4 years.
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It doesn't sound like it would be very smooth lol if I had more space I'd pick up another project. I got the wife sold on a square body suburban if we can find one haha.

I did alittle looking for a toggle switch and I seen this. Seems easy enough to do and uses a cruise control kick out brake switch to open the circuit. Think ill give this a go. That's the 4 pin connector I have. Screenshot_20240912_095653_Firefox.jpg
 
Blue85 said:
Up here, we worry about getting the trans warm enough to drive condensation out and the engine warm enough to give good heat. Overheating just means you're low on coolant. :dunno:
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If the engines warm your warm lol. It's a different world up here lol.
 
Not that this is a big point, but keep in mind that when you let off of the brake and the switch closes again, it can lock again if conditions are still in place.
OR you take off from a stop and it locks immediately when 2nd gear hits.
I may or may not have seen this in a buddy's Monte Carlo! :thinking:

But you are digging in and finding information! Just what will keep you interested in the "old trucks".
:saweet:
 
when I was playing around with locking up 2nd and third I would open the toggle switch at stops. With the multiplier of the converter, the engine couldn't make power/rpm well.
 
6872xtc said:
Not that this is a big point, but keep in mind that when you let off of the brake and the switch closes again, it can lock again if conditions are still in place.
OR you take off from a stop and it locks immediately when 2nd gear hits.
I may or may not have seen this in a buddy's Monte Carlo! :thinking:

But you are digging in and finding information! Just what will keep you interested in the "old trucks".
:saweet:
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Good point. The pin diagram I got from the chevelle group shows that the brake switch goes to a pin that will only lock it up in fourth gear and no other gear. And that the other pin allows you to do it manually it any gear. Can anyone confirm that this is how it works?
Screenshot_20240912_215455_Firefox.jpg
 
2nd and 3rd lock up needs to be wired inside the Trans as well. AFAIK you can't just supply power to that pin and have it lock up
 
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