What have you done to your square lately??

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Normmus

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Norm
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1977
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K10
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350
I drove the 77 K10 for the first time this year. Needed to pick something up in the city. Part way through the drive the brake warning light came on so I pulled over and popped the master cylinder cap off. The rear most reservoir is empty. Was able to accomplish the mission but now have a problem to diagnose. I still have brakes but stopping power is reduced.
 

Tank6x2

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350, TH400.4:10 gears 2WD
Spent the last couple of weekends Attempting to stay focused on just the firewall- cutting it apart, fabricating the brake support plate, modifying the new driver side firewall but after painting the interior of the rain tray today started preparing for the roof skin removal, popping out and busting spot welds along the seam of the door trims.
 

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Tank6x2

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Edmonton Alberta Canada
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350, TH400.4:10 gears 2WD
I drove the 77 K10 for the first time this year. Needed to pick something up in the city. Part way through the drive the brake warning light came on so I pulled over and popped the master cylinder cap off. The rear most reservoir is empty. Was able to accomplish the mission but now have a problem to diagnose. I still have brakes but stopping power is reduced.
Kinda sounds like the master needs a reseal/ rebuild, hydro boost or vacuum boost?
 

DoubleDingo

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Right where I am
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Bagoomba
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1981
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81-C20 Silverado Camper Special-TH400-4.10s
Engine Size
Carb'ed Vortec 350
Drove it a bit today: grocery run, kids wanted McDowells for lunch. Took my daughter to a friend's house and picked her up. In between places i put a half bottle of Lucas Transmission fix in. It is shifting in to 2nd gear a bit hard sometimes. I noticed a little difference after and it felt like it was smoothing out. More cruising around tomorrow afternoon for errands and such. Maybe the other half of the bottle goes in, we'll see.
Wonder if it's shifting different because it's getting more vacuum?
 

Grit dog

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454, 350
I drove the 77 K10 for the first time this year. Needed to pick something up in the city. Part way through the drive the brake warning light came on so I pulled over and popped the master cylinder cap off. The rear most reservoir is empty. Was able to accomplish the mission but now have a problem to diagnose. I still have brakes but stopping power is reduced.
Look for the wet spot.
 

Normmus

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Saskatchewan
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Norm
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1977
Truck Model
K10
Engine Size
350
Look for the wet spot.
I did, and couldn't find one, at least not on the back side of the wheels. Possible it blew a line
edit - it's parked on melting snow so tough to spot any drips
 
Last edited:

HotWheelsBurban

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Carol
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1990
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R2500 Suburban
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Kinda sounds like the master needs a reseal/ rebuild, hydro boost or vacuum boost?
Or leaking rear wheel cylinder/cylinders. Had that happen to my truck. If you leave it unfixed long enough the shoes will get contaminated linings and the brakes will grab.
If the backing plate shows signs of dampness this is likely the issue.
 

Tank6x2

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C30
Engine Size
350, TH400.4:10 gears 2WD
Or leaking rear wheel cylinder/cylinders. Had that happen to my truck. If you leave it unfixed long enough the shoes will get contaminated linings and the brakes will grab.
If the backing plate shows signs of dampness this is likely the issue.
Best part of ripping and tearing- gotta find it to fix it
 

Sgt Gus

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Texas
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Mark
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87
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R20 3/4 ton
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454ci/7.4L
Drove it. Filled it up and drove to nearby town, about 1/2 a tank away (15 miles). Just kiddin of course.

Beautiful day for a drive.

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What gauges are in there? Do you have in a build page? Sweet...
 

JamesSam

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Sam
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1987
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Silverado V10
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5.7 L 350 v8
Good questuon It is happening right after the fix. I am thinking it is related somehow myself.
Would the 700R4 change gears at different RPM with intake bolts tightened? Would it be possible to over torque intake bolts? Or am I way off here?
 

bucket

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K5 thru K30
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350-454
Would the 700R4 change gears at different RPM with intake bolts tightened? Would it be possible to over torque intake bolts? Or am I way off here?

Two things come to mind. Either your vacuum leak was bad enough that it affected your throttle position in relation to rpm (your trans uses rpm and throttle angle to determine shift points) or they moved the throttle bracket when tightening your intake bolts and then re-adjusted your T.V. cable.
 

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