Transmission wants to go!!

[MagmaJct]

I couldn't find a good way to title this post, how this works.

Ever since I've had my truck (a bit over a year) it seems to have a problem that I think is with the transmission.

The idle speed is correct, and the truck does not have power brakes.

At a stop, I have to hold the brakes real firm to keep the truck from moving. I once almost rear ended someone in a fast food drive through because I was changing the volume on the stereo and I didn't hold the brake hard enough.

It has an automatic transmission TH350? (I'm not sure on the model.)

The truck is a 1971 C10 with stock 350 engine. Ideas?

[Longhorn Man]

is the pedal slowly dropping out from under your foot? Or maybe you are used to power brakes and your foot just relaxes a bit as you sit at the light?

[maddog1331]

My 71 is the same way, no power brakes either. I really have to keep my foot on it, but after I drive it awhile I get used to it.

[red71c10]

Originally Posted by Longhorn Man

is the pedal slowly dropping out from under your foot? Or maybe you are used to power brakes and your foot just relaxes a bit as you sit at the light?

X2 I have the same set up on my truck and I'm still getting used to the manual brakes. Even though it has front discs, it does take some extra effort to hold the truck at lights etc...

[spinning wheels]

Originally Posted by MagmaJct

I couldn't find a good way to title this post, how this works.

Ever since I've had my truck (a bit over a year) it seems to have a problem that I think is with the transmission.

The idle speed is correct, and the truck does not have power brakes.

At a stop, I have to hold the brakes real firm to keep the truck from moving. I once almost rear ended someone in a fast food drive through because I was changing the volume on the stereo and I didn't hold the brake hard enough.

It has an automatic transmission TH350? (I'm not sure on the model.)

The truck is a 1971 C10 with stock 350 engine. Ideas?

I would bleed the brakes, re adjust the shoes if drums up front. Or put new shoes on the front, if the drums are still within specks. If you have front disk, install new pads if disks are within specks.

I had a car that used to creep forwards at signals or stop signs. Replaced the rotors and installed new pads. The problem went away.

[spinning wheels]

Oh yeah, forgot to mention.


To the board.

[truckdude239]

what speed stall converter are u using in teh transmission?

[Longhorn Man]

he said it was all stock

[MagmaJct]

It's all stock as far as I know. My uncle wasn't *too* much into mods. Well, I take one part back, the carb is a Carter AFB because the original was stolen back in the 90s.

Because it has manual brakes, I was worried that was my problem, "just not used to it". But I was hoping that there was something wrong, that way I could "fix it".

[red71c10]

I'm sure that's it. I just had my brakes gone through and that included new master cylinder, calipers, pads & shoes etc... and I'm having to make the adjustment to manual brakes. I think you said it was, but make sure your idle is set correctly so it takes as little effort as possible to stop it and hold it. Just drive it all the time until you get used to it. It's like any other part of driving, after a while it'll be second nature. Of course you can always upgrade to a brake booster!

[texanidiot25]

Slide it into neutral at the lights.

[MagmaJct]

Oh my gawd, I'm a idiot. Well, sort of. I'm an idiot because I said in my original post, that the idle was correct. But I'm not an idiot about how the automatic transmission response to RPM, because I really didn't know! I'll break this post down:

See, for some reason, I remember setting the idle when I first got the truck from my uncle after he died. But I've had this problem with the the truck wanting to go since I got it.

A few days ago the truck started well, considering the choke wasn't quite adjusted correctly. After about 30 seconds, the engine stalled at idle. I tried to restart it, but it wouldn't. The engine flooded so bad it hydro-locked the engine and fuel was leaking out of the throttle shaft and pooled on the outside of the intake manifold.

Turns out one of the needle valves stuck, so I had to take the Carter AFB carb apart and solve the flooding problem. In the past, the stock carburetor was stolen, and my uncle replaced it with the AFB. Turns out the original carb had a fuel filter in its inlet, the AFB has strainers on the needle valves.

After getting the carb back together, I decided to dial it in more precisely. I found the idle it supposed to be 550 RPM in Drive. So I hooked up my tachometer, and even though it wasn't steady, it was around 1000 - 1200 RPM!

I don't know why I remember setting the idle in the past, but it wasn't set now, and I've always had this problem. Could it be it *couldn't* be set at idle because it would stall? I have made a lot of "small" repairs to this engine, so it's possible I couldn't get a stable low idle when I tried a year ago!

So I started the engine, chocked the wheels, and set the parking brake, and put the transmission into Drive. I adjusted the idle to about 550 RPM as the sticker says. As I lowered the idle, I "felt" the truck "relax" off the brake and chocks a bit, startled me. (Yes, I'm nervous setting idle with the tranny in Drive.)

I increased the RPM again, and I "felt" the truck "move" forward a bit against the brake and chocks.

I've only ever owned vehicles with manual transmissions. I understand the basics of an automatic transmissions, but I didn't realize there was a sort of "cut in" RPM.

When I took the truck on a test drive, I found that I could stop MUCH easier, and that at idle, I can relax my foot a bit and not worry about rear ending the car in front of me. Interestingly enough, the engine no longer feels as if it wants to stall.

I suspect the high idle was causing the torque converter to "kick in" putting a strain on the engine, causing it to act as if it wanted to to stall.

The engine is quieter to! (Duh!)

Thanks everyone for your help.

[spinning wheels]

I would check your trans fluid. If its brown in color or stinks. Now would be a good time to change the trans filter and add some fresh trans fluid.

If you drove your truck for some time, a whole year? Chances are that trans fluid took some heat.

Good luck and thanks for letting us know you solved the creeping problems.

[MagmaJct]

Checking the trans fluid is one of many things on my "to do" list. But don't worry, I didn't drive the truck the whole year. It gets very little mileage, as I drive my other car the most.

[69GMCLonghorn]

I love hearing about problems like this with a happy ending. When I'm slaving away on my "pride and joy", throwing tools, cursing up a storm and getting nowhere, I'll think of you, and get even more pi**ed off! HAHA

Seriously, glad you solved the problem.