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I have a 85' b2 w/ a 2.8L V6. Every time I start it up and let it warm up for about 2 minutes, when I go to put the gear in reverse it jumps. It probably jumps like 1 foot, eventhough I have the brake on as hard as my foot will push. What is wrong with my truck?

auto or manual? I'll guess auto. Probably needs a rebuild, assuming you are able to stop and don't have any other brake issues.
--L

dont know much about tranny's but if it's a slush box it sound's like a problem with the TQ loading up or maybe the valve body getting plugged or blocked up and then slamming it into gear. when was the last time you serviced your tranny?

even if it hit really hard you should still be able to hold it with your breaks. you should only be shifting it into gear at like 700-900 RPM's. have you checked them yet?

hey never thought of that you have a good point DB.

If its an A4LD, an auto, then yes it will jump, those tranny's are a real mess. They shouda only made em for the 4-bangers and not a 6 cylinder. I would probably suggest a rebuild also.

does the truck physicly move in reverse or does it just make a loud noise and jerk with out moving at the wheels?

I have an A4LD tranny and it jumps when I put it in reverse and drive. I don't know if the tires move or not, but it jumps like hell when it does. I can hold it but its just the jerking that pisses me off.
Just yesterday when I went to start it up, I usually have to pump the gas twice while I try to start it. But I pumped it before trying and when I started it it revved up to about 2000 RPM and stayed there idling. I pushed the gas and it slowed down. I don't know if it was the gas pedal stuck or if it was the choke, but that pissed me off too. I have a problem with the back hatch too. When I go to close it I have to slam it so hard it seems like the whole damn hatch will shot straight through the truck. Why do I have to slam it? Thanks in advance.

I have an A4LD tranny and it jumps when I put it in reverse and drive. I don't know if the tires move or not, but it jumps like hell when it does. I can hold it but its just the jerking that pisses me off.
Just yesterday when I went to start it up, I usually have to pump the gas twice while I try to start it. But I pumped it before trying and when I started it it revved up to about 2000 RPM and stayed there idling. I pushed the gas and it slowed down. I don't know if it was the gas pedal stuck or if it was the choke, but that pissed me off too. I have a problem with the back hatch too. When I go to close it I have to slam it so hard it seems like the whole damn hatch will shot straight through the truck. Why do I have to slam it? Thanks in advance.

what is your idle RPM set at?

I don't have an tach on my truck, but I can tell you that the timing is set at 10 degrees above TDC. If that is any help. Today I took it to my cousins and there is a hill at about a 35 degree incline. The hill is about an 8th of a mile long. Before I went up it I stopped at the bottom of the hill and put it in 1st and let go of the brake. It started crawling up the hill at about 2-3 mph and I had my foot away from the gas pedal. I don't know the exact speed because the speedo didn't register that low of a speed. I have heard of trucks that have really low gears in their rear ends that crawl up hills with pushing the throttle. But my truck is pure stock(except for the alternator and where I overhauld the carb).

try turning the idle down a little. it sounds like it is set too high. that would cause a loud "clunk" and jerk when you put it into gear.

I turned the idle down and I tried it and it didn't jump. But, when I pushed the gas, it idles down and then it stalls. I turned the idle up some and tried it again and it just barely keeps running. But if I rev it up higher, it stalls. I've tried turning the idle up but its too high and jumps.

Sounds like your truck is in need of some serious maintenance and tune-up.

I second that......

replace the plugs, check the plug wires, pull the cap inspect and clean or replace, new button, and tune the carb. you might even want to check the coil and replace the air filter if needed.