For a while now, when I shift into gear, my maverick will lurch forward/back and clunk into gear. It does it the most when shifting to reverse. I've got a c4, shifter on the column, not sure if that's important but just putting that out there. What could it be?
I'm confused so you may need to help us clarify what.. "lurch forward"... really means. Usually a car cannot ever lurch forward until AFTER it has already shifted(or clunked) into gear. Are you saying that the engine rpms come up as the trans prepares to shift into gear and then the car jumps/clunks forward as it finally completes the shift into gear? Any of the above troubleshooting ideas will not make a car lurch. That would be down ignition timing and/or carb settings. A cracked hose or slightly leaking vacuum modulator on the trans can cause all kinds of funny shift behaviors too.
When the car is idling, it idles relatively high as it warms up. If you give it about 10 minutes it will idle down to a very low rpm, and stay consistent. When I shift the column from park to reverse, once the column gets into reverse and is locked in place, the car will "drop and lurch" with brakes applied, total movement is about 6-12" forward or backwards depending on drive or reverse (mind you, brakes still applied). I don't have to rev the engine to get it to shift. I replaced the u joints a while back. Probably around 2,000 miles ago. Since I purchased the car, I've put 3000 miles on it (currently driving an 88 gt while I fix my maverick).
when you say.. "drop and lurch".. do you mean that the car just clunks its way into gear from the same idle speed as it had in park? or the engine accelerates slightly and makes the clunking even worse as it bangs into gear at a higher rpm than idle speed? The only way I can see a car lurching that hard against the brakes is if the carb is fooling about on you. You might want to check the high idle cam on the carb to make sure it's not moving about when the car is shifted into gear. Another thing to look for is the vacuum advance mechanism on the distributor. An advance mechanism with a mind of its own can easily cause surging or chugging. Make sure the hoses are good and do a basic suck test against the vac advance diaphragm to make sure it's not leaking or blown out.
exactly. by around 250 rpm. so, is he saying that the car is surging going into and seemingly also when finally engaged into gear(brake push)? otherwise, how could a little engine like this be pushing on the brakes so hard after gear engagement rpm drop? If it idles IN gear at much more than about 600-650 rpm?(stock motor could even be way down by 500 rpm in gear).. I'd start troubleshooting at the carburetor. Would also be checking the vacuum operation of the disty's vac advance diaphragm(this can cause rpm fluctuation), trans vac modulator(this can cause high line pressure/bump or bang shifts). Orrrr.. you may have no issues with any of that and the trans simply needs to have the bands adjusted properly. If the planetary can't be stopped from spinning on a dime.. the trans will eventually clunk, slip-shift, and/or shift-flare itself to death. Pretty hard to help you troubleshoot this without much info.
I'll try and get a video posted up this weekend. That's really the only way I know how to describe it. I realize that while in gear the engine runs lower rpm, but that's not what I'm getting at. It should be a fluid movement (transition). Smooth shift from park to reverse, engine rpm drops, and you let off the brake and you begin to roll. It feels like I have to fight it from jumping forward or backwards when shifting into a different gear. Reverse sounds the worse, it sounds like its engaging almost too hard/forcefully on the back differential.
