hi and how are you? from park to reverse i hear a knocking or banging sound coming from under the car. the sound also occur when changing from reverse to drive. What could it be. my car is automatic 76 280z.

also i have another question. is it a good idea to swap my car from automantic to manual? if yes what might be the cost to do the swap i.e include parts and labor. What parts do i need to do the swap.

rkas, check the bolt tightness of your diff mounts, especially the diff to moustache bar.

Can't help with the pricing stuff...

Considering that you can reproduce the problem with the car standing still, you might get a volunteer to shift in and out of reverse, while you listen outside the car to determine where the sound comes from. For obvious reasons I probably wouldn't actually get under the car to do this, but you can narrow down the noise to a general area this way.

Is it good to put in a manual, rather than a stick? I don't know how difficult it is, but sure, a stick is always better in a sports car. On the other hand, I don't think an automatic necessarily detracts from the value of the car. My '66 mustang had both a C4 automatic and power steering (which was quite rare and mechanically somewhat weird). I added power brakes. The car commanded a good price when I sold it. Of course automatics are more commonplace in Mustangs. I think there's something to be said for the "rare" factor.

If there is not a worn mount.

Make sure to use brake when engaging gears.

Adjust rear brake with emergency brake per FSM.

If adjusters are frozen you can adjust by hand in the drum.

If they don't move service your brakes.

With the rear drum brakes adjusted right this noise will be eliminated.Auto trans Quirk.

Edited March 1, 201114 yr by black gold man

RZKAS

Checking and adjusting all the fastening points for the trans mount and differential mounts are good ideas but as well you should check for a universal joint that could be going bad. With the car on jack stands you can check for excess play in either end of the driveshaft without the car running. If it is in bad enough shape it will actually make the "CLUNKING" sound as you rotate it back and forth with your hand. To answer the part about changing over to a manual gearbox,,,Yes it can be done but the cost can multiply quickly. You will need a different set of pedals which will have the clutch pedal attached. The firewall should have the hole that will allow for the changeover if not it has to be cut in the correct location which should be done by a professional. Then you have to find a 5 speed gearbox which is no big task but it may need repairs to get it working properly. Don't forget about the extra hydraulic tubing for the clutch slave cylinder and positioning the clutch hydraulic fluid reservoir. So unless you have a little mechanical ability it is a job I would not suggest on your own. But good luck.

thanks for the ideas. i will try to see where exactly the sound it coming from. when driving the car, there is no sound. the sound only occurs when shift from park to reverse and drive. only when shifting/changing gears that when i hear the sound