I have a thudding noise coming from the back (I Think)of my 99, 20vtec the sound is in time to the wheels and it makes the thudding even when I am in neutral.I have had wheel bearings go on other cars but they were all on the front end and were easy to find because the sound changed when cornering,any one got any suggestions?
Also should my head lights dim and then brighten when the air con kicks in or is the alternator on the way out?

 

My lights do the same except its also when I roll down the windows..whats the fix for this?

 

As far as the lights dim, mine does the same thing. Not just the a/c though. At idle it's generally dimmer than it is when in motion.

 

The thudding noise from the back of your car could also be a bad belt in your tire, had a problem like that on another car i owned and when I replaced the tire it went away,

As for the dimming question, yes its normal for the lights to dim when you turn on something that uses lots of power. If the lights only go dim for a second and then go back to normal then its fine, if the lights go dim and dont come back up till you stop useing or turn off what ever you turn on then you might have a problem.

 

For the lights dimming, check all your fuses and then check your battery. All Honda dealerships have a battery machine, have them check the Cold Cranking Amps, and the core temperature. If all else fails, you are going to need a new alternator. Make sure you buy a Genuine Honda Alternator, they come with a really great warranty.