My 1994 Mitsubishi Gallant has 158,000 mile makes a loud thump upon braking, could this be my transmission?

Answer 1

You dont specify where the thump is coming from, front or rear. Lets assume the front, since you describe it as being "loud" I take that to mean you can hear it really well, hence its coming from the front. If all these thing are true, I doubt its your transmission or even your brakes, its sounds like something more substantial, lets say motor mounts or my actual guess @ 158K showing on the clock would be your struts if you havent had them changed. and there are two possibilities with that, 1 they have ceased to damp and you are hearing your car "bottom out" as all of the weight transfers forward and the vehicle is settling on the bump stops, or the top bushing for the struts is totally shot and the fore aft movement is causing the noise. it could also be another part of the suspension, lets say ball joints, but that will give you other issues.
If you do your own work, you can check the shock/strut action by performing the bounce test, if you dont take the car to a reputatble suspension shop (hopefully a "Tuner" type independent shop, as they are suspension specialists) if not Midas or Meineke or something comparable will have to do. In the next category up Goodyear does a great job on my company car and contrast them to Firestone, Sears automotive,..etc, just remember the larger the organization the less specialized the attention is going to be and you run the risk of getting the new guy who doesnt know as much or the odd employee who doesnt care whether or not your car get repaired correctly the first time.

As I always state, go to your local Pep boys Auto Zone etc and buy the Haynes manual for your car, I'd shop 3 or 4 until I found a Haynes, Chiltons are not as good, the troubleshooting section is as good as it gets and should point you in the right direction.

If you find a good indie shop nearby tak care of the guys there, your first time in, take a case of water to the manager/owner, tell him/her you know their folks get thirsty, you get the idea, small stuff goes a long way,... Good Luck
Sparky

Answer 2

It sounds like a suspension problem, I would have some one look at it and find out before it's to late

Answer 3

Your rear brakes are out of adjustment.

Answer 4

Could be a motor or trans mount more then likely.

Answer 5

its probably something in the front end suspention, take it to a garage and have it checked out.