96 240SX grinds badly in reverse

[FreelanceWizard]

Hi, everyone. Hopefully someone can help me with this issue. My recently acquired 1996 240SX SE with about 95k miles on it has recently started grinding horribly in reverse. Now, I understand this is a relatively common problem with 240s (to which a specific fix seems difficult to find), but my problem goes one step further: the car often "jams" in reverse, as if the brakes were being applied. This latter symptom didn't occur since I recently (about a month ago) replaced my rear brake pads and rotors. I also occassionally hear a hissing/scraping noise from what sounds like the rear passenger side wheel.

During the pad/rotor change, I noticed that the passenger side rear caliper had a bad seal and was very hard to turn down; the friend who was helping me out thought it was in need of a rebuild, but we didn't have the time or parts to do that at the time. Could the caliper be stuck and be causing this problem? If not, does anyone have any ideas?

On the advice of the same friend, I had the differential fluid changed, which seems to have had no effect on the problem. The mechanic who did the deed didn't notice anything odd with the differential or the used fluid.

As per the sticky post, here's the relevant info on the car:1996 Nissan 240SX SE (open differential, stock)Location: Memphis, TNMileage: 95kRelevant Component Info: Rear brake pads and rotors changed one month ago, rear calipers rebuilt once at 50k (according to the prior owner; this hasn't been verified), rear differential fluid changed (for what might very well have been the first time) in the last week.Transmission: 5 speed manual, stock

I have another tricky question about fuel injection fuses blowing on a 240SX that another friend of mine owns, but that's for later once I collect all the relevant infomation.

EDIT: This problem doesn't seem to affect driveability in any other gear, and I don't have any problems shifting gears; the car shifts very smoothly and doesn't grind while going forward. I figured people might ask about that, so there you go.

[Big Red]

I have the same problem in both my cars.

The rear calipers have a tendancy to "freeze" but it's more noticable in reverse.

Is the noise a mechanical grind like a missed shift or more like a pulsating groan?

[FreelanceWizard]

It's definitely a pulsating grind/groan sort of thing. It's very reminiscent of the sort of sound you'd hear if you slammed on your brakes while in reverse; that's why caliper sticking/freezing came to mind for me, at least (that, as well as the fact that it wasn't doing this until after the brakes were done). The car definitely acts as if the brakes are engaged; it jerks around quite a bit and gives a lot of resistance.

Of course, as I mentioned above, this doesn't seem to affect driveability in any other gear, which is really weird. The moment I put the car into 1st (which it's quite happy with -- I have no shifting issues), it occassionally feels as if the brakes are sticking for a split second before everything starts to work normally. I get no grief until the next time I try to drive it in reverse; it shifts into reverse just fine, but then the grinding starts. ;P

[NISTECH]

I assume you have isolated the grinding noise to the very rear of the car and not below the shifter here?? make sure all your brake hardware (factory)is in place, make sure both the caliper pins slide smoothly, make sure your ebrake cable is not too tight(make sure the ebrake pivot returns to its full rest on the pin after releasing the ebrake,if not loosen the cable adjuster a bit till they will return to the rest poistion.)

as far as your buddies car if it is a SOHC [89 to 91) check the harness along the valve cover at the rear see if the harness conduit wore through and a wire has worn through contactting the very rear valve cover bolt on the passenger side of the valve cover. you will have to lift the harness and look under the bottom of it.

[FreelanceWizard]

In the end, when we took the rear right wheel off to take a look, it seems the lower caliper mounting bolt had somehow vanished. (!!) Whether it had broken or fallen out remains a mystery. Thankfully, the Advance Auto Parts down the street happened to have the necessary bolt, and with it replaced, the sound vanished.

Thanks for the suggestions.