strange noise coming from under car/Transmission? Can anyone help!?

Hello MG people!

Here's a head scratcher!

Perhaps you may be able to shed some light for me!

The 1974 B I drive has been going along very well on the freeways here in LA now for about a year or so... all of a sudden I now have a kind of dull grinding noise that appears to be coming from the transmission area. I can hear it as I'm driving, not loud but very much a new, unwanted addition to the B's condition>

The noise stops when I'm at a stop. The engine and compression is excellent, gears are working fine and everything else works but this bloody noise-almost sounds like metal on metal..a noise that's impossible to detect foe a novice like me!

There is good clean gear oil in the transmission sump behind the radio console.

Is there a way I can see if my transmission is shot by visual inspection/tests????

ANYTHING would help at this point, the car drives well otherwise but I don't thinlk I should drive now with this new noise.

Any thoughts.

Thanks

Terry

When moving, does the noise go away if clutch pedal is pressed?
RS

Is it dependent on vehicle speed or engine speed?

No, the noise is still there upon clutch pedal depressed

sound is a little louder as we get faster but basically the same grinding noise

Check brakes and see if something wrapped around drive shaft. Then...?
RS

have you checked the wheel bearings...these often make a deceiving noise??

Every once on a while a trig or branch can get lodged alongside the driveshaft and make a sound like you describe. Check to make sure there's no rubbing the length of the driveshaft. If the car makes a snapping or 'clink' sound when you put it in reverse and go to back up, it's likely a universal joint. Transmissions seldom go bad in B's. Throw out bearings and clutches do, occasionally.

Universal joint ??

Just guessing but I did have that problem last summer and it was a very unusual noise.

My two cents :)

Ya beat me to it Scot ;)

Naomi, So glad to see you a bit more active on the forum! Keep it up.
Fellow VA. resident.
RS

you guys are cool...I'll check the things you're talking about

Thanks so much...my Universal joint on MGB? Anyone have a pic so I now what it should lt should look like?...

terry

Is a universal joint replacement something I could do myself!!????

First time can be a bit daunting but not hard. You'll need a good vice, some strong nose pliers to remove 4 clips on each end, a socket to push the cups in and out, and patience! Look for a John Twist video. I'm sure he has one.
RS

While you're under there, check the exhaust for a hole or a leak. Just in case. Basil

Terry, there are two universal joints. Plan to replace them both. Also when you order them order 8 new nylock nuts for the ones you will likely destroy when you remove them.

Also, MARK the position of the flanges where it hooks to the differential AND where the yokes connect - before you take the u-joints apart - so that when you put them back together they will be in the same position and not change any balance in the shaft.

See my earlier post about a similar problem.. I spent a couple of hours and changed the u joint and the problem was solved.. U joints are another MGB pain in the a.. but are doable (new word)

pmittler Wrote:

No doubt a U joint, but when you said "gear oil"; what exactly do you have in there?

Here are a couple of fotos of the Universals. The top photo is of the rear set, and the bottom photo is of the front set.

Disregard the tiewrap and magnet on the front flange, that was a temporary thing for the cruise control speed sensing pickup before I switched to using the ignition pulse signal.

If the oil you have in the tranny really stinks, it is likely gear oil, which is NOT recommended, particularly if you have an overdrive unit. If it doesn't stink to high heaven, it is probably the recommended motor oil.

Trailer weighs 1122 pounds.
Yes I feel it... but mostly when stopping which is why it now has electric brakes.

Check the rear rim inside lip.. I had the parking brake leaver rubbing the inside edge of the rim one time because there was too much slack in the cable..

I'll leave you to try it and decide yourself whether it is any fun to change U-Joints.

I decided a looooong time ago it was not, so these days Ii just haul the drive shaft to a machine shop and let them do it. I get the parts from them as well...cheaper that way, usually.