Sudden Noisy Gears/transmission/Clutch 74 B

Hello Dear B friends:

Here's a tough one! Several months ago I had my gearbox replaced with what I was told was a good used 4 speed 1974. For a few odd moments in those months since I've heard a gear(s) grinding..No slipping..all gears work fine thus far. But suddenly tonight, after a full week of driving without incident, the car started making bizarre grinding noises that appear to come from the gears..but the car drives fine and no problem changing gears..just incredibly noisy..NOT NORMAL I SUSPECT! Is my clutch suspect..the was new a year ago
Got home, checked fluid level in clutch and trans..both seem ok...( its night so I'll check again when cold in am but a bit concerned it may be serious)

any thoughts?


I hope I'm not doomed for another gearbox..the last was way too expensive a job!

Thanks for your input

Terry

Does it make noise with the clutch engaged and idling in neutral???If so then I would suspect the input shaft bearing.

Input shaft or layshaft bearings. RAY

Yes, it seems the noise is both at the idle and engaged position...

Input shaft? Yikes, sounds painful....where or how do I remedy this situation?

Thanks again

Terry

Gonna have to take it all apart again.

Terry, you are probably going to have to pull the power unit again anyway, but before you do try this.

Get the car warmed up enough to idle smoothly.

Lock down the parking brake and set the box into neutral.

Reach down and with you hand start to depress the clutch pedal. As the resistance begins to build a little do you feel a certain "roughness" at the pedal? Does the noisy sound change? If so you probably have a failing/failed clutch release bearing.

The input bearings on B boxes are very stout and rarely fail unless the box is run nearly dry of lube.

I am not saying that you definitely don't have a bad first motion shaft bearing, but it is more likely that the release bearing is a goner.

Pull the assembly and look at the release bearing before you order up another box.

Another check would be this.

At idle with the gear stick in neutral, depress the clutch pedal completley. If the noise goes away completley or almost so, the box might be at fault. What you have done is to disconnect the spinning engine from the box and in so doing the box shafts and gears have stopped moving and the bearings have been released from their loads. Sticking the gear lever into first is sort of a way to check for this stopping, but the synchrnoizer might be masking things. Instead, with the clutch pedal depressed all the way, wait about three or five seconds and then try to select reverse. If it slips into reverse without complaint/grinding you know that the gears are motionless and if the gears are motionless and there is no noise and the clutch release bearing is being loaded you can rule out the release bearing and figure on something inside the box.

BTW: If there is anything wrong with the release bearing put the evil eye on the thrust plate part of the pressure plate. If it is loose in the diaphragm fingers or the surface is buggered up go on and replace the pressure plate and the disc. Might as well toss a spigot bearing in too.

Before buttoning things up with a new clutch, slip the new disc over the first motion shaft splines and make sure that there is no binding there, and check the fork fulcrum bushing for excessive lateral slack

You mentioned a high cost for the previous replacement. I don't know what you might consider "high cost" but aside from the labor time to do the work you should know that used NON-OD B boxes are almost worthless and you shouldn't pay more than a hundred or a hundred and fifty bucks for one all cleaned up. They are so robust that they almost never fail and are available everywhere. You know the supply and demand thing, well the supply is high and demand is low, hence the low price value.

Hope this helps, Jack

Thank you Jack! Very helpful information...sounds like I have one heck of a job ahead!

Many, many thanks for your valuable time, always appreciate hearing from you