View Full Version : Bridgeport Head Tear Down - Backgear Lever Movement?

12-06-2018, 07:30 PM
So I've got a Bridgeport J-head from the 70s and I finally decided to give it a little love. The head has been making nasty noises and it was stuck in backgear since I bought it. I went through the head completely and found that the pulley bearings needed to be replaced. The grease had turned to soap and the bearings were all nasty feeling. All of the open bearings appeared clean and in good shape. In fact, I was surprised at how good everything else was. The auto down feed gear train looks like it's never been used, the original downfeed handwheel was still with the machine, etc. I think it just sat for a long time unused and that took it's toll. A lot of components were just gummed up with oil turned to varnish.

Anyway, the backgear remains a problem... sort of. I don't even know the proper terms for these parts but you know the collar that you spin to disengage the dog clutch when going into backgear? When I turn mine, it goes all loose and sloppy very quickly, i.e. the part that travels up and down stops traveling down the ring lifts up away from the aluminum housing instead. It's almost as if the 4 compression springs that are supposed to push the clutch together are too short. Consequently, it feels like the clutch doesn't fully engage, although I think it actually does. I'm going to keep tinkering but has anyone run into this before? Any ideas?

Functionally, it seems to work and I can manually move the pulley/clutch assembly up and down 1/8" freely (with the ring removed, obviously) before bottoming out. It just seems like it's not adjusted right. Or am I being too picky?

12-06-2018, 07:57 PM
Take it apart and look at the pins used for levering it up and down that are in the bearing housing. They can get loose and slog out their threads. Take pics and post.

12-06-2018, 07:59 PM
If some body for any reason removed the lever that is used to engage back gear and just put it back they lost the movement that is required . Are you in back gear if yes where is the back gear lever it should be in the back position, if not take out the 2 screws that hold the handle in, while holding the gear down pull the lever assembly out, let the gear up, now put the lever in the block to the front position and reinstall the lever assembly, swing the lever to the back gear position does the gear go down to the back gear position, to me it's an easy fix but I've rebuilt way to many J and J2 BRPT heads when my co. was open. Oops my bad I was repairing a J2 head.

12-06-2018, 08:20 PM
Take it apart and look at the pins used for levering it up and down that are in the bearing housing. They can get loose and slog out their threads. Take pics and post.

That was actually my first thought. I've run into that before on other machines but these pins are tight and square - not bent or wallowed out.

Solved I was just being an idiot. When I got the machine, that pulley/clutch assembly that moves up and down was gummed in place from old oil that had hardened up. I got it all cleaned out and reassembled. I thought I was having the same problem when testing it on the bench. After posting here, I realized the issue was that I didn't have the backgear engaged (i.e. lever "b"). The result is that sometimes the dog clutch is not aligned properly and spinning the spindle (as you normally would to get it to drop) doesn't work. There's enough friction between the faces that the whole thing just spins. So nothing is actually wrong with it. :rolleyes: Time to go home.

Thanks guys for the advice.