VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 1936 Pickup throwout bearing chattering

Hello all, I'm restoring a '36 pickup and the throwout bearing is vibrating and chattering on the trans input shaft. It's so bad it's beginning to destroy the carbon bearing. I've tried adjusting the ball on the throwout arm and the more I adjust it closer to the pressure plate the more it bounces around. I believe I will need to pull the trans and replace the bearing unless someone has an answer. Also how do you keep the arm parallel with pressure plate? It pivots on the ball and comes in contact with the springs on the pressure plate. Could I possibly have the wrong throwout bearing? Maybe the ID is too large? Don't know.
Thanks guys, Ken

If I am not mistaken it shouldn't contact any springs. The pressure plate should have a smooth flat machined thing that the carbon runs on. The carbon bearing gets some oil seeping through it from it's little oil port, and the carbon just rubs on the flat thing. Alignment doesn't matter like it would with a bearing, because it just slides on that flat thing. Maybe someone else can explain it better.

Ken, Congratulations on your first ride.
I was watching your video last night. If your cab was in place, the clutch pedal would bump the toe board and not come up as far as it does at present. This would limit the total travel of the bearing to a range where your vibration might go away. bloo is referring to the clutch throw out bearing plate which you have in place.
Your vibration is happening long before any contact with the plate takes place. If you need a new bearing or plate, I have them.
Call if you like at 573 864 6539

Mike

Thanks bloo and 35Mike for responding. I'll give you a call Mike, because I'm still not understanding why the bearing ratchets back and forth on the input shaft. And I'll probably take you up on a new bearing.

Well I took your advice Mike and built a device to keep the clutch pedal in position like it would be if the cab was mounted, and it worked great. Thank for your help and I'll put you in my contacts for any future questions. I'll get a video up shortly to show how I did that. I actually took it down the road today, but now I have another problem the generator started smoking and got pretty hot. I don't have any wires running from it yet do you think that might be the issue? Thanks again Mike

Ken,
While it is probably not recommended to run a generator that is not hooked up, I have done so on several occasions. I do not recall any of them getting hot. My thoughts would be that only a bad or dry bearing, or grounded field coil would cause this.
I am no automotive electrician, but I will be talking to one later today. I will ask him fir some input.
There are many others here who are better qualified to address this question.
Glad the clutch pedal stop has solved the problem with your throw out bearing.

Mike

I agree that most likely the generator issue is bearing/bushing related. If there is enough wear in those or on the shaft the armature will rub against the field coils.

Hi everyone

It depends on the generator.
Third brush generators should NEVER be run with an open charging circuit.
When run with nothing else attached, the armature terminal should be jumped to ground.

The reason is that without any form of voltage regulator, most third brush generators will TRY to push current out the armature terminal and keep building voltage to do so.
That voltage will push more current through the field circuit... which will make the generator produce higher voltage... which will push even more current through the fields... which will make the generator produce even higher voltage.. which will... well I'm sure you can see the feed back loop that develops that can fry your generator.

This is why back when John Deere had third brush generators on their tractors the manuals were very adamant that when run without a battery,
the battery cables MUST be tied together.


Also, my Dad taught me this many years ago! :-)

I forgot that there was some residual magnetism in the generator. It becomes "self-exciting".

Third brush units are a slightly different breed!

If run for an extended time as Ole pointed out the feed back loop in the generator will eventually fry a third brush generator. Short runs are not a problem. I only fried one generator until I learned my lesson. Now I connect them to a battery with cut-out or alligator clamp.

Thanks guys for the generator input. I hope I didn't fry it. I'll start it up and see if I'm getting any output from it. I kind of wondered if that was a bad idea running it without it being wired to the battery.

I hate it when we change gears on a thread without using the clutch!

Sorry I switched gears on this thread. But just an update, the generator was not fried and I fastened a wire from the cutout to the battery and all is good. Thanks again fellas.
Ken