Help needed identifying transmission problem.

[jowwel]

Hey Everyone,

My 1971 Chevy C10 pickup is giving me some trouble in the transmission department.

A few months back, it started protesting when I would shift from 1st to 2nd (It's a 3-on-the-floor setup in an "H" shape. 1st is lower left, second is upper right.). I noticed that it would shift more easily when the engine was still cold than it would after it warmed up. I also noticed that I could easily shift from Reverse into 2nd if need be, and that there was no trouble between 2nd and 3rd, or with downshifting of any kind.

As it got worse and I would be unable to get it into second from first at all without double clutching several times. Eventually, I just gave up and started parking on downhill slopes as much as possible and starting it up in Second. I cringe each time I do it, but I gotta get around somehow.

About a month ago, I also noticed that the truck would start to protest and vibrate when accelerating while in reverse. This started to get progressively worse as well until the shaking became unbearable. I now pop it into neutral and push the thing back into my parking spaces in the city with my feet. I'm not making this up. Last week, I noticed that I can no longer put the truck into reverse at all. The stick just won't go in.

I have checked all my linkage and it is fine. My friend has suggested that it might be the "syncro", which I am not familiar with. My suspicion is that my 41 year old transmission is calling it quits.

Do any of you have any insight into the problem for me, or have some advice on how to investigate the cause of the problem further?

Any help at all would be great. Thanks in advance.

PS. One more tidbit that might factor in: I changed the clutch in February/March. Perhaps I screwed something up?

[68gmsee]

First check the lube in the transmission and if that's okay, I would suggest remove it and double check the pressure plate, throw out bearing, pilot bushing and clutch plate for any problems. It's possible the synchronizer in the tranny is shot but I would first eliminate the other potential problems.

If the clutch is not releasing it will definitely cause the problem you're having. Also if the pilot bushing is seizing. Clutch and pressure plate contamination or defective can cause the vibrations you're having as well as worn input shaft bearings in the transmission.

[crazy longhorn]

Originally Posted by 68gmsee

First check the lube in the transmission and if that's okay, I would suggest remove it and double check the pressure plate, throw out bearing, pilot bushing and clutch plate for any problems. It's possible the synchronizer in the tranny is shot but I would first eliminate the other potential problems.

If the clutch is not releasing it will definitely cause the problem you're having. Also if the pilot bushing is seizing. Clutch and pressure plate contamination or defective can cause the vibrations you're having as well as worn input shaft bearings in the transmission.

2nd all of that crazyL

[jowwel]

OK, since I'm newish to this sort of work, I'll ask a few obvious questions here... Thanks again for helping me out.

Originally Posted by 68gmsee

First check the lube in the transmission

My understanding of how to check the lube in the transmission is to remove the plug in the side of the transmission and stick my finger in there one knuckle deep and feel for the lubrication level. Is that method accurate?

Originally Posted by 68gmsee

I would suggest remove it and double check the pressure plate, throw out bearing, pilot bushing and clutch plate for any problems. It's possible the synchronizer in the tranny is shot but I would first eliminate the other potential problems. If the clutch is not releasing it will definitely cause the problem you're having. Also if the pilot bushing is seizing. Clutch and pressure plate contamination or defective can cause the vibrations you're having

Having just replaced the clutch several months ago, this should be easy to check out. It's possible that I screwed something up, but I don't think I did.

Originally Posted by 68gmsee

Clutch and pressure plate contamination or defective can cause the vibrations you're having as well as worn input shaft bearings in the transmission.

Assuming the clutch checks out, what steps will I need to take to investigate if the input shaft bearings in the transmission are worn down?

[68gmsee]

Fluid: I just fill the transmission until it just start to ooze out of the top hole.

Even though you just replaced the clutch/pressure plate they could be defective. Parts are not what they used to be, especially if you bought at the local auto parts store. Also, you may be able to look to see if the clutch disc is being released by having someone depress the pedal while you observer from underneath. Don't overlook the pilot bushing. It's possible it's binding and grabbing the input shaft.

To check the input shaft bearing you basically see if the bearing is noisy or wobbly. These are all preliminary checks before you take the transmission in to have a shop look at it. I've replaced the synchro in the past but it's been many, many years ago. If that turns out to be the culprit, I'd have a shop do it, though. It can turn out to be a big pain. And don't overlook the salvage yards for a replacement transmission. I picked my saginaw about 15 years ago for about $30. There are a lot of vehicles that used these type of transmission back in those days.

[jowwel]

Thanks, that is all very helpful and reassuring.

[jowwel]

Originally Posted by 68gmsee

To check the input shaft bearing you basically see if the bearing is noisy or wobbly. These are all preliminary checks before you take the transmission in to have a shop look at it. I've replaced the synchro in the past but it's been many, many years ago. If that turns out to be the culprit, I'd have a shop do it, though. It can turn out to be a big pain. And don't overlook the salvage yards for a replacement transmission. I picked my saginaw about 15 years ago for about $30. There are a lot of vehicles that used these type of transmission back in those days.

Hey, I just found a Saginaw 3 speed for sale for $50. The owner had this to say:
"I pulled it from my truck to put in a 4 speed. It has a decent amount of play in the shaft... I would recommend replacing the bearings at least on the front of the trans. It worked when I pulled it but I would at least pull the cover and check the gears "

Also, my truck is a 71 C10, the transmission is of an 82 C10. Does that mean it won't fit then?

With all that in mind, does that sound like a good deal to you?

[cableguy0]

For 50 bucks your basically buying a core that needs rebuilt. I would bother with it if you dont have the ability to rebuild it yourself.

[crazy longhorn]

Originally Posted by jowwel

Hey, I just found a Saginaw 3 speed for sale for $50. The owner had this to say:
"I pulled it from my truck to put in a 4 speed. It has a decent amount of play in the shaft... I would recommend replacing the bearings at least on the front of the trans. It worked when I pulled it but I would at least pull the cover and check the gears "

Also, my truck is a 71 C10, the transmission is of an 82 C10. Does that mean it won't fit then?

With all that in mind, does that sound like a good deal to you?

Did he say up/down play...or in /out? Dont tell him, but they all have up/down play Take hold of both the input & output shafts...in/out(end play), is what you need to watch for. The rear bearing, has a wave washer behind it....loose bearing, or broken wave, will cause enough end play to "feel". As for the front bearing, I replace that any time I do a clutch(cheap ins.) The price is not bad on the trans...if its decent shape, but you wont know till you get there. If he lets you pull the side cover, you can inspect for broken or chipped gears....check the brass rings. Do they all still have the teeth on them? Also, they will rock back /forth about 1/8"....if you find one that spins, thats an issue. As far as fit, I cant say....you need to do the measure crazyL

[geezer#99]

Could be a broken motor mount, tranny mount or steady bearing is shot too!