Testing rebuild transmission

[rjkoop]

Done the rebuild and install of my 5 speed transmission and clutch on my '81. I wanted to try to test things out a bit before I take it on the road. So was going to start it and ensure the clutch engages correctly in 1st gear. And try out reverse a bit in my garage.

I was also hoping to try to run it through the gears (low RPMs) to ensure the gears engage correctly and there's no strange noises. Is it ok (for a short time) to have the car up on jack stands in the rear and run it through the gears maybe switching about 2000 rpm? I'd probably only be running it this way for a minute tops.

Obviously ensure it's very stable on the jack stands, point the car into the driveway (no cars in the driveway!), block the front wheels, etc...

Richard

[18Fiatsandcounting]

Yes, it's OK to do this, but do take rigorous precautions that the car is securely up in the air. You don't need to raise all 4 wheels, just the two rear wheels. I don't know why, but it always creeps me out when I do this, especially when the speedometer reads 80 mph and the car isn't moving!

Just make the shifts and engine acceleration as gentle as you can, i.e., no sudden lurches that might cause an issue with the jack stands.

It's also a good way to check for drivetrain or axle/wheel vibration.

-Bryan

[rjkoop]

Yes, it's OK to do this, but do take rigorous precautions that the car is securely up in the air. You don't need to raise all 4 wheels, just the two rear wheels. I don't know why, but it always creeps me out when I do this, especially when the speedometer reads 80 mph and the car isn't moving!

Just make the shifts and engine acceleration as gentle as you can, i.e., no sudden lurches that might cause an issue with the jack stands.

It's also a good way to check for drivetrain or axle/wheel vibration.

-Bryan

Thanks Bryan.

Richard

[rjkoop]

So started the car for the 1st time in about a year. Started great after about 5 seconds.

Was able to put it in 1st and reverse and turn the car around in my driveway. Noticed a bit of a squealing noise while it was in gear and a bit of smoke coming from around the transmission area. I'm thinking the clutch isn't adjusted correctly. Essentially I had to push the pedal in about 3/4 of the way to the floor to get it to disengage (ie. where the car would start to roll on it's own on my driveway's slope).

So I'm getting confused about do I need to tighten the clutch adjustment bolt or loosen it so that the pedal only has to go an inch or two before disengaging the clutch?

Richard

[18Fiatsandcounting]

The smoke could just be oil burning off from the exhaust downpipe, but the squeal is a bit concerning.

To answer your question about the clutch adjustment: If you tighten the special "ball pivot adjustment nut" on the clutch release fork/cable, it will tighten the cable. So, you need to tighten this nut in order to adjust the clutch so that it starts to release (pedal gets suddenly stiffer) when the pedal is depressed an inch or so. I've always tested this one inch of play with my hand, so test the play, reach under the car and adjust the nut, sit back up again and press the clutch with your hand to see the result, and repeat until you get it where you want it. I've always found it easier to gauge the play with my hand rather than with my foot.

-Bryan

[rjkoop]

Think I'm giving up on this transmission. I think I have to accept that the transmission rebuild was beyond my skill level.

I adjusted the clutch cable to the point where I had it on a bit of slope (driveway) and pushed the clutch in an inch and it started to roll. So it should have been adjusted correctly. Then I started it and I still have the squealing when I roll the car forward in 1st and backyard in reverse... and the bit of smoke! Argh!

Think I'm going to look at a professionally rebuilt one.

https://www.midwest-bayless.com/fiat-12 ... ioned.aspx

Richard

[18Fiatsandcounting]

Sorry it didn't work out Richard. If I were closer I'd take a look at it for you.

On the clutch pedal adjustment: That doesn't quite sound right. The clutch should just at the point of starting to release when the pedal has been depressed an inch or so, but my recollection is that it shouldn't release the clutch enough for the car to start rolling until the pedal is depressed 2 or 3 inches. I've never measured it, so that's just a ballpark guess.

Maybe something is really wrong with the clutch or its adjustment? If it's engaged but slipping even when the clutch pedal is out all the way, that would cause some smoke as the clutch eventually starts to overheat. Might also cause the squeal.

Did you take a look at the clutch when the transmission was out? Could the clutch be covered in oil and thus shot?

-Bryan

[davidbruce]

Richard, a few things come to mind. Is it possible your friction disc is in backwards? I don't remember what my Fiat one looked like but most are asymmetrical. That is the splined boss in the centre protrudes farther on one side than the other. Could it be rubbing on the pilot bearing or the front ot the tranny? Did you replace the pilot and throw out bearing when you changed the pressure plate and disc? Did you have your flywheel resurfaced? If so and they did not machine the same amount from the friction and the pressure plate mounting surface the clutch will not function properly. Wouldn't be the first time. I wouldn't condemn the rebuild before confirming everything in the clutch is correct.

[rjkoop]

Richard, a few things come to mind. Is it possible your friction disc is in backwards? I don't remember what my Fiat one looked like but most are asymmetrical. That is the splined boss in the centre protrudes farther on one side than the other. Could it be rubbing on the pilot bearing or the front ot the tranny? Did you replace the pilot and throw out bearing when you changed the pressure plate and disc? Did you have your flywheel resurfaced? If so and they did not machine the same amount from the friction and the pressure plate mounting surface the clutch will not function properly. Wouldn't be the first time. I wouldn't condemn the rebuild before confirming everything in the clutch is correct.

Thanks. I'll take the existing transmission out and check.

Yep. I remember the friction disk was directional. I think I put it in right but I'll double check. I replaced the pilot and throwout bearing too. Didn't have the flywheel resurfaced.

When I take the trannie out I'll check all these things. But if I don't find something wrong I'll be worried that the problem is inside the trannie. But honestly the noise and smoke would lead me to believe that it's in the clutch area and NOT the trannie.

Richard

[18Fiatsandcounting]

But honestly the noise and smoke would lead me to believe that it's in the clutch area and NOT the trannie.

I'm in agreement: Noise can come from the transmission, but squeals and smoke sound like something clutch related. Like davidbruce implied, I wouldn't give up on your transmission rebuild skills quite yet.

-Bryan

[rjkoop]

Ok. Transmission removed. Last time it took me about 8 hours. This time 2 hours!

Didn't notice anything obviously wrong but what do I know? Here's some pictures in case anyone seems something.











And the video...

https://youtu.be/OghNT55frrQ

Richard

[davidbruce]

HI Richard. The only thing I see that concerns me is the amount of grease I see. There should be a very light smear of grease on the splines and nowhere else. The clutch fingers and release bearing face should be dry. Did you grease the face of the bearing or is that due to centrifugal force flinging it outward? Did any grease reach the friction surface? Hard to tell from the pictures. My guess is the smoke may be grease burning off a place it's not supposed to be. And whatever is causing the smoke could be causing the squeeling. I personally would clean all of that excess grease off, including washing the friction disc with brake clean and letting it dry. Invest the 2 hours in reassembling and adjusting the clutch and see what you have. I personally have always installed my clutches dry except if the pilot bearing was a bronze bushing. That was the only place I greased but lots of people use a little on the splines. I presume the clutch worked fine before the trans came out and you did the clutch because you were in there anyway? You may want to measure the step betwen the friction surface and the presure plate mounting surface. Spec should be in the manual. Everything you have said makes me think clutch/flywheel issue. And if it's any consolation I know all too well how much faster the tranny comes out for the second time!

[rjkoop]

Yep. Now that I look at the pictures I see what you mean. I'll do a thorough cleaning of everything and use very little grease if any at all this time. I noticed that there is a bit of play on the input shaft but I think it's very minor. And from what I've read when the input shaft slides into place in the flywheel it tightens things up more.

I had a leak (looks like it was coming from the transmission pan area - did some tracing with baby powder and looked for the route of the oil) so I'm going to ensure that's 100% gone before I put things back together.

Thanks for instilling some more confidence in my rebuild.

For adjusting the clutch I found it difficult to feel when it engages. I found it better to have the car on a slight slope and push the clutch in and when it starts to roll with the clutch pedal depressed 1" then it's adjusted correctly. Does that make sense?

Richard

[davidbruce]

Hi Richard. My interpretation of the shop manual is tighten or loosen the adjustment on the clutch cable so that when you push on the clutch pedal it will travel approx. 1" before it meets resistance other than that of the return spring. If you loosen it right off and then tighten until there is just a small amount of slack in the cable. Press the pedal with your hand and you should feel the change in resistance and it will probably be about 2" down at this point. Tighten it up until this change in resistance is at that 1" of pedal travel. That should be the point where the release bearing contacts the clutch fingers. Not where it disengages the clutch. If it is too tight the bearing is constantly in contact with the clutch fingers and that is not what you want. I hope this makes sense. It sounds like your cable may have been too tight and possibly contributed to the problem. As an aside I have an oil leak that was a bear to track down. There was a minute leak from the distributor gasket when the oil got hot and thinned out. Very minor and extremely hard to see and it dripped directly on to the exhaust. No real smoke but I could smell the burning oil.

[18Fiatsandcounting]

Hi Richard, I agree with Dave on this. At one inch of clutch pedal travel, the clutch should NOT be released enough for the car to start rolling. That one inch of travel just takes up the slack in the cable and pedal mechanisms, and the clutch shouldn't be releasing until the pedal is pushed down 2 or 3 inches or possibly even more.

So, if the clutch is released enough for the car to start rolling at one inch of pedal travel, it might not be fully "engaged" when the clutch pedal is all the way up, and it could then slip. Add some grease or oil to that scenario, and you would definitely get smoke and perhaps squealing after a short while. It will also eventually burn out your clutch.

-Bryan