transmission chatter is killing me

[fan-of-the-fiat]

I'm getting a lot of a rattle-like noise from the transmission area in my 1976 spider when the clutch is NOT engaged. I'm guessing I'm getting some bad bearings. The noise goes away when the clutch is pressed in or when I get to the 4th and 5th gears. I've never rebuilt a transmission before, so I'm looking for some advice on what parts I may need in order to do this. Also, if I undertake this, what other items should I service while I've got the transmission out? Is this difficult? If so, should I just buy a used transmission and hope that the bearings have got some life left. Are there other things that could be causing this noise that are easier to fix? Just looking for some feedback. I just got her running again due to a bad ignition and now I'm trying to avoid ruining my transmission. Any help is greatly appreciated! Thanks again.

[So Cal Mark]

well, any tranny repair is going to be fairly expensive. Hard parts are getting harder to find, even bearings. A set of bearings is now over $300 alone. It's common to find worn synchros, sliders and forks. I'd look at those pieces very closely if you take it apart.
A used tranny is abit of a gamble, unless you can really trust the source you get it from. Unfortunately, no easy, cheap solution for this

[E Prod Racer]

Before you tear down the transmission, check to see if the pilot bearing is any good, or even missing. This bearing is in the end of the crank, that engages the input shaft from the tranny, and would either be ignored when a clutch is changed, or replaced with a junk part (bad pilot bearings are out there, actually MOST of them). They may or may not be included in a clutch kit, and those included ones are usually the worst quality. A bad one can cause a racket, and eventually ruin the input shaft bearing, and the nose of the input shaft. Try to get a good one, and see if the problem goes away.

[fan-of-the-fiat]

Thanks for the replies. I'm hoping it's the input shaft bearing, since I think that's easier to replace. I guess I'll know more once I drop the transmission. thanks again for the feedback...

[So Cal Mark]

if it makes the noise in neutral, it's probably the bearing inbetween the input and main shafts. That bearing doesn't turn in 4th (1:1) and not much in 5th. Is the fluid level correct?

[jaubine]

Thanks for the replies. I'm hoping it's the input shaft bearing, since I think that's easier to replace. I guess I'll know more once I drop the transmission. thanks again for the feedback...

Hey, did you ever get around to finding the source of your rattle? what you described in your original post is identical to some chatter I'm getting as well from the undercarriage of my '79 spider. I dont hear it in neutral, 4th, or 5th gear - only in 1st, 2nd, and 3rd gear, when the engine and tranny are spinning at ~2500 or higher RPM's.. I've also heard it (albeit briefly, once) when I was in reverse, backing up into my garage under idle power.

I recently had the car up on ramps and looked underneath; I noticed a metal anchor "link" (about 8 inches long by 1.5 inches wide, had another peice of metal that looked wielded at offset angle, perpendicular to the link; one end of the link had a 8mm(?) nut tack wielded to it) that was bolted to part of the exhaust, that was missing the bolt that tied it to the underside of the transmission; I put a new bolt in to secure it thinking that was the source, but it kept rattling afterwards..

Let me know what you found..

[ragtop2000]

I also have a similar rattle. Mine comes from a bearing or rear input seal on the transmission. It is located between the flex donut and the rear of the transmission where the drive shaft enters the transmission. If I move the drive shaft slightly back and forth or tap it with a screw driver, it makes the rattle noise. I'm guessing it's a bad bearing buy the noise if makes. It's hard for me to identify the exact part # with the manual I have because the drive shaft and the transmission parts are on separate pages. My best guess is from Bruce's part # 4274012 for a transmission bearing. Can anyone verify this and tell me how hard this would be to replace?

Thanks!

Jon

[So Cal Mark]

it would be odd for a tranny bearing to cause a rattle, my bet is that it's the collar on the front on driveshaft just behind the flex joint

[ragtop2000]

Thanks for your reply. If it is that collar, any ideas on how to stop the rattle? I can't find anything about it in my service manual or parts book. She's a 79 spider if that matters!

[So Cal Mark]

that collar is just crimped on the tube

[jaubine]

if it makes the noise in neutral, it's probably the bearing inbetween the input and main shafts. That bearing doesn't turn in 4th (1:1) and not much in 5th. Is the fluid level correct?

Hey Mark,

I was pulling my spider out of the garage this morning and had it running in neutral and heard the chatter while I was shutting the garage door (clutch was out).. Definitely sounded like it was coming from the front of the tranny rather than the rear..

If the bearing you speak of is the one to replace, do you have (or know of) a specific part number for this? How difficult will it be to replace (excluding tearing the transmission out of the car)?

Thanks!

[So Cal Mark]

a more likely culprit would be the release bearing, does it change with slight pressure on the clutch pedal?
As for removing and disassembling the tranny, it's hard to state the difficulty level. If you have the proper tools and a lift, it's moderately difficult, if it's your first time and you're laying on your back I'd say it's pretty hard

[ragtop2000]

Mark,
This is a reply from two posts before, about the drive shaft collar. I put the car up on stands today and the rattle noise is coming from something just in front of the flex joint not behind it. I shot some heavy grease around it and the noise went away. It's probably a temporary fix. Any ideas on a permanent fix?
Thanks,
Jon

[So Cal Mark]

just in front of the flex joint is the nut that holds the flange on the output shaft. It has a washer that gets folded over to keep the nut from loosening

[jaubine]

Mark,
This is a reply from two posts before, about the drive shaft collar. I put the car up on stands today and the rattle noise is coming from something just in front of the flex joint not behind it. I shot some heavy grease around it and the noise went away. It's probably a temporary fix. Any ideas on a permanent fix?
Thanks,
Jon

I just put mine up on stands as well, and finally located the source of mine, and what you describe is exactly the same as what I have.. it looks like it's coming from a flange washer or cover of some sort, in between the transmission drive shaft and the forward yoke. I can easily move it and it causes a very distinct rattle. I'm not exactly sure what part this though...

I think this is what I'm describing above, though I'll get under the car with a camera and see if I can get a clear shot of the thing..