Is my trans messed? I just did clutch and...

[997_rich]

Stock M20 with G260 gearbox ('89 325i). I bought it this summer and I'm bringing it back to a tightened up street car.

There was a little bit of a rattle when the clutch was just catching starting a few months back. I assumed this was throwout bearing or clutch going bad or the friction plate hopelessly glazed from being so old. So, all in one shot I did:

• new engine and trans mounts in poly (engine was broken)
• new friction plate
• new RMS
• new pressure plate
• new throwout bearing
• new clutch slave and line
• new pilot bearing
• new throwout arm
• new throwout arm pivot
• greased throwout tube and replaced
• reused flywheel but checked runout and roughed it up with emery block. flywheel is pinned so there's only one way it can go on and this is a single-mass flywheel.
• previously did trans oil with the spec gear oil
• did guibo previously

Now I'm still getting the issue but it seems worse. whatever I did seemed to tighten everything up except the real issue. Symptoms:

• Seems like a lot of vibration in the trans with clutch in or out (this is a new symptom but it could just be the poly bushings.
• The gearbox(I believe it's the gearbox) whines when under load when gears are engaged in very gear -you hear it when hard accelerating. It sound like straight cut gears in a race car.
• when the clutch is half engaged you can hear a slight rattly sound. if i hold my foot there with light engine power i can make the rattle extend as long as I like.
• one more sympton, when i pulled the trans, the input shaft could "joystick" around about 1-2mm in any direction but it couldn't move laterally- just joystick.. i'm not sure if this is normal for this car- the pilot bearing should hold it from joysticking when in the car.

I'm pretty experienced but this one is a bit more annoying than usual so trying to reason it out before I go pulling the trans again.

I'm starting to think there's something wrong with the trans input shaft (is there a bearing deep in the trans case?). I can imaging that the shaft allows the friction plate to bobble around a bit between the flywheel and pressure plate and make this shaking. And that bobbling causes the trans input shaft bearing to rattle?

two questions:

• is trans input shaft joysticking normal?
• any idea WTF is going on?

[jlevie]

A very slight movement on the input shaft with the transmission in neutral is normal. But a lot of movement or rattle when the transmission is in neutral and the clutch engaged is from wear in the input shaft bearing.

Whine from the transmission is from wear inside the box. Bushings harder than OE will make that more obvious.

[997_rich]

thanks- is there just one bearing on the trans input shaft (the bearing right under the guide tube) or is there another bearing at the other end of the shaft deep inside the trans?

I wouln't be surprised if there is wear inside the box from someone running this box dry sometime in the past.

[jlevie]

From memory, there is only one input shaft bearing.

[997_rich]

Ok, updates on this one. I traded out the poly trans mounts for rubber trans mounts and there is now very little noise. Comparable noise to before I dug into this project. The whine is hardly noticable.

What seems to still be a problem is that about 1/2 engaged clutch I get a slight rattle for a second. If i stay half on the clutch the rattle will stay. it's almost like ball bearings bobbleing around. I'm getting pretty confident that this is the trans input bearing wearing out.. or something in the trans wearing out.

on the trans input shaft there are 2 bearings. Ball bearings on the outside of the case and small needle bearings on the other side.

At this point I think I'll drive it for a while and see if it gets worse. I may try to get someone at a track day check it out or something. I see there are some e30 trans experts in south jersey.

[Exodus_2pt0]

I have a good g260 sitting in my shop if you want a spare!

[997_rich]

Exodus- does the trans input shaft on that one joystick around? if so, about how much does it joysticK? 1mm in all directions?

I may be interested. I have family in DC so I might run down.

[Exodus_2pt0]

I'll let you know on the play tomorrow

[997_rich]

I've been thinking about this chatter for some time now.

One thing i neglected to do when i put it all back together was to put in the pilot bearing cover in place. My old pilot bearing was an unsealed bearing. My replacement was sealed so I thought I didn't need the cover.

I found a few pics on the internet of the cover.

Do I need this pilot bearing cover? does it serve a mechanical purpose- like pushing back on the trans input shaft to load the trans input shaft bearing?

[997_rich]

here are some pics of the bearing cover.

[jlevie]

The cover is only used for the original open bearing.