Mechanics

NEW SOUND - VERY NOISY IN NEUTRAL WITH CLUTCH E

1996 BMW Z3

Transmission problem
1996 BMW Z3 4 cyl Two Wheel Drive Manual 207Kkm miles

Started a few months ago, I like to engage clutch in neutral at traffic stops, etc to reduce TOB wear. Now rattling, clunky sound. I can also create kind of a clacking whack sound if I slightly jerk the clutch in and out, loading and unloading the tranny.
I see lots of forum talk about neutral rollover, getrag typical, etc. I don't believe it mainly because it is a new sound.
I pulled the transmission to put in new clutch kit - everything looks good except significant lateral play at the end of transmission input shaft. Wacking with the heeel of my hand, I swear that is the kind of sound I was hearing. Front pilot bearing seems very good, clutch disc is a bit rattly & loose, but lots of meat on it. I don't mind changing out the clutch (I have an upgrade conversion kit - to single mass flywheel) but I sure don't want to put all of this back together to have same problem.
I suspect (hope) I just need to replace input shaft main bearing and seal, but there is also an inner race bearing (tapered?) Per the BMW parts picture I have. I can't find any proper exploded view of this tranny, I've never been inside a transmission before. Anything more than the input shaft bearings may be more than I can handle properly.
I pulled the bolts to separate the front bell housing from the main gearbox, won't separate. There's a couple of Torx head bolts and one allen head bolt that look to hold internal linkages or such, they look like they may span the separation line. - If I pull these do I drop stuff inside and get into a real jam?
Any help, a proper diagram for the exact xmission would be REALLY good. Getrag S5D 250G.
Also, the two bearings are like a jillion $ from dealer service dept, they only have uncertain stock in GERMANY, & they are just common bearings - if I knew cross ref or something.
Oh yeah, the output shaft seems real tight, no end play or lateral play.
Everything is dry at both seals and within clutch compartment.
And I'm high & dry with my roadster up on blocks in my driveway! The family heirloom 71 Cutlass (don't look or sound like when my grandad bought it!) Is pressed into service as daily driver (and that's not good).
Dave

pos - I was quoted
input shaft seal - $44, input shaft main bearing $105, input shaft roller bearing $14 (same & more for output shaft items). Holy smokes! Save me money on this adventure & you bet I'll donate!
Avatar
Z3dave
September 5, 2010.




There is a Tech bulletin about missing locating dowels, it is as follows: ENGINE, TRANSMISSION, OR CLUTCH RELATED COMPLAINTS TECHNICAL SERVICE BULLETIN Reference Number(s): SI B 11 04 06, Date of Issue: June 7, 2006 Related Ref Number(s): 11 04 06 ARTICLE BEGINNING SUBJECT Engine, Transmission, or Clutch Related Complaints SITUATION Various complaints concerning the engine, transmission, clutch, or noise characteristics of the vehicle have been traced to the absence or damage of the alignment dowels between the engine and transmission. In many cases the dowels required to center the engine/transmission were not fitted, or were damaged, during a previous repair in which the engine and transmission were separated. If the alignment of the engine flywheel to the transmission input shaft, or torque converter, is incorrect any of the following complaints may result: 1. Clutch complaints: slipping, shudder, or poor disengagement. 2. Noise from transmission input shaft. 3. Transmission pops out of gear. 4. Difficulty changing gears. 5. Internal damage to an automatic transmission. PROCEDURE When performing any repair, which involves separating the engine and transmission, always check that the dowels are undamaged and properly in place before reassembly. WARRANTY INFORMATION Information only. Any damage as a result of missing or damaged dowels is not a warranty matter. BMW: All GROUP: Engine IMPORTANT: For engines with a magnesium crankcase only aluminum dowels may be used. Always refer to ETK for the correct dowels for the engine and model concerned.

Merlin2021
Sep 5, 2010.
The possibility of internal transmission issues seems to be highly likely. There are sources in the BMW car club monthly magazine that can inspect/repair the transmission, have you considered them? Another possibility you may wish to consider is a transmission from a salvage yard. Autobahn dismantling in El Cajon is one I can recommend (619)444-2290 Here is a link to an exploded view: http://www.realoem.com/bmw/partgrp.do?model=CH73&mospid=48091&hg=23&fg=15

Dr. Hagerty
Sep 5, 2010.
Just keeping the wrench warm for you doc.

Merlin2021
Sep 5, 2010.
No worries Merlin, thanks for taking it on.

Dr. Hagerty
Sep 5, 2010.
OK you two... thanks to both for your quick replies.
The locator dowels are in place and fine. Tech bulletin likely not applicable in this case.
Doc, I believe the noise is internal tranny. I am concerned with the lateral play on the unsupported input shaft (when removed from pilot bearing).
See photo, is this reasonable play?


http://www.2carpros.com/forum/automotive_pictures/569400_96_Z3_Getrag_input_shaft_lateral_play_2.jpg


The output shaft is tight, no lateral or end play, seems good.
All clutch and transmission functions were good except for the chatter & clacking in neutral with clutch engaged, as well as the slap clack sound with rapid loading and unloading tranny. (I could make this happen consistently in first gear, slow speed, and throttle & clutch play to rapidly change the tranny from loaded to unloaded to loaded.) Sure sounded like the same kind of sound I can make slapping the free end of the input shaft.
The link to diagrams is very helpful, looks like I will be releasing some linkage in separating the front and rear housings. See photo, I am guessing these need to be disconnected to separate.


http://www.2carpros.com/forum/automotive_pictures/569400_96_Z3_Getrag_separation_bolts_sml_mrkup1_1.jpg

.
I do have a great mechanic available next week for back-up, but if I never take on a tranny I'll never learn.
Any additional pointers would be appreciated.
I'll post results also.
Dave

Tiny
Z3dave
Sep 6, 2010.
You are quite possibly chasing a noise generated from the single mass flywheel. The reason BMW uses a dual mass flywheel is for noise suppression in the gearbox. I am sure I did not realize this fact in your initial post and I apologize for sending a false or misleading statement.
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Dr. Hagerty
Sep 6, 2010.
Interesting comment.
The existing dual mass flywheel has max 5 deg of " easy" rotation, no apparent lateral or in-line play. Disc-mating surface is flat and clean.

Nb The new Beck/Arnley kit I have is called an " upgrade" as it contains a single mass flywheel and a spring-mounted friction disc.

For now, may I ask for one last opinion that hasn't been answered? I am still concerned about the lateral play on the input shaft - is the amount of play reasonable?

The shaft has 2 bearings inside the tranny case, shouldn't the free end be solid as a rock? I seems to me that the pilot bearing is not intended to pick up slack.

Tiny
Z3dave
Sep 6, 2010.
The input shaft depends on the pilot bearing to hold it in position, the movement of the input shaft when compared to other transmissions is normal, or as we used to tell em, " They all do that"

Dr. Hagerty
Sep 6, 2010.

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