# Manual Trans - Diagnostic Tips



## BMW_tech (Sep 20, 2007)

A transmission which is difficult to shift (_especially into first gear_) is primarily a clutch related problem and only in isolated cases a failure in the transmission itself. The following diagnostic tips will assist in troubleshooting a clutch, gear shift linkage or transmission problem :

*IMPORTANT* :

*Engage the parking brake and assure that no people or objects are in the vehicle's path*.

1) Run the engine at idle speed.
2) Press the clutch pedal to the floor.
3) From the neutral stick shift position engage first gear.

If first gear is difficult to engage, hold the stick shift at the resistance point (_approximately half of the total stick shift travel_) with constant force. * Then switch the ignition off with the other hand*.

*Diagnosis 1*:

If first gear now engages completely, there is a problem in the clutch system.

_Example_ : The stick shift moves to the end position without any additional pressure applied.

_Explanation_:Because the clutch does not uncouple completely, a residual torque is transmitted to the transmission input shaft when the engine is running. This inhibits the release and meshing of the sliding sleeve, in the transmission, at the end of the synchronization process. Turning the engine offrelieves the input shaft of this torque thus simulating a completely uncoupled clutch.

Possible causes for a clutch problem as per Diagnosis 1 above :

A) Input shaft taper splines not lubricated properly / grease dried out.
B) Clutch disc difficult to move on transmission input shaft.
C) Clutch disc wobble.
D) Air in the hydraulic system of clutch mechanism.
E) Release bearing defective or difficult to move on the guide sleeve.
F) Clutch disc or pressure plate broken / worn out.

*Diagnosis 2*:

If the stick shift remains at the resistance point, there is a problem in the external gear shift linkage or in the transmission.

*Possible causes* :
A) External gearshift linkage binding (_shift rod joints stiff_).
B) Stick shift bellows boot incorrectly installed (_positioned too high or too low on the stick shift lever_).
C) Sound deadening between the outer gear shift linkage and the body incorrectly installed and/or distorted.

*Possible causes inside of the transmission*:

A) Faulty synchronization.
B) Internal gear shift linkage binding.

E36 Z3 2.8, 3.0 / E36 M Coupe, M Roadster S52, S54 / E36 M3 S50, S52 / E39 528i, 530i / E46 328i, 330i _up to 1/2003 production_ / E46 325xi, 330xi _up to 1/2003 production_ / E53 3.0i _up to 1/2003 production_ :

This concerns all models referenced above manufactured prior to 1/2003

---The Manual Shift Lever is difficult to move into and out of the 5th gear and reverse :

---The Manual Shift Lever does not automatically move from the 5th and reverse gears back to the center/neutral position.

---No Manual shift lever guidance indicating looseness of shifter

The 5th gear and reverse gear selector shaft pin is sticking *due* to a defective bushing mounted in the selector shaft bore of the transmission. 5th and reverse gear selector shaft pin bushing must be replaced separately. P/N : 23 11 7 542 726Bushing Repair Kit (2). Note that E 36 M3 has a different repair instruction than the other models mentioned above. See TIS for further details or S.I.B. 23 04 04.

E39 *540i* with S6S 420G manual transmission produced from 6/96 - 12/99
E39 *M5* with S6S 420G manual transmission produced from 9/99 - 12/99

*Increased force may be required on the shift lever to disengage 3rd gear* when shifting through the gears on 540i and M5 models equipped with six speed manual transmissions. The increased force on the shift lever needed to shift out of 3rd gear is due to slight wear in the shift rod detent ball housing, located in the transmission, which houses the detent ball. The transmission should not be replaced for this complaint, the three detent balls and springs should be replaced with new detent sleeves and springs included in repair kit P/N 23 31 7 506 947.

New detent sleeves and springs have been installed in production on all E39 540i and M5 models with manual transmission (S6S 420G) produced from January 2000 to eliminate this situation.


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## Vitacura (Jul 22, 2005)

Some great info. Thanks! :thumbup:


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## desertrat (Jun 4, 2007)

Vitacura said:


> Some great info. Thanks! :thumbup:


+1 :thumbup:


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## oranje335i (Apr 2, 2008)

Great info, thank you.

With all of my manual vehicles I have occasionally experienced resistance shifting into first gear and reverse. I have found that this can generally be easily resolved by keeping the clutch engaged, shifting into another gear (generally I select a notch over and shift into third), shifting back to neutral, and then trying first or reverse gear once again, all while keeping the clutch engaged. This doesn't appear to be related to any type of transmission or clutch failure, but I have been curious as to what the cause is. Can you help?

BTW, your info/knowledge is great. Wading past all of the 'What color should me car be?" posts on this site drives me nuts sometimes, so thanks for sticking around and providing useful info. If you have time, maybe you could comment on my 'Engine Oil Consumption' post from yesterday on the three series forum.


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## sprintman (Feb 22, 2008)

What a load of rubbish! Change the OEM [email protected] to a decent oil oil and all the so called 'problems' go away. Yes OEM stuff baulks at going into first and hates going into second but it's just the oil. Such an easy fix guys.


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## BMW_tech (Sep 20, 2007)

sprintman said:


> What a load of rubbish! Change the OEM [email protected] to a decent oil oil and all the so called 'problems' go away. Yes OEM stuff baulks at going into first and hates going into second but it's just the oil. Such an easy fix guys.


Now there's a guy who fixes everything with Slick 50, WD40, and Krazy or Elmer's Glue. 
Let me ask you something, when bushings and linkages are worn from a million shift lever engagement and movement. The transmission mounts deterioration from the heat and outside elements, and the material used on the clutch disc that never wears. Worn gears from spirited,normal,and daily traffic driving over the years and accumulated mileage. These possibilities can be eliminated and repaired by changing the fluid? 
What's rubbish is comments like these. Did you read the thread, next time if you didn't finish reading (or don't know how to) don't bother to post a reply. Keep it in your stomach, you'll fart it out in the bathroom and not in public like you just did. You've been eating too much kangaroo meat?


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