Clutch or Transmission Issue?

Hey guys, I can't tell if my symptoms are due to a transmission issue or a clutch issue. Here's what I got on my 93K Mile 325i Manual:



With the engine off, gear lever easily slips into each gear.

With the engine on, the first time I shift into 1st or 2nd gear, after depressing the clutch, the gear lever "snags". It's hard to put it in gear. However, with the clutch still depressed, I will go back to neutral, and then throw it into 1st or second again. This time, it will easily slip in and out of gear. The "snagging" is always felt right after I depress the clutch and only in 1st, 2nd, and 3rd.

I can replicate the feeling on command stopped at a stoplight. From neutral, depress the clutch, try to shift into 1st. It will snag. With clutch still depressed, try again. It will shift smoothly.

This problem is also made worse when I try to shift quickly from 1st to 2nd. However, when the car is not in motion, It doesn't really matter how soon after first depressing the clutch, the first time I try for a gear after depressing the clutch for the first time, it will almost always snag. Happens to me about 80% of the time. I also sometimes hear a faint, fading knocking noise "Knock knock knock" after the gear engages post-snag. Again, after a 2nd or 3rd try, it will be fine.


Now the question is, could this be an issue with my clutch hydraulics making it slow to engage? Air bubbles in the system?

Appreciate any help on this.

Originally Posted by raymoon

Hey guys, I can't tell if my symptoms are due to a transmission issue or a clutch issue. Here's what I got on my 93K Mile 325i Manual:



With the engine off, gear lever easily slips into each gear.

With the engine on, the first time I shift into 1st or 2nd gear, after depressing the clutch, the gear lever "snags". It's hard to put it in gear. However, with the clutch still depressed, I will go back to neutral, and then throw it into 1st or second again. This time, it will easily slip in and out of gear. The "snagging" is always felt right after I depress the clutch and only in 1st, 2nd, and 3rd.

I can replicate the feeling on command stopped at a stoplight. From neutral, depress the clutch, try to shift into 1st. It will snag. With clutch still depressed, try again. It will shift smoothly.

This problem is also made worse when I try to shift quickly. The fast I try to shift into gear after the clutch is depressed, the harder it will be. The slower/longer I wait after the clutch is depressed, the easier it seems.



Now the question is, could this be an issue with my clutch hydraulics making it slow to engage? Air bubbles in the system?

Appreciate any help on this.

It does sound as though your clutch isn't fully disengaging which could be causing the snagging. A couple of things might cause this. If you have a hydraulic clutch release then start with bleeding the clutch hydraulics. Maybe cylinder piston seals need replacing. That would lead to hydraulic pressure. If cable type then maybe an adjustment or replacement. Those are the best case scenarios. Next is the actual clutch assembly. Sometimes the rear crankshaft seal can leak and oil can get on clutch plate. The heat can cause the oil to burn and get sticky causing difficulty disengaging. Another possible cause might be cracked clutch diaphragm. If this is the case then a replacement clutch assembly is required and change the rear crankshaft oil seal while you have it exposed. You don't mention clutch judder. I would expect clutch judder with the latter. So I would start from the pedal and check hydraulics or cable. I don't think its your gearbox.

Originally Posted by RayPooley

It does sound as though your clutch isn't fully disengaging which could be causing the snagging. A couple of things might cause this. If you have a hydraulic clutch release then start with bleeding the clutch hydraulics. Maybe cylinder piston seals need replacing. That would lead to hydraulic pressure. If cable type then maybe an adjustment or replacement. Those are the best case scenarios. Next is the actual clutch assembly. Sometimes the rear crankshaft seal can leak and oil can get on clutch plate. The heat can cause the oil to burn and get sticky causing difficulty disengaging. Another possible cause might be cracked clutch diaphragm. If this is the case then a replacement clutch assembly is required and change the rear crankshaft oil seal while you have it exposed. You don't mention clutch judder. I would expect clutch judder with the latter. So I would start from the pedal and check hydraulics or cable. I don't think its your gearbox.

I believe our cars are hydraulic. I also believe the clutch and brake system share the same resevoir/system, so a spongy/weak clutch should be accompanied by a spongy/weak brake? My brake pedal is great, no sponginess at all. Therefore, the system probably doesn't have air bubbles.

Would the only way to check the clutch cylinder piston seals is to actually take it out and inspect it?

If there is burnt oil on my clutch plate, what's the solution for this?

No I do not have any clutch judder, clutch pedal movement is smooth and I've never felt any vibrations/judders from it. *crossing my fingers*



Also, I have to ask. What could actually be snagged? If the clutch wasn't fully disengaged, wouldn't the gear grind when I try to throw it in? This isn't happening.

Only happens with first gear.
Sometimes gotta clutch in twice to get it into first from neutral.
Happens when the car is facing up hill a bit.

Originally Posted by MercForHire

Only happens with first gear.
Sometimes gotta clutch in twice to get it into first from neutral.
Happens when the car is facing up hill a bit.

Happens to me about 80% of the time when shifting from 1st to 2nd. This is the worst symptom. Ruins the whole rythym of the shift. I also sometimes hear a faint fading knocking noise after the gear engages post-snag. "Knock knock knock"

Originally Posted by raymoon

I believe our cars are hydraulic. I also believe the clutch and brake system share the same resevoir/system, so a spongy/weak clutch should be accompanied by a spongy/weak brake? My brake pedal is great, no sponginess at all. Therefore, the system probably doesn't have air bubbles.

Would the only way to check the clutch cylinder piston seals is to actually take it out and inspect it?

If there is burnt oil on my clutch plate, what's the solution for this?

No I do not have any clutch judder, clutch pedal movement is smooth and I've never felt any vibrations/judders from it. *crossing my fingers*



Also, I have to ask. What could actually be snagged? If the clutch wasn't fully disengaged, wouldn't the gear grind when I try to throw it in? This isn't happening.

They may share the same reservoir but the clutch and braking circuits are independant. They have to be otherwise if you pressed the clutch in the brakes would activate and vice versa and you wouldn't want that. So it is feasible to have spongy clutch hydraulics caused by leaky slave cyliner or master cylinder seals without experiencing brake haydraulic issues.

If there is burnt oil on clutch plate the only solution is to replace the clutch assembly including the pressure plate because that will have become contaminated as well. You would also chnage teh rear crankshaft oil seal while you were in there. It takes a bit of effort to get to (removing transmission etc) so you are advised to repace as much as you can at the time.

The snagging is due to the synchromesh gears not the main gears.

Another thought has just occured to me. There is a mechanical linkage system between the bottom of the gear stick and the shift lever input shaft of the gearbox. If that linkage is worn, loose or maladjusted this could also cause your snagging problem because of lost movement between the gear lever and the box. So check that out as well.

If you are not experiencing judder it would suggest there is no issue with the clutch assembly so that's a positive.

So, check gear shift/gearbox shaft linkage and clutch hydraulics in that order.

Just read my manual and there is a bearing at the bottom of the gear selector which can be replaced if worn. Which does, of course, suggest that wear can occur. Any such wear might cause shifting issues.

I have the same problem, but has recently grown to include all gears when first selecting from rest, but slip in smooth when rolling/moving. Last week I had my gearbox oil checked along with the clutch hydraulics, all is perfect. I have slight wear at the nylon ball joint on the vertical gear lever stick, but this would case problems all the time, not just when the car is at rest. I think if the was a physical problem with the clutch then it would happen regardless of the car being at rest or in motion as the system of disengaging the gearbox from the engine is the same on both situations. Try bliping the throttle to rock the engine and going for the gear at the same time. I have a sneaky suspicion it is worn / knackered engine mounts that is throwing the whole engine & gearbox assembly out of alignment with the selector rods enough to case the problem. Perhaps trying gear selection from rest on left & right side slopes and also nose down and nose up on a hill would shift the weight of the engine & gearbox about on the worn mounts and see if gear selection improves or not. BTW my car has 81k miles on the clock.

Originally Posted by RayPooley

Just read my manual and there is a bearing at the bottom of the gear selector which can be replaced if worn. Which does, of course, suggest that wear can occur. Any such wear might cause shifting issues.

Do you have the Bentley Manual? What page are you refering to if you are. I thought that there is a white plastic bushing at the bottom of the gear lever which can be worn. However, I took it to a dealership (while replacing the recalled taillight ground wires) and mentioned the issue to the head floorman. I said I thought maybe my bushing at the bottom is worn. He took the gearlever with both hands and tested for lateral movement (as opposed to angular movement (off the pivot point). He concluded that the bearing is fine as there wasn't too much play. He didn't have time to test drive it though.

Is there an actual bearing deeper in there?

Sounds like the synchros?

Originally Posted by WheyArea

Sounds like the synchros?

What exactly do you mean by this. Synchros are just the rings that touch before the gear teeth actually engage correct? I assume synchros can be worn when the speeds of the gear and the collar are constantly at very different speeds requiring the rings to use a lot more friction in order to snychronize the 2 before they engage. When they're worn, they don't match up with one another and therefore dont produce the same amount of friction, so therefore take longer/don't synchronize the 2 anymore. Tell me if this is correct I'm just using my logic here.

If the synchros are worn/done. The only way to fix this issue would be a tranny rebuild?





A bit of a tangent, but I also don't completely understand double clutching. Double clutch up-shifts: depress clutch, shift into neutral, release clutch. depress clutch, rev to match, shift to gear, release clutch. But how long is the gap between releasing the clutch and redepressing the clutch? Almost instantaneous? And how is this exactly different than just depressing the clutch shifting to neutral, letting the engine revs fall to the proper speed of the next gear before moving the gear lever, and then selecting the gear, then releasing the clutch. Not sure I understand the logic behind releasing the clutch and then depressing it again to choose a gear. If the clutch is depressed the engine should be disengaged from the gearbox. Gotta be something I'm not understanding here.

Originally Posted by raymoon

Do you have the Bentley Manual? What page are you refering to if you are. I thought that there is a white plastic bushing at the bottom of the gear lever which can be worn. However, I took it to a dealership (while replacing the recalled taillight ground wires) and mentioned the issue to the head floorman. I said I thought maybe my bushing at the bottom is worn. He took the gearlever with both hands and tested for lateral movement (as opposed to angular movement (off the pivot point). He concluded that the bearing is fine as there wasn't too much play. He didn't have time to test drive it though.

Is there an actual bearing deeper in there?

No. It is a bush bearing. (bearings come without balls or rollers). If the guy tested it then I guess its fine.

I had the similar problem a couple months ago. I would be at a stop light and tranny wouldn't go into 1st. I would have to go 1st> Neutral> 1st. I changed the clutch and flywheel (the car was due anyway) and even then, I still had the problem. It wasn't often, but at least once a day. After speaking to a mech he mentioned the teeth may not be lining up correctly, so I was basically having to reset it by going into neutral.

Long story short, my car got totaled and I never figured out what it was. I just suggested it because it was the last hypothesis I had before losing my baby

The purpose of the synchros is to increase the rotational speed of the target output gear, through contact between the target gear and the synchro, to synchronize the target gear rpm and the collar so that they are turning at the same rpm when they mesh. If the gear box gears are still under load because of a partially or fully engaged clutch then this is difficult to accomplish and you get what you call snagging.

Highly unlike that all the synchos have shot craps at the same time. There are various bushings in the shifter that can eventually wear enough that it makes shifting more and more difficult. It's a VERY subjective question, but how sloppy is your shifter?

Originally Posted by snaponbob

Highly unlike that all the synchos have shot craps at the same time. There are various bushings in the shifter that can eventually wear enough that it makes shifting more and more difficult. It's a VERY subjective question, but how sloppy is your shifter?

What do you mean by have shot craps at the same time? The answer to how sloppy my shifter is also subjective because this is my first manual transmission car. Are you asking how much play is there in the gear lever (When engaged in car? When in neutral?)

Originally Posted by RayPooley

The purpose of the synchros is to increase the rotational speed of the target output gear, through contact between the target gear and the synchro, to synchronize the target gear rpm and the collar so that they are turning at the same rpm when they mesh. If the gear box gears are still under load because of a partially or fully engaged clutch then this is difficult to accomplish and you get what you call snagging.

That makes sense. Is there a way to test if my clutch is fully engaging or not?

Originally Posted by WheyArea

I had the similar problem a couple months ago. I would be at a stop light and tranny wouldn't go into 1st. I would have to go 1st> Neutral> 1st. I changed the clutch and flywheel (the car was due anyway) and even then, I still had the problem. It wasn't often, but at least once a day. After speaking to a mech he mentioned the teeth may not be lining up correctly, so I was basically having to reset it by going into neutral.

Long story short, my car got totaled and I never figured out what it was. I just suggested it because it was the last hypothesis I had before losing my baby

That is a huge bummer.... . The fact that your car got totalled...and the fact that you never figured out the problem...

Have you inspected your Clutch Slave Cylinder (mounted at the bottom of the bell housing) Left side of the car.
This is the easiest place to start, assuming you have fluid in your brake reservoir, as the clutch hydraulics share this with the brakes.

Ranging from easiest/cheapest
Low fluid
Air Bubbles (maybe a simple bleed)
Slave cylinder (maybe seals have gone bad, but the fact that you can create the symptoms on demand...not so sure)

Drop trans:
Shifter assembly pin can break or become dislodged causing the shift release fork to not line up with throwout. (not common, but happened to me.)
Throwout Bearing
Pilot Bearing
etc..

Originally Posted by raymoon

What do you mean by have shot craps at the same time? The answer to how sloppy my shifter is also subjective because this is my first manual transmission car. Are you asking how much play is there in the gear lever (When engaged in car? When in neutral?)

"Shot craps" = failed. Others have suggested hydraulic issues, and that is certainly the first place to check. At 93K, one would not expect a worn out clutch, but if previous owners slipped it a lot, it could very well be worn out. Does it slip at ALL under load?