Help diagnosing 1st gear issue

[pitkin_g]

Hi All,

Car - 2011 BWM E92 M3, Manual.

I have purchased the car with the following issue:

1st gear issue only

-Engine off
---All gears are engaging - no issues
-Engine on - stationary
---Neutral —> 1st gear —> GRIND/not engaged
---Neutral —> 2nd or 3rd or any other gear —> 1st gear —> engage OK
-Engine on - moving
---Downshift to 1st gear —> GRIND/not engaged

I have changed the clutch/flywheel, pivot fork/pin, TOB, full shifter refresh. Previous owner stated that master cyl and slave cyl have been changed and clutch is bled.

Any advice to what it can be outside of a transmission/syncro issue?

Thanks

[MineralWhiteF80]

Do you know why the previous owner changed the clutch master/slave cylinders? That seems odd since these aren't parts that fail very often. Also, they can be a pain to bleed CORRECTLY and most people think they bled it right but didnt.

Assuming that your clutch hydraulic system is properly bled and all of the other parts are installed correctly:

What type of transmission fluid do you have and how old is it? How many miles on the transmission itself?

If you have miles on the car and the transmission fluid is fresh, AND you have changed the fluid filter in the transmission, then you may be looking at a possible syncro problem.

Syncro problems aren't uncommon in these cars. I bought an m3 brand new and it suffered 2nd gear syncro problems in the first two thousand miles. BMW engineer, a technican, and foreman all confirmed it wasnt ME who was the problem. BMW put a transmission in the car under warranty, and the new transmission had a grind going into first gear on the TEST DRIVE after replacement driven by the technician (who also had multiple m3s) they put a third transmission in it and it worked mostly fine for 43k miles I had the car.

[pitkin_g]

No info on the reasoning from previous owner. I am thinking troubleshooting the same issue.

Fresh transmission fluid that I filled while installing the clutch. I believe I used - MTL Manual Transmission Fluid 75w80 or 75w90. I have not changed the fluid filter.

Car and transmission have 120K.

Originally Posted by MineralWhiteF80

Do you know why the previous owner changed the clutch master/slave cylinders? That seems odd since these aren't parts that fail very often. Also, they can be a pain to bleed CORRECTLY and most people think they bled it right but didnt.

Assuming that your clutch hydraulic system is properly bled and all of the other parts are installed correctly:

What type of transmission fluid do you have and how old is it? How many miles on the transmission itself?

If you have miles on the car and the transmission fluid is fresh, AND you have changed the fluid filter in the transmission, then you may be looking at a possible syncro problem.

Syncro problems aren't uncommon in these cars. I bought an m3 brand new and it suffered 2nd gear syncro problems in the first two thousand miles. BMW engineer, a technican, and foreman all confirmed it wasnt ME who was the problem. BMW put a transmission in the car under warranty, and the new transmission had a grind going into first gear on the TEST DRIVE after replacement driven by the technician (who also had multiple m3s) they put a third transmission in it and it worked mostly fine for 43k miles I had the car.

[Ajolives]

Just curious, if you start the car in first gear (clutch engaged), can you get out of first and into second while stationary/driving or does it grind both ways?

[pitkin_g]

Originally Posted by Ajolives

Just curious, if you start the car in first gear (clutch engaged), can you get out of first and into second while stationary/driving or does it grind both ways?

I can easily get out of 1st and engage 2nd in this situation

[RocketyMan]

This sounds like your 1st gear synchro is bad. From your previous posts, it sounds like it can shift into any of the other gears just fine, yeah?

The Redline MTL is good stuff as it won't hurt any "yellow metals" in the trans. As mentioned above, you could try some ATF in the trans to see if the synchros can grip better.

But from experience, 1st gear should really only be engaged at like 5 mph or lower. When stationary, it can be a challenge to align the "dogs" on the slider. So usually what I do is just put pressure on 3rd or 2nd (without actually shifting into that gear) to help slow down the countershaft, then it slips right into 1st easy. Just a food for thought...

[pitkin_g]

Yes, all other gears are engaging perfectly fine. Interesting thought on ATF, i wasnt aware of that.

I can try your theory tomorrow about putting pressure on another gear before engaging 1st. Ill see if that works.

Thanks

Originally Posted by RocketyMan

This sounds like your 1st gear synchro is bad. From your previous posts, it sounds like it can shift into any of the other gears just fine, yeah?

The Redline MTL is good stuff as it won't hurt any "yellow metals" in the trans. As mentioned above, you could try some ATF in the trans to see if the synchros can grip better.

But from experience, 1st gear should really only be engaged at like 5 mph or lower. When stationary, it can be a challenge to align the "dogs" on the slider. So usually what I do is just put pressure on 3rd or 2nd (without actually shifting into that gear) to help slow down the countershaft, then it slips right into 1st easy. Just a food for thought...

[amrazM]

transmission is no good, no fix here other than a new gearbox. never seen one lose first but then again there are alot of people that shove the transmission back into 1st at 25mph.

[RocketyMan]

Originally Posted by pitkin_g

Yes, all other gears are engaging perfectly fine. Interesting thought on ATF, i wasnt aware of that.

I can try your theory tomorrow about putting pressure on another gear before engaging 1st. Ill see if that works.

Thanks

Another thing I just thought of when dealing with changing the oil in the trans, there is an oil pump that needs to be constantly ran in order to properly fill the trans. If not, you end up being nearly half a quart short of oil. I'm not sure how bad this would affect the trans being half a quart low.

Did you make sure to run the oil pump when filling?

https://www.m3post.com/forums/showpo...85&postcount=1

[pitkin_g]

That I have missed completely. Never had to do this on any other car. I will look into that. Overall issue existed though prior of me draining it in the first place so I doubt it is the culprit.

Originally Posted by RocketyMan

Another thing I just thought of when dealing with changing the oil in the trans, there is an oil pump that needs to be constantly ran in order to properly fill the trans. If not, you end up being nearly half a quart short of oil. I'm not sure how bad this would affect the trans being half a quart low.

Did you make sure to run the oil pump when filling?

https://www.m3post.com/forums/showpo...85&postcount=1

[RocketyMan]

Possibly very true. But might be worth a shot. Otherwise the synchro could just be done.

[Ervin87]

You have an internal transmission problem with the syncro. This is very common with inexperienced manual drivers, thinking these transmissions are built for drag racing where they can just beat on it.

[pitkin_g]

Thank you all for the input. I was able to find a used transmission supposedly in good working condition. I guess it is always a gamble buying a used transmission without an actual test drive while still in the car. I will report after the install.

[pitkin_g]

Finally, new used transmission is installed. It feels good to have 1st gear back. Performed proper oil pump activation to drain and refill (manual activation - ISTA did not work). All seems good after few hundred miles. So the verdict is confirmed - bad transmission overall.

[RocketyMan]

Originally Posted by pitkin_g

Finally, new used transmission is installed. It feels good to have 1st gear back. Performed proper oil pump activation to drain and refill (manual activation - ISTA did not work). All seems good after few hundred miles. SO the verdict is confirmed - bad transmission overall.

I had to do a manual pump activation on mine as well. Before I got the pump to work using ISTA. Now, i'm just not sure what changed.

Anyway, thanks for reporting back!