# 325i Manual Transmission Shudder when downshifting



## 2001E46 (Nov 12, 2002)

I've got a 2001 325i with the 5-speed manual transmission. Ever since the day I got it I've experienced a very uncomfortable shudder in the transmission when downshifting. It only happens when I downshift at low rpms without rev-matching with the throttle. 

It's most noticeable when I'm slowing down for a turn in local driving. Say I'm in third gear and gently slowing down to make a right turn at around 15mph. When the rpms drop to about 1200 I take it out of third and put it into second. As I gently let off the clutch in second, right at the point where it engages, the entire car shudders and makes a really low booming sound. The entire car vibrates for about 1/2 a second and then it goes away. I can make the shudder last a little longer if I let off the clutch slower, but I can never make this transition without the shudder. 

I took the car in to the dealer and they took it for a test drive. The tech said that he didn't notice anything out of the ordinary. He then went on to tell me that BMW's have a spring-loaded flywheel and that they were designed to "give" a little when shifting to smooth out the transitions. 

Is this normal? Do other E46 325i's shift this way too? I've never driven another one so I don't know. 

Please help!


----------



## The HACK (Dec 19, 2001)

2001E46 said:


> *...snip...The tech said that he didn't notice anything out of the ordinary. He then went on to tell me that BMW's have a spring-loaded flywheel and that they were designed to "give" a little when shifting to smooth out the transitions.
> *


Your tech is right. Modern BMWs are equipped with dual mass flywheels that is suppose to help the engagement of the clutch...They've got these "springs" inbetween different part of the clutch that, once engaged, will cause the "shudder" you described instead of a full on STALL. Make sure you rev-match when down shifting to eliminate this annoying "shudder".


----------



## Alan(iX) (Apr 29, 2002)

*E46 Clutch Check Valve*

The E46 has an additional check valve in its hydraulic system.
Could be contributing to what you are feeling.

Here is how to remove it:

http://www.uucmotorwerks.com/html_techtip/techtips/check_valve.htm

Alan Alfano
88 325iX


----------



## PunchIt (Dec 24, 2002)

*Re: E46 Clutch Check Valve*



Alan(iX) said:


> *The E46 has an additional check valve in its hydraulic system.
> Could be contributing to what you are feeling.
> 
> Here is how to remove it:
> ...


No offense, but I don't think that is what he is feeling.

I think we have a 5spd driver who thinks he is in an automatic. If you are getting the RPMs down to 1200, you should just put the clutch in and let it roll to the stop sign or light or whatever.

If you are slowing down to take a turn, YES rev match so you can accelerate out of the turn and not hold people up behind you...I can't imagine you are moving to fast if you are doing 1200RPM in 3rd gear. banghead:

just my $.02

DM:


----------



## ezzthetic (Aug 24, 2002)

Over the last few days I am getting the same issue but it is not on downshift. It is happening in first gear only. I thought at first that due to this being my first BWW and only owning it a few months now, that the difference in the clutch and driver error were the issue. But it has only been over the last week that I have noticed it. I am heading into the dealer for something else on Friday so I asked them to take a look...

My symtoms are:
When in first, I get a slight shudder that is short but mostly felt in the clutch and the shifter. Again, it is only in first gear and I don't notice it any other time than take off. I am sure that this will be another issue that the dealer can't repeat when I get out there so... Anything else I can do to have them look at it outside of driving it?


----------



## PunchIt (Dec 24, 2002)

ezzthetic said:


> *
> 
> My symtoms are:
> When in first, I get a slight shudder that is short but mostly felt in the clutch and the shifter. Again, it is only in first gear and I don't notice it any other time than take off. I am sure that this will be another issue that the dealer can't repeat when I get out there so... Anything else I can do to have them look at it outside of driving it? *


When do you get this? When you first start driving from a start? When the car is cold?

I know that my car, and I think I have heard this echoed on the board, is harder to shift smoothly when cold. The clutch, engine, and tranny have to "warm up" to proper operating temp before they stop acting grumpy.

DM


----------



## PunchIt (Dec 24, 2002)

Daniel said:


> *
> 
> When do you get this? When you first start driving from a start?
> DM *


Sorry, I meant a stop.


----------



## ride365 (Dec 19, 2001)

*Re: Re: E46 Clutch Check Valve*



Daniel said:


> *I think we have a 5spd driver who thinks he is in an automatic. If you are getting the RPMs down to 1200, you should just put the clutch in and let it roll to the stop sign or light or whatever.
> *


yeah 1200 rpm is really low. isn't idle 1250 rpm? {or am i thinking of my motorcycle?)

try making your downshifts sooner-- higher rpm-- and see if the problem still exists.


----------



## ezzthetic (Aug 24, 2002)

Daniel said:


> *
> 
> When do you get this? When you first start driving from a start? When the car is cold?
> 
> ...


Yea, it usually is worst when it is cold BUT I do notice it after driving and that the engine has warmed up. At least that is what the guages are reading... But then again, it only started recently and it has only been cold recently. Again, as I said, I have only owned it for about four months. Still getting used to it.

Thanks Daniel.


----------



## Nick325xiT 5spd (Dec 24, 2001)

*Re: E46 Clutch Check Valve*



Alan(iX) said:


> *The E46 has an additional check valve in its hydraulic system.
> Could be contributing to what you are feeling.
> 
> Here is how to remove it:
> ...


Search for my posts on the CDV, the UUC article is out of date. Currently, some 323 and 328 cars had the CDV, and all xis do. The RWD 325 and 330 do not have a CDV, unless it is integrated into the slave cylinder.

Additionally, this does not in any waqy sound like a CDV issue.

I have two possible suggestions:
One has been covered: Rev match.
The other is: Change the transmission fluid to Redline D4 ATF. If nothing else, it will give you much better shifting and better synchro response. The people at BMW who claim the original oil lasts forever are at the very least allowing for a pretty substantial amount of breakdown and contamination.


----------



## Plaz (Dec 19, 2001)

*Re: Re: Re: E46 Clutch Check Valve*



ride365 said:


> *
> 
> yeah 1200 rpm is really low. isn't idle 1250 rpm? *


My 330 idles at about 750rpm.


----------



## PunchIt (Dec 24, 2002)

*I MAY HAVE BEEN WRONG*



Daniel said:


> *
> 
> No offense, but I don't think that is what he is feeling.
> 
> ...


I might have been wrong :dunno:

Ok, I tried driving in 3rd gear (slowing down from 40mph) and found that once I hit 1200rpm there was NO shudder. The car wasn't moving too fast, but I didn't find the shudder that I expected (similar to the car about to stall shudder)

So, it could be that I was wrong in suggesting that the original poster thought he was driving an automatic, OR that my 330 just has more torque than the 325, and that is why I didn't get the shudder.:angel:


----------



## Mystikal (Dec 20, 2001)

The shudder is here too. Seems normal.


----------



## 2001E46 (Nov 12, 2002)

I wonder if this is the case with all 325 Manuals... 

I used to drive a Honda with a manual transmission and I could downshift and drop it into gear without any vibration. Now it might complain if I dropped it too hard at too high an RPM by screeching the tires, but the transmission never felt like it was going to break...


----------



## brave1heart (Jan 7, 2002)

No shudder in my '01 325i, although I almost always match the revs. BTW, idle is ~ 650-700 RPM's in my car.


----------



## Mystikal (Dec 20, 2001)

yeah, the shudder is only when you force the clutch to raise the revs. I kinda like the light, low-pitched shudder/burble is produces. :eeps:


----------

