kicking out of first

Hi everyone I have what I think is a problem on a 5 speed '90 535i.
On occassion when I start off after being stopped there is a loud bang and the shifter is thrown out of first. This happens as I am letting
the clutch out.
If I give sufficient throttle and let the clutch out quickly it doesn't happen.
Is this normal?
Thanks
Michael Thanks
Michael
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No. It doesn't sound normal at all.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sounds like a synchronizer going out allowing it to slip out of gear.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
waffled on about something:

Hmmm
IIRC the synchronizer or synchromesh purely aligns the teeth to allow a smooth transition. Once the drive gear is engaged it plays no further part until the next gear change.
If the synchromesh is worn, you'll get a grinding gear change from teeth not messing as you try to select a new gear.
Jumping out of gear under load either means you've been grinding too many teeth and have now damaged the gears, or your selector fork/linkage has become damaged and isn't pushing the drive gear fully into place.
Dodgy.
--
MUSHROOMS ARE THE OPIATE OF THE MOOSES

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In a synchro transmission all of the gears are ALWAYS in mesh so there is never any opportunity to 'grind the gears'. The gears that are not engaged are however free to turn on their respective shafts and so are unable to transmit power. The way a gear is engaged is to slide a splined coupling into the gear. This coupling is always splined to the shaft and is splined to the gear when it is engaged thereby making it possible to transmit power. The spline teeth that engage the gear have two sections to them; a tapered section that aligns the spline teeth as it engages and a parallel section to transmit the torque after it is engaged. When you 'miss a gear' it is the tapered section that tosses you out of the gear that you didn't quite get. If the gearbox is abused by numerous instances of releasing the clutch before the splined coupling is all the way home, the engagement teeth can become worn and the parallel section becomes tapered thus tossing you out of the gear even though the coupling is all the way engaged. There is no cure short of replacing the sychros so it is probably time to start shopping for a used gearbox. This kind of damage is often caused by a leaking clutch master or slave cylinder that releases the clutch prematurely even though you haven't taken your foot off the pedal so it would be a good idea to check that before replacing the box.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jack wrote:

Here's a better (and more acurate) description: http://www.singster.co.uk/mascot%20mar-apr%202003%20 (4).html
The key is in the "cone clutch"
--
-Fred W

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 23 Nov 2005 08:50:48 -0500, Malt_Hound

Yeah, I'm guilty of spending far too much time inside motorcycle gearboxes, hence me almost stumbling into saying selector fork!
Dodgy.
--
MUSHROOMS ARE THE OPIATE OF THE MOOSES

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dodgy wrote:

Yeah. I think you are right. A worn syncro would not cause it to pop out. Moist likely it's not going all the way in due to misaligned shifter / linkage
--
-Fred W

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I agree. If the synch rings are the fault, then muchmore wear has happened that is causing this problem. The synch rings shouldn't play any role in keeping the gears engagde. If the gears are slipping apart, then they have been abused to the point that they need to be replaced. The synch rings could be seriously worn at this point as well, but that isn't why the gears slip apart.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I would make sure your shift linkage bushings are in good shape. ZIf they have worn you might not be fully engaging the gear.
Blake
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.