:: Gear slip

[Qube]

For the scant 10 years I've been driving manual, I've never had a gear slip on me. Yesterday I was driving, pushed her into first as normal... and took of gently. Yes. GENTLY. She slipped out of first into neutral violently. I could have sworn I got rear ended and she slipped out of gear. Stopped at the side and absolutely no hint of damage on the rear so verdict is it slipped.

Now, OTHER than user error, are there any precursors to this? Low fluid? Anything? I tell ya, that was a nasty experience.

[Ferret]

For the scant 10 years I've been driving manual, I've never had a gear slip on me. Yesterday I was driving, pushed her into first as normal... and took of gently. Yes. GENTLY. She slipped out of first into neutral violently. I could have sworn I got rear ended and she slipped out of gear. Stopped at the side and absolutely no hint of damage on the rear so verdict is it slipped.

Now, OTHER than user error, are there any precursors to this? Low fluid? Anything? I tell ya, that was a nasty experience.

It /is/ possible by a longshot that your gearbox is low on oil, but it would have already done damage by this point if that's the cause.

I dont mean to scare, but this is usually the first sign that your synchromeshes are on their way out... the only way to fix that is to have the gearbox rebuilt.



While I'm thinking about it, how's your clutch, is there any chance it could have bitten? That's usually caused by a crank oil leak, which causes the clutch to snatch and judder.

[filip00]

our cars are old, mine has 155k miles, and no gear slip ever, but if one happens, i won't be shocked or surprised, the cars are old, driven everyday, with a lot of hp going thru the gearbox.

i think you should be fine if it doesn't happen again ;) :D

[Qube]

Synchros seem fine in rev shift tests. HOWEVER, it has refused second before in higher rev downshifts unmatched. I'll chalk this up to a fluke unless it happens again.

Clutch is good with mid pedal engagement. That's easy as I have a full Sachs kit on standby for replacement. Now what do you mean that the clutch could have bitten?


...synchromeshes are on their way out... the only way to fix that is to have the gearbox rebuilt.

...how's your clutch, is there any chance it could have bitten? That's usually caused by a crank oil leak, which causes the clutch to snatch and judder.

[Barney Paull-Edwards]

sounds like that bloody valve in the clutch line to cushion drive line from dumped clutch starts, DELETE and drive sensibly, or not!

[Dave M]

our cars are old, mine has 155k miles, and no gear slip ever, but if one happens, i won't be shocked or surprised, the cars are old, driven everyday, with a lot of hp going thru the gearbox.

i think you should be fine if it doesn't happen again ;) :D

Yep. Every day mine shifts flawlessly is money in the bank. 525,000 km on original ZF 5-speed. Crosses fingers and knocks on wood :D.

Dave

[632 Regal]

I'll hopefully guess that you didnt push into 1st quite enough and it wont happen again. I vote fluke.

[Qube]

Oh goodie. Happened again. I wonder how slow I'm doing to need to start to avoid this now... or maybe start in second :| Once more and I'll start getting worried.

[632 Regal]

start looking into used boxes to get an idea.

Oh goodie. Happened again. I wonder how slow I'm doing to need to start to avoid this now... or maybe start in second :| Once more and I'll start getting worried.

[whiskychaser]

Oh goodie. Happened again. I wonder how slow I'm doing to need to start to avoid this now... or maybe start in second :| Once more and I'll start getting worried.

If you are tired and didnt press the clutch home fully, or there is some play in the mechanism, the gear doesnt go fully home. Result-a big thump, loads of revs and you are going nowhere. Starting in 2nd is just avoiding the issue and will damage your clutch. If your gut feeling tells you it shouldnt be jumping out of first, it probably shoudnt.

[filip00]

that's a shame.

[Ferret]

Oh goodie. Happened again. I wonder how slow I'm doing to need to start to avoid this now... or maybe start in second :| Once more and I'll start getting worried.

Uhoh, might be time to molyslip the box and try to get the synchros back up to reasonable efficiency.

Though, I'd check your clutch hydraulics first - it could be that your clutch isnt disengaging completely. If this is the case the box will appear to have gone most of the way into first and actually just be sat on the synchros. The same symptoms wouldnt appear in 2-5 because they'll mesh happily while the vehicles rolling.

[Bruno]

I have seen the same thing on a customer's E34, popping out of 1st all the time. We change the gear fluid with Redline MTL and it never happened again.

[Qube]

I have seen the same thing on a customer's E34, popping out of 1st all the time. We change the gear fluid with Redline MTL and it never happened again.

So, when am I coming by to change the fluid? Heh ;)

[Turbo Ready]

Don't use second gear to get the car rolling, not good for the engine nor clutch. Try holding the first gear in and accelerate until you shift into second and see what happens, listen for noise and note vibration if any.

There can be quite a few factors which can cause this, from a worn shift fork, a worn shifter assembly, worn synchro teeth or worn first gear teeth just to name a few of many possibilities.

I worked on a few gearboxes many years ago, I have been planning get familiar with BMW gearboxes. I have one form an e30 to pull apart now so hopefully will get working on them. I am lover of manual gearboxes and have been driving vehicles with them all my life, learned to drive on a stick shift car on my own.

[Bruno]

Didn't we flush your tranny fluid recently? Last year?
Do you remember if we replaced the fluid with ATF or MTL???

[Qube]

Didn't we flush your tranny fluid recently? Last year?
Do you remember if we replaced the fluid with ATF or MTL???

Nah. Just checked it and saw it as still good. I haven't touched it since the PO so it's now at least two years old.

[Bruno]

Let's swap it with MTL cannot hurt anything but the wallet :-) (13 Cdn / jugs x 2)

[mamilapon]

I'll hopefully guess that you didnt push into 1st quite enough and it wont happen again. I vote fluke.
I'm with Jeff on this.

[rob101]

I'm with Jeff on this.
I've done the same thing. kind of half engaged took off then smack! into neutral. Same kind of feeling Mr Qube described. Only ever did that once though:p

[Qube]

I think it's the car saying quit doing aggressive takeoffs... though I haven't done it in a long time.

"Mr Qube" Heh. Neat.

[Bruno]

Oh goodie. Happened again. I wonder how slow I'm doing to need to start to avoid this now... or maybe start in second :| Once more and I'll start getting worried.

I have a line on a used box, we still should change the fluid 1st.
Or we can install a lightweight flywheel.

[Qube]

Bah. Again. Ok. Fluid this Saturday? :)

[Bruno]

Bah. Again. Ok. Fluid this Saturday? :)

I should have some MTL at home, call me tonight to double check.

Thanks

[Qube]

Updated Fix: no more occurance since Bruno's post above... and the change to Redline.

[Ross]

Same here, I get lazy sometimes and don't engage all the way.
If you're sure it was all in then the box could be getting tired. Popping out of gear I think is indicative of worn bearings on the shafts not synchromesh.

[31Hertz]

I had the same problem in my 87 535... It turned out the slave cylinder was shot. I changed it and the hose out and flushed the fluid; all returned to normal (better than normal actually). Perhaps yours is on its way out even though the lube change has helped...

[bsell]

Oh goodie. Happened again. I wonder how slow I'm doing to need to start to avoid this now... or maybe start in second :| Once more and I'll start getting worried.

How does first feel in relation to third and fifth? Does the lever go as far forward in first as third and fifth? If not, you may have some linkage bushings going bad causing the syncro to seat half-way. Then when you give her the gas, she spits out of gear.

If the linkage is solid, you could have a worn fork causing the half-engagement. I have seen forks worn horribly by the driver resting his hand on the gear lever while driving. The constant pressure ground the fork down to next to nothing which caused partial or no gear engagement. To test this fork wear, gently rock the lever back and forth while in first, third, and fifth gears to see if there is any difference. If the first/second fork is shot, there should be more slop in first than third and fifth.

Remember folks, the gear lever is not a hand rest!;)

Brian