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Strange Gearbox Problem **Story Time**


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#1 Bozo

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Posted 28 May 2014 - 08:50 AM

I was driving back home from work last night and as I was waiting at the traffic lights with the clutch in and in first gear, I heard a slight *creak*.

I thought that perhaps a bird landed on my roof...

The lights turned green and I resumed driving. The vehicle felt odd almost as if it were rolling on it's own even with the clutch in.

I changed from first gear to second and it was ok, but the vehicle had this strange feel to it.

I was at about 45Kmph when I tried to change into third and **BAM** it would not get into gear!

I tried double clutching and even forcing it into gear, but it would not work.

I pulled her up onto the nature strip to give it a little rest.

It gets into gear when the engine is off, but not when running.

I spoke to Mark (Scoota G) and he suggested a few things which may be cause. He then recommended that I stick it into gear while the engine was off and attempt driving home which I did.

I put it into second and travelled the remainging 2Km's back home with a max speed of 50Kmph.

Upon returning home, before pulling up the driveway I noticed the gear changes were back to normal again!

WTF!!!?

I then decided to take it for a little race run around the block and she seemed to be behaving normally... I even stuck it into reverse and reversed it up a block 300m.

NO PROBLEMS!


Has anybody ever experienced a similar problem? If so, what was the cause and what was your approach in rectifying the issue?

#2 dat2kman

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Posted 28 May 2014 - 09:04 AM

Bleed your clutch master and slave cylinder.
Check the, f fitted, adjustable slave pushrod.
You will need a second person in the car actuating the clutch pedal, while you ensure full mvement at clutch fork.

Use axle stamds when working under car.

#3 Linton

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Posted 28 May 2014 - 09:05 AM

my guess would be clutch master cyl, was the pedal soft when you couldnt change gears

#4 be-zed

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Posted 28 May 2014 - 10:00 AM

I had a problem very similar to yours Bozo . But mine wouldn't go into forth gear . My box is from a mid 80's Nissan using a 260 bell housing and it did the same thing almost word for word as yours . But I was on a run with the ZCCQ which involved  a lot of up and down mountains and I was pushing it hard from time to time.I managed to get it home on the other gears with no problem .
But I decided to pull the box out and have a look at it some 2 weeks later as it is not an every day car . Before doing so I tried the box just to get a fell of what the problem may have been , only to find the problem was gone just like yours . That was almost a year ago now and I have not had any problems with it since . But I also haven't done any mountain runs in that time. I have even done a day at Lakeside without gear box problems .Unfortunately I can not say that day was totally problem free.The only thing I can point to with mine is there was a lot of hard acceleration and deceleration going through the box on that run . That may have something to do with the lock out  of one gear with heat sink. Other than that only God knows what was going on. 

#5 nizm0zed

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Posted 28 May 2014 - 05:41 PM

I had my R31 lock out all gears once, was cruising in 5th then tried to downshift to fourth, came out of gear smoothly then wouldnt engage any gear until i had stopped and shut the engine down.
Turned out that the sandwich plate that holds all the gears had cracked where the reverse layshaft goes in.

I knew that at the time though, because i had been driving around with no reverse for at least 6 months before hand... ;D

#6 DreamZproject

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Posted 28 May 2014 - 07:13 PM

How the F do you drive without a reverse gear!?!?! Don't tell me you put your leg out the door!!!

#7 lampy

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Posted 28 May 2014 - 07:47 PM

I have a 2nd gear roll pin shear on the selector fork on second gear a few months ago (71b) . Would go into 2nd sometimes and not others.
Might be something to check if you have the box apart

#8 nizm0zed

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Posted 28 May 2014 - 08:24 PM

How the F do you drive without a reverse gear!?!?! Don't tell me you put your leg out the door!!!


My house had a sloped driveway, that made it easy to get out in the mornings, otherwise you just had to be careful where you parked.
Yes, sometimes that does mean 'leg out the door' to get out of a spot.

Because racecar 8)

Funny story though, that car got stolen once, it was abandoned not too far away with no damage because they parked it in a dumb spot and couldnt reverse out, lol.

#9 dat2kman

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Posted 28 May 2014 - 10:24 PM

I have a 2nd gear roll pin shear on the selector fork on second gear a few months ago (71b) . Would go into 2nd sometimes and not others.
Might be something to check if you have the box apart

A little trick,
Use a second roll pin inside the first.

#10 glenn260z

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Posted 28 May 2014 - 10:45 PM

I had a similar issue with an RX7 I use to own. The pilot bearing crapped out effectively seizing the input shaft to the flywheel (bypassing the clutch). Might explain the strange noise.
Sounds like yours could have done the same then might have spat the parts of failed bearing out allowing the box to work as normal again.

#11 Lurch ™

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Posted 29 May 2014 - 07:36 AM

A little trick,
Use a second roll pin inside the first.


MYTH!
The double roll pins on sector forks for the 71B gearbox are 'works only' items & are now NLA.
No roll pin - in either metric or imperial - fits inside the standard selector fork roll pin (unless the fork & shaft are modified).

#12 Zedman240®

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Posted 29 May 2014 - 10:10 AM

MYTH!
The double roll pins on sector forks for the 71B gearbox are 'works only' items & are now NLA.
No roll pin - in either metric or imperial - fits inside the standard selector fork roll pin (unless the fork & shaft are modified).


whats the hole size? is it in between a metric and imperial?

#13 Lurch ™

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Posted 29 May 2014 - 10:53 AM

That's correct mate.

#14 dat2kman

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Posted 29 May 2014 - 12:08 PM

I'd better stop doing that then!

#15 Lurch ™

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Posted 29 May 2014 - 12:20 PM

I'd better stop doing that then!


I'd love to know what size roll pins they are then, mate?

#16 dat2kman

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Posted 29 May 2014 - 01:51 PM

I'll measure them, the selector fork and shaft get drilled out a touch, then one is metric and other is imperial, they both stick out a few mm more than normal.
Std factory ones with a part number are shorter and fit flush each side.
Check with Les?
Who is the Stan fella, old guy pissibly retired? Other bloke down there is Carl Zinner?? Not sure on spelling.

#17 HKSZ

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Posted 29 May 2014 - 02:50 PM

Stan Holmes?

#18 Bozo

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Posted 29 May 2014 - 04:17 PM

I had a problem very similar to yours Bozo . But mine wouldn't go into forth gear . My box is from a mid 80's Nissan using a 260 bell housing and it did the same thing almost word for word as yours . But I was on a run with the ZCCQ which involved  a lot of up and down mountains and I was pushing it hard from time to time.I managed to get it home on the other gears with no problem .
But I decided to pull the box out and have a look at it some 2 weeks later as it is not an every day car . Before doing so I tried the box just to get a fell of what the problem may have been , only to find the problem was gone just like yours . That was almost a year ago now and I have not had any problems with it since . But I also haven't done any mountain runs in that time. I have even done a day at Lakeside without gear box problems .Unfortunately I can not say that day was totally problem free.The only thing I can point to with mine is there was a lot of hard acceleration and deceleration going through the box on that run . That may have something to do with the lock out  of one gear with heat sink. Other than that only God knows what was going on.


The problem has indeed gone... I'm just afraid of a re-occurrence - especially if I'm carrying an extra special female passenger  :-X

But since it hasn't re-occurred for yourself then I'm pretty satisfied (for both you and me :D)

#19 Gareth. J.

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Posted 29 May 2014 - 04:33 PM

So they changed to double roll pins on the later 71C boxes? My R32 box had/has double roll pins on everything.

#20 pauly_adams

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Posted 29 May 2014 - 10:10 PM

I had a similar thing happen to me a few years ago, it turned out my clutch fingers were worn, I bled my clutch and it came good then it died a few weeks later




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