Author Topic: 5 speed gearbox strip.  (Read 914 times)

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Offline Sparkrite

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5 speed gearbox strip.
« on: Saturday,May 21, 2022, 02:07:41 AM »
As a result of a troublesome clutch (oil on friction plate from gearbox output shaft seal) I have had to remove the gearbox.
My question about the output shafts/seals, is this a job I can do as a novice,is it basically just unwinding the strange "circular nut" replacing the seals and o rings. Should the shafts have any in/out movement. Should I split the box. I have removed the bellhousing and its seal, replaced the selector shaft rear seal but also noticed the 5th gear lever rod also has a slight leak and seems to have a pin throught it and the lever. To add the box worked fine except leaked from all the above seals.

Offline Rainer

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Re: 5 speed gearbox strip.
« Reply #1 on: Saturday,May 21, 2022, 03:38:17 AM »
Before you screw the nuts out of the box, mark their position and count the turns when unscrewing them.  They need to go back in the exact same position as they set the position of the ringgear.
Do one by one, this way it is not possible to overtighten one nut by a full turn.
Depending one your gearbox or combination of them, you may or may not have an o-ring on the outside of the nut, replace if present, otherwise use sealant, i had success with hylomar.
Also replace the o-rings below the driveshaft spacers, had one gearbox leaking from them.
If you do not have special tools for the nut, a broken of 90 degree snap ring pliers could do the job.

Rainer

Offline SilverBeast

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Re: 5 speed gearbox strip.
« Reply #2 on: Saturday,May 21, 2022, 04:11:32 AM »
This thread is worth reading for details of drive shaft in/out movement http://www.lotuseuropa.org/LotusForum/index.php?topic=900.msg6770#msg6770

It's important to set the castellated circular nut back in the same position (as described by Rainer above) as getting it wrong changes the end float on the bevel gear (?) internally which will increase wear and noise.  If the shimming of the driveshafts is incorrect it will also cause breaking of the roll pin (s) due to suspension loading which can allow the driveshaft to move on the spline of the gearbox output shaft.

Offline jbcollier

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Re: 5 speed gearbox strip.
« Reply #3 on: Saturday,May 21, 2022, 05:52:12 AM »
You have the box out, do the side seals properly and set the ring gear pinion backlash at the same time.

Offline Sparkrite

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Re: 5 speed gearbox strip.
« Reply #4 on: Monday,May 23, 2022, 11:32:40 AM »
I have tried to undo the castelated nuts but they will not budge, not even at 70 lb/ft . I cant see evidence of a sealer in the joint so how much more force is it safe to use.

Offline jbcollier

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Re: 5 speed gearbox strip.
« Reply #5 on: Monday,May 23, 2022, 12:17:52 PM »
If you have access to an oxygen-acetelyne torch, you could try heating the case around the nut.

Offline Pfreen

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Re: 5 speed gearbox strip.
« Reply #6 on: Monday,May 23, 2022, 01:59:40 PM »
Some penetrating oil may help as well.  It must be they corroded together.  The bearings  wouldn't turn freely if that torque was taken up by the bearings or crown wheel.

Offline 4129R

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Re: 5 speed gearbox strip.
« Reply #7 on: Tuesday,May 24, 2022, 12:12:32 AM »
I have tried to undo the castelated nuts but they will not budge, not even at 70 lb/ft . I cant see evidence of a sealer in the joint so how much more force is it safe to use.

If the PO used Loctite on the threads, you would need to heat the threads up to release the Loctite, as in the steering rack.

I presume you are using the correct multi fingered tool to undo the castellated nut, which has a large nut welded to the end.

Offline Sparkrite

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Re: 5 speed gearbox strip.
« Reply #8 on: Tuesday,May 24, 2022, 05:10:59 AM »
I applied some heat and it came off, I had to make up my own tool for the castelated nut and it worked a treat.
I cant see any o ring though. Within the castelated nut there is a steel insert which houses a felt ring, then there is the oil seal. At the gearbox, all I can see is the output shaft with a ring around it which sits proud of the bearing. 

Offline jbcollier

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Re: 5 speed gearbox strip.
« Reply #9 on: Tuesday,May 24, 2022, 05:46:25 AM »
Surrounding the output shaft is the diff carrier bearing.  The ring is the seal run.  it is removable.  It pops off with a hook tool.  There is an o-ring behind the ring you also need to change.  The seal ring goes on AFTER you have refit the nut/seal.  Use some pipe and a hammer to pop the seal ring over the new o-ring.

Once you have done both seals, remove the bell housing and check your ring/pinion backlash.

Offline Sparkrite

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Re: 5 speed gearbox strip.
« Reply #10 on: Tuesday,May 24, 2022, 12:47:54 PM »
Thanks again Jbc,it now makes more sense.

Offline Sparkrite

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Re: 5 speed gearbox strip.
« Reply #11 on: Wednesday,May 25, 2022, 06:03:25 AM »
I am now trying to remove the gearbox end housing but it has come out about 3/4" and something is stopping it from going further. Do I need to undo the round slot head screw on the outside. Does anyone have any tips

Offline RafM

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Re: 5 speed gearbox strip.
« Reply #12 on: Wednesday,May 25, 2022, 07:36:50 AM »
The rocking lever will be engaged with the selector forks, try putting it in 4th gear and easing it off.

I've found it a bit awkward getting the cover on and off in the past.

Offline jbcollier

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Re: 5 speed gearbox strip.
« Reply #13 on: Wednesday,May 25, 2022, 08:01:00 AM »
I have a pdf of the Renault manual on the 365.  It's much, much better than the Lotus version.  Ping me your email and I'll send it to you.

jbcollier (AT) shaw (DOT) ca

This is what they say:

To remove the rear cover, remove:

- the plug, spring and 5th gear detent plunger
- the speedometer drive, cover fixing bolts
- shift into 4th gear and remove the cover

Offline Sparkrite

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Re: 5 speed gearbox strip.
« Reply #14 on: Wednesday,May 25, 2022, 08:11:22 AM »
I managed to get it off now, however It seems the main nut of the 5th gear assembly had previously come undone and the gear chewed away at inside of the housing case. This was probably the reason why someone had been there before with all the silicone on the joint face.
Is it possible to buy the 5th gear and the sliding housing which is attached to the selector fork (sorry I dont know the name) and how best to ensure that nut doesn't unwind in the future. Maybe tap down the lip into the flat on its shaft