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Author Topic: Final drive input bearing  (Read 3158 times)

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #15 on: January 22, 2022, 10:23:05 AM »
Well this explains to poor back brake  :P

Nothing visible around the outside, just slowly filling the inside! I notice this one has two brass bushes where the brake shaft goes through - another source of leaks. I assume the straight through tube was an upgrade. Big cleanup inside the drum tomorrow. I did the wheel bearing seals last time (with the wheel half out due to the oversize tyre) and it was relatively dry in there then - but I couldn't get a really good look.

Object in background is another CarbonBal balancer for a friend.
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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #16 on: January 28, 2022, 01:10:07 PM »
Good news:
The new FD is on  :)
There is a detectable difference in gearing  :)

Bad news:
The big bearing (the one I didn't change despite my mate smacking the seal down too far onto the ball cage) growls like a dog over 40MPH  :thud:

Other news:
My mate is going to have a pentagram smeared in gear oil on his front door and sacrificial gaskets hung around the periphery  :furious3:

The big seal was down hard on the carrier, to the extent it had depressions on the back. I asked him how hard he had hit it after the test ride and the answer was [bullshit interpreter] "Far too much". "It's only rubber". No it has steel inside it.... It's coming off again this weekend and I'll clean and spin it before pulling it to be sure it is that and not a clearance / shimming issue. I note the old one has noticeable backlash (but makes very little 'diff' noise) and the replacement has less. Plus the gears look good to the eye. We have karma though, he swapped the mufflers for nice shiny ones and is now in a world of pain with balance pipes and parts that don't fit  ;D

The unit was unknown and had half the input bearing off and multiple stripped threads. So I don't blame my friend 100%. Maybe 99...    :ROTFLMAO:
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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #17 on: January 29, 2022, 04:00:00 PM »
I have to take it all back. The big bearing is fine. There is no play in the gears with the cover off and big gear resting on its small shim. Which can't be right.

So I must have closed the backlash with the new nose bearing. Thoughts?
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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #18 on: January 30, 2022, 08:54:21 AM »
Pics of blued main gear, wear on pinion gear.
No discernable backlash in gears with the crownwheel resting on it's shim !

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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #19 on: January 30, 2022, 10:53:43 AM »
Shims are 37x47 1.4mm on gear side and 90x100 0.6mm + 0.4mm (1mm) on plain side.

Cutting some temporary shims says I need about +0.2mm on gear side (which is cheap and easily available).
« Last Edit: January 30, 2022, 11:31:20 AM by dogshome »
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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline Tony Smith

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  • Graduate, Wallace and Gromit School of Engineering
Re: Final drive input bearing
« Reply #20 on: February 01, 2022, 08:44:41 PM »
Backlash is set by the slightly conical bronze bush that sits on the underside of inwards side of the crown Whedon did you outfit back in and right way round?

The shims on the big bearing are measured to zero clearance, running clearance is set by the housing gasket.

I have rebuilt a lot of FDs and the only backlash bush I have ever replaced was in an FD assembled from parts by someone else

Too be honest it is easy to get too excited by backlash, if Prussian blue on the gears indicates a correct contact patch I would ignore the backlash.

Beware the little bearing on the end of the pinon shaft, it can fail silently and that will need up your backlash/contact patch.

It is also a bastard to change.
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1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #21 on: February 02, 2022, 01:03:25 PM »
RE: Bastard. It looks OK i.e the inner race that is pressed on the pinion shaft is clear and not worn.

Replacing the input pinion bearing from a 2 part to a single part has moved the pinion incrementally towards the axle. The blue is in the centre of the teeth, but there is definitely zero backlash and it complained under a very short test ride! GrrrRRRR!!! Wear on the pinion suggests it was too far back before anyhow.

I sort of get it now, the pinion is set by marks on the case and that shim should not need altering if the gears were meant for the case. I think the input ball has worn or the shim was not quite right to start with due to the pinion nose wear. My swapping it has moved it axle-ways slightly, which is just enough to take the tiny amount of play out.

The old one (which works fine with a slight and quaint MGB - whine in a closed cobbled street with high brick walls!) has loads of backlash. I think this one would be a breeze to rebuild as it's known and has not been partially disassembled / tampered with i.e no shim changes (which is how it should be as you said).

I am sure I have to increase the gear-side play and reduce the plain side on this unknown, partially stripped part though.
« Last Edit: February 03, 2022, 05:23:23 PM by dogshome »
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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #22 on: February 04, 2022, 12:29:10 PM »
I've popped the large bearing off now and put some light oil in it. It came off very easily using the holes provided in the crownwheel. Listen closely.
https://youtu.be/nsTiR0ZlOc8
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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #23 on: February 04, 2022, 02:44:24 PM »
Quote from: Tony Smith on February 01, 2022, 08:44:41 PM
Backlash is set by the slightly conical bronze bush that sits on the underside of inwards side of the crown Whedon did you outfit back in and right way round?


Pointy inner edge towards crown wheel (moving part) and turned down outer edge towards needle cage / case?
« Last Edit: February 04, 2022, 02:47:48 PM by dogshome »
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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline Tony Smith

  • Mt. Olympus Resident
  • ****
  • Posts: 2331
  • Graduate, Wallace and Gromit School of Engineering
Re: Final drive input bearing
« Reply #24 on: February 04, 2022, 05:58:36 PM »
Yes "pointy" side toward crownwheel.
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1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #25 on: February 04, 2022, 09:32:43 PM »
 :dankk2:
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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline dogshome

  • Lives in Foothills of Mt. Olympus
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  • Posts: 402
Re: Final drive input bearing
« Reply #26 on: February 06, 2022, 10:10:39 AM »
If I had a brain, I would have done this before doing anything else!

HOW TO TEST IF A FINAL DRIVE IS ANY GOOD WITH A GUN DRILL AND 24mm SOCKET:

https://youtu.be/RenY5UBd9LA

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肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O
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