The Gearbox & Diff thread

[spetz]

How do you know if/when your bearings need changing?

[Sahin]

crunch crunch crunch crunch crunch crunch crunch crunch crunch crunch crunch crunch crunch crunch crunch crunch

[silverGPX]

And whirring/vibration

[spetz]

Will it crunch, or is that only when synchros are worn?

[Bennoz]

It actually sounds clunky at idle. You hear a whirring-knocking sorta noise coming from the gearbox, put your foot on the clutch & it goes away (sorta like a thrust bearing failure) as when your foot is on the clutch, no part of the box is moving (assuming your at a stop.)

The first bearing to go on every single FTO box is the primary input shaft bearing. Ie the one closest the clutch, the one that you test by trying to wiggle the shaft that goes into the gearbox. It's the first to cop the torque load from the motor.

Primary shaft - Engine side x1
NSK Roller Ball Bearing
NSK B25-157 (B25-157Aa)

As far as I'm concerned, its an under spec bearing. It should have been something better, such as a barrel roller. Because every box I reco, this bearing is fucked.

[Bennoz]

Will it crunch, or is that only when synchros are worn?

Generally, yes.

[spetz]

Thanks Bennoz for the explanation.
is there a need for machined etc when you do a reco?
And how much time does it take you to recondition a gearbox?

[Bennoz]

Thanks Bennoz for the explanation.
is there a need for machined etc when you do a reco?
And how much time does it take you to recondition a gearbox?

No, not really anything to machine. All the tolerances in the box are governed by a range of thick cir-clips. As they wear, there's a range of different thickness replacements you can order depending on the thickness you need. On the diff, it's just a simple shim. Again, different thickness shim are available based on what you measure up.

A problem free reco, usually takes me about 4 hours to do.

[aza013]

It actually sounds clunky at idle. You hear a whirring-knocking sorta noise coming from the gearbox, put your foot on the clutch & it goes away (sorta like a thrust bearing failure) as when your foot is on the clutch, no part of the box is moving (assuming your at a stop.)

The first bearing to go on every single FTO box is the primary input shaft bearing. Ie the one closest the clutch, the one that you test by trying to wiggle the shaft that goes into the gearbox. It's the first to cop the torque load from the motor.

Primary shaft - Engine side x1
NSK Roller Ball Bearing
NSK B25-157 (B25-157Aa)

As far as I'm concerned, its an under spec bearing. It should have been something better, such as a barrel roller. Because every box I reco, this bearing is fucked.

Hum sounds like my one may need doing after reading that, as its just starting to make some of them sounds lol.

[Supplanter]

What it be possible for you to fit a more suitable replacement bearing?

[Taz]

My 98 GPR has a Helical LSD in it - if it somehow matters to your research the end serial is WR4616

[Gholdwayne]

Anyone know if the F5M42 syncros can be acquired locally?

[Astron_Boy]

Anyone know if the F5M42 syncros can be acquired locally?

Bennoz.


And Gholdy! you AWOL prick!

[Gholdwayne]

Ah ok, hopefully Bennoz will sell/give me some...

Yeah man, mostly communicating on facebook and been in another planet pretty much


But yeah, sent my car in to a transmission specialist mechanic to:

- Replace gearbox bearings
- Put in Exedy HD clutch
* Might also tell them to replace the rear main seal?

I just thought, might as well replace the syncros, they're not too bad - but should I? The gearchange crunches are very occasional anyway...

[Storm]

Slightly different question but does anyone know the final drive ration of the different boxes used in Mivec, non Mivec and LSD boxes?

[Shhtuart]

Slightly different question but does anyone know the final drive ration of the different boxes used in Mivec, non Mivec and LSD boxes?

gearratios.jpg (158.23 KiB) Viewed 3087 times

That's all i could find, I don't see how the LSD boxes would have different gear ratios?

[Storm]

Slightly different question but does anyone know the final drive ration of the different boxes used in Mivec, non Mivec and LSD boxes?

gearratios.jpg

That's all i could find, I don't see how the LSD boxes would have different gear ratios?

I don't know about the LSD boxes but it would appear that Mivec and non-Mivec cars have (probably not every one of them but mainly) different differentials, as noted by the different tripod joint sizes. there is also a conception that non-Mivec boxes are better for acceleration.

I don't think Mitsi would have put different gear ratios for every gear but it does seem like the diffs are different so I assume their final drive ratios could be different to take into account the extra few horse power that Mivec kicking in would bring.

Or not, as the case may be!

[Daniel2019]

there is also a conception that non-Mivec boxes are better for acceleration.

I assume their final drive ratios could be different to take into account the extra few horse power that Mivec kicking in would bring.

Or not, as the case may be!

Correct, they are slightly different between Mivec and non mivec.

Theres a Bennoz quote about it buried somewhere. Cbf looking at 2am.

[Storm]

Cbf looking at 2am.

Don't blame you, time difference from Scotland makes for drawn out conversations! lol

[Daniel2019]

Cbf looking at 2am.

Don't blame you, time difference from Scotland makes for drawn out conversations! lol

Still cbf and its 10:45am..

Although im 99% sure there isnt a difference between LSD and non-LSD models. I dont see why there would be. Just mivec/non mivec boxes.

Edit: Dammit, isnt the little cletus gen-y emoticon