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I thinks its time for a gearbox rebuild...how to identify.


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#1 WogsRus

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Posted 24 June 2015 - 07:55 PM

Ok so last week my 260z developed a crunch at low speed from second to first, it has now developed it up/down into third.

SO loos like i have an issue, when hot you can hear the rumble of main bearings.

So, what should i try first.

Re-bleed the clutch as i change the slave some time ago
Try some redline or automatic tranny fluid
Then do a rebuild.

Question is, how do i identify what tranny i have. The engine is an l28 and all i know in my 2+2 i can do like 55 in first about 100 in second before i even get into third.

Is there a way to identify the gearbox.

I found these guys who do ridiculously cheep kits

http://www.americanp...-transmissions/

So help please

#2 PB260Z

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Posted 24 June 2015 - 08:36 PM

Hi,

Definitely check the clutch release, but if you can hear bearings rumbling probably time for a rebuild.
I am pretty sure a thread exists on identifying gearboxes somewhere on here.

Cheers

PB

#3 Lurch ™

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Posted 24 June 2015 - 09:19 PM

Only way to know for sure is to remove the gearbox, select 1st gear, then rotate the input shaft & count the number of rotations of the output turns.

2.9 means it's a 260Z CR box with steel Porsche steel syncros (no new parts available).
3.3 means it's a 280ZX/240K/Bluebird gearbox with brass Warner type syncros.

FWIW we can convert the 260Z gearbox's to brass scynros & completely rebuild it for around $2k, if you are interested.

#4 WogsRus

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Posted 24 June 2015 - 09:19 PM

silly question, what if i over fill the gearbox, i know all say thinner oil but makes no scene, thicker oil will better slow the synchors down???

#5 WogsRus

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Posted 24 June 2015 - 09:20 PM

thanks lurch. What is the best gearbox for close ratios that will bolt into the L6 bellhousing?

#6 Lurch ™

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Posted 24 June 2015 - 09:23 PM

silly question, what if i over fill the gearbox, i know all say thinner oil but makes no scene, thicker oil will better slow the synchors down???


Correct.
You could try changing the oil, but I doubt it'll fix the selection issues...

thanks lurch. What is the best gearbox for close ratios that will bolt into the L6 bellhousing?


Standard 260Z gearset (unless you go aftermarket).

#7 WogsRus

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Posted 24 June 2015 - 09:27 PM

thanks lurch, will investigate on the weekend.

#8 dat2kman

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Posted 25 June 2015 - 12:13 AM

What oil you using now?
Most likely standard gear oil!
Try Redline Lightwright Shockproof, that may help reduce some of the baulking.
Other thing, on each up or down gearchange, just pause momentarily in the neutral plane, to allow the synchros a chance to "catch up"

Some 260Z ( and 2+2) boxes came with later brass type synchros, much easier and less costly to rebuild, you wont know until t has had tye bell taken off to find out which you have.

If t turns out you have a stock ratios bx, throw in a new Kameari gearset, that will give you nce clse ratio set!

#9 WogsRus

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Posted 25 June 2015 - 08:06 AM

No idea re oil, suspect standard as i have only had it 6 months and never opened it up.

Yeah at the moment just driving gingerly, which is hard to do with 200hp on tap.

I though in order to help synchroes best thing to do is to overfill the oil and perhaps add some Nullon teflon gearbox treatment, that way there is more drag on the gears and synchroes.

Yeah i have another two boxes form a 2+2 so will open these up and rebuild the one that is in best condition and slot it in. Would love a set of close ratio gears, however i anit got the cash now.

#10 WogsRus

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Posted 27 June 2015 - 03:58 PM

OK SOOOOOOO ITS FCUCKED, looks like the synchroes have died due to clutch drag, it appears even after bleeding and adjusting the clutch drags at 7000rpm, where with the clutch disengaged in gear the car will drag forward.


SOOOOO it looks like time for e a new box or rebuild.

The previous owner installed a new clutch in the car, i wander if they installed the wrong one.

The material coming out from the gearbox looked like a lot of metal, so i suspect my current gearbox runs cinted synchroes.

SO, where do i get a rebuild kit with cinted metal synchroes,

ALSO, alternatively, if i wanted to get another gearbox under it, what would be best, 280ZX, early 260Z late 260Z ????




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