Psychotron

Can someone please confirm the standard and performance axle gear ratios for '89 to '91 vettes with a zf 6-speed manual transmission? Best I can tell is something in the 3.33 to 3.54 range for rear-end gear ratio as standard, but if so, what was the performance option ratios for these years?

Also, what was the standard and performance axle ratios for automatic trans for 89-91?


[Modified by OTCgrad, 7:11 AM 6/22/2002]

Psychotron

ttt

DON M

For the '90 auto it is GM1 2.59 and the G92 hi performance were GU2 2.73.
Of course all autos have the D36 carrier and sticks are D44.
Check your G codes, they will tell you what was installed at the factory.

Psychotron

Okay, from what I've heard the manual trans (6-sp.) didn't HAVE a performance ratio option, it was only available with automatics. Is this true? If that's the case, that makes some sense of my confusion. Someone please let me know, thanks.

90Z51Vette

My 90 has GT7 3.33 rear gears along with Z51 and a ZF 6 speed.

:cheers:

vader86

For automatics, the performance axle was 3.07. If they offered 3.33 as an option in A4's i would be surprised, seems like too much gear for a factory L98 auto.
Sticks were standard with 3.45, but 3.33 and 3.54 were options.

Psychotron

But if the 3.33/3.45/3.54 is too much gear for the L98 auto, wouldn't it be too much gear for the L98 6-speed? And why would the 3.45 be standard and 3.33 be an option? Better mileage? Would it be called 'performance option' then? :confused:

I just mainly need to know if I can look for a 6-speed, knowing it will have 'at least' that low of a ratio in standard form, or if I need to look for a performance option to have a ratio that low. From the jist I get, they went from the 4+3 and 3.07's as standard in '88, to the 6-speed and 3.33's or 3.45's standard in '89-91, with 3.54's as the performance option?

vader86

3.45 wouldnt be too much gear for 6 gears. All i know for sure is that 3.33 was offered, and 3.45 was standard in M6's. And 3.54 was offered in SOME years as an option.

Psychotron

At the risk of sounding like an idiot, when you say M6 you're referring to the RPO code MN6 for the 6-speed? I've seen it called zf a lot, but only seen the M6 reference twice. By the way, thanks for the info. I think either 3.45 or 3.33 will be perfect, so I should be good to go if it will have something in that range for sure.

dgoodhue

The standard ratio for the MN6 changed a few times during the 89-90 period. (off the top of my head 3.54 to 3.33 to 3.45) The changes were done mid year, and for me this is a confusing time for 6 speed ratio's. There may have been a rare optional performance axle ratio (it would probably be 3.54).

SLEV89

6 speed Manual Transmission

RPO code - ML9
MN6 is likely just an abreviation for 'manual6' (anyone know?)

ZF is the abbreviation for Zahnradfabrik Friedrichshafen (the manufacturer).
see: http://www.zfdoc.com/techinfo.htm

:seeya

Psychotron

As long as I know it's one of those in a standard issue 6-speed car, I'm good to go. :D Thanks for the info guys!

Psychotron

According to my master RPO list, MN6 is also listed as a 6-speed tranny. Maybe it's the C5 version? I'm trying to figure out why he called it an M6 (above).

:eek: Good Lord. Now I know why it's abbreviated! :lol:


[Modified by OTCgrad, 12:40 PM 6/24/2002]

SLEV89

haha :lol:
that is a mouthful, and then some!

:cheers:

vader86

M6=6speed manual, ZF6 in this case
A4=4 speed automatic

Black Beast

I believe that L98's with ZF6 in 1990 at least, were 3.33 RPO GT7, which my car has. The "meaning" of ZF in it's long spelled out wording intrigued me a few years ago and I asked a German who was trained as a machinist in Germany before he came to Canada what it sort of translated to. His answer was:

"Tool and Die Manufacturer by the Port of Friedrich". This sort of made sense, as "Fabrik" is German for fabrication(manufacturing) and Haven is the word for port. I figured since we were being **** on the subject, :rolleyes: others might enjoy that interpretation!!

Best regards,

Dan Young,



[Modified by Black Beast, 8:27 PM 6/24/2002]

NavyVet

Early production 1989 6-spds had 3.54s. They switched to 3.33s mid year. There were no options for a 6-spd performance axle. In 1990, 3.45s became available for 6-spds. Here are the RPO and actual differential codes:

1989 3.54 - GH0 - 8YJ - on tag (yellow) at left end of differential carrier brace
1989 3.33 - GT7 - 8YW
1990 3.33 - GT7 - 8YW or CQP
1990 3.45 - GM3 - 6YD or CQR
1991 3.45 - GM3 - CQR

Automatics for each year had standard ratio of 2.59. The performance axle option RPO Code was G92 each year and that got you 3.07s.

I'm pretty sure this is all correct. Paul


[Modified by NavyVet, 8:50 PM 6/24/2002]

Psychotron

:cool: Thanks. (to all who've posted) You've helped a bunch! :cheers:

jwg2

just out of curiosity, does anyone know the ratios for each of the gears in the 6 speed?

dgoodhue

Yeah mostly right to my knowledge except for auto. Usually convertible got 2.73 with the G92 RPO code and their are some rare exceptions, that is why it is help not to just look at G92, but the RPO axle code. (the other Gxx code)