ZF6 conversion... what speedo gear?
Thread Starter
Team Owner
Joined: May 2002
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
ZF6 conversion... what speedo gear?
What rear end ratios came in 1989? I've got a 1989 ZF I'm dropping in my 85 vette with 3.07 rear end. Also wondering if that 3.07 rear is gonna need to be shorter to make my .5:1 overdrive useable.
Do I need a different speedo gear, and if so, will my 4+3 speedo gear fit in the tailpiece of the ZF?
Do I need a different speedo gear, and if so, will my 4+3 speedo gear fit in the tailpiece of the ZF?
Team Owner
Joined: Aug 2000
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From: San Pedro CA
I honestly don't know. However, I think that www.zfdoc.com might have the answer. If not, call him, and I am sure he can give you the answer.
There is also a chance that the 3.07 gear was used with that ZF6. I think they are colour coded... I just don't know the code.
I am sure this has been of little help, really.
There is also a chance that the 3.07 gear was used with that ZF6. I think they are colour coded... I just don't know the code.
I am sure this has been of little help, really.
Thread Starter
Team Owner
Joined: May 2002
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Ok then. Why is the sky blue? What does ZF stand for? What does 4+3 equal? 
Damn. CAC shows 5 or 6 different ratios. I'm sure at least 3 of the short ones were available on the stick. I guess it's a poop shoot here. I'll check for color codes.
Damn. CAC shows 5 or 6 different ratios. I'm sure at least 3 of the short ones were available on the stick. I guess it's a poop shoot here. I'll check for color codes.
Last edited by CentralCoaster; Oct 11, 2005 at 11:16 PM.
Thread Starter
Team Owner
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Eureka!
http://www.corvetteforum.net/c4/vett...Gearshtm.shtml
This came outta a 91 with a 3.45 OR 3.54 rear end. Hmm. One speedo gear for TWO ratios? Looks like the drive gear has one tooth difference.
Numbers on the tag seemed to indicate it was from an 89.
My 85's speedo has the same number of driven teeth as what's in this ZF. Interesting.
So these drive gear, driven gear are all easily swappable? Wonder if my 4+3 parts willl fit in there.
http://www.corvetteforum.net/c4/vett...Gearshtm.shtml
This came outta a 91 with a 3.45 OR 3.54 rear end. Hmm. One speedo gear for TWO ratios? Looks like the drive gear has one tooth difference.
Numbers on the tag seemed to indicate it was from an 89.
My 85's speedo has the same number of driven teeth as what's in this ZF. Interesting.
So these drive gear, driven gear are all easily swappable? Wonder if my 4+3 parts willl fit in there.
Last edited by CentralCoaster; Oct 11, 2005 at 11:36 PM.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Driven gear is on the output shaft under the ext housing.
If you are lucky it will take the same style gear as an auto / 4+3 so you will be able to use your original gears unless you have changed tyre sizes.
Speedo calc shows 19 tooth driving 45.
Mr CFI-EFI will know exactly.
If you are lucky it will take the same style gear as an auto / 4+3 so you will be able to use your original gears unless you have changed tyre sizes.
Speedo calc shows 19 tooth driving 45.
Mr CFI-EFI will know exactly.
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Race Director
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From: Indianapolis IN
You can not get a red 3.07 tranny gear, they dont make it for the ZF, but you can call ZFDOC, the last time I talked with him, he was going to make some .
Otherwise, I used the Dakota Digital speedo calibrator on my 85 with 3.07's, but now I have 3.42's.
Otherwise, I used the Dakota Digital speedo calibrator on my 85 with 3.07's, but now I have 3.42's.
Thread Starter
Team Owner
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Originally Posted by LD85
Otherwise, I used the Dakota Digital speedo calibrator on my 85 with 3.07's, but now I have 3.42's.
I like that idea better. Surely I'll want to put a lower gear in after this. I mean, what am I gonna do? Drive the damn thing?
WTF is a 3.42? never heard of that ratio...
Pro
Joined: May 2002
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From: Lengede
Originally Posted by CentralCoaster
I like that idea better. Surely I'll want to put a lower gear in after this. I mean, what am I gonna do? Drive the damn thing?
WTF is a 3.42? never heard of that ratio...
WTF is a 3.42? never heard of that ratio...
Race Director
Joined: Feb 1999
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From: Indianapolis IN
Originally Posted by vettef6
LD85 probably means 3.45!!
yes I have 3.45's, but the 3.45 is discontinued from production from what I was told by several Ring & Pinion manufacturers
and had I not bought a used set of 3.45's I would have HAD to buy 3.45's, so if you look for gears 3.45'3 may be hard to come buy
Advanced
Joined: Oct 2003
Posts: 94
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From: Chattanooga TN
I just reused my 4+3 speedo and gear....b/c it fit...it works fine. But, mine is a black tag...early model tranny. I would say, if the gear fits, wear it.....uuuuh? wait a minute... I mean put it in and try bench testing it. Mine works fine, like I say.....I have the 3.07. And on your ZF tag.....if it has a blue tag and has a crash through style for the reverse lockout...it is a later model 92??-96 if it's a collar lockout and black tag it is an early model such as an 89-91. What I did was put my gear in there and looked to see if the gear was off center or not...it was dead center and the teeth went together fine.
Thread Starter
Team Owner
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Good to hear. I do have a black tag. Not sure about the shifter, I identified it by the tag that is black.
The shift **** is the same part number too.
The shift **** is the same part number too.
Le Mans Master
Joined: Jul 2001
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From: Santa Maria, CA
Originally Posted by 89sleeper
Both my 89s coupe and roadster have 3:54 gears in rear axle both are 6 speeds
I was mistakenly under the impression all 89's w/ 6 speeds had 3:33's.
