do I have 3.55's?
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 3,022
Likes: 3
From: Chandler Arizona
do I have 3.55's?
I know that most m6 c4's are equipped with 3.45's, but I was under the impression that 3.55's had also been offered for the later c4's?
I'm only asking because I easily see about ~1800rpm at 70-75mph. Not necessarily focusing strictly on the tach, but I'm certain I'm at about that rev range...
thoughts?
315/35-17's BTW-
I'm only asking because I easily see about ~1800rpm at 70-75mph. Not necessarily focusing strictly on the tach, but I'm certain I'm at about that rev range...
thoughts?
315/35-17's BTW-
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
It's not 3.55 but 3.54 and it was offered in "earlier" rather than "later" years. Could one have found it's way into your '93 in the past 17 years certainly but quite unlikely I'd think.
You mention not paying attention to the tach and you mention an "approximation" of RPM"s. The .09 of axle ratio, the likely inaccuracy of the OE tach and/or speedometer I doubt you could arrive at a "confirmed" conclusion using either.
You could check the build information on the D44 housing to confirm what gear was in the housing "when assembled"!
A 605491-3 would be a 3.45 for most MY's. A 605491-4 would be a 3.54 for MY's 90+. If the complete rear had been swapped from earlier than '91 there's a couple more possibilities 3.45 (605322-9) or 3.54 (605492-1/605322-7/605417-4)
possibilities
You mention not paying attention to the tach and you mention an "approximation" of RPM"s. The .09 of axle ratio, the likely inaccuracy of the OE tach and/or speedometer I doubt you could arrive at a "confirmed" conclusion using either.
You could check the build information on the D44 housing to confirm what gear was in the housing "when assembled"!
A 605491-3 would be a 3.45 for most MY's. A 605491-4 would be a 3.54 for MY's 90+. If the complete rear had been swapped from earlier than '91 there's a couple more possibilities 3.45 (605322-9) or 3.54 (605492-1/605322-7/605417-4)
possibilities
Drifting
Joined: Jun 2007
Posts: 1,478
Likes: 4
From: Formerly from the Great White North but now residing in the Desert Southwest NM (The Land of Dis-Enchantment?)
It's not 3.55 but 3.54 and it was offered in "earlier" rather than "later" years. Could one have found it's way into your '93 in the past 17 years certainly but quite unlikely I'd think.
You mention not paying attention to the tach and you mention an "approximation" of RPM"s. The .09 of axle ratio, the likely inaccuracy of the OE tach and/or speedometer I doubt you could arrive at a "confirmed" conclusion using either.
You could check the build information on the D44 housing to confirm what gear was in the housing "when assembled"!
A 605491-3 would be a 3.45 for most MY's. A 605491-4 would be a 3.54 for MY's 90+. If the complete rear had been swapped from earlier than '91 there's a couple more possibilities 3.45 (605322-9) or 3.54 (605492-1/605322-7/605417-4)
possibilities
You mention not paying attention to the tach and you mention an "approximation" of RPM"s. The .09 of axle ratio, the likely inaccuracy of the OE tach and/or speedometer I doubt you could arrive at a "confirmed" conclusion using either.
You could check the build information on the D44 housing to confirm what gear was in the housing "when assembled"!
A 605491-3 would be a 3.45 for most MY's. A 605491-4 would be a 3.54 for MY's 90+. If the complete rear had been swapped from earlier than '91 there's a couple more possibilities 3.45 (605322-9) or 3.54 (605492-1/605322-7/605417-4)
possibilities
.....and by any chance, do you have a good 3.54 in a Dana 44 case just lying around?
Instructor
Joined: Dec 2008
Posts: 228
Likes: 1
From: Atlanta GA
When I looked around it looked like 92 was the last year RPO GHO was available (3.54). This should be stamped into the center section and it will also have the gear ratio stamped as well (if it has not been modified of course).
There was something like just under 600 produced in 92 which was the largest qty in any year. The D44 w/3.54 rear I got for mine came from a 92 as well.
There was something like just under 600 produced in 92 which was the largest qty in any year. The D44 w/3.54 rear I got for mine came from a 92 as well.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
my 86 has 3.54 gears, case scribble sez 3.07...am certain cause i put the 3.54's in...ONLY way know 'what's in your rocket' is to raise the rear wheels and get under it, attach 3 temporary pointers (clamp+ coathanger wire is good) at the driveshaft and both rear wheels, and ref marks at the pointers ( another duct tape miracle), with trans in neutral, roll the driveshaft by hand and count till the wheels go one full rev...for higher accuracy you might rotate driveshaft/count for 10 wheel revs, do the mat.
Cruising
Joined: Jul 2009
Posts: 13
Likes: 0
since on the topic of gears, is the 3.73 worth it. i bought a car with 3.73's and i drive alot of freeway miles, i like the low end grunt but i dont like the 80mph at 3k rpm. is it worth looking into switching back to stock? ive never driven one with stock gears and id hate to kick myself for loosing that bottom end.
Team Owner
Joined: Sep 2003
Posts: 25,394
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I've got a set of new GM 3.54 gears (long time discontinued) I've never thought about selling them but I'll likely never use them either. I've got a new housing, trac-lok, short axles, the kit and I believe a new pinion flange. I've got a new bat-wing also. I guess it's enough stuff to build a complete new assembly!!
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Team Owner
Joined: Sep 2003
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Melting Slicks
Joined: Feb 2006
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From: backwoods upstate ny
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 3,022
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From: Chandler Arizona
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 3,022
Likes: 3
From: Chandler Arizona
the car was nearly stock when purchased. Only had flowmasters and a foam-like drop in air box.
Team Owner
Joined: Sep 2003
Posts: 25,394
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Your car should be black/black, has FX3 and dual power seats ? The rear as it left BG is GM3 (3.45). I thought maybe the engine code might determine 1st design with dual grooved belt but the ZVB build shows only the M6 build and it could have been either. Your car was built 11Nov92.
Last edited by WVZR-1; Apr 10, 2010 at 10:40 PM.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 3,022
Likes: 3
From: Chandler Arizona
Team Owner
Joined: Feb 2006
Posts: 23,218
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From: San Antonio Texas
I always wondered why GM would go to the trouble to tool up two gear sets so close in ratio. I wouldn't think there would be a cat whiskers difference between 3.45 and 3.54 ! Did they discover some kind of harmonics that were displeasing to the drive-line, or some other good reason to discontinue the 3.54 in favor of another ratio so numerically close?
Team Owner
Joined: Oct 2007
Posts: 26,745
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From: PA
I always wondered why GM would go to the trouble to tool up two gear sets so close in ratio. I wouldn't think there would be a cat whiskers difference between 3.45 and 3.54 ! Did they discover some kind of harmonics that were displeasing to the drive-line, or some other good reason to discontinue the 3.54 in favor of another ratio so numerically close?