2.73's to 3.73's
Thread Starter
TECH Fanatic
Joined: Jun 2007
Posts: 1,062
Likes: 2
From: Westminster, MD
2.73's to 3.73's Thoughts on Motive 3.73's (for 2 series carrier) and Motive's install kit from WS6Store?
http://www.ws6project.com/user_stor/...ries-carrier-/
http://www.ws6project.com/user_stor/...tallation-kit/
I was also planning on replacing the diff cover with one from WS6Store but what is the best one for the money? ProForm Perfect Launch, MAC, or TA Performance?
http://www.ws6project.com/user_stor/...rential-misc-/
http://www.ws6project.com/user_stor/...ries-carrier-/
http://www.ws6project.com/user_stor/...tallation-kit/
I was also planning on replacing the diff cover with one from WS6Store but what is the best one for the money? ProForm Perfect Launch, MAC, or TA Performance?
http://www.ws6project.com/user_stor/...rential-misc-/
Teching In
Joined: May 2011
Posts: 11
Likes: 1
I am also looking to upgrade my rear end from a 2.73 to a 3.73. I bought a rear end from a '97 Camaro (2.73 2 series carrier) to install into my '97 Firebird because I wanted posi and rear disc brakes.
The install kit says from 98-02, so I'm assuming this will NOT work with my 97 rear end correct?
If not, I was looking at http://www.thunderracing.com/shop-by...-Install-Kits/
Part # 69-G875373-X (Motive Performance Gears, 3.73 Gear Ratio, 2 series carrier, GM 7.5" 10 bolt rear end)
and
Part # 85-308TK (Ratech Complete Gear Install Kit, GM 7.5" 10 Bolt)
Does anyone have any info or tips, or any more knowledge on sponsors that may sell what I need? I'm looking for a kit that I can bring to a shop that has everything needed to correctly install new gears into my rear end.
The install kit says from 98-02, so I'm assuming this will NOT work with my 97 rear end correct?
If not, I was looking at http://www.thunderracing.com/shop-by...-Install-Kits/
Part # 69-G875373-X (Motive Performance Gears, 3.73 Gear Ratio, 2 series carrier, GM 7.5" 10 bolt rear end)
and
Part # 85-308TK (Ratech Complete Gear Install Kit, GM 7.5" 10 Bolt)
Does anyone have any info or tips, or any more knowledge on sponsors that may sell what I need? I'm looking for a kit that I can bring to a shop that has everything needed to correctly install new gears into my rear end.
LoL go straight to the source Motive gears Im doin a set on my stock 3.23 trans am Because I want 73s & found a new set cheap enuff on the way to get a few rims to widen TA would be my choice on covers If you dont have posi get it or have yours rebuilt if youve got one Use a good synthetic gear lube too
Thread Starter
TECH Fanatic
Joined: Jun 2007
Posts: 1,062
Likes: 2
From: Westminster, MD
I'm looking for user reviews, to see how they hold up strength and reliability wise. Not sure if maybe since they are adapted for the 2 series carrier they would be weaker or anything
I bought the Motive 3.73s and install kit from Ws6 Store. Had them put in lastyear. been holding up great. Just a slight wine at times but nothing unbearable. Best advice I can give you from my experience: there's a thread on here with what RPMs the gears will run at at 60 mph. take it out and double check what you ahve. I thought I had 2.73s and turned out the previous owner blew the rear and put in a different carrier with 3.23s. Bought the gears for the wrong carrier. It was headache.
Thread Starter
TECH Fanatic
Joined: Jun 2007
Posts: 1,062
Likes: 2
From: Westminster, MD
I checked the other day actually as I was driving.
Current gears (2.73) IIRC
60mph - tach ~1500rpm
70mph - tach ~1750rpm
80mph - tach ~2000rpm
Guess I'll have to try hunting around for that thread with the 3.73 rpm's
Current gears (2.73) IIRC
60mph - tach ~1500rpm
70mph - tach ~1750rpm
80mph - tach ~2000rpm
Guess I'll have to try hunting around for that thread with the 3.73 rpm's
TECH Fanatic
Joined: Jan 2011
Posts: 1,358
Likes: 0
From: Michigan
I did the motive swap last year and it was a very good move. 2.73s are too slugish off the line, from a roll, everywhere. Only thing their good for is gas mpg. You'll love the 3.73s.
Before I ran 1900 rpm at 70mph...now it's 1900 at 55mph.
70 is like 24-2600rpm...
Exhaust note is considerably louder all around because of the increase of rpms, which is a plus for me...
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Thread Starter
TECH Fanatic
Joined: Jun 2007
Posts: 1,062
Likes: 2
From: Westminster, MD
Lol yeah its a GU2, that's how I knew I had 2.73's in the first place when I looked at the RPO codes. I do have a DD to get me back and forth to work but I tend to do a LOT of highway driving keeping a constant 70-90 miles an hour and I as looking at other threads and that would put me around 3k rpm all the time and that is really going to suck down gas. I knew there would be an increase in rpm but I didn't know it would be that much. I really have to take this into account now....as far as making the car louder because of higher engine speed I would like it but the general public and cops probably won't 
it's already pretty damn loud when I'm on it and I like being about to let off and let it go stealthy
it's already pretty damn loud when I'm on it and I like being about to let off and let it go stealthy LS1 Tech Stories
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several years ago,I went from 2.73 to 3.73 in a a4 98 head cam car.....
i think i did use motive gears. worked out great!
if my mind serves me correct,on the 2 series differentials the ring gear bolts a little lower than the 3 series diff. so the ring gear is thicker.
wait till you see the 2.73 pinion compared to the 3.73,big difference in mass diameter.....
i think i did use motive gears. worked out great!
if my mind serves me correct,on the 2 series differentials the ring gear bolts a little lower than the 3 series diff. so the ring gear is thicker.
wait till you see the 2.73 pinion compared to the 3.73,big difference in mass diameter.....
