Guest

I see pre-built rear end gears for $1200 and up, but I also see the COH sells the 3.73 gears alone for about $400 (i think). They say that 3.73s will fit in the stock housing.

I want to upgrade from the 3.42s to 3.73s (please, no 3.90/4.10 talk). Why not just have the gears changed for less money than buy a more expensive unit? Are there installation risks? :smash:

If pre-built is the only way to go, what's the difference between Getrag, SLP etc.?

Finally, can anyone recommend good, reasonably priced sources for this stuff? :steering:

boblackhardtop

Simple math.
Good used 3.42 goes for ~$500. Sell it & buy complete diff. ( 3.73, 3.90, 4.10 of your choice for ~$1200 ) & your net cost will be ~$600-700
If you wanna built, 3.15 casing run $300-400 ( not to mention shipping cost back & forth +$100 ), new ring & pinion $400-500, new bearings, seals, etc... plus labor ~$300-400. Oh & there's the HASSLE...Your final tally about $800+ using your own 3.42 casing.



[Modified by boblackhardtop, 1:57 AM 6/8/2003]

Guest

Well, I like the thinking at $1200, but sometimes I see the pre-built 3.73s at over $2000. Then I don't which to get. :rolleyes:

boblackhardtop

Those are OEM factory fresh Getrag unit, not rebuilt using motive ring & pinion. If you're not in a hurry there's a group purchase every now & then at ~$1600-1700. If you want 3.90 or 4.10 you're limited to just rebuilt unit, Getrag don't make them that high.

jmzvet

I would love to have someone install 3.90s or 4.10s in my carrier but I can't find anyone who will do it in SoCal.

Guest

I've read that nothing larger than a 3.73 will fit the stock housing.

blktie8

After 3.15 the housings are the same ,the Z06 has some reinforcing.
Many vendors will turn your 3.15 into gear of choice give eastcoast
supercharging a call first.
John

Guest

Will a 3.73 Z06 rear end work on a 2003 C5 coupe?

:steering:

boblackhardtop

All C5 diff. are interchangeable. You have to reprogram PCM for auto. for manual it's just a simple swap.
Z06 comes w/ 3.42 the ratio is changed at the trans. It is about equivalent to a 3.90 in 1st 3 gears while final drive ratio stays the same. It's not a 3.73.

size of ring & pinion is the same for all ratio 2.73, 3.15, 3.42, 3.73, 3.90, 4.10. The higher the numeric ratio the more the number of teeth hence the smaller & weaker they are. But I have yet to see one break, other component will fail 1st, like the output shaft.

Carsnob

I've been pondering the same question for quite some time myself. I wonder would it be cheaper to get a z06 trans installed? That way you get the benefit of higher gear ratio for the first 3 gears where it counts, but when you want to get good gas mileage you have the 3.42's out back turnin' low rpms.

TXNC5

I was told by a vendor that the diff case had to be machined some to get the larger gears to fit.

Does anyone know if this is true? (I was inquiring about 4.10's.)

I already have a hardend output shaft, and I have a line on a ring & pinion set for around $200. I checked around, and I can get new seals, gaskets, bearings for another 200-250. So, I figure I could do it myself for around $500 + my time. Anyone done this?

boblackhardtop

Check w/ PHILSVT or Andy at A&A corvette.

0rodney@rpmtransmissions

I was told by a vendor that the diff case had to be machined some to get the larger gears to fit.

:bs NOT Necessary.

Mike Mercury

incorrect.

doing this woukld benefit you in 1st, 2nd, and 3rd gear only. As 4th thru 6th have the same ratios in both trannys. If you change the rear axle ratio, it will benefit you in all 6 gears.

SpinMonster

:iagree: With some good surprises!

Carsnob

but how often is it really necessary to accelerate stronger in 4-6th gear? I know that with my current gear ratio's and 3.42's I shift into 4th as I am going thru the traps. Also, if I need to get on it going down the interstate I always go to 3rd anyway. If I could accelerate faster in those first three gears that would be good enough for any drag race and you still get your good gas milage in 6th. Aren't the Z06 5th & 6th slightly taller than the M6 too with 4th being the only one unchanged at a 1:1 ratio? I will have to look it up. If so, way I see it is better acceleration in all gears but 4th. NOW the real arguement. Would it be cheaper/easier to replace the trans as opposed to going to say 3:73's and up gears?

cthoreen

Hey MMI. If you decide to go to a new diff and want to sell your 3.42 3rd member I'd be interested in buying it from you. I have 3.15's and want to switch. :)

Mike Mercury

I understand your point; but it's sometimes nice to feel like you can pass someone on a freeway without having to downshift.

Swapping a tranny is more labor than just swapping the rear carrier. But hey; it's your car... do what's best for your particular driving style.

Carsnob

That's the kind of answer I have been looking for. I did some research and found a used M12 is about the cost of a 4.10 assembly. I guess the labor would put it over the top. So the gear swap is the way to go I guess.

Guest

I see a group purchase on the General board. :grouphug: