Rear Gears - ZR-1 Net Registry Forums

HIZNHRZ · 09-22-2007

Okay, next questions for the experts. With roughly 425Hp and and 410ftlbs at the rear wheels, would you go with 3.90 rear gears or 4.10s?

I'm looking for a nice compromise between highway pleasure cruising and rear gears that optimize my engines Hp and torque numbers at the drag strip.

jonszr1 · 09-23-2007

I am about the same hp as you i have 410 but would go to 373s of i did it over took the 373s out of my yellow car thats stk and just loved them in the black car . if your looking for the best of both worlds thats what i would go with . 410s gas mileage goes down to 20 with 373s 24 -26. hope this helps

Aurora40 · 09-23-2007

I've thought 3.73:1's would be a nice gear also. And the speedo correction gear is like a $10 GM part vs a $140 custom part.

The only thing is 3.73:1 isn't a huge change. It costs the same for the gears as 4.10:1, and costs as much to install. But for less "improvement".

A 3.90:1 might be a good in-between. A fair amount of change, but not quite so gear-shortening as the 4.10's. I thought 3.90:1 gears were hard to find? Or maybe it was the speedo correction gears?

If you math it out on the LT5 vs the L98, with a 3.33:1 rear and a 5,500 rpm redline, to have the same shift points in MPH at 7,100 rpm, the LT5 should have a 4.30:1 rear end. In reality the L98 shifts earlier, giving it even shorter gear ranges than that.

Not sure what that is worth, though.

As an aside, guess you decided to go with the 500hp package?

jonszr1 · 09-23-2007

very nice and thought provocking post. heck i wish a gear vendors od wasnt so expencive. that would be the best of both worlds . put 430s in and have the gear vendors to reduce 22% to 335s now that would be cool plus you would have an 11 speed .it uses a timed selinoid to shift extreamly fast.wouldnt that freek people out . i can hear the shifts now

kenthompson · 09-23-2007

Quote:

Originally Posted by jonszr1

very nice and thought provocking post. heck i wish a gear vendors od wasnt so expencive. that would be the best of both worlds . put 430s in and have the gear vendors to reduce 22% to 335s now that would be cool plus you would have an 11 speed .it uses a timed selinoid to shift extreamly fast.wouldnt that freek people out . i can hear the shifts now

I have a GV unit that I'm thinking about selling. The adapter is for a 4l80e though. Do they make an adapter to a ZF 6 speed?

KT

HIZNHRZ · 09-23-2007

Bob,

I'm clearly leaning towards the top end package. While a stroker is the dream, I'm going to have to dream some more as I've got one more college education to bank role.

I've done the rear gear math and certainly have my own opinion. I've never been much of a drag racer but because my reflexes are not as sharp as they once were I'm not all that interested in track day at Summit Point unless I take a class or two. I feel like my stock ZR1s performance pushed me beyond what I was confident with.

With drag racing, I do'nt have a good feel for the time impact of shifting other than to say that every .01 of a second wasted is included in your timeslip. As far as gears, I'm looking for opinions based on a combination of theory and practical experience. I'm also not sure I'm following your cpmparison to a L98. You have both knowledge of the theory and practical experience; what does you gut tell you?

jonszr1 · 09-27-2007

[quote=kenthompson]I have a GV unit that I'm thinking about selling. The adapter is for a 4l80e though. Do they make an adapter to a ZF 6 speed?

I do believe they have an adapter for every tranny if you got a gearvendeor it might be fun to try it out on zr1. which unit do you have the deep sump ar the shallow sump. i believe an aparter run aprox 300. sure would be cool an 11 speed zr1 . mighjt have to have earl campbell leggs though

Tim · 09-26-2007

Wow, Great posts. Learned a lot. I went with 4.09:1 based mostly on the useability of 6 th gear at highway speeds as the rpms were so low I sometimes had to downshift to pass. I have not noticed much diff in milage. Plus I enjoy the pull in 1st and 2nd.

blackjack · 09-26-2007

when i changed my rear end ratio,my first choice was 3:90..because it wasnt readily available,i went with 4:10...and now with 2 summers of driving the z with the new ratio,i still would like to try the 3:90,as i find first gear almost useless...too much wheelspin,even with yokos avs sport...we must not forget that in the great white north,the asphalt is often colder than down south,except maybe for july and august,and spinning the tires is a lot easier on cool pavement...im also curious to know how the onboard computer figures my gas mileage,in relation with the gear change...is it lying to me??
i still get 25 mpg,according to the oracle.
bj
91/1735
ported plenum & ih
2.5'' exhaust with x pipe,no resonator
lucas injectors
haibeck chip

DaveK · 09-27-2007

Blackjack

I'm the same. Have 4.10s in mine and 1st is gone almost before you can think about it. I also get 24/25mpg usually.

I wouldn't think that the computer knows anything about the gears when it does the calculation - it's likely to be just simply miles travelled/fuel used.

The gear wouldn't affect that, unless you didn't do the odometer correction, in which case it would be sending too many pulses and recording more miles than were physically travelled.

09-22-2007	#1
HIZNHRZ Join Date: Apr 2004 Location: Germantown, MD Posts: 732	Rear Gears Okay, next questions for the experts. With roughly 425Hp and and 410ftlbs at the rear wheels, would you go with 3.90 rear gears or 4.10s? I'm looking for a nice compromise between highway pleasure cruising and rear gears that optimize my engines Hp and torque numbers at the drag strip.

09-23-2007	#2
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,406	Re: Rear Gears I am about the same hp as you i have 410 but would go to 373s of i did it over took the 373s out of my yellow car thats stk and just loved them in the black car . if your looking for the best of both worlds thats what i would go with . 410s gas mileage goes down to 20 with 373s 24 -26. hope this helps

09-23-2007	#3
Aurora40 Join Date: May 2005 Location: Leesburg, VA Posts: 2,704	Re: Rear Gears I've thought 3.73:1's would be a nice gear also. And the speedo correction gear is like a $10 GM part vs a $140 custom part. The only thing is 3.73:1 isn't a huge change. It costs the same for the gears as 4.10:1, and costs as much to install. But for less "improvement". A 3.90:1 might be a good in-between. A fair amount of change, but not quite so gear-shortening as the 4.10's. I thought 3.90:1 gears were hard to find? Or maybe it was the speedo correction gears? If you math it out on the LT5 vs the L98, with a 3.33:1 rear and a 5,500 rpm redline, to have the same shift points in MPH at 7,100 rpm, the LT5 should have a 4.30:1 rear end. In reality the L98 shifts earlier, giving it even shorter gear ranges than that. Not sure what that is worth, though. As an aside, guess you decided to go with the 500hp package?

09-23-2007	#4
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,406	Re: Rear Gears very nice and thought provocking post. heck i wish a gear vendors od wasnt so expencive. that would be the best of both worlds . put 430s in and have the gear vendors to reduce 22% to 335s now that would be cool plus you would have an 11 speed .it uses a timed selinoid to shift extreamly fast.wouldnt that freek people out . i can hear the shifts now

09-23-2007	#6
HIZNHRZ Join Date: Apr 2004 Location: Germantown, MD Posts: 732	Re: Rear Gears Bob, I'm clearly leaning towards the top end package. While a stroker is the dream, I'm going to have to dream some more as I've got one more college education to bank role. I've done the rear gear math and certainly have my own opinion. I've never been much of a drag racer but because my reflexes are not as sharp as they once were I'm not all that interested in track day at Summit Point unless I take a class or two. I feel like my stock ZR1s performance pushed me beyond what I was confident with. With drag racing, I do'nt have a good feel for the time impact of shifting other than to say that every .01 of a second wasted is included in your timeslip. As far as gears, I'm looking for opinions based on a combination of theory and practical experience. I'm also not sure I'm following your cpmparison to a L98. You have both knowledge of the theory and practical experience; what does you gut tell you?

09-27-2007	#7
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,406	Re: Rear Gears [quote=kenthompson]I have a GV unit that I'm thinking about selling. The adapter is for a 4l80e though. Do they make an adapter to a ZF 6 speed? I do believe they have an adapter for every tranny if you got a gearvendeor it might be fun to try it out on zr1. which unit do you have the deep sump ar the shallow sump. i believe an aparter run aprox 300. sure would be cool an 11 speed zr1 . mighjt have to have earl campbell leggs though

09-26-2007	#8
Tim Join Date: Aug 2004 Location: ND Posts: 87	Re: Rear Gears Wow, Great posts. Learned a lot. I went with 4.09:1 based mostly on the useability of 6 th gear at highway speeds as the rpms were so low I sometimes had to downshift to pass. I have not noticed much diff in milage. Plus I enjoy the pull in 1st and 2nd. __________________ THanks, Tim

09-26-2007	#9
blackjack Join Date: Aug 2005 Location: north of montreal Posts: 510	Re: Rear Gears when i changed my rear end ratio,my first choice was 3:90..because it wasnt readily available,i went with 4:10...and now with 2 summers of driving the z with the new ratio,i still would like to try the 3:90,as i find first gear almost useless...too much wheelspin,even with yokos avs sport...we must not forget that in the great white north,the asphalt is often colder than down south,except maybe for july and august,and spinning the tires is a lot easier on cool pavement...im also curious to know how the onboard computer figures my gas mileage,in relation with the gear change...is it lying to me?? i still get 25 mpg,according to the oracle. bj 91/1735 ported plenum & ih 2.5'' exhaust with x pipe,no resonator lucas injectors haibeck chip

09-27-2007	#10
DaveK Join Date: Jul 2004 Location: Sudbury, Ontario. Canada Posts: 1,537	Re: Rear Gears Blackjack I'm the same. Have 4.10s in mine and 1st is gone almost before you can think about it. I also get 24/25mpg usually. I wouldn't think that the computer knows anything about the gears when it does the calculation - it's likely to be just simply miles travelled/fuel used. The gear wouldn't affect that, unless you didn't do the odometer correction, in which case it would be sending too many pulses and recording more miles than were physically travelled. __________________ 1991 #1516 Black/Black davidmkelly.com Author of fast-paced, sci-fi thrillers.