Need opinion on gear ratios
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Joined: Jun 2002
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From: San Antonio Texas
Need opinion on gear ratios
Am going to change gear ratios and would like opinions from some people who have run these ratios. I have and LT4 with SLP Claw intake and Corsa cat back system. Am running 125 shot N20. Stock gears are 3.42's and was wanting to hear from 3.90 and 3.73 users. don't want to go to 4.10's because it is a daily driver. Last time at the track times ranged from 12.8 @ 115 mph to 12.5 @ 119.7 mph this was done on dunlop 5000 street tires.
Thanks in advance for the info and opinions.
[Modified by owensLT4, 11:17 PM 11/18/2002]
Thanks in advance for the info and opinions.
[Modified by owensLT4, 11:17 PM 11/18/2002]
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From: San Antonio Texas
Re: Need opinion on gear ratios (bogus)
Thanks for the reply. Drag raidals will be a must when the new gears are installed. Spinning alot now short time running from 2.1 to 2.35.
Elite Torch Red Member
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From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
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Re: Need opinion on gear ratios (owensLT4)
4.10's in the LT4 is not bad at all. I can't say from experience, but many people I have talked to that have 4.10 in theirs.
I still believe that the 3.45 is the best compromise for street/strip.
I was getting 1.93 60's out of my stock '95 on street tires.
I still believe that the 3.45 is the best compromise for street/strip.
I was getting 1.93 60's out of my stock '95 on street tires.
Instructor
Joined: Dec 2001
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From: Mobile al
Re: Need opinion on gear ratios (owensLT4)
Just a thought but if you go with the 4.10 in 6th will still give you less gear than a stock A4 with 3.07's in overdrive.
I have done the calculations a bunch of times.
I think that a 6 speed with 4.09/4.10 would be perfect.
Heck you could even hook the CAGS back up ;)
Just my .02
I have done the calculations a bunch of times.
I think that a 6 speed with 4.09/4.10 would be perfect.
Heck you could even hook the CAGS back up ;)
Just my .02
Le Mans Master
Joined: Jul 1999
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From: Phoenix AZ
Re: Need opinion on gear ratios (owensLT4)
I have 4.09's in my LT4, and it is a daily driver as well. I think they are great...almost a perfect ratio of the 6-speed. 75-80mph in 6th is just humming along at about 2100-2200...with stick manifolds and Corsas it's dead quiet. I'm sure you can find SOMEONE in TX that has 4.09's, give them a try, I think you'll like them!
Team Owner
Joined: Sep 2001
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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Re: Need opinion on gear ratios (Zix)
Most of these guys are running 4.10s in their LT1/4s and i havent seen anybody who didnt love them. You will really wake the engine up and most of them have dropped a couple tenths from just this mod.
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Joined: Jun 2002
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From: San Antonio Texas
Re: Need opinion on gear ratios (Jim Holbrook)
Thanks for all the replies. But is there anyone out there that has any knowledge of the 3.90's installed in a LT4/LT1 with 6M. With a 6200 rpm pill I am having to shift to 4th now before the 1/4 and I am afraid if I go to the 4.10's I will have to shift the 5th and don't really want to. My power is at the top end now ZO6's get me out of the hole but I can catch alot of them at the other end. (dyno's 418 rwhp 540 rwt).
Looking for more info please.
Looking for more info please.
Burning Brakes
Joined: Jan 2001
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From: Manhattan
Re: Need opinion on gear ratios (owensLT4)
this website may help. it calculate mph for gears and has the info for 6m corvettes. http://www.f-body.org/gears/
Le Mans Master
Joined: Jul 1999
Posts: 8,683
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From: Phoenix AZ
Re: Need opinion on gear ratios (owensLT4)
My power is at the top end now ZO6's get me out of the hole but I can catch alot of them at the other end. (dyno's 418 rwhp 540 rwt).
Looking for more info please.
Looking for more info please.
Elite Torch Red Member
Joined: Sep 1999
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From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
Cental/South NJ Events Coordinator
CI 1-2-3-4-5-6-7-8-9-10-11-12 Vet
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St. Jude Donor '03-'04-'05-'06-'07
Re: Need opinion on gear ratios (owensLT4)
This timeslip shows me(4477) vs Dave T from the forum(6960)
he has 3.92 gears in his 94 sixspeed.
At this time, the only mods he had were B&B Tri Flo and the 3.92 gears. I was stock.
he has 3.92 gears in his 94 sixspeed.
At this time, the only mods he had were B&B Tri Flo and the 3.92 gears. I was stock.
Safety Car
Joined: Sep 2000
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From: Hinckley Ohio
Re: Need opinion on gear ratios (owensLT4)
With 4.10 gears 6300 rpm will get you 115 MPH in 4th gear with OEM diameter tire. Using 6300 rpm as reference 3.90's=121mph, 3.72's=126.9mph, & 3.45's=137mph.
Since you are already running 119 mph with the 3.45's I would agree the 4.10's would be to low, assuming you don't won't to shift into 5th. Seems to me 3.72's would be your best choice.
For highway use even 4.10's are great, 2000 rpm = 73 mph in 6th. I only lost about 2mph on highway, and it is true this(4.10 in 6th) is less gear than the factory auto with performance ratio (3.07). So 3.72 or 3.90 will still be fine for the street.
Since you are already running 119 mph with the 3.45's I would agree the 4.10's would be to low, assuming you don't won't to shift into 5th. Seems to me 3.72's would be your best choice.
For highway use even 4.10's are great, 2000 rpm = 73 mph in 6th. I only lost about 2mph on highway, and it is true this(4.10 in 6th) is less gear than the factory auto with performance ratio (3.07). So 3.72 or 3.90 will still be fine for the street.
Racer
Joined: Jan 2002
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From: Cave Creek AZ
Re: Need opinion on gear ratios (owensLT4)
Assuming that you're using 26" diameter tires and shifting at 6300rpm, here are some approximate speeds.
w/ 3.73 gears you'll be running about 119mph at 6300 in 4th
w/ 3.90 gears you'll be running about 114mph at 6300 in 4th
w/ 4.10 gears you'll be running about 108mph at 6300 in 4th
for different tire sizes or different rpms you can simply do a ratio to figure out the speed. Hope this helps. :)
w/ 3.73 gears you'll be running about 119mph at 6300 in 4th
w/ 3.90 gears you'll be running about 114mph at 6300 in 4th
w/ 4.10 gears you'll be running about 108mph at 6300 in 4th
for different tire sizes or different rpms you can simply do a ratio to figure out the speed. Hope this helps. :)
Safety Car
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From: Hinckley Ohio
Re: Need opinion on gear ratios (lead_foot)
Leadfoot, I'm not sure why our numbers are different, you used 26 inch which off hand I don't know if this is correct or not, BUT the oem tire size on a 96 LT4 is 801 rev per mile per BFG web site. I am sure of my data as I have verified it with the speedo/tach in every gear before & after I put in the 4.10's.
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From: San Antonio Texas
Re: Need opinion on gear ratios (Zix)
One question was, what have I done?? The car is a stock LT4 convert. with a corsa cat back syaten and SLP claw intake. The one thing that makes a difference is the Nitrous. Am running a wet system with .055 nitrous jet and .029 fuel jet.
Racer
Joined: Jan 2002
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From: Cave Creek AZ
Re: Need opinion on gear ratios (LT4BUD)
ttt
What I did was use 60mph as a reference on my car. I have the 3.45 rear ratio. At 60mph the tach looks like I'm turning slightly under 3000rpm. I figured 2950. Of course the crumby tach that GM put in the Vette is not very easy to read. But I know that it's under 3000 rpm. I still have the original Goodyear GSC P285/40ZR17 tires that have a 25.9" diameter according to Goodyear's web site. So that's where I came up with the 26" number.
I then did a little spread sheet that calculates mph and rpm as you change any one parameter. Everything is just a simple ratio once you have a reference point. For example if you change the rear ration from 3.45 to 3.90 you speed in 4th at 2950 ( the number I used) is 3.45x60/3.9=53mph. For rpm you invert the ratio. I use my spread sheet as a rough estimator.
So I'm not sure why we're so different.
What rpm are you turning in 4th at 60mph? :)
What I did was use 60mph as a reference on my car. I have the 3.45 rear ratio. At 60mph the tach looks like I'm turning slightly under 3000rpm. I figured 2950. Of course the crumby tach that GM put in the Vette is not very easy to read. But I know that it's under 3000 rpm. I still have the original Goodyear GSC P285/40ZR17 tires that have a 25.9" diameter according to Goodyear's web site. So that's where I came up with the 26" number.
I then did a little spread sheet that calculates mph and rpm as you change any one parameter. Everything is just a simple ratio once you have a reference point. For example if you change the rear ration from 3.45 to 3.90 you speed in 4th at 2950 ( the number I used) is 3.45x60/3.9=53mph. For rpm you invert the ratio. I use my spread sheet as a rough estimator.
So I'm not sure why we're so different.
What rpm are you turning in 4th at 60mph? :)
Le Mans Master
Joined: Jul 2000
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From: OKC OK
Re: Need opinion on gear ratios (owensLT4)
If I was running NOS and it was my daily driver, I'd go with either 3.73 or the stock 3.45. You really don't want to shift into 5th gear while drag racing.
Melting Slicks
Joined: Apr 2002
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From: down that one road next to that big tree
Re: Need opinion on gear ratios (Mr Mojo)
a strong clutch and 4:10's are the hot ticket, with a 6spd and a very high 6th gear like the zf has a 4:10 isn't going to be all that bad for daily driving. some guy on here posted a link calculator to show tire size, gear ratio and rpms. a 4:10 has you going across the line at 6,000 or so in 4th, perfect :cool:
Safety Car
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From: Hinckley Ohio
Re: Need opinion on gear ratios (lead_foot)
Lead foot
I just checked "my" spreadsheet and it looks like with factory gears and tires you should be tacking 2765 rpm at 60mph in 4th gear. I would tack 3285 with my 4.10's.
I used 801 rev per mile in my calcs. from the BFG site. As you noted it would be pretty difficult to tell 2765 from 2950. You could use the 25.9" * pi / 12 to figure how many feet you would go in on tire revolution and then divide this into 5280 feet to see how many tire revs per mile.
In any event I don't think 4.10's would work if you limit engine revs to 6300 and use factory size tires since you would be limited to 115 mph in 4th. See my earlier post.
I just checked "my" spreadsheet and it looks like with factory gears and tires you should be tacking 2765 rpm at 60mph in 4th gear. I would tack 3285 with my 4.10's.
I used 801 rev per mile in my calcs. from the BFG site. As you noted it would be pretty difficult to tell 2765 from 2950. You could use the 25.9" * pi / 12 to figure how many feet you would go in on tire revolution and then divide this into 5280 feet to see how many tire revs per mile.
In any event I don't think 4.10's would work if you limit engine revs to 6300 and use factory size tires since you would be limited to 115 mph in 4th. See my earlier post.