View Poll Results: 6spd LT1 with bolt ons: Which gears for 1/4 mile?
Stock 3:42
1
2.70%
3:73
12
32.43%
4:10
24
64.86%
Voters: 37. You may not vote on this poll
3:73 or 4:10 Rear gears: Lets Debate
10-17-2006, 02:48 PM
#1
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3:73 or 4:10 Rear gears: Lets Debate
Im sure this has been asked before but lets hash it all back up. Gears are an expensive mod so I want to make the right decision.
6spd car with stock 3:42's, It will have normal bolt ons. Headers, catback, cold air, possibly some supsension. What will the best 1/4 mile gears be?
6spd car with stock 3:42's, It will have normal bolt ons. Headers, catback, cold air, possibly some supsension. What will the best 1/4 mile gears be?
10-17-2006, 03:34 PM
#2
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Re: 3:73 or 4:10 Rear gears: Lets Debate
4.10's without a doubt 
. Until you start running between ~112 - 115 mph, and you "run out of gear" (because of rev limit and stock ~26" tire size) then 4.10's are, no question, the best gear to run. They're the lowest, hence, best accelerating, and they'll run you through the traps near the top of 4th gear (right in the heart of your engine's power band). What's to argue? 
Now if you start running power adders, ie: nitrous, blower, turbo, etc., and you run speeds approaching ~120 mph and faster, then you need to re-think which ratio you run. But at that point, a simple increase in rev limiter can gain you more speed potential (assuming you have an engine BUILT to take it) and running 28" tires nets you more speed as well ... you can run into the 130's with 4.10's still, with the right RPM & tire combo.
I currently have a set of 3.90's waiting to go in my car (bought them when I first broke the 4.10's I had and my car was still an auto). I had a "theory" that blew up in my face
, thinking the 3.90's were going to be 39 / 10 teeth, ring / pinion respectively. Same way 4.10's are 41 / 10, ring / pinion. I "thought" that would make them stronger? 
As it turns out, they're actually 43 / 11 (now I'm not so sure about their strength?! 
) ... but hey, I'm one of only a few people to ever run 4.10's with an A4, so I guess I'll be a "pioneer" of these Motive 3.90's for the factory 10-bolt?
. Until you start running between ~112 - 115 mph, and you "run out of gear" (because of rev limit and stock ~26" tire size) then 4.10's are, no question, the best gear to run. They're the lowest, hence, best accelerating, and they'll run you through the traps near the top of 4th gear (right in the heart of your engine's power band). What's to argue? Now if you start running power adders, ie: nitrous, blower, turbo, etc., and you run speeds approaching ~120 mph and faster, then you need to re-think which ratio you run. But at that point, a simple increase in rev limiter can gain you more speed potential (assuming you have an engine BUILT to take it) and running 28" tires nets you more speed as well ... you can run into the 130's with 4.10's still, with the right RPM & tire combo.
I currently have a set of 3.90's waiting to go in my car (bought them when I first broke the 4.10's I had and my car was still an auto). I had a "theory" that blew up in my face
, thinking the 3.90's were going to be 39 / 10 teeth, ring / pinion respectively. Same way 4.10's are 41 / 10, ring / pinion. I "thought" that would make them stronger? As it turns out, they're actually 43 / 11 (now I'm not so sure about their strength?! ) ... but hey, I'm one of only a few people to ever run 4.10's with an A4, so I guess I'll be a "pioneer" of these Motive 3.90's for the factory 10-bolt?
10-17-2006, 06:45 PM
#3
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Re: 3:73 or 4:10 Rear gears: Lets Debate
what he said
I was going to run 4.10's but with a smaller tire I will be running out of gear on the top end with nitrous. I think I am either going to go with 28" tall tires and 4.10s or stay with 26" tall tires and go 3.73's
I was going to run 4.10's but with a smaller tire I will be running out of gear on the top end with nitrous. I think I am either going to go with 28" tall tires and 4.10s or stay with 26" tall tires and go 3.73's
10-17-2006, 09:02 PM
#4
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Re: 3:73 or 4:10 Rear gears: Lets Debate
Pete nailed it. The primary criteria for picking a gear for the 1/4m. is that you want to be pretty near the redline in 4th as you go through the traps. Of course, you also need to consider tire size, convetrer slip (in an automatic) etc. to pick the ratio. Your motor won't want to rev much past 5,600-5,700, so estimate your trap speed and go from there. I suspect optimum would be around 4.10 with a 26" tire. That would put you at ~105mph at 5,600rpm. A 3.90 would give you a little room to grow, but I don't think you can get 3.90's for a 10-bolt? Of course, you could use a taller tire as well.
Go here https://www.camaroz28.com/calcs/index.shtml for a simple calculator.
Rich
Go here https://www.camaroz28.com/calcs/index.shtml for a simple calculator.
Rich
10-17-2006, 10:33 PM
#5
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Re: 3:73 or 4:10 Rear gears: Lets Debate
Hey Rich, Motive actually DOES make a 3.90 for the factory 10-bolt! I've got a set in my garage right now! I believe they just started manufacturing them this year 
. The ones I got are "Made in Italy", and I "heard" that the Italian made Motives are the better quality ones? I guess we'll see once I get them installed, which will be over the winter when I have the car off the road 
.
I've got a set in my garage right now! I believe they just started manufacturing them this year . The ones I got are "Made in Italy", and I "heard" that the Italian made Motives are the better quality ones? I guess we'll see once I get them installed, which will be over the winter when I have the car off the road .
10-17-2006, 10:38 PM
#6
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Re: 3:73 or 4:10 Rear gears: Lets Debate
Pete I always thought 3:90's would be the best gears for these cars. I never thought they made them! Would you say then that 3:90's are the best or stick with your original decision of 4:10's?
10-18-2006, 03:34 AM
#7
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Re: 3:73 or 4:10 Rear gears: Lets Debate
Het Pete: thanks for the info. I'd say 3.90 would be great for a bolt-on type car. The quality of Italian industrial products follows a bimodal distribution. They are either great (think Ferrari) or not so great (think Fix It Again Tony). Funny that Fiat own Ferrari!
Rich
Rich
10-18-2006, 02:13 PM
#8
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Re: 3:73 or 4:10 Rear gears: Lets Debate
Auto car = 4.10's without a doubt. i ran a nice set of 4.10 motives in my 10 bolt until my first trip to the track which resulted in this video:
http://video.google.com/videoplay?do...40716999213136
blew 3 teeth on the ring a 3 on the pinion. hah it started as a chip in one of the ring gears teeth. got a 12 bolt with strange 4.10's in there now, shouldnt happen again ;-D
3.90 would put a little more use back into 1st gear, and a little less pickup in 5th and 6th. personally 4.10 is the way i'd always go, but as said before if you add forced induction, step it down in the gearing.
http://video.google.com/videoplay?do...40716999213136
blew 3 teeth on the ring a 3 on the pinion. hah it started as a chip in one of the ring gears teeth. got a 12 bolt with strange 4.10's in there now, shouldnt happen again ;-D
3.90 would put a little more use back into 1st gear, and a little less pickup in 5th and 6th. personally 4.10 is the way i'd always go, but as said before if you add forced induction, step it down in the gearing.
10-18-2006, 02:20 PM
#9
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Join Date: Jan 2006
Posts: 23
Re: 3:73 or 4:10 Rear gears: Lets Debate
Auto car = 4.10's without a doubt. i ran a nice set of 4.10 motives in my 10 bolt until my first trip to the track which resulted in this video:
http://video.google.com/videoplay?do...40716999213136
blew 3 teeth on the ring a 3 on the pinion. hah it started as a chip in one of the ring gears teeth. got a 12 bolt with strange 4.10's in there now, shouldnt happen again ;-D
3.90 would put a little more use back into 1st gear, and a little less pickup in 5th and 6th. personally 4.10 is the way i'd always go, but as said before if you add forced induction, step it down in the gearing.
http://video.google.com/videoplay?do...40716999213136
blew 3 teeth on the ring a 3 on the pinion. hah it started as a chip in one of the ring gears teeth. got a 12 bolt with strange 4.10's in there now, shouldnt happen again ;-D
3.90 would put a little more use back into 1st gear, and a little less pickup in 5th and 6th. personally 4.10 is the way i'd always go, but as said before if you add forced induction, step it down in the gearing.
Why did you do that?
10-18-2006, 02:29 PM
#10
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Re: 3:73 or 4:10 Rear gears: Lets Debate
Right now I'm running 3.23's (original gears to the diff that I had the 4.10's in). ANYTHING will be an improvement for me, and since I'm still just getting used to the 6-speed, and I've never driven one with 4.10's, I won't know how to compare except to say that "the 3.90's are great!
(aka: better) ".But I still maintain that the 4.10's are probably the best 1/4 mile gear, if that's what you're looking for. But let me add this disclaimer: *if your car is "relatively stock", just average bolt-ons, and you're not trapping extreme high speeds
*. Obviously then, as I mentioned, you will run out of gear, without compensating somehow.For me, I've gotten into road racing this summer (which is what led to my 4.10's breaking and my 4L60E burning up
) so at this point, I'm less concerned with 1/4 mile performance, and I'm just looking at "improving" my car's gearing. The 3.90's will certainly do that for me, and leave the car very streetable still (not that 4.10's WON'T, because until 3.90's were ever an option, 4.10's always were my first choice). And think about this ... even with 4.10's, in 6th gear, cruising around ~70 mph, the engine is turning ~1800 RPM, which is almost identical to an A4 w/2.73's in 4th gear (OD) !!! 
And yet you've got better acceleration across the board, and you'll still get better fuel mileage! 
10-18-2006, 03:20 PM
#11
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Location: Lawrence, KS, USA
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Re: 3:73 or 4:10 Rear gears: Lets Debate
I have an M6, and I'm pushing about 400hp with my current setup, and I currently prefer to run a 3.73 gear (I actually went back to them after installing 4.10's), but I chose this gear mostly because I liked what the cruising RPMs were in each gear. Once I rebuild the motor and slap on a turbo, I plan on dropping to a 3.42 (or numerically lower, depending on final power output) gear, in order to keep my trap speed RPMs in the peak of 4th gear...
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