ilmor Posted May 7, 2010 Report Share Posted May 7, 2010 Am I correct that if I change my rear gears from 3:55 to 4:10 that my RPM's in 5th gear will rise about 600 RPM? Link to comment Share on other sites More sharing options...
jmn444 Posted May 8, 2010 Report Share Posted May 8, 2010 calculator there's a bunch of these on the net, just measure your back tire hieght, find out what ratio 5th is on our cars, and plug in diff rear ratios to find out rpms at various speeds. I used this when picking a 3.80 for my '68 Link to comment Share on other sites More sharing options...
rush_junky Posted May 8, 2010 Report Share Posted May 8, 2010 ShelbyTexan (Ken) has 4:10 gears and he reads 2600 going 70. Link to comment Share on other sites More sharing options...
ilmor Posted May 8, 2010 Author Report Share Posted May 8, 2010 Thanks guys! Link to comment Share on other sites More sharing options...
RACERX009 Posted May 9, 2010 Report Share Posted May 9, 2010 Thanks guys! I did 3.73 and thinking now 4.10's would be alot better !!! Link to comment Share on other sites More sharing options...
ilmor Posted May 9, 2010 Author Report Share Posted May 9, 2010 I did 3.73 and thinking now 4.10's would be alot better !!! I've seen that said more than a few times. Link to comment Share on other sites More sharing options...
shelbytexan Posted May 9, 2010 Report Share Posted May 9, 2010 I've seen that said more than a few times. I installed the brenspeed tune,4 inch aluminum d.s. and jba shorty headers and these three items didn't even come close to doing what the 410's did for the car. I've said it before and i'll say it again,nothing does more for your car for the money than 410's. These gears put you in the rpm range you need to be in for great performance. I now have the whipple H.O. 550 on my car and the 410's aren't needed now but it certainly doesn't take long to get to 110mph. If you are n/a then you can't do any better than 410's. If you want the feel of 50 or more hp then these are the gears you need.5th gear will now turn into your new passing gear. Good Luck, Ken. Link to comment Share on other sites More sharing options...
stkjock Posted May 10, 2010 Report Share Posted May 10, 2010 Assuming stock tire size: Link to comment Share on other sites More sharing options...
ilmor Posted May 10, 2010 Author Report Share Posted May 10, 2010 Great chart! Thanks! Link to comment Share on other sites More sharing options...
sgt1020 Posted May 11, 2010 Report Share Posted May 11, 2010 Hey guys! I'm thinking about doing 4.10's in my car. Is it really worth it?? Also, will I have to have my speedometer re calibrated? Link to comment Share on other sites More sharing options...
stkjock Posted May 12, 2010 Report Share Posted May 12, 2010 Hey guys! I'm thinking about doing 4.10's in my car. Is it really worth it?? Also, will I have to have my speedometer re calibrated? yes and yes Link to comment Share on other sites More sharing options...
jmn444 Posted May 12, 2010 Report Share Posted May 12, 2010 yes and yes glad to see you are sticking around a little here! Link to comment Share on other sites More sharing options...
sgt1020 Posted May 12, 2010 Report Share Posted May 12, 2010 Will the 4.10's really kill my gas mileage? I am still naturally aspirated, but within 3 or 4 years I'm looking to have shelby put the SC package on it. I'll just put 3.73's in at the time if I do decide to get the SC. But a ton of people say 4.10's will eat gas if you drive above 65 on the highway. I do 80% city/town driving and maybe 20% highway driving. It is also not a Daily Driver. Worth it or not worth it? Link to comment Share on other sites More sharing options...
shelbytexan Posted May 13, 2010 Report Share Posted May 13, 2010 Will the 4.10's really kill my gas mileage? I am still naturally aspirated, but within 3 or 4 years I'm looking to have shelby put the SC package on it. I'll just put 3.73's in at the time if I do decide to get the SC. But a ton of people say 4.10's will eat gas if you drive above 65 on the highway. I do 80% city/town driving and maybe 20% highway driving. It is also not a Daily Driver. Worth it or not worth it? Well worth it. I lost about 2 miles per gallon with 410's. If you are doing town driving then you will have a whole lot more fun factor. I don't know of anyone who has wished they had kept there old gears..I have a s/c now and still love the gears. Link to comment Share on other sites More sharing options...
sgt1020 Posted May 13, 2010 Report Share Posted May 13, 2010 Sweet! Thanks for the advice! Link to comment Share on other sites More sharing options...
SGT3131 Posted May 13, 2010 Report Share Posted May 13, 2010 Well worth it. I lost about 2 miles per gallon with 410's. If you are doing town driving then you will have a whole lot more fun factor. I don't know of anyone who has wished they had kept there old gears..I have a s/c now and still love the gears. Hi Guys, I added the 4:10's last year and support all the positive comments I have read. The chart previously listed is pretty close to what I am seeing. I installed the whipple 55o back in Janurary and as mentioned I really do not need the 4;10's now however as mentioned you get there much quicker if you can keep the tire spin down. I love the combo as is. I checked my mileage 3 times over the past couple of weeks and I am averaging 18 or 19 miles to the gallon. That is running 75 to 100 mph for 60 miles each day (in a very safe enviorment) and about 30 miles a day in town driving and I usually get into it about 3 or 4 times during the day. Given the way I drive the car I think 18 to 19 is good. I can shift below 2200 rpms and not go over 70 and average 21 or 22 mpg. The 3 ot 4 miles per gallon I save by shifting at the lower rpm and staying below 70 is not worth the fun I have driving like it was built to be driven. Take Care, -Billy Link to comment Share on other sites More sharing options...
shelbytexan Posted May 16, 2010 Report Share Posted May 16, 2010 Hi Guys, I added the 4:10's last year and support all the positive comments I have read. The chart previously listed is pretty close to what I am seeing. I installed the whipple 55o back in Janurary and as mentioned I really do not need the 4;10's now however as mentioned you get there much quicker if you can keep the tire spin down. I love the combo as is. I checked my mileage 3 times over the past couple of weeks and I am averaging 18 or 19 miles to the gallon. That is running 75 to 100 mph for 60 miles each day (in a very safe enviorment) and about 30 miles a day in town driving and I usually get into it about 3 or 4 times during the day. Given the way I drive the car I think 18 to 19 is good. I can shift below 2200 rpms and not go over 70 and average 21 or 22 mpg. The 3 ot 4 miles per gallon I save by shifting at the lower rpm and staying below 70 is not worth the fun I have driving like it was built to be driven. Take Care, -Billy My sentiments exactly. It's a Shelby,have fun with it. Link to comment Share on other sites More sharing options...
LuLu Posted May 16, 2010 Report Share Posted May 16, 2010 4:10s will launch you away from the stop light fairly quick, and this is cool when driving the "stop light Gran-Prix" on a Saturday night. But, I'm a "top end" fan/freak too, so, I'm sticking with the stock 3:55s because I love top end speed. Nothing more fun (for me) than burrying the speedo into "oh shit" territory (on the appropriate roads, of course). LuLu's new engine spins over 7500 RPM with the parasitic loss included, and without breaking a sweat getting it done either, do the math. She broke 150 MPH on a DynoJet dyno, and I can't give that up. Real time road travel will be a lot less, but I know she can do it. Yup...410s will give you a much improved launch, but you loose out on the top end and I don't want to give this up. BTW...I still get 30+ MPG while cruising at posted speed limits on the highway. Neat...Eh? Link to comment Share on other sites More sharing options...
ilmor Posted May 16, 2010 Author Report Share Posted May 16, 2010 4:10s will launch you away from the stop light fairly quick, and this is cool when driving the "stop light Gran-Prix" on a Saturday night. But, I'm a "top end" fan/freak too, so, I'm sticking with the stock 3:55s because I love top end speed. Nothing more fun (for me) than burrying the speedo into "oh shit" territory (on the appropriate roads, of course). LuLu's new engine spins over 7500 RPM with the parasitic loss included, and without breaking a sweat getting it done either, do the math. She broke 150 MPH on a DynoJet dyno, and I can't give that up. Real time road travel will be a lot less, but I know she can do it. Yup...410s will give you a much improved launch, but you loose out on the top end and I don't want to give this up. BTW...I still get 30+ MPG while cruising at posted speed limits on the highway. Neat...Eh? All good points, and some of the reasons why I don't know if I'll ever make up my mind on this one. About top speed, however, if I lived somewhere (besides CT) where I could actually achieve top speed that would be more of a factor in the decision. At the same time, I like the nice sound of the 4.6 when cruising the interstates w/ the 3:55 gearing, as well as the mileage. I don't really want to give up 2 mpg, but then again I don't even put 3000 miles per year on the SGT. On rare occasion I do get to an autocross or a track day. I suppose that the 4:10's would get me around both tracks (esp. autocross) a bit quicker, however the 3:55 setup has performed well. I never do any drag racing, only because there are no dragways w/in a reasonable distance from me. Maybe the best thing to do is just put this decision off and keep saving for something else! Link to comment Share on other sites More sharing options...
i8acobra Posted May 16, 2010 Report Share Posted May 16, 2010 Looking at the chart posted above, I wouldn't run 4.10's if you like to drag race. 4.10's are going to require a shift to 4th to get through the 1/4. A shift in a manual tranny car will usually cost you 2 or 3 tenths. I'd stick with 3.73's. I have 3.31's now and am planning on going to 3.55's. With the 3.31's, I'm not even close to hitting 4th in the 1/4. My goal is to pick a rear gear that will have me around 6,500 to 6,800 rpm in 3rd at the end of a 1/4 mile. Link to comment Share on other sites More sharing options...
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