3 tons Posted July 27, 2013 Report Share Posted July 27, 2013 I'm considering upping my rear axle ratio on my 200t GT with manual trans...At present, she's turning a cool 2k RPM at 70 mph, this considering that 4th gear is listed at 1.00 to 1.0 overdrive, and 5th gear (another O/D...) is a whopping 0.675 to 1.0. When passing (having double overdrives...) 5th gear seems waaay flat, while 4th gear is marginally better. Obviously, the 3.55 was chosen by Shelby with Federal CAFE ratings (low RPM's) in mind. (Note, I've also noticed that there was no $1k gas guzzler penalty for a stock Mustang GT). Either way, I'm now considering upfitting to a 3.73 or 4.10 (ford gears) or a 3.90 aftermarket. For those of you (w/manual trannies) that have switched axle ratios from the stock 3.55's, I would like to know what your highway RPM's are when cruising at a steady 70mph for your particular ratio? Much Appreciated! 3 tons Link to comment Share on other sites More sharing options...
Ecrissman Posted July 28, 2013 Report Share Posted July 28, 2013 I cant speak on the RPM for your specific car but I can tell you I always ran 3:91 or 4:10 in my bracket cars. If your not worried about gas mileage it adds excellent off the line grunt. I never considered them cruising gear in any of my cars, it also made a nice upgrade in my jeeps when I ran 35's or 38's tires on them. Link to comment Share on other sites More sharing options...
billltoole Posted July 28, 2013 Report Share Posted July 28, 2013 Next cruise I will get some data on the 3:73s I just installed. I wanted 4:10, however it appeared I was going to lose cruise control functionality with them. I went with 3:73s and a bama tune and it has really changed things for the better! I still second guess myself about not getting the 4:10s, but I do take the car on some long road trips and the cruise control does come in handy. Link to comment Share on other sites More sharing options...
MyBlueHeaven Posted July 29, 2013 Report Share Posted July 29, 2013 Next cruise I will get some data on the 3:73s I just installed. I wanted 4:10, however it appeared I was going to lose cruise control functionality with them. I went with 3:73s and a bama tune and it has really changed things for the better! I still second guess myself about not getting the 4:10s, but I do take the car on some long road trips and the cruise control does come in handy. Who told you that cruise control won't work with 4.10's? I have 4.10's with a manual trans and my cruise still works fine. I think you got some bad info Link to comment Share on other sites More sharing options...
SGT0128 Posted July 29, 2013 Report Share Posted July 29, 2013 I have 410's and my cruise workes just fine. I believe I'm around 2700 at 75-80 mph. It's really never been an issue at all. I highly recommend the 4.10 gear over 3.73. Link to comment Share on other sites More sharing options...
mwbgtb Posted July 29, 2013 Report Share Posted July 29, 2013 I had the 4.10's installed 6 months ago and never had a problem with the cruise control, When I am in 5th gear and hitting 70 mph, I am running about 2450 rpm's. I drive daily (300 miles per week) and lost about 2 mpg when going to work and back and that is a mix of city and highway.. Link to comment Share on other sites More sharing options...
billltoole Posted July 29, 2013 Report Share Posted July 29, 2013 Well I guess I am a dumb a**. It was on the frpp site so I believed them!! Here is the link http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=22362 NOTE: To maintain cruise control function on 2005-2010 Mustang automatic and manual transmissions, gear change is limited to equivalent of 5% higher or lower ratio (<+/-5% change). For example, a gear change from 3.55 to 3.73 results in a gear ratio reduction of 4.8% so cruise control will continue to operate normally. A gear ratio change from 3.55 to 4.11 results in a gear ratio reduction of 13.6% so cruise control operation is lost. Link to comment Share on other sites More sharing options...
3 tons Posted July 29, 2013 Author Report Share Posted July 29, 2013 Thanks for the really great ensight! At this point (though still somewhat in flux...) I'm leaning more towards the 3.73's primarily because of highway driving RPM's, and not wanting to shift out of 1st prematurely...My guess is (considering cost / benefit) that there should still be a fair bump in acceleration over 3.55's, enable 4th gear to no longer be 1.00 to 1.0 (thus, 4th no longer O/D), and still have O/D when in fifth, great for extended highway speeds. JMO, but still quite open to further council !! Best Regards Always, 3 tons Link to comment Share on other sites More sharing options...
ledfoot73 Posted July 30, 2013 Report Share Posted July 30, 2013 I've run 4:10's since my car had 2500 miles on it. I have 53k on it now. The 4:10's were the best mod I have done to it. I really can't imagine why anyone with a manual transmission Shelby GT would not want this gear. The overdrive gearing in the automatic with 3:73's runs about like the 4:10's with the manual transmission on the highway as a result of the taller overdrive gearing in the manual. I have to say that if I had not gone for the 4:10's, I really don't think I would have put 3:73 in it, the jump is just to small. A good portion of my driving is on the highway and it definitely is not over geared. Link to comment Share on other sites More sharing options...
old man Posted July 30, 2013 Report Share Posted July 30, 2013 I have 410's in my 07 automatic GTH. The cruise works fine, of course the car had a program adjustment for the speedometer reading. The gas mileage averages about 14 in the city, higher on the highway. I drove about 500 miles on a trip with no problems last year.The rpm is about 2500 on the highway at 70. The 410's really make a huge difference off the line. Link to comment Share on other sites More sharing options...
mywickedshelby Posted July 30, 2013 Report Share Posted July 30, 2013 have 4.10s in my SGT since 08.....best mod I ever did......love them......400 rpm increase.in 5th......cruise control works fine....too bad you got bad info on that..... 5th gear went from being dead to power anytime you need it......... good luck whatever you decide.... Link to comment Share on other sites More sharing options...
AndyGJ Posted July 30, 2013 Report Share Posted July 30, 2013 I'm looking to try the 3.73 in mine, but have not had the extra time or $$$ to get it to my installer. I hope to get it to him later this month for this upgrade, and looking to do the LCAs at the same time. I'll get before and after readings at 70 mph to let you know what I notice when done. Andy. Link to comment Share on other sites More sharing options...
3 tons Posted July 30, 2013 Author Report Share Posted July 30, 2013 FWIW, I caught on another thread (??) that the speed control issue was on the earlier generation, not on the S197. Link to comment Share on other sites More sharing options...
Kvin C Posted August 1, 2013 Report Share Posted August 1, 2013 At first, I wasn't going to reply here, because it just seems like piling on. Yet on the other hand, since this question comes up over and over (and over) again, perhaps it should be said again - go with the 4.10s!! It may sound exotic at first, but trust this naturally cautious old man........in reality, it ain't. In fact, it is a perfect and natural fit for the SGT, particularly if you haven't employed any other power-adders (i.e. supercharger or turbo). Do them, you absolutely will never regret it. Link to comment Share on other sites More sharing options...
3 tons Posted August 3, 2013 Author Report Share Posted August 3, 2013 Thanks again for all your input!....FWIW, I tried out driving on the freeway while at a steady 2,500rpm in 4th gear and found the rpms and noise to be quite acceptable - though I still have yet to decide (< >)... Link to comment Share on other sites More sharing options...
MyBlueHeaven Posted August 3, 2013 Report Share Posted August 3, 2013 Go with the 4.10's, you'll regret it if you don't, 3.73 = to close to the 3.55's. You can't beat the difference of the 4.10s, and I drive mine daily, mostly highway. Link to comment Share on other sites More sharing options...
SGT0128 Posted August 3, 2013 Report Share Posted August 3, 2013 Go with the 4.10's, you'll regret it if you don't, 3.73 = to close to the 3.55's. You can't beat the difference of the 4.10s, and I drive mine daily, mostly highway. Agreed. Link to comment Share on other sites More sharing options...
shelbytexan Posted August 8, 2013 Report Share Posted August 8, 2013 410's all the way. 373's are just to close to make a significant difference.There is no better mod for the money,period.I installed the 410's and it felt like I gained 50 h.p. I am now whipple s/c'd and I still enjoy the 410's. Who cares if you don't stay in 1st gear very long. You have to change gears sooner or later anyhow. Link to comment Share on other sites More sharing options...
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