blueone Posted August 26, 2008 Report Share Posted August 26, 2008 I am about to order a K/B super charger from SPP for my 08 SGT and I wanted to order a 4.10 gear with it and have it all installed at one time but I noticed this note in the description for the 4.10 gear. 3.73 and higher gear ratios require a special carrier cross shaft to clear the larger diameter gears . Will my car require a special carrier cross shaft? Will the K/B kit come with everything that is needed for the install? I know that SPP can give all the answers I need but I would to like be prepared so I will ask the right questions before I call and place my order. Thanks, Jeff Link to comment Share on other sites More sharing options...
68fastback Posted August 27, 2008 Report Share Posted August 27, 2008 I am about to order a K/B super charger from SPP for my 08 SGT and I wanted to order a 4.10 gear with it and have it all installed at one time but I noticed this note in the description for the 4.10 gear. 3.73 and higher gear ratios require a special carrier cross shaft to clear the larger diameter gears . Will my car require a special carrier cross shaft? Will the K/B kit come with everything that is needed for the install? I know that SPP can give all the answers I need but I would to like be prepared so I will ask the right questions before I call and place my order. Thanks, Jeff I thought in the 8.8" the 4.10s are no problem -- there are plenty of folks running them in '07 and '08 MGTs, so SGT should be no problem, I would think. Is it possible you were looking at a page for a mustang with the 7.5" diff? Here's the link to the FRP gear-set page ...only clearance issue they note is the 5.14s requiring cover clearancing on the 8.8 The only thing I can possibly suppose if there is an issue is that the the axle-swap SAI did on the SGTs was to a non-standard 8.8 assembly ...which seems pretty unlikely. Dan Link to comment Share on other sites More sharing options...
RACERX009 Posted August 27, 2008 Report Share Posted August 27, 2008 I am about to order a K/B super charger from SPP for my 08 SGT and I wanted to order a 4.10 gear with it and have it all installed at one time but I noticed this note in the description for the 4.10 gear. 3.73 and higher gear ratios require a special carrier cross shaft to clear the larger diameter gears . Will my car require a special carrier cross shaft? Will the K/B kit come with everything that is needed for the install? I know that SPP can give all the answers I need but I would to like be prepared so I will ask the right questions before I call and place my order. Thanks, Jeff I had 373 gears installed by ford dealer with no problems Link to comment Share on other sites More sharing options...
LuLu Posted August 27, 2008 Report Share Posted August 27, 2008 I am about to order a K/B super charger from SPP for my 08 SGT and I wanted to order a 4.10 gear with it and have it all installed at one time but I noticed this note in the description for the 4.10 gear. 3.73 and higher gear ratios require a special carrier cross shaft to clear the larger diameter gears . Will my car require a special carrier cross shaft? Will the K/B kit come with everything that is needed for the install? I know that SPP can give all the answers I need but I would to like be prepared so I will ask the right questions before I call and place my order. Thanks, Jeff IMHO...SPP and SAI would rather post disclaimers than do actual field research. I've been told by a trusted friend and FMC engineer that this combination is not a good mix of mods. 4:10s with a blower will leave you running around the neighborhood in 5th gear by 45 MPH due to tranny gearing. Thus, I suggest you pursue each mod independently. The tranny gearing on the Tremec 3650 manual 5 spd are rather "tall", and you may not appreciate the drive on local streets. For sure, 1st gear will be a short drive. Don't forget to upgrade the drive shaft and rear control arms. I suggest an adjustable upper rear control arm. One stop shopping? With regard to the added "cross shaft" question, it has been my experience that this is a problem (but, fixable) with 4:56 gears and taller. 4:10s slipped right into place on my 8.8" Marauder housings, 4:30s, likewise no hitch. Just to be safe, do these mods one at a time, eh? Best of luck to you. Link to comment Share on other sites More sharing options...
Torrence Posted August 27, 2008 Report Share Posted August 27, 2008 I get my car back Friday and I am having 4.10's installed + I have a whipple... I will let you know. I am changing from 3.90's which were great, but the gear whine was unbearable... Link to comment Share on other sites More sharing options...
shelbytexan Posted August 27, 2008 Report Share Posted August 27, 2008 i had thought about changing my gears to 390 but was told they whine because they are made by motive and knowone else makes them. i think i'll go with 410's also as 373's are to close to the 355's. Link to comment Share on other sites More sharing options...
TClark1976 Posted August 31, 2008 Report Share Posted August 31, 2008 I have read through a lot of information in several different threads about retuning and modifications. . . . . I have come to a question - Is it necessary to retune the EEC when you change to the 4:10 gears? If so, why and to what benefit?? Wouldn't it be simple to hypothesize that you are simply moving the rpm curve and not really 'changing' anything and thus would not need to retune?? Thank you in advance for advice and thoughts. Hope it's helpful to the originator of this thread aswell.................. Trevor Link to comment Share on other sites More sharing options...
68fastback Posted August 31, 2008 Report Share Posted August 31, 2008 I have read through a lot of information in several different threads about retuning and modifications. . . . . I have come to a question - Is it necessary to retune the EEC when you change to the 4:10 gears? If so, why and to what benefit?? Wouldn't it be simple to hypothesize that you are simply moving the rpm curve and not really 'changing' anything and thus would not need to retune?? Thank you in advance for advice and thoughts. Hope it's helpful to the originator of this thread aswell.................. Trevor Trevor, I don't think you need to retune at all for gears but you will need access to a 'tuner' or a cal-tool to correct for the gears so your speedo (and related functions) work right. I'm sure others can tell you exactly how they've done that. Dan Link to comment Share on other sites More sharing options...
LuLu Posted August 31, 2008 Report Share Posted August 31, 2008 If you do not retune the PCM to reflect the new gear ratio, 4:10s will show your speed to be faster than you are actually traveling. As I recall it, at 70 MPH, the speedo showed 78-80 MPH, but it's been a while. This isn't a serious problem to fix, but remember that until you do, you will be racking up mileage you haven't traveled. Technically, I would consider any correction to the PCM to be "retuning". Yes, a hand held programmer is required, but a dealership may be able to make the correction without that expense. Check around? As long as the tech making the correction adjusts the grar ratio only, there will not be any changes to your present tuning/performance specs. Link to comment Share on other sites More sharing options...
motorjock205 Posted August 31, 2008 Report Share Posted August 31, 2008 and the 4:10 gears won't whine??? I had 3:73 gears in my 96 GT, and I loved it...it had lots of low end grunt (Translated = very short time in 1st or 2nd gears when romping on it) but it was still decent on gas mileage on the highway runnin 80 MPH too...4:10 gears are going to KILL your gas mileage on the open road even with the over drive in 5th...and 1st and 2nd and probably 3rd are going to be very short hops when you get on it...I wouldn't go anything above a 3:73 with a S/C at all...I think you are defeating the purpose of the gears...the S/C will only add to a shortened engine life, because you're gonna over rev the engine several times at first, and it won't be long before you'll be replacing the engine...Just my $.02 worth... Link to comment Share on other sites More sharing options...
LuLu Posted August 31, 2008 Report Share Posted August 31, 2008 I had 3:73 gears in my 96 GT, and I loved it...it had lots of low end grunt (Translated = very short time in 1st or 2nd gears when romping on it) but it was still decent on gas mileage on the highway runnin 80 MPH too...4:10 gears are going to KILL your gas mileage on the open road even with the over drive in 5th...and 1st and 2nd and probably 3rd are going to be very short hops when you get on it...I wouldn't go anything above a 3:73 with a S/C at all...I think you are defeating the purpose of the gears...the S/C will only add to a shortened engine life, because you're gonna over rev the engine several times at first, and it won't be long before you'll be replacing the engine...Just my $.02 worth... This is very true. If anyone has plans to supercharge, wait on your gear change, or, you may be making another change down the road. Link to comment Share on other sites More sharing options...
blueone Posted August 31, 2008 Author Report Share Posted August 31, 2008 IMHO...SPP and SAI would rather post disclaimers than do actual field research. I've been told by a trusted friend and FMC engineer that this combination is not a good mix of mods. 4:10s with a blower will leave you running around the neighborhood in 5th gear by 45 MPH due to tranny gearing. Thus, I suggest you pursue each mod independently. The tranny gearing on the Tremec 3650 manual 5 spd are rather "tall", and you may not appreciate the drive on local streets. For sure, 1st gear will be a short drive. Don't forget to upgrade the drive shaft and rear control arms. I suggest an adjustable upper rear control arm. One stop shopping? With regard to the added "cross shaft" question, it has been my experience that this is a problem (but, fixable) with 4:56 gears and taller. 4:10s slipped right into place on my 8.8" Marauder housings, 4:30s, likewise no hitch. Just to be safe, do these mods one at a time, eh? Best of luck to you. I went ahead and ordered the s/c from SPP and decided to wait on the 4.10 gear after reading your reply,what you and motorjock had to say makes sense to me. After reading several post and checking around about the 4.10, the 3.73 seems to be a better choice for my uses. The main reason I wanted to get it all done at one time is that I did not realize that you could adjust the gear ratio without affecting the tune that came with the s/c. One at a time seems like a real good idea for a rookie like me. Thanks to everyone for your replies. Jeff Link to comment Share on other sites More sharing options...
LuLu Posted August 31, 2008 Report Share Posted August 31, 2008 I went ahead and ordered the s/c from SPP and decided to wait on the 4.10 gear after reading your reply,what you and motorjock had to say makes sense to me. After reading several post and checking around about the 4.10, the 3.73 seems to be a better choice for my uses. The main reason I wanted to get it all done at one time is that I did not realize that you could adjust the gear ratio without affecting the tune that came with the s/c. One at a time seems like a real good idea for a rookie like me.Thanks to everyone for your replies. Jeff You are welcome, sir. Remember that if you do not adjust the gear ratio in the PCM for the "taller" gear, the speedo and odo will run fast and report speed and mileage higher than you are traveling. This can be corrected. Can/will SPP provide you with a tune that includes 3:73 gears? If so, this would save you a step in achieving your goals. Link to comment Share on other sites More sharing options...
motorjock205 Posted September 2, 2008 Report Share Posted September 2, 2008 I went ahead and ordered the s/c from SPP and decided to wait on the 4.10 gear after reading your reply,what you and motorjock had to say makes sense to me. After reading several post and checking around about the 4.10, the 3.73 seems to be a better choice for my uses. The main reason I wanted to get it all done at one time is that I did not realize that you could adjust the gear ratio without affecting the tune that came with the s/c. One at a time seems like a real good idea for a rookie like me.Thanks to everyone for your replies. Jeff You may find that the 3:55 gears with the S/C is a perfect combo for you too...3:73 gears require some experience and 4:10 gears require even more...as far as I'm concerned, 4:10 gears or higher only belong on the race track and not on the street...3:73 is plenty for street/daily driver use in almost all applications...if you feel that the 3:55 gears just aren't getting you there fast enough, make the switch to 3:73's, but again, be careful for a while so you don't over rev the engine...remember, you were used to lower gearing and it taking just a tad longer to get where you will be much quicker now...You mentioned that one at a time seems like a real good idea for a rookie like you...well, I believe in taking small steps in the beginning, because the S/C is going to give you such a big grin in the first place, the gears would not even be noticed....one at a time is good...try it, you'll like it! Link to comment Share on other sites More sharing options...
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