Is it worth it...3.55 to 3.73?

MikeVistaBlue06 said:

Agree.



I went from 3.31 to 3.73 with my auto tranny and noticed a helluva difference.

BTW 4.10s in a manual transmission setup gives the same final drive ratio as 3.73s do in an automatic. Final drive ratio = high gear ratio x back end ratio.

Do not get the 3.90's. They are from Motive and they whine like hell based on everything I have read about them. Be sure to get FRPP gears from Ford as well.

All said: 4.10s for you are perfect.

Search gears as well for numerous discussions on this and the math.

Hope this helps.

Mike

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This actually brings up a question:

When you go from 3.31's to 3.73's (in my case, and of course with an auto trans), do you have to re tune the trans shift points/line pressures AND the speedo , or JUST the speedo? My local shop only mentioned changing the speedo setting, not any trans re tuning......now I'm wondering if things are set up right? Reason why I'm asking is because if its not shifting at the right times, maybe thats why I don't feel a big difference in the 331 to 373

I went from 355s to 373s. You do notice a little bit of a difference. It did feel stronger going from 3rd to fourth, max speed in third is about 103 mph. Top speed not sure, I have buried the needle a few times. If you are going to do a lot of 1/4 mile racing, give the 410s a shot.

ixtlan said:

Damn only had to edit like 10 times.

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Coulda just linked to this too...

JimmyD said:

This actually brings up a question:

When you go from 3.31's to 3.73's (in my case, and of course with an auto trans), do you have to re tune the trans shift points/line pressures AND the speedo , or JUST the speedo? My local shop only mentioned changing the speedo setting, not any trans re tuning......now I'm wondering if things are set up right? Reason why I'm asking is because if its not shifting at the right times, maybe thats why I don't feel a big difference in the 331 to 373

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You have to enter the new ratio into hte PCM so the speedo reads right, but you don't have to really change your shift points. You can of course and also add pressure to firm them up.

However, what I would recommend is that when you get your new gears in, and have a hand held tuner (like an SCT), then get a dyno tune and let the guy on the dyno tune the shiftpoints as well. Manny tuned some of mine on the highway with me as the passenger!

Hope this helps.

Mike

Dragon said:

Thanks for all the replies. I think that I will forget about the 3.73 gears and go with the CAI and tune first.

I will see how that goes and consider the 4.10. Just a little suspicious that those gears will make by car rev like crazy on the freeway.

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With stock tires you should turn about 2000 rpm @ 60mph with the 4.10s and 2600 @ 80mph.
If you want to see what your new RPM with 4.10s would be at a given freeway speed, then look at the tachometer reading as it is now and multiply it by (4.10 ÷ 3.31 = 1.24)

Hope this helps.

Mike

4.10's for the mother fucking win!!!!!

don_w said:

Coulda just linked to this too...

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The numbers on the OD ratios look a bit off to me....

A V8 Manual transmission has a 5th ratio of 0.68 while the automatic is 0.75. (that was in 2005, they may have changed now).

There is a calculator at the end of this link as well.

http://www.s197forum.com/forum/showthread.php?t=1758&highlight=gear+ratios

Hope this helps.

Mike

MikeVistaBlue06 said:

You have to enter the new ratio into hte PCM so the speedo reads right, but you don't have to really change your shift points. You can of course and also add pressure to firm them up.

However, what I would recommend is that when you get your new gears in, and have a hand held tuner (like an SCT), then get a dyno tune and let the guy on the dyno tune the shiftpoints as well. Manny tuned some of mine on the highway with me as the passenger!

Hope this helps.

Mike

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Thanks Mike, my local shop did the tune (SCT2 XCalibrator) before I had the gears, then after he put the gears in, changed for the correct speedo reading. He doesn't have a dyno, so I scheduled dyno time with JDM next month to dial in my tune.

MikeVistaBlue06 said:

The numbers on the OD ratios look a bit off to me....

A V8 Manual transmission has a 5th ratio of 0.68 while the automatic is 0.75. (that was in 2005, they may have changed now).

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I got them directly from the 2005 Ford spec sheet...

don_w said:

Coulda just linked to this too...

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It is linked to the same sheet.
Wonderin where I got that at.
Musta been yours eh?

ixtlan said:

It is linked to the same sheet.
Wonderin where I got that at.
Musta been yours eh?

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Yep, 'tis mine.

Thats one FINE spread sheet yaz made there.
Handy as hell.

It is a great spreadsheet. I saved it to my desk top!

Sorry to be bringing this old thread up again......but I thought other member's may have made this mod in the time since.

That being said, do you guys still think going from 3.55 to 3.73 would be a waste or a small to non-noticable difference?

I have an 07 manual GT V8 with 3.55's and 275/40/18 at the rear wheels. I also have a Steeda Cold Air intake and SCT Tune and a x-pipe with mid-muffler race exhaust. (if that makes a difference).

Thanks in advance

RDCOUG said:

Sorry to be bringing this old thread up again......but I thought other member's may have made this mod in the time since.

That being said, do you guys still think going from 3.55 to 3.73 would be a waste or a small to non-noticable difference?

I have an 07 manual GT 4.6 with 275/40/18 at the rear wheels.


Thanks in advance

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IMO, yes it is a waste. My cousin had a S197 with identical mods as mine at the time except he had 3.73s and I had 3.55s. Could barely tell a difference in the two.

Unless you plan on going FI, go with 4.10s. If you have 3.55s now(which I assume you do) you will only add about 250rpm at 70mph in 5th gear. If you are worried about mpgs, don't be. Around town I did not see a drop in mpg at all. I never/very rarely drive on the intersat/hwy so I can not truthfully comment on that.

gafireman said:

IMO, yes it is a waste. My cousin had a S197 with identical mods as mine at the time except he had 3.73s and I had 3.55s. Could barely tell a difference in the two.

Unless you plan on going FI, go with 4.10s. If you have 3.55s now(which I assume you do) you will only add about 250rpm at 70mph in 5th gear. If you are worried about mpgs, don't be. Around town I did not see a drop in mpg at all. I never/very rarely drive on the intersat/hwy so I can not truthfully comment on that.

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So if you blown, like me, no to 4.10?

gafireman said:

IMO, yes it is a waste. My cousin had a S197 with identical mods as mine at the time except he had 3.73s and I had 3.55s. Could barely tell a difference in the two.

Unless you plan on going FI, go with 4.10s. If you have 3.55s now(which I assume you do) you will only add about 250rpm at 70mph in 5th gear. If you are worried about mpgs, don't be. Around town I did not see a drop in mpg at all. I never/very rarely drive on the intersat/hwy so I can not truthfully comment on that.

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I actually do drive quite a bit on the freeway/interstate and also definitely plan on some long tube headers, intake manifold and stage 1 cam's within the next year or so. I plan on staying naturally aspirated - no turbo or supercharger (i say that now of course).

Loots it is really up to you. Everyone has a different opnion but most supercharged guys run 3.73s or 3.55s and turbo guys run 3.55s or 3.31s(some run 4.10s with a centri to help it get in the boost faster). There are a lit if gear threads out there, do some searching and I am sure you will find the answer you are looking for.

RDCOUG said:

I actually do drive quite a bit on the freeway/interstate and also definitely plan on some long tube headers, intake manifold and stage 1 cam's within the next year or so. I plan on staying naturally aspirated - no turbo or supercharger (i say that now of course).

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Well, if you plan on changing cams, definitely go with 4.10s. I ran the 3.55s with my Hot Rods for a few months and let's just say it was far from ideal. The 4.10s just help get the car moving so much easier/quicker(not to mention it is much easier to drive). From what all the guys here have said you can expect to lose maybe 1-2 mpg on the hwy with 4.10s vs 3.55s. Not a bad tradeoff if you ask me!

USCav19D said:

If you ain't Cav, you ain't shit.

That being said, I'd say go with the 4.10s. A friend of mine has an 07 GT with 4.10 gears, and there's a big difference between that and my Bullitt.

The twin screw under the hood doesn't hurt either.

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I'm confused... "If you ain't Cav, you ain't shit." so.. "If you are Cav, you are shit."??

That being said, 4.10s are a great gear for daily driving and drag racing, but if you plan to do something like high performance driver education (HPDE) on a road course, a 3.55 is a much better gear. All depends on how you plan to drive your car. Light Fighter, Climb to Glory.

Gray Ghost GT said:

I'm confused... "If you ain't Cav, you ain't shit." so.. "If you are Cav, you are shit."??

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Uh that post was made in 2008.....

Mike