F23 & F40 thoughts - Transmission Forum

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F23 & F40 thoughts
Monday, December 07, 2009 6:53 PM
F40
1-3.77
2-2.04
3-1.32
4-.95
5-.76
6-.62
Final Drive 3.55
F23
1-3.58
2-2.02
3-1.35
4-.98
5-.69
Final Drive 3.94

so heres what i was thinking how can i make first a little more useable with this much more power. obviously the F23 is gear for a cavalier 4 cylinder and not the 3800 but the F40 came on the 3900 and it makes basicly the same power so
"IF" i took the 1st gear from a F40 and replaced my F23 1st and kept everything else the same i would slow my 1st gear down which would give me a little more out of it. correct????? right now first is pretty much usless and all the other gears are close enough to not worry about

is my hours of pondering and checking ratios and combos worth looking more into??? i was thinking of ordering a 1st gear for an F40 from GM and then ordering an LSD and havign them both installed ito a F23.

what do the transmission guys on here think am i in the right direction or am i missing something




JBO since July 30, 2001

Re: F23 & F40 thoughts
Monday, December 07, 2009 7:01 PM
Quote:

what do the transmission guys on here think am i in the right direction or am i missing something


will the guts from one physically fit the other?

IDK about the F40, but the F23 and F35 have almost nothing in common.. the guts are completely different.





Re: F23 & F40 thoughts
Monday, December 07, 2009 7:34 PM
Even if it will physically fit all you have to do is look at the ratios...

3.77 is a shorter gear than 3.58, to make first more "useable" with more power you want to move first to a longer gear, so you need to find a gearset that has a ratio that is < 3.58

Put it this way, a gear ratio is a measure of the difference between the outside diameters of two gears...if the ratio is high then there is either a high torque multiplication or a high RPM multiplication depending on which gear is being driven. The reason first gear is not useable in our cars when torque output is high is because there is a very high torque multiplication in first gear. So as stated before, if the F23 first is 3.58, you need to drop to a 3.30 or 3.00 ratio to reduce torque multiplication and extend the useful MPH range.



Buildin' n' Boostin for 08' - Alex Richards
Re: F23 & F40 thoughts
Tuesday, December 08, 2009 4:06 AM
if ur lookin for more options for f40 gearsm the mini type s uses the f40 and saab uses a awd f40.
Re: F23 & F40 thoughts
Tuesday, December 08, 2009 3:31 PM
I thought a 3.77 would be a toller gear and according to the calculators if i increase the ratio it will runn slower like if i used a 3.30 i would be 34mph at 6000 but with a 3.77 i'm 29mph at 6000?????

this is something i was goin to look into, see if i can get a gear from the dealer see if they can order it in if its what i need buy it if its not then send it back, they have done that for me in the past, i'm not 100% if it will work it was something i'm looking at



JBO since July 30, 2001
Re: F23 & F40 thoughts
Tuesday, December 08, 2009 4:37 PM
NOTa2_4 wrote:

I thought a 3.77 would be a toller gear and according to the calculators if i increase the ratio it will runn slower like if i used a 3.30 i would be 34mph at 6000 but with a 3.77 i'm 29mph at 6000?????

this is something i was goin to look into, see if i can get a gear from the dealer see if they can order it in if its what i need buy it if its not then send it back, they have done that for me in the past, i'm not 100% if it will work it w26.as something i'm looking at


Exactly, the RPM output from Input shaft to output shaft falls, which means torque multiplication increases...It works like this...

3.58 = say I'm making 100TQ @ 100RPM and the 3.58 ratio which is taking the driven gear and dividing the teeth by the teeth on the driving gear would result in torque multiplication since the smaller gear is driving the larger one and a drop in output RPM...therefore...

Output = Input torque * Ratio
Output = Input RPM / Ratio

100Ft/lb * 3.58 = 358ft/lb output
100RPM / 3.58 = 27.93RPM output

now with a 3.77 gear...

100Ft/lb * 3.77 = 377ft/lb output
100RPM / 3.77 = 26.52RPM output

So if your talking about making first more usuable you want to lengthen the gear, in other words you want to reduce the amount of torque multiplication...you can see we make 19 more ft/lbs out of the same input torque by using a 3.77 gear however the shaft ends up turning just over 1 RPM slower than with a 3.58.

IF your spinning in first and want to eliminate that possibility and bring first closer to second...you need to reduce torque multiplication...in doing so you WILL be able to go faster in MPH in first gear before having to shift.

understand?







Buildin' n' Boostin for 08' - Alex Richards
Re: F23 & F40 thoughts
Tuesday, December 08, 2009 4:46 PM
ok i gotcha now so basicly the opisite to what i was thinking so
so PJ says the F35 is way different then like internals like is everything different cause the if we can mix and match gears from that it may work the way i need it too.

may have to compare some parts that way they





JBO since July 30, 2001
Re: F23 & F40 thoughts
Thursday, December 10, 2009 6:22 PM
how much would a custom gear be? i would try for something closer to low 3's(3.33ish)...of course, i know pretty much nothing, so, you probably shouldn't do that, lol...just what kinda makes sense to me...but i have no idea what kind of calculations have to go into it.
Re: F23 & F40 thoughts
Thursday, December 10, 2009 7:57 PM
A 3.2XX ratio would be adequate and would give you what you needed. The first and last numbers after the decimal being partially controlled by what physically fits in the case. The problem is not cutting one gear, you need a pair of them cut and designed to fit in that application...not cheap by any means, but if you really are looking for a killer trans...you might as well...



Buildin' n' Boostin for 08' - Alex Richards
Re: F23 & F40 thoughts
Thursday, December 10, 2009 10:48 PM
Your efforts would be better spent changing out the FDR which you CAN do.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Re: F23 & F40 thoughts
Thursday, December 10, 2009 11:53 PM
Joshua Dearman wrote:

Your efforts would be better spent changing out the FDR which you CAN do.


While this would be a very viable and easy option it would still not change the horrible gap between first and second...making first more usable by reducing the gear ratio to bring it closer to 2nd would make the 1-2 shift much more natural as well as making first more usable...

Just my .02 FDR changes everything but does nothing for the gear changes themselves.



Buildin' n' Boostin for 08' - Alex Richards

Re: F23 & F40 thoughts
Friday, December 11, 2009 5:33 AM
sure, but both gears can use some taming IMO, but this talk of changing 1st is pretty much useless....but changing an FDR is very possible.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Re: F23 & F40 thoughts
Sunday, December 13, 2009 12:54 PM
so with the stock j body tire size and the stock trans gears and FDR at 6000rpm your speed would be (mph)
1-30
2-54
3-81
4-111
5-158

now with the stock j body tire size and the 3.38 1st gear out of the cobalt F35 and stock FDR at 6000rpm your speed would be (mph)
1-32
2-54
3-81
4-111
5-158

changing the FDR to the F40 3.55with the 3.38 1st gear from a F35 and stock F23 2,3,4,5
1-36
2-60
3-89
4-123
5-175

thinkin i might like the looks of this 3rd option



JBO since July 30, 2001
Re: F23 & F40 thoughts
Sunday, December 13, 2009 4:47 PM
I'd probly still save the F23 1st and just do the FDR...it's the "best bang for your buck" change.

Call it Fourth Option: Stock F23 1st-5th w/ F40's FDR

1-34
2-60
3-89
4-123
5-175




Edited 2 time(s). Last edited Sunday, December 13, 2009 4:53 PM

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Re: F23 & F40 thoughts
Tuesday, December 15, 2009 8:22 PM
i WANT that fd, 123 @6k would be AWESOME, right now when i went threw the traps at 135 i was damn close to the rev. limitor in 4th at 7200rpm...




R.I.P. Brian Klocke, you will never be forgotten
Re: F23 & F40 thoughts
Saturday, December 19, 2009 11:28 PM
So in theory, If one wanted shorter/longer gearing really cheap it could be achieved by changing the size of ones tires? For instance, if I wanted shorter gears and Im running a 205/55R16 tire. I could change to a 205/40R16 tire to achieve this. Is this correct? This isnt exactly what anyone is getting at I know but the thought hit my mind and it could be used in this situation to save money.
Re: F23 & F40 thoughts
Sunday, December 20, 2009 9:45 AM
Ethan Duke wrote:

So in theory, If one wanted shorter/longer gearing really cheap it could be achieved by changing the size of ones tires? For instance, if I wanted shorter gears and Im running a 205/55R16 tire. I could change to a 205/40R16 tire to achieve this. Is this correct? This isnt exactly what anyone is getting at I know but the thought hit my mind and it could be used in this situation to save money.


Yes because a 40R16 is smaller in diameter than a 55R16 you will rev higher for the same speed yes. Your speedo will be off however and will read higher than normal.



Buildin' n' Boostin for 08' - Alex Richards
Re: F23 & F40 thoughts
Sunday, December 20, 2009 12:54 PM
How's does one fix this problem
Re: F23 & F40 thoughts
Sunday, December 20, 2009 1:32 PM
You don't(at least on our cars), this is a big reason why actually changing gearing is the way most people adjust their gearing. Actually there is a way but it would require more work than changing gears.

EDIT: unless HPT can, but I know nothing about HPT.




Edited 1 time(s). Last edited Sunday, December 20, 2009 1:33 PM

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Re: F23 & F40 thoughts
Tuesday, December 22, 2009 7:02 PM
your limited to how big of tire you can go and not to mention to small you loose grip as theres less flex in the sidewall which accually helps the tires bite into the track. i got part break downs but the pictures are showing the F40 final drive gear holds on with 10 bolts and hte F23 uses 12might have to tear apart an F23 and see what i can come up with as also looking at getting the LSD from an F35



JBO since July 30, 2001
Re: F23 & F40 thoughts
Tuesday, December 22, 2009 9:02 PM
NOTa2_4 wrote:

your limited to how big of tire you can go and not to mention to small you loose grip as theres less flex in the sidewall which accually helps the tires bite into the track. i got part break downs but the pictures are showing the F40 final drive gear holds on with 10 bolts and hte F23 uses 12might have to tear apart an F23 and see what i can come up with as also looking at getting the LSD from an F35


Interesting, if we might have to re-drill the flange bolt pattern on the diff...it would be relatively easily done.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Re: F23 & F40 thoughts
Thursday, December 24, 2009 7:06 PM
i might go price this out for the gear but with that many bolts and buy the look of the picture there wouldn't be enough space to re drill anything without weakening the part and the diff is the last thing you wanna weaken. obviously a picture may not be exact but thats currently what i'm workin on



JBO since July 30, 2001
Re: F23 & F40 thoughts
Friday, December 25, 2009 8:02 AM
Yeah, gotta wonder how much gear would be left with all those holes in it........


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Re: F23 & F40 thoughts
Saturday, December 26, 2009 8:34 AM
the only way to make a 10 bolt gear fit a 12 would be to weld every hole shut and re drillem all but then you will effect the strength of the gear itself there would be a bunch of weaker points and i think its reliablity would be worse then an isuzu trans

according to my sheets i have (god i need all 3 transmissions in front of me) but if the LSD diff from the F35 will fit in a F23 then the F40 final drive should fit on there both the same bolt pattern from what i can see. might go hunt down a couple core transmissions

then you would get the advantage of the gear change and a factory LSD option

i think i'm gonna make this a project to continue to look at if anyone has an F35 diff out post up some pics for me i have access to a F23 just don't wanna pull it apart until i need to as its in good shape



JBO since July 30, 2001
Re: F23 & F40 thoughts
Tuesday, December 29, 2009 6:26 PM
Listening and subscribed.


Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!





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