F23 trans swap? (Page 1/2)
fierogt28 JUN 30, 12:29 AM
Those that are installing F23 trans swaps, are you choosing the 3.84 ratio unit?

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

ericjon262 JUN 30, 01:01 AM
you have ti with the metric bell housing, unless you're like me and a handful of others who swapped the metric bell onto the ecotec 3.63 gearset case.

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Will JUL 02, 09:36 AM

quote
Originally posted by fierogt28:

Those that are installing F23 trans swaps, are you choosing the 3.84 ratio unit?





The "metric" bellhousing F23 has a 3.94 ratio.
The Ecotec trans that followed has a 3.82 ratio.
The early Cobalt XFE transmission has a 3.73ish ratio.
The late Cobalt XFE trans has a 3.63 ratio.

Whether you keep the 3.94 or not would be a matter of preference for how you drive and your engine's powerband and torque delivery.
fierogt28 JUL 07, 10:48 PM
If we are talking about a 3800 S/C swap...ideal trans ratio would be? (most common)

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

pmbrunelle JUL 07, 11:29 PM

quote
Originally posted by fierogt28:
ideal trans ratio would be? (most common)



That's like asking the forum what clothes you should wear, what food you should eat, or what car you should drive.

Personal preference.

Edit to add a slightly less cryptic answer:
Use what you have now (2.8/Getrag) in conjunction with your imagination to help you pick ratios.

If you had the Getrag you have now, would you like the same gearing but with an engine having 70% more torque?
Are you happy with 1st gear today? How about with more torque?
Are you happy with 2nd gear today? How about with more torque?
Are you happy with 3rd gear today? How about with more torque?
Are you happy with 4th gear today? How about with more torque?
Are you happy with 5th gear today? How about with more torque?

If you like the existing gearing, keep the Getrag (possibly with a rebuild), or get something with similar ratios.

If you don't think you like your current gearing, then imagine if you would like each gear(1-2-3-4-5-(6)) to be shorter or taller. Then, find the gearbox that most closely matches your desires.

[This message has been edited by pmbrunelle (edited 07-07-2020).]

cam-a-lot JUL 08, 07:36 AM
I had an F23 with the 3.94 ratio and 3800 SC motor. Loved the tranny, hated the gearing. For that engine, I found the shifts to be far too short.

I like the stock Getrag gearing with the 3800 SC much more, but am concerned about the longevity and availability of parts for the 30+ year old Getrag, so if I do go ahead with an F23, I will be going with the 3.63 gear set.
La fiera JUL 08, 10:58 AM
I have the Metric 3.94 and it fits my engine's powerband very well, I'm very happy with it.
fierogt28 JUL 08, 11:18 PM

quote
Originally posted by pmbrunelle:


That's like asking the forum what clothes you should wear, what food you should eat, or what car you should drive.

Personal preference.

Edit to add a slightly less cryptic answer:
Use what you have now (2.8/Getrag) in conjunction with your imagination to help you pick ratios.

If you had the Getrag you have now, would you like the same gearing but with an engine having 70% more torque?
Are you happy with 1st gear today? How about with more torque?
Are you happy with 2nd gear today? How about with more torque?
Are you happy with 3rd gear today? How about with more torque?
Are you happy with 4th gear today? How about with more torque?
Are you happy with 5th gear today? How about with more torque?

If you like the existing gearing, keep the Getrag (possibly with a rebuild), or get something with similar ratios.

If you don't think you like your current gearing, then imagine if you would like each gear(1-2-3-4-5-(6)) to be shorter or taller. Then, find the gearbox that most closely matches your desires.




I was more concerned about the 3800 S/C project on how it would hold up with the F23 trans.
Since there is more replacement parts for the F23 out there than the stock getrag, its just an option.
Some people on the net have 6-10 or a batch of F23s for sale, just checking in to see what best option is best.

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. Beechwood interior, All original.

pmbrunelle JUL 09, 12:04 PM
As a general rule, taller gear ratios are better for transmission durability.

But considering that Justinbart made it into the ten-second club (quarter mile) with an F23 transmission, I think that a stock or lightly modified 3800SC should be no problem, regardless of the ratios.

I would pick the ratios based on the best feeling for the driving experience.
fierosound JUL 09, 01:38 PM

quote
Originally posted by pmbrunelle:

I would pick the ratios based on the best feeling for the driving experience.



Agreed.

But hard to do unless you can drive a buddy's car with same engine/transmission you are considering.

It's a real pain in the butt if you "guess wrong".


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