Final drive changing questions.
#1
Senior Member
Thread Starter
Join Date: Aug 2002
Location: Morgan County, Indiana
Posts: 653
Likes: 0
Received 0 Likes
on
0 Posts
Final drive changing questions.
Hey i have an automatic n/a s5 1990 gxl, I would like some info on changing the hoghead to a 5spd manuals, because the automatic has a 3.69 gear and the manual has a 4.11 gear, i would like to know how many mph ill lose on the topend. Currently i can do 140mph.
#2
Rabbit hole specialist
iTrader: (11)
The auto is a 3.9, the manual is a 4.1.
Doing the calculations for a stock FC with 205/60-15 tires and holding at 7000 RPM (autos redline at 7k, right?) in a direct drive gear (1:1, which is third for an auto), we get:
3.9 Final drive - 131 mph
4.1 Final drive - 125 mph
So, you could lose about 5 mph. Keep in mind these calculations are rough estimates, speeds probably won't be exactly as given due to A LOT of other variables.
Doing the calculations for a stock FC with 205/60-15 tires and holding at 7000 RPM (autos redline at 7k, right?) in a direct drive gear (1:1, which is third for an auto), we get:
3.9 Final drive - 131 mph
4.1 Final drive - 125 mph
So, you could lose about 5 mph. Keep in mind these calculations are rough estimates, speeds probably won't be exactly as given due to A LOT of other variables.
#6
What Subscription?
Join Date: Apr 2001
Location: Aiken SC USA
Posts: 5,926
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by JerryLH3
All manuals had a final drive ratio of 4.1:1, but obviously the actual differential varied between model and year (LSD, open, clutch, viscous).
Autos had the 3.909:1, but auto verts had the 4.1:1.
All manuals had a final drive ratio of 4.1:1, but obviously the actual differential varied between model and year (LSD, open, clutch, viscous).
Autos had the 3.909:1, but auto verts had the 4.1:1.
Wrong, read my post above yours
Trending Topics
#14
Do a barrel roll!
iTrader: (4)
Yes....thats what Im saying. Just buy a 4.1 LSD rear end for around $150. And if you're serious about making your car fast, just bite the bullet and do a 5-speed swap. The auto tranny makes the FC an absolute slug, pretty much no matter what you do excluding a full custom tranny/converter setup.
#15
Senior Member
Thread Starter
Join Date: Aug 2002
Location: Morgan County, Indiana
Posts: 653
Likes: 0
Received 0 Likes
on
0 Posts
im not a brain surgeon, i cant do that kinda stuff, i can change rearends, but in the end even a n/a 5spd isnt fast, 15.3 isnt fast at all.
#20
To make your auto as fast as a manual you will need to spend alot more time and money than just swapping in a 5-spd. Besides while you are in there you can add an aftermarket clutch and put some Redline or other sythetic gear lube in there.
#21
89-91 Auto came with a 4.1 check mazdatrix website here: http://www.mazdatrix.com/g5.htmRX-7
Stock Rear Axle Ratios
Year / Model Ratio
79-82 3.909
83-84 12A 3.933
84-85 13B GSLSE 4.076
85 12A 3.909
86-88 5-spd All 4.10
86-88 Automatic 3.909
89-92 Turbo 4.10
89-92 non-turbo, non LSD 4.10
89-90 non-turbo, viscous LSD, "GTUs" only 4.30
93-95 w/manual trans 4.10
93-95 w/automatic trans 3.909
Stock Rear Axle Ratios
Year / Model Ratio
79-82 3.909
83-84 12A 3.933
84-85 13B GSLSE 4.076
85 12A 3.909
86-88 5-spd All 4.10
86-88 Automatic 3.909
89-92 Turbo 4.10
89-92 non-turbo, non LSD 4.10
89-90 non-turbo, viscous LSD, "GTUs" only 4.30
93-95 w/manual trans 4.10
93-95 w/automatic trans 3.909
#22
Rabbit hole specialist
iTrader: (11)
Originally posted by black7
89-91 Auto came with a 4.1 check mazdatrix website here: http://www.mazdatrix.com/g5.htmRX-7
89-91 Auto came with a 4.1 check mazdatrix website here: http://www.mazdatrix.com/g5.htmRX-7
Jerry
#25
Senior Member
Thread Starter
Join Date: Aug 2002
Location: Morgan County, Indiana
Posts: 653
Likes: 0
Received 0 Likes
on
0 Posts
ok im confused, whoes telling the truth?.... and btw, i can afford a larg amount of money spent over a larg amount of time, just cant afford something huge all at once.