Question about gears

88GT 5pt0 · 01-13-2004, 01:14 AM

Does anyone know who makes 3:90 gears? I saw them somewhere before but can't remember where. Also I used to have an 85mph speedo but I put reverse glow gauges on and took it to a place by my house to have it changed to 140mph but it's still 5 mph off, so if I get a 3:90, or end up getting a 3:73 what should I do to make the speedo accurate?

ArtMan · 01-13-2004, 04:18 PM

Not sure but I think the 3.90 gear was used in 60s era Fords with the 9" rear end (like the Boss 302). I don't think this rear set is available for the 87-93 generation Mustang with the 8.8" rear.

For the 87-93 year Mustangs the speedo is set accurately (supposedly) by changing the drive gear in the speedo cable where it meets the transmission housing. These speedo gears are refered to by the number of teeth on them. I think the 23 tooth gear is for the 3.73s.

If you're saying that reinstalling the old speedo without a gear change still resulted in 5 mph error, you've got something else going on there. don't know.

PWR_RYD93 · 01-13-2004, 04:51 PM

Actually the Ford 9" differentials had a 3.89 ratio, but that's not available for the 8.8's. Basically your ratio choices are 3.55, 3.73, 4.10, 4.33, 4.56, and 4.88.

88GT 5pt0 · 01-13-2004, 05:31 PM

I have for sure seen 3:90 gears for 87-93's they are brand new

PWR_RYD93 · 01-13-2004, 05:53 PM

Do you know who makes them? I know Richmond and Ford Motorsports don't. Maybe Zoom?

Stang_Crazy · 01-13-2004, 09:23 PM

Somebody does because I have seen 3.90's as well.

andy669 · 01-13-2004, 09:47 PM

www.motivegear.com

Andy

429mustang · 01-14-2004, 08:07 AM

Anyone know if they make good gearsets? The 3.90's seem like a good size, I'd just hate to put them in and have them break/be noisy.

88GT 5pt0 · 01-29-2004, 04:27 AM

I knew I saw them somewhere, Pro 5.0 has them

01-13-2004, 01:14 AM	#1
88GT 5pt0 Registered Member Join Date: Jun 2003 Location: Chicago Posts: 73	Question about gears Does anyone know who makes 3:90 gears? I saw them somewhere before but can't remember where. Also I used to have an 85mph speedo but I put reverse glow gauges on and took it to a place by my house to have it changed to 140mph but it's still 5 mph off, so if I get a 3:90, or end up getting a 3:73 what should I do to make the speedo accurate? __________________ My Cardomain Website

01-13-2004, 04:18 PM	#2
ArtMan Registered Member Join Date: Dec 1998 Location: Scarsdale, NY Posts: 45	memories Not sure but I think the 3.90 gear was used in 60s era Fords with the 9" rear end (like the Boss 302). I don't think this rear set is available for the 87-93 generation Mustang with the 8.8" rear. For the 87-93 year Mustangs the speedo is set accurately (supposedly) by changing the drive gear in the speedo cable where it meets the transmission housing. These speedo gears are refered to by the number of teeth on them. I think the 23 tooth gear is for the 3.73s. If you're saying that reinstalling the old speedo without a gear change still resulted in 5 mph error, you've got something else going on there. don't know.

01-13-2004, 04:51 PM	#3
PWR_RYD93 Registered Member Join Date: Sep 1998 Location: IL Posts: 1,155	Actually the Ford 9" differentials had a 3.89 ratio, but that's not available for the 8.8's. Basically your ratio choices are 3.55, 3.73, 4.10, 4.33, 4.56, and 4.88. __________________ Craig Supercharged 93 GT "I drive way too fast to worry about cholesterol!" Then I went to the doctor.... whoa 312! Hello Lipitor

01-13-2004, 05:31 PM	#4
88GT 5pt0 Registered Member Join Date: Jun 2003 Location: Chicago Posts: 73	I have for sure seen 3:90 gears for 87-93's they are brand new __________________ My Cardomain Website

01-13-2004, 05:53 PM	#5
PWR_RYD93 Registered Member Join Date: Sep 1998 Location: IL Posts: 1,155	Do you know who makes them? I know Richmond and Ford Motorsports don't. Maybe Zoom? __________________ Craig Supercharged 93 GT "I drive way too fast to worry about cholesterol!" Then I went to the doctor.... whoa 312! Hello Lipitor

01-13-2004, 09:23 PM	#6
Stang_Crazy It's never clean enough! Join Date: Jan 1999 Location: Shaler, PA Posts: 1,542	Somebody does because I have seen 3.90's as well. __________________ ~Dan 2001 SVT Lightning 89' GT : Taking up garage space and waiting for a buyer... Rice Hater's Club - Member #11

01-13-2004, 09:47 PM	#7
andy669 Registered Member Join Date: Jan 2001 Location: Moline Il Posts: 901	www.motivegear.com Andy __________________ 88 coupe 91 LX NMRA Pure Street 5120

01-14-2004, 08:07 AM	#8
429mustang Registered Member Join Date: May 2001 Location: westerville, OH USA Posts: 618	Anyone know if they make good gearsets? The 3.90's seem like a good size, I'd just hate to put them in and have them break/be noisy. __________________ 1990 Notchback: BBK Ceramic Coated Full length headers, Dr. Gas 3"- 2 1/2" x-pipe, Flowmaster 40's/turndowns.

01-29-2004, 04:27 AM	#9
88GT 5pt0 Registered Member Join Date: Jun 2003 Location: Chicago Posts: 73	I knew I saw them somewhere, Pro 5.0 has them __________________ My Cardomain Website

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
how can you tell what size gears you have?	Kamaro Killer	Windsor Power	7	04-03-2002 02:55 PM
Odd Rice question	Coupe Devil	Blue Oval Lounge	9	03-04-2002 03:31 PM
power question	66StangGuy	Classic Mustangs	1	02-27-2002 06:55 PM
OIL for my new gears...	scale	Windsor Power	2	01-25-2002 01:52 AM
superchargers and gears... combo?	SCOTTLT79	Windsor Power	4	05-31-2001 08:55 PM