Would gears require changes to Speedo?

[Ted87GT]

One of the changes I am thinking about is new gears. Probably 3.55 or so. I would guess that means I also need to do something to the speedometer too. Anyone know what needs to be done? What parts needed, etc?

 

[BlownStangGT]

You will need to buy a new speedo gear. Im not sure which one you will need, but I need to get a white 23 tooth for my 3.73s and 5 spd. My speedo was off about 15, its now off 10 with a dif gear, but i need the white one to make it closer.

 

[Ted87GT]

Where is that gear located? In the speedo or attached somewhere else?

 

[ms93gt]

The speedo gear is located on top of the tranny, it clips right on so will be no hazzle what so ever to change. I say a 5 min job.

 

[PhLoBuS]

i need to get a new gear box

 

[Jo_885o]

W/ 373's u need a red 21 tooth for a 5 speed.

 

[5.0LOfFun]

W/ 373's u need a red 21 tooth for a 5 speed.

Not true, the white 23 tooth gear is the correct gear, just got mine from steeda.com

 

[Jo_885o]

So what does this say maybe i cant read....http://www.mustangunlimited.com/itemdy01.asp?T1=F1302+01&Category=Drivetrain&CatKey=74-01

 

[SAYNOTORICE]

Ted87GT and ms93gt, get 3.73's, you will be dissapointed with 3.55's

 

[Blakthorn]

i have an automatic 87 vert 5.0 and looking to get 3.73 gears - stock speedometer 85 mph, hopefully looking to get the 140 mph speedo - so which tooth do i need

 

[4dStang]

I have 3.73's in my car (formerly 2.73's) and used the 23 tooth from steeda. The MPH is off by seven. I just keep in mind that when I want to go thirty, I go 37.

People sure get pissed off at me when I drive like 23 in a 30 cause I forget!

But if your Mustang (not cobra) came with 2.73's you need the 23 tooth to get it close, but if you want it right on, you will have to change the DRIVE gear in the tailshaft of the tranny. That means a tranny pull. I'll live with being 7 off until I tear my tranny out then maybe I will change the gear.


Chris

 

[4dStang]

Funny, Here is what steeda says. I swear I put in a 23 tooth. Maybe it was a 21 tooth.




2.73 Gear Ratio / Maroon 16 Speedo Gear $9.95
3.08 Gear Ratio / Yellow 18 Speedo Gear $9.95
3.27 Gear Ratio / Pink 19 Speedo Gear $9.95
3.55 Gear Ratio / Black 20 Speedo Gear $9.95
3.73 Gear Ratio / Red 21 Speedo Gear $9.95
4.10 Gear Ratio / White 23 Speedo Gear $15.95


I guess I'll pull the gear and check to see what color it is.

 

[ms93gt]

I really want 3:73's but until I find out whats wrong with my car I'll decide. The problem is I did an aod to 5 speed swap and now when I drive at 65 my rpms are at 2500, thats bad! My cousin's mustang has 3:73's and at 65 he;s at 1800. I figure if something is wrong it won't fix it that much to put be down farther than 1800 rpms, so I said i'll just get 3:55's. But I really do want 3:73's :

 

[89MustangGX]

There was a change in Speedo gears in 90(?). The internal gear went from 7 tooth to 8 tooth. This means the correct gear will depend on year of your car (tranny). There's also a 6-tooth gear available if you go really low in gears. Those require disassembly to change.

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Oh, and speedo gears are never off by '7 mph' -- the faster the gear rotates, the more it will be off. So if you are off by 7 mph at 30 mph, you may be off by 15+ mph at 60 mph and so on.

 

[SAYNOTORICE]

im pretty sure that the speedo gear is wrong...if you are at 2500 at 65rpms and its not that you should be worried about other things

 

[87gtconv]

I got mine from Ford (Mistake $13.20) 3.73 Gear Ratio / Red 21 Speedo Gear. It is the right gear according to Ford and BBK charts! For 3.73 gears you need 21 teeth (RED) forf 83 to 89 model years, a 23 teeth for years 90 to 98. Automatics from 83 to 98 need a 21 teeth (purple). Newer models require an electronic speed calibrator.

 

[4dStang]

There was a change in Speedo gears in 90(?). The internal gear went from 7 tooth to 8 tooth. This means the correct gear will depend on year of your car (tranny). There's also a 6-tooth gear available if you go really low in gears. Those require disassembly to change.

-----

Oh, and speedo gears are never off by '7 mph' -- the faster the gear rotates, the more it will be off. So if you are off by 7 mph at 30 mph, you may be off by 15+ mph at 60 mph and so on.

You would think that but I have tested it at many radar sites and no matter what speed I go, it is seven! Been there and tested it. If you don't believe me...... Been driving it that way for 2 years and it has always been seven. I was confused and thought the speed would change the faster I went but it doesn't.