Engine Rpm's After 3:55 Gear Install?

[BNAZ]

I Just Installed The 3:55 Ford Gears And Was Surprised How Much Higher My Engine Revs At. I Had 3:08's (factory Option On '90) And Reved At 1750 At 70 Mph. I Didnt Install The 23 Tooth Speedo Gear So My Speedo Is Off. Reads 80 But Probably Is At 65-70 Mph.
The Tach Reads 2100 Rpm. Does This Sound Right. I Didn't Expect
300-400 Rpm Jump From 3:08-3:55 Gears. Can Anyone Help.
Thanks

 

[ss93cobra]

Sounds about right to me...

 

[BNAZ]

Thanks Ss93cobra. You Originally Had 3:27's I Think So I Feel Better. Did You Change Speedo Gear And Was It Accurate.
One More Question, Gears Are A Little Whiney When I Let Off Throttle And Cruise. They Are A Little Louder. Is This Normal.
I Did Break Them In W/ City Driving Only Before Going On Highway
Thanks

 

[srothfuss]

If the noise is really loud then there is a problem with the backlash. If it's not too loud then it is just from the gears being new.

When they cut the gear, it's cut with a 90 corner in it. This corner needs to be worn in (developed wear patterns) before the noise will start to disapear.

 

[ss93cobra]

Thanks Ss93cobra. You Originally Had 3:27's I Think So I Feel Better. Did You Change Speedo Gear And Was It Accurate.
One More Question, Gears Are A Little Whiney When I Let Off Throttle And Cruise. They Are A Little Louder. Is This Normal.
I Did Break Them In W/ City Driving Only Before Going On Highway
Thanks

I originally had 3:08's as you did. Regarding noise, see post above.

 

[runningmole]

2k RPM is 65 mph in my car w/ 3.55s and correct speedo gear

 

[1bad86GT]

I just put in my 3.55s, and get about 2250 at 70mph with the 20 tooth speedo gear. It should be pretty accurate, but I think my speedo is a little off because of my pony wheels and bigger tires.

 

[jrichker]

The following chart is for stock tire size...

 

[rock4451]

i just put 3.55s in today. i used to have stock 1987 .273s. huge difference pulls 100 times harder. 373s from what i hear are good for town and occasional highway but for interstate and a lot of highway, go with 3.55s. personally i like 3.55s for town, too

 

[trueblue01]

The following chart is for stock tire size...

Any charts for an AOD car?

 

[cobra2798]

i just put 3.55s in today. i used to have stock 1987 .273s. huge difference pulls 100 times harder. 373s from what i hear are good for town and occasional highway but for interstate and a lot of highway, go with 3.55s. personally i like 3.55s for town, too

I have 3.73's and for around town I think I would prefer the 3.55's. I just do so much shifting around town with the short gears, on the highway I think they are fine.