Differential ratio

[FINSRIN]

Hi all,
Went to change differential oil and goop was too thick to pump out. Removed diff and scooped it out and got majority off gears. Outside was grimey enough to pass for original. Which ain’t proof it is. Taking out diff noticed tag read 3.00 and confirmed are 3.00 by turning the gears. The 60 has 352 Cruise-O. Every reference I read says ratio is 3.10. Build date is Aug 16 1960. Could it be that late builds were getting 3.00 like the 61s ?

Is a small change in ratio, but interesting to discover. Anyone else finding 60s with 3.00 gears ?
Bill

[Guest]

Mine is 3:10 ...

haven't heard of 3:00 in a 60' bird, but stranger things have happened. I have some 3:64 nascar gears going in mine when the new o.d. trans goes in. Mike

[YellowRose]

Differential ratio

I looked through the Mechanical Specifications for each year of the Squarebird on Automotive Mile Posts. According to them, the 3.00 was not offered in the Squarebirds. It was not until 1961 when they listed it as one of the options for the Bulletbird, as you noted. It is entirely possible that they started putting in 3.00's in the latter stages of the production run.

http://automotivemileposts.com/tbird1960specifications.html

[FINSRIN]

3.64

3.64 - that sounds right on.
3.50 to 3.73 with OD seems to me like good gears for all around driving.
Have 3-speed/OD with 3.73 in a Studebaker (as from factory) and works out to be good set up.
60 Tbird has 119k miles. Inside and out diff was filthy enough to pass for original. Ford made lots of 3.00 cars, so was likely swap if 3.10 went bad. If no one else is finding 3.00 in late production, then its probably been swapped.
Bill

[LuckyJay]

Look at Greg Prince's photos. There is one of a 3.00 tag on his very late 1960 production differential.

[YellowRose]

Differential ratio

Yup, that is right, Jay! I totally forgot about that picture with the 3.00 tag on it. I looked at the web page below in the History Forum that I created for him and there is the tag in a couple of pix. So it looks like they had gone to the 3.00 diff towards the end of the '60 production run as they were gearing up for the '61 run. His Tbird is as original as you can get.

[GTE427]

There are date codes on the housing and carrier that can be found and decoded, thus you can determine when the components were made.

For the housing, look on the drivers side, front of the tube, near the spring perch. A code such as 0GC translates to 1960, July, Third week. This is a stamped code and if rust was allowed to form, the code is likely gone.

For the carrier, look for a raised sequence of characters such as 0G20, translates to 1960, July, 20th. This code may be hidden by the crud, but can be found as it's part of the casting.

These dates can help determine if the differential could be original to the car. In your case with a build date of 8-16-60, date codes up till one month prior would indicate the diff could be original to the car, likewise date code later than the cars build date would indicate the diff was replaced.

Let us know what you find. Codes vary depending on the year, what I listed about should apply to a 1960 circa Ford

[FINSRIN]

got the number

Looks like number is 0F15.
What does that work out to be ?
Maybe June 15, 1960 ???

[GTE427]

You got it. The housing is of the correct date for a 60 model, did you find the code on the carrier? How does the June date compare to the car's build date?

[byersmtrco]

Early on (while the car was still under warr) San Jose Ford put a new
3rd member in ours. The 3:10 was no longer offered by Ford, and the
std replacement was the 3:00. That's what it's been ever since (2 or 3 3rd mbrs later)

My 87 Monte Carlo SS had the 200R4 O/Drv w/3:73 Rr ratio.
It was perfect. 2300 rpm @ 70 mph.

[FINSRIN]

is from differential

The 0F15 is from differential. Did not get number on axle housing.
Thunderbird build date is Aug 16, 1960
Are we on to an undocumented (in car books) ratio change mid to late in model year ?