Different diff ratios

[pbgbottle]

all my mid 70 3rd's that have 37/9 stamped on them are 4.11

37 divided by 9 = 4.11111111111111111111111

so the calculator tells me

 

[bsevans]

Negative.

My bad, you're correct.

 

[zuluzeugma]

I cleaned it up a bit.

I cleaned it up a bit and made the colors darker. It should be more useful now. Natvet, I'll email you the spreadsheet when I'm in the office next week.

 

[Hugh Heifer]

Interesting. looks like only about 200 rpm difference between 3.7 and 4.1 while running 33's Is that accurate? (A little hard to see the colors)

I have a '72 and was considering switching to the 3.7s while running 33's to get a bit lower RPM but it appears the benefit is not that great.

But certainly a problem if the diffs were different.

 

[emtee]

Mid '70s 40s are 4.10 not 4.11.

I knew I wasn't crazy...does the same hold true for HZJ 80 diffs? I could swear the electric locker I've got for the front of my 40 is 4.10; running a stock 4.11 in the rear. Doesn't look like the difference is too big of a deal. But I'm still dreaming of a FF rear with another HZJ 3rd in the rear end...

 

[Pin_Head]

Advanced differential 101 quiz question:
So why don't we have simple integer ratios, like 4:1 or 3:1?

 

[vk7ybi]

To prevent wear patterns forming, with the same teeth meshing each rotation of the crown wheel?

 

[Pin_Head]

To prevent wear patterns forming, with the same teeth meshing each rotation of the crown wheel?

Ding, ding ding!
We have a winner.

In fact with ratios 41/10 and 37/9, every tooth on the pinion will mesh with every tooth on the ring, so the wear is as even as possible.

 

[emtee]

Is that what they refer to as a searching gear set? Or searching 'something'? The name's right there on the tip of my brain...

 

[Mr. Toad]

Ding, ding ding!
We have a winner.

In fact with ratios 41/10 and 37/9, every tooth on the pinion will mesh with every tooth on the ring, so the wear is as even as possible.

heh he heh heh Prime numbers rule!

 

[vk7ybi]

Ding, ding ding!
We have a winner.

In fact with ratios 41/10 and 37/9, every tooth on the pinion will mesh with every tooth on the ring, so the wear is as even as possible.

What do I win?

 

[vk7ybi]

Is that what they refer to as a searching gear set? Or searching 'something'? The name's right there on the tip of my brain...

Hunting maybe?

Hunting Tooth Gear Sets

 

[vk7ybi]

I think I played with the numbers a while back and found that if you had 29 inch tyres on the front and a 3.7 ratio, and 33 inch tyres on the back and 4.11 you could nearly get away with that.. But why would you?

 

[MarcoPolo]

follow up ?

Advanced differential 101 quiz question:
So why don't we have simple integer ratios, like 4:1 or 3:1?

So correct me if I'm wrong... but there is no 4:10 's out there, because of this issue? Or if so, it was because Toyota caught on after the fact??
A friend having work on his told me he had 4:10 in his (forget what year) and I stated mine had 4:11 - 76'

 

[Pin_Head]

What do I win?

You win the honor of being the first to answer correctly.

So correct me if I'm wrong... but there is no 4:10 's out there, because of this issue? Or if so, it was because Toyota caught on after the fact??
A friend having work on his told me he had 4:10 in his (forget what year) and I stated mine had 4:11 - 76'

41/10 is 4.10:1 and 37/9 is 4.11111/1

Both of these gear sets wear evenly and mesh every tooth.

 

[emtee]

Hunting maybe?

Hunting Tooth Gear Sets

Hunting...that was it!

 

[MarcoPolo]

follow up

Advanced differential 101 quiz question:
So why don't we have simple integer ratios, like 4:1 or 3:1?

Has it always been 4.11, or was there at one time a 4.10? A freind of mine has a 71'-40 and told me his is a 4.10.
was this something Toyota changed after the fact?

 

[Pin_Head]

Toyota used 4.11. Other axles have 4.10 and you could mix these without worrying about it.

 

[vk7ybi]

I think there would be greater difference between new tyres on one axle and worn ones on the other, which a lot of people do, than between 4.11 and 4.10.