3.73 diff gears in a 2h

[shamuslan]

Hi anyone have any experiance running 3.73 gears in the diff as opposed to 4.11 in a 45 series ?It has a 2h in it and at the moment does about 2900rpm at 100kph .I think 3.73 would drop it to about 2500?Would this gear ruin first gear ie have to ride the clutch to take off ?does it also make top gear to hard to pull for the sluggish 2h?Any opinions or experiances would be great!
Cheers

 

[Ron B]

Someone correct me if im wrong ,but 79 up uses 3.73,s.

 

[dgangle]

I have changed my 4.11 third members to those from an FJ60 with the 3.70 ratio and love it. It is very highway freindly and starting out in 1st gear is no problem whatsoever. Sometimes I will start offf in 2nd. I have a 350 Chevy with H42 and 33's. When the 33's wear out I will got 35's. There has been quite a few threads on this exact topic. If you are so inclined, a search will reveal more read.

here's one I found easily https://forum.ih8mud.com/40-55-series-tech/290589-4-11-3-73-third-member-swap-questions.html

 

[shamuslan]

I wonder how well it would go with something that has just under 100hp the 350 chev wouldn't have a problem anyone out there done this swap with a 2h or 2f?

 

[cruiserbrett]

I've put 3.70:1 diffs in my tired F engine powered 4 speed FJ55, and while not a speed demon by any means, it works great. keeps the engine RPM down, and easily will go 80mph, but still is happy cruising at 65mph, and got 16.5 mpg on a 7000mi cross country and back trip...

 

[shamuslan]

sounds good! i dont want speed just dont want to be slipping the clutch to get going and having to drop a gear every hill I come to on the highway

 

[dgangle]

depending on how you drive, the first is unlikely and the second is probable.