reverse-cut axles

[Rob Owens]

can someone explain to me what this is and why you use them? i've heard it
before, but forgot, so you probably won't have to go into too much detail to
jog my memory.

thanks

-rob

[John Radecki]

If you look @ the gear contact pattern on a ring and pinion in a rear axle,
you would find that there is much better contact when the truck is being driven
foward. Back in the olden days (before 1977, even later for some), front axles
used the same ring and pinions that the rear axle did. This worked ok, except
that in the front axle, when the truck was being driven foward, the ring and
pinion was behaving the same was as the rear ring and pinion would if the truck
were being driven in reverse.
Ford asked Dana to design a better front axle, and they came up with this
reverse cut design. Its a special set of gears that have the contact patter
backwards so that when used in a front axle, the contact is strongest when the
truck is being driven foward. Sicne they were designing this to be a front
axle, they also raised the pinion height. This helped with front driveline
angles. These new axles first showed up on 1977.5 ford 4x4 pickups, and in the
1978 bronco

[Bill Beyer]

Reverse cut axles are designed with the pinion entering the case at the top
of the unit. They were created as front axles to do 2 things: first, reduce
the drive line angles on factory lifted vehicles and second to make a
stronger ring/pinion set up for the front axles which rotates in the
opposite direction form the rear axle. When you run an axle in reverse it
puts more stress on the weak (coast) side of the ring/pinion gears so
reverse cut axles have the angles in the gears cut opposite of a standard
axle.

--
"If you can't dazzle them with brilliance, riddle them with bullets"

Rob Owens <ro...@MailAndNews.com> wrote in message
news:38AC...@MailAndNews.com...

[Roger Brown]

Rob Owens wrote:
>
> can someone explain to me what this is and why you use them? i've heard it
> before, but forgot, so you probably won't have to go into too much detail to
> jog my memory.

There's some good info on the Toyota reverse cut diff on Marlin Crawler's web
site:

http://marlincrawler.com/hidiff/index.html

Marlin figures that running a R&P in reverse weakens it about 20%. I think he
has confirmed that, when he was initially trying to run the reverse cuts gears
on his rear axle (for the higher pinion clearance) and broke one or two. Has
not broken one on the front yet.