Reverse-Cut vs. Standard-Cut:

Often mistakenly referred to as "reverse rotation," the term "reverse-cut" is perhaps the single most misunderstood term by four wheelers and even many in the axle business. A reverse cut housing is not just like a standard cut housing turned upside down. It is a specially designed housing for fount driving axles. Contrary to popular belief, it does not turn backwards or in reverse. The term "reverse-cut" actually refers to the direction of the spiral cut in the ring gear.

In a reverse cut axle, the spiral on the ring gear is opposite form a standard -cut ring gear. The idea behind reverse cut is to strengthen the operation of the gear when it is used for a front axle application.

In the early day of four wheel drive, the front axle used the same gears and housing as an ordinary rearend. This was done for economic reasons, since the components were already in mass production. They simply added the necessary parts to enable steering. However, all ring and pinion gears are cut in such a way that they are inherently stronger when pushing the vehicle in the forward direction and weaker when driving in reverse. That means that a standard cut (rearend style) gear, when used in the front, must push on the weaker side of the gear to move the vehicle in a forward direction.

This practice continued until the late 1970s, when Dana designed a new axle that would be stronger for front axle use and also provide better driveline angles for the shorter front driveshafts then being used in new trucks. The reverse cut housing and reverse cut gear set can be identified by the pinion gear, which is located above the centerline of the axle shaft. Therefore, standard cut gears are always strongest when used in rear axles and reverse cut gears are stronger when used in front axles.

Reverse cut axles have also become popular for lifted short wheelbase vehicles like Jeeps, early Broncos and Land Cruisers. The reason is because the higher pinion location greatly reduces rear driveshaft angles. However, not all reverse cut axles are strong enough for use as a rearend. The cut of the gear that makes them stronger for the front axle use also makes them somewhat weaker for the rear axle use. The best and most popular reverse cut axle for rearend use is the Dana 60, a good choice because of its large ring gear diameter, tooth strength, ability to accept 35 spline axle shafts and wide selection of ratios and differentials.

Two other reverse cut axle are the Dana 44 and a new Ford 8.8" reverse cut. The Dana 44 makes an excellent front axle, but just isn't strong enough for rear axle use. The Ford 8.8", reverse cut rearend (new from Currie Enterprises) has a slightly larger ring gear than the 8.5" of the Dana 44 but is not nearly as strong as the Dana 60, which has a 9.75" ring gear. The new 8.8" uses a special third member that bolts into a removable carrier Ford 9 inch housing and its sometimes mistakenly referred to as a reverse cut Ford 9 inch. Both the Dana 44 and the ford 8.8" can accept a maximum of a 30 to 31 spline axle shaft.

The bottom line is that reverse cut gears (front axle style) and axle assemblies are inherently stronger for front axle use because of the way the gear mesh when moving the vehicle forward direction. They also provide better driveline angles because the pinion is located above the centerline of the axle. The gear set used in each type of axle are not interchangeable. Standard cut gears cannot be used in place of reverse cut and vice versa. The housings are also not interchangeable. However, differential cases, be open, limited slip or locker are compatible with both styles, as long as the spline count matches the axle shaft.

-Reverse-Cut vs. Standard-Cut taken from FourWheeler January 1999

Below is the base article that started it all. I was so feed up with all the miss information of the "Web Knowledge" so many people were posting I decided to research it my self. After reading several books from Dana Corp and spending may hours/days on the Dana web page I decided to write a small article to help people avoid the mistakes I made. All though some of the Books are no longer available from Dana the information is still out there. I welcome all and any correction you may have, please see where to contact me on the main page. I'm not the fountain, just a guy who had some drive to do research as in re search and search and search.



This article was written to document the early years of Dana 44 Reverse Spiral Solid front axle. It also includes information on the regular Dana 44 axle to compare the two, it is even expending into some Dana 60 info. It will concentrate on the Ford front straight axle from the mid 60's and several other axles. Additionally this article should dispel some of the myths about the first front drive axle that Dana / Spicer built with a Reverse Spiral Gear Set. The Dana 44 Reverse Spiral axle will be refereed to as the Dana 44RS within this article.

Dana designed the first reverse spiral axle in the early sixties for Ford. Dana released the 44RS for production in January 1965. Early enough to possibly be under a few rare 1965 F100's, however no written confirmation on this has been found. The 44RS was a complete new design in axle, with special design to lube the pinion that was above the fluid level. This axle has also been called the Dana 44 High Pinion, Dana 44 Reverse Rotation, Dana 44 Reverse Cut, Dana 44 High clearance and many more names. A reverse spiral axle has the center line of the pinion contacting the ring gear above the center line of the axle, and thus has different lubrication passages. This axle offers a strength increase over a standard rotation axle while in forward movement. It allows the drive shaft to contact the pinion yoke at a much higher level of connection, thus keeping the drive shaft several inches higher. The gears are not interchangeable with gear sets that are designed with the pinion below the centerline of the ring gear, however the carrier is. Reverse Cut refers to the direction the ring gear is cut for reverse spiral housing. The axiom of the reverse cut is to strengthen the gear while in the front drive axle of operation. Standard cut gears can not be swapped with reverse cut gears, however in the Dana 44 the ring gear carrier can be swapped. High pinion, Hy-Pinion or Hi-Pinion are all slang used in and out of the industry for a reverse spiral axle. High Clearance is a Ford marketing term used for the reverse spiral axle. Reverse rotation: is the single most misused axle term. Reverse Rotation is a slang term used to describe a reverse spiral cut housing. Neither the axle nor the axle shafts travel in a reverse motion, or travel 'backwards' compared to a regular housing. This term only shows the ignorance of the person or company using it.

good info tj, so lets all get collars and weld aluminum on our front diffs

The collar myth has been busted,no worky .

The gears are stronger in reverse - but the gears didn't break.

The housing broke.

the angle of the gears in reverse - causes more force against the housing - i.e. they push apart more.

going forward they tend to pull together (not a lot - but by comparision)

I was just about to say pretty much the same thing but you beat me to it. It's the "shearing/deflection" forces hat are greater in reverse. And the D30a has a weak pinion support surface that greatly reduces the strength in the area most directly affected by these forces. If it's not as big of a problem you suggest, why did Jeep issue a TSB on this and the dealerships are fully aware of the problem and don't even ask questions, and the D30a axle housings are in such demand for this very same breakage problem, that there is a national 30+ day backorder???