Techniek - DANA assen
In de jaren '60, '70 en '80 werd er bij 4x4 voertuigen veel gebruik gemaakt van DANA assen. Onder andere Chevrolet, Dodge, Jeep en Ford maakte gebruik van DANA assen in een eventueel licht gemodificeerde uitvoering. Er zijn verschillende types die voornamelijk verschillen in hun sterkte en dus ook doeleinde. In onderstaand artikel worden de onderlinge verschillen uitgelegd. Jammer genoeg weten we niet van welk bedrijf deze informatie afkomstig is, want er wordt regelmatig gesproken over 'hun' produkten.
Our custom hand machined Dana 600 outer (top-right) with the correct length will fit right into a Dana 60, and special 35 spline lockouts are needed to fit into the new shaft. We typically use these for extreme cases.
The 12% increase in base shaft size is still significant enough to award even the weakest point of the Dana 60 an appreciable upgrade over the Dana 44. The U-joint size and increase along with the much, much larger 60 yoke, are the real players in the 60's legendary strength. Even though the comparatively puny looking Dana 44 axle is overshadowed by it's brawny brethren, it's historic performance and surprising durability is still impressively respected by many. Used in the proper application, with premium materials and respect towards it's operation, the Dana 44 can stand up to similar conditions as the Dana 60, EXCEPT for heavy weigth and loaded applications.
So true is it that the Dana 60 outer shaft size nearly mirrors that of the Dana 44 outer shaft, except for the 60 has finer splines. The Dana 60 measures only .022" larger than the Dana 66 at the outer diameter of the splines. However, the 60's finer splines are 'ground into the shaft', as compared to the Dana 44's weaker course splines extruding outwards from the shaft.
Even so, the Dana 60's accelerated stress point is right where the recessed splines meet the solid shaft area. By not having a relieved (smaller diameter) shaft behind the splines, instead of the stress bearing evenly distributed over the entire length of the shaft, it is concentrated at the smallest point of the shaft - in the depth of the short area where the splines are itself. This is where the Dana 60 typically twists off first.
Here are two similar appearing front outer drive axle stub shafts. The vulnerable Dana 44 of the left appears very close in size of the revered Dana 60 in the right. Although the big 60 has a much larger u-joint and yoke construction than the 44, the weakest point is very similar to one of the Dana 44's weakest point. Even though the 44 also see attrition in the u-joint area as well as the stub shaft, the 60 in this respect, is not that much more spectacular in the carnage remaining in the aftermath, as well as the agony of digging deeper into the wallet. Dana 60's can be upgraded to larger 60 style outers... at a greater cost.
These front outer drive axle stub shafts tell their tale of woe. The comparatively weaker Dana 44 normally sees u-joint failure, while a stronger u-joint solves that problem, the next stress point would be the knuckle area. Even though the awesome Dana 60 has much more beef in the u-joint and knuckle area, it's vulnerable point is obviously the outer shaft area, which can be reduced with an expensive conversion upgrade, using Dana 70 style outers. The downfall of the 60 failling at the shaft area, is that the typical 'twist' break usually spreads the spindle outwards, therefore requiring the aid of a torch to get the wheel and hub assembly off. Lots of cash, there.
This familiar scene typically raises questions of the driveshaft's integrity, when in reality, that's usually not the deciding factor. Hardly ever does a driveshaft twist solely on 'too much power'. Typically this is a result of a dented or rusted shaft, or extreme pinion yoke angle caused by excessive axle wrap. Other signs of this condition include externally broken u-joints and pinion shafts, as well.
Here is a variety of typical front drive axle u-joints. These joints are subjected to a little bit different set of rules, since they rarely rotate the needle bearings, except for when turning while locked in 4WD. When they do finally turn, they really see a beating, since the joint angle can see far in excess of what any other u-joint would ever experience. Axle joints are usually the weakest link in the driveline, except for the massive Dana 60 joint. The strongest joints are constructed with no grease fittings and better seals to keep the grease in and the water out. Since these needles see relatively little usage, there's really no need to weaken the joint with cross drilled trunions, in order to grease the joint. The pockets seen in these non-greasable joints do not necessarily weaken the trunion since they are shallow in depth and do not enter the cross area. They're designed to allow an air pocket when assembling the permanently sealed caps, with a place for the grease to go.
An u-joint being subjected to a stationary fixed position, especially if at a near 'zero' angle, will risk being damaged due to a condition called 'brinelling'. This results in the needle bearings pounding themselves into the trunion due to prolonged contact in that same area. When an u-joint is on an angle, the twisting motion of th ecap slowly rotates the needles bearings to a new location every time it moves. Without that twisting motion, the needles stay in the same spot and create tiny dents, or grooves in the trunion over time. Then when the u-joint in fact move (as in a hard acceleration in a rear driveshaft), the brittle needle bearings rumble over these dent-like 'speed-bump', and usually disintegrate, resulting in an immediate u-joint failure. The most common cause of this condition is improperly aligned driveshafts. The straight-on condition will deteriorate the u-joint over time, and usually when in a power required situation, the u-joint will seemingly fail all at once. In reality, it was the 'straw that broke the camels back'.
Bron: Performance Unlimited
Auteur: Randall J. Thomas
[ vorige pagina ]