Thank you for considering me for your drive shaft needs. Through the years I have experienced a little bit of a "bad rap" over my refusal to knowingly build a drive shaft intended to run in conjunction with the Rubicon Express slip yoke eliminator. Some people seem to think that I have some sort of personal problem with the company or their people. That, I will assure you is not the case. Personally I have the highest regard for them and almost all of their products.
In addition to liability concerns, my rationales are for what I perceive to be sound mechanical reasons. I will outline them for you here.
1. The method of cutting off, drilling and tapping the output shaft of the transfer case while still in the vehicle, is something that I would neither recommend nor attempt myself. I have seen many shafts ruined in this endeavor.
2. After the shaft has been shortened, you will still have a substantial area of unsupported shaft beyond the rear output bearing. This is not entirely a result of Rubicon Express’s design, but I would also consider this to be a problem on a factory original shaft. The result of this is known as "overhung load." The drive shaft which would install against the modified shaft will weigh about 15 pounds while the factory original drive shaft weighs about 9 pounds. This in itself will nearly double the overhung load. We must also consider that under a load, the drive shaft will have a tendency to want to straighten out. This will also increase the overhung load.
3. You should also understand that in order for the new output flange to install on the output shaft, there must be some minor internal clearance between the splined bore of the flange and the splines on the shaft. Because of this clearance, you will then have the potential for minor independent movement between the flange and the shaft. This independent movement, over time (sometimes a very short time) will wear down the splines on the output shaft and enlarge the splines in the bore of the flange. When this happens, it will, because of the looseness between the parts, allow the flange to run eccentric. This will cause a vibration problem with the vehicle. Most people, upon discovering this problem, will re-tighten the retaining bolt. Unless the output shaft has been cut off perfectly square, this will cause the face of the flange to be less than perfectly perpendicular to the centerline of the output shaft. This will usually cause even a more severe vibration problem. When people have a vibration problem and a drive shaft that I have built, their problem becomes my problem. I see this problem as avoidable and prefer to do so.
With any of the other conversion kits available, there will be a more substantial shortening of the output shaft, reducing the overhung load. Furthermore on any of the other conversions, the rear output flange or yoke is solidly "sandwiched" between the retaining nut or washer and the rear output bearing. This secure attachment will prevent the wearing of the splines on the mating parts. Thus, preventing the problem as outlined above.
May I suggest you consider installing one of the other conversions available for your vehicle? The initial cost differential, I believe to be modest. But the mechanical quality differences are substantial. Ultimately you should find the longevity, performance and strength gains to be well worth the minimal cost and time spent up front. After all "doing the job right the first time" is generally the most cost effective.
If you have any other questions or would like to place an order, it may be best to call.
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Tom Wood
Tom Wood's Custom Drive Shafts Inc.
Toll Free US 1-877-497-4238
Worldwide 801-737-0757
