Re: Bulletproof 700r4
Yep. The extra pinion was added for two main reasons. The housing of the 5 pinion is NOT cast iron. It is a powdered metal process that is cheaper to do than machined castings. It basically removes two expensive steps of the process. Spreading the load better over that powdered metal reduces chance of failure of the component. 2nd reason. The pinions are helical gears. This is the twist you see on the gears. It makes them run MUCH quieter. The problem is that this produces thrust just like a screw. This puts a lot of force against the thrust washer of the housing. Putting on this extra pinion helps reduce the chance of the pinion basically burrying itself into the housing and failing.
Your better off with the cast iron 4 pinion planetaries with the oil slinger and cross drilled shafts that the pinions ride on. They run much cooler and respond VERY well to cryo because of the hot casting process.
The sprag issue and the 2nd billet servo.
That servo has a LOT of surface area. The syty valvebody has a VERY stiff shift accumulator spring in the valvebody. The VERY firm shift of the corvette servo is made because of the combination of this shift valve spring. I'm NOT talking about the accumulators in the hat and case. I'm talking about the valvebody. You already had a big downshift and upshift load on the sprag. Couple that with a wide band and big servo and you've now pushed up the "bang" level. That servo has NO cushioning affect for 3rd. This screws up the shift timing when going from 4th to 3rd. That billet servo is a RACING servo. It should not be used on street vehicles. If you do a manual shift from 4th to 3rd two things happen. You engage the overruns which places an additional load on the sprag but....if you use the billet servo, you take away timing and cushion. This is basic, but it breaks the overrun clutch hub and/or flips the sprag elements. Now, the technology has improved and we have clutches that can hold to MUCH higher levels than just 5 years ago. So you have unyielding clutches that are holding past the capability of these TINY housings your expecting to hold together and you now using a servo that takes all the cushion off of the parts.
OK. So why did your output shaft break? Well, in 3rd gear, the front planetary is being DRIVEN or pushed by the front little sun gear. What is that sun gear splined into? The sprag. What is the front planetary splined onto? The output shaft.
Now. When you are in OD. The band grabs the drum which grabs the sun gear shell and then, in turn grabs the sun gear and holds it still. The rear sun gear is in the center of the REAR planetary. So the planetary is FORCED to spin around the stationary sun gear. In 4th the planetary is the driving force via the 3-4 clutches turning the reaction shaft which is splined into the rear planetary. This DRIVES the rear ring gear which is splined onto what? The OUTPUT shaft. What does this mean? In direct/3rd the sprag is basically grabbing the output shaft. If you are in 4th, the rear planetary is "grabbing" the output shaft. One is all the way at the tip, the other is all the way at the other end. See where this is going? You take that cushion out and do a 4 to 3 shift, forced throttle or manual, and eventually your gonna break the sprag, or one of the two planetaries. More often than not, the output shaft will twist and break because both planetaries are trying to do their job at the same time. I don't mean to make your head hurt but this is the STRONG feeling I've developed and why I will NOT use a billet servo in the 700. It's just not good for a trans you want to be a "streetable" unit.
