Join Date: Aug 2006
Location: Phoenix, AZ
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Just my $.02 but with DP programming the shifts should not be "jarring". Jodys trans tuning yields some of the most consistent and smooth shifts while still being quicker and firmer than stock. If you are having "jarring" shifts, there may be something else going on.
Case in point. We did a chip in a 2002 truck a while back. In "stock" it seemed to shift ok, typical sloppy stock shifting. In any program with significant power increase the shifts (one in particular) were downright violent. At first we figured that the truck had unknown valve body work since it had been purchased used, so I had Jody adjust the tuning accordingly (as he would with a BTS, SunCoast or trans with TransGo kit). This involved reducing the programmed line pressure increase since we were assuming that the trans/valve body already had it turned up. Guess what...NO CHANGE...still shifted violently. We tried adjusting this several times in the programming and finally came to the conclusion that it wasn't something we could program out. We ended up making a call to John Wood and driving the truck to him to get the trans looked at. As soon as we described the symptoms he told us it had a stock valve body and the clutches were worn and not doing their job. This was over the phone, without looking at the truck. When he pulled the trans down, he was 100% right, clutches were toast. After he rebuilt it and we put the original program back in, shifting was perfect.
So, why were the shifts so hard with worn clutches, even with reduced line pressures? With the extra power of the chip the trans would slip very badly during shifts (the one in particular). This slippage would occur for about a second until the clutches generated a bunch of friction and heat and then grabbed like nobodys business (SLAM!). It wasn't a firm shift...it was SSSLLLIIIIPPPPPP....BANG! Like most people would, we felt initially that the problem was the trans programming in the chip. In reality, it was the extra power of he chip and the poor internal condition of the trans. I have found this same situation in a bunch of customers trucks since. If you're putting a chip in a well worn trans and getting overly harsh shifts (particularly from a programmer that is known for having fantastic trans shifting), there is a good chance that there are other factors involved. Before you blame your programmer, consider the above.
As a side note, it should be mentioned that the above can happen in varying severities. Some have had shifts I would call "overly firm" where others had "VIOLENT" shifts. The difference was the condition of the trans, with the "VIOLENT" behavior coming from the more worn units. For the situation where the issue is at the less severe end of the spectrum, upgrading the valve body to a unit that mechanically helps improve the shifting can reduce the problem and offer some additional trans life. This is particularly true of the 02-03 trucks, and is the primary reason I've been working with JW to offer his valve body setups. This isn't a "FIX" if you've got significant internal wear, but it can buy you some time before you need to do a rebuild. If the trans is in good shape, it can certainly buy you some peace of mind and longevity by making sure that the shifts work as they are supposed to.
Hope that helps.