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2nd gear lockup mod for 47re transmissions


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  • 1 month later...

Here's what I followed to gain second gear lockup in my trans. My pacbrake controller will lock it up when it wired to think it's controlling a 48re. I can also command lockup with my mystery switch.

http://www.cumminsforum.com/forum/94-98-performance-parts-discussion/573451-2nd-gear-lockup-would-nice-can-done.html

Why is it that the pac brake can lock up the converter in 2nd without modifying the valve body. Another site shows grounding the #7 wire on the trans. connector (lock solenoid) through a 33 ohn resistor and switch to ground. The info on many different internet site is very confusing.

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How is your mystery  switch wired ?  I am not doubting you. I am just trying to sort through all the various info. My trans shop says all I need is the mystery switch but it will set a code. The truck shop internet site shows using a 33 ohn resistor to not set a code. Truck shop site does not mention a mod on the valve body. I only want to set the selector in 2nd, get rpm around 2000 and lock the converter to climb a grade then flip  the switch off when I top the hill. In the past I would stay in 1st but max speed is 30mph. If I go into 2nd trans heats immediately.

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Yep, Wired up the mystery switch just as shown in the Truck Shop site as described above. It did nothing. Just had the trans built and the shop I used was not crazy about the J B Weld plug. Soo! I am back to what I have done for the last 165K miles. On steep grades I will go to 1st. On the last trip after the trans and converter build, my wife even griped about the 30mph on hills. She says tape up those damn gauges and drive. That is what got me going on this 2nd lock up thing again.

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  • 3 weeks later...

I have a Pacbrake and it did not lock up 2nd until I did the mod.

Packbrake literature says it will do 2nd gear lockup. BUT, with further investigation it only locks up in 2nd on 48RE trans. Also found BD and Suncoast sell a rebuilt valve body for 47RE with a propritory secret modified valve body that will lockup in 2nd which ALSO needs a mystery switch   I think we know their secret.

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I wonder if people are not so hot about the epoxy idea, they drill into the passage larger than the width of the passage. Use a tap and thread it and put a bolt in place with sealant to block the passage?

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Probably best would be to mill a flat bottom hole down into the passage and then insert a aluminum dowel pin that is the proper length. My trans shop is really doesn't like the JB Weld idea and may do this. He has the VB out today. Hope to report back in a few days.

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There are some who still buy buggy whips too. JB Weld is amazing stuff. The mod requires a rice grain bead. I think make sure to use a solvent to remove any residue of transmission fluid for a good bond. I can understand a shop not wanting to rely on a do it yourself fix. I'd do the same. But if you're doing the mod yourself, I think it makes sense.

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Well it is done. The teck also reversed the converter timing valve and spring as mentioned in the article. Seems to shift hard 4 to 3. Did he need to do the valve reverse? Anyway, I took it out to a long steep grade that I used to pull in !st to keep from heating oil. Pulled selector into 2nd and accelerated up to 2000 rpm then locked converter. Pulled most of the hill at 2700 rpm except the last 1/4 mile it lugged down to 2000. Trans temp at top was 190 going to the cooler and engine was at 210f. This was with a combined load of 17,900#.    Mission accomplished!!!

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