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Some assistance regarding TransGO sk 48-re kit install

1811 Views 54 Replies 5 Participants Last post by  Gatuncrocs
My vehicle is a 2004.5 2500 Cummins with the 48re.
The truck had a transmission rebuild right before I purchased it and everything works fine.

I want better shifting & to make the transmission last longer, so I decided to install the TransGO sk48re kit along with the following Sonnax parts: manual valve 22771-09, lube regulated zip valve 22771a-02k, front servo cover 22827-01, billet piston kit 22841-04k. A DNJ gm governor solenoid kit was already installed by previous owner.

I currently have the valve body apart and have read through the TransGO shift kit instructions and have decided NOT to do the following steps (please correct me if I’m wrong):

I won’t drill these holes:

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I will not perform this notch, since I’m using the Sonnax valve:

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I will not install this green spring:

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I will not install this gold spacer (I have tv cable & no issues with shuttle shift):
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I will not grind the switch valve:

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I will not use spring, shim & PR valve from kit since I’m using Sonnax valve:

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I will perform the rest of the steps, although I’m unsure if I should drill this hole or not:

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Is my plan flawed somehow? Thanks for any input!


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I'll give my standard responses for guys that are dead set on using the Transgo kit.

1. The PR spring setup is the only thing of much value in that kit. That part they got right.
2. Their manual valve is junk. Use a Sonnax valve.
3. Do NOT grind the switch valve land.
4. Do not install their TV PR spring.
5. You don't need the Sonnax PR valve (see point #1). It won't hurt to use it, but it's not necessary.
6. You need to make the mods to the OD accumulator in order for their silly plate to work.
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Transgo doesn't send a PR valve with the kit, so your choice would be to either use the OEM PR valve, or use the Sonnax PR valve you said you got. You can use either and you'll never know the difference. The Transgo PR spring setup accomplishes the same thing as the Sonnax valve does.

That plate is used as part of their way of reversing the hydraulics of the OD accumulator. It works, but it's a fairly convoluted way of doing it.
No, you want to run the Transgo PR spring setup with either PR valve. The PR spring setup is what raises the line pressure and ensures lube/converter oil even at maximum line pressure.
Did you install the Sonnax manual valve?
OK. You don't need the notch if you use the Sonnax manual valve. The green TV PR spring is too long, and doesn't work well at all with a TTVA. You're better off with the OEM spring anyway.

The gold spacer is a band aid for a problem that one of the mods in that kit may or may not introduce. Some do, some don't.
Yeah, for the effort and near-permanent modifications (it takes a little doing to reverse a Transgo kit) you have to put out to install it, the results are fairly lackluster.

The accumulator port will be the most useful to you.
That's quite low for a Transgo PR spring setup. I don't get too hung up on idle line pressure (I'm more interested in pressures under different amounts of load), but that's pretty low.

You'll only see pressure at the accumulator in forward gears.
Yeah, something is screwed up. That's a very low number, and you shouldn't have the PR adjuster screwed in at all.
OK. That is the minimum setting. But you should be seeing quite a bit more line pressure than you are, even with it backed off all the way.
Yes, there's room to adjust, but you shouldn't have to. There seems to be something else wrong. There are several elements that control line pressure besides the PR spring. It sounds like something didn't get put back together right.

Don't worry about pressure at idle. Get it operating in a proper range under load. You should see 170+ at WOT with the boost valve on.
Well something is not happy in there. That would be low pressure on a stock valve body. Might be time to retrace your steps.
Someone put a DNJ GM solenoid conversion on it at some point. Not my favorite, but they do work (until the solenoid wears out and starts sticking, the same way they do in their GM applications). Before Borg Warner came out with the HD solenoid, they were the answer for high line pressure applications, but are no longer necessary. The metal transducers are a little more robust than the stock plastic ones, but still should be protected from high line pressure.

It would sure be interesting to know why you had to wind that PR spring up 6 turns to get the pressure you should be getting with zero turns. Something is not happy in there. Six turns of preload gets a little scary from a PR valve travel standpoint.

The 2-3 shuttle shift washer is simply annoying. But if they're going to mod that part throttle circuit like they do in the kit, you aren't left with many options.
I disagree with pretty much all of that.

There will be too much flow to where? To the converter charge circuit? That circuit is regulated separately anyway (unless you grind the switch valve like they tell you to). More volume in would simply be regulated at the switch valve, not even an inch away. The line-to-lube passage in the Sonnax valve is absolutely inconsequential in this situation. The only thing that would make a difference in line pressure between them is if the dimensions at the PR spring end of the valve were different between the Sonnax and the OEM valves. They are not. I use the same style of PR setup that Transgo uses on a daily basis (different spring rate, but same type of setup...I also do not use the little shim under the D-shaped washer, which further increases flow to the converter). The Sonnax valve and the OEM valve are interchangeable from this standpoint. If they come in with a Sonnax valve, and the system vacuum checks properly, the Sonnax valve gets disassembled, cleaned, and reinstalled. No line pressure issues...

The Transgo manual valve (and their filed notch) is not a very good setup. The Sonnax is much better, and simpler...and no filing. (The Superior is even better yet, they just don't sell them separately.) The WOT 1-2 shift thing with the rear band with the rear band has very little to do with the manual valve, and much more to do with the rate of the rear servo return spring. Nobody installing this kit is driving their truck that way anyway, and if they are, they have the wrong a mile.
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Well you can definitely put the OEM valve in to eliminate it as the problem (or, but my experience has not shown that they are correct. If you were dealing with simply a low line pressure situation at idle (minimum pump volume), then I would entertain their theory. You are not. The pressure is low consistently, across the board, regardless of pump rpm.

They are correct in that their "dual seats and springs" setup does do the same thing, but I have not found the additional passage in the Sonnax valve, as small as it is, to have much (if any) bearing on line pressure regulation. The pump output (especially on a 48RE, which has a higher pump output than a 47RE) should be sufficient to satisfy system demand. I still believe that your problem lies elsewhere.
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