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Some assistance regarding TransGO sk 48-re kit install

1809 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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Thanks for your input. I am a bit worried about doing some steps and not others, that’s why I decided to ask questions on here. I’ve read lots of complaints on this forum about people who weren’t happy after installing a TransGO kit. I’m aiming to get the best results from mixing the kit with the Sonnax parts…. Some more feedback from people who’ve done something similar, or just have a bunch of experience with different builds would be awesome
Yeah, I’ve read lots of people recommending to not drill that one or two holes for the TCC lockup.

Unfortunately, I don't have a good transmission shop nearby….I’m not in the USA.

Am I wrong in assuming the Sonnax valves are superior to the TransGO supplied units? From what I’ve read, I thought using them meant I didn’t have to do the notch & grind the valve….which sounds good to me, but I don’t have experience.
Thanks Bookworm, that’s very helpful!

I did read somewhere that the notch is for when you drive in 2nd gear manually…so in Drive you wouldn’t notice anything. I’m still leaning towards not notching.

I already drilled the hole in the body & plugged the hole. There are two other holes that the kit wants you to plug which I did as well (no idea what that accomplishes). I also enlarged the two holes on the separator plate & drilled one extra hole on the small lower plate, per the instructions.

I’m definitely not going to drill the one or two holes for TCC lockup & I’m leaning towards not notching the body or grinding the switch valve, unless someone else with experience chimes in here.

I would like to hear opinions on whether I should use the PR springs, washer & shim that come in the kit in conjunction with the Sonnax PR valve. I’m guessing that I shouldn’t, because the Sonnax instructions want you to leave the pressure regulator adjusted at .030-.035” which is basically stock location and the TransGO kit wants you to adjust almost flush with plate.
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Interesting. Yeah, sounds like you must have put the TransGO kit springs on the Sonnax valve. My plan so far is to install using factory spring & adjust according to the Sonnax instructions, which is very close to stock settings.

I must say, part of me is saying just to forget the Sonnax parts and do everything according to TransGo instructions. My only hesitations are all the negative things I’ve read on here about harsh shifting & the loss of the core value, which will be an issue down the line when/if I do a complete transmission overhaul at which time I’d probably install a Goerend kit, TC & valve body.

Decisions decisions!
Excellent information, thanks! So, if I go with the Sonnax valve, I guess a good starting point is to not install the kit springs & shim & to adjust to the recommended specs supplied by Sonnax instructions. Then pressure test & go from there.
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I think that would be a good starting place.

But then, I ain't nobody special🙂
Your information is appreciated! I just ordered a pressure tester because of it!
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.
Thanks! My tentative plan is in line with your advice, except for the option of using the transgo pr valve + spring instead of the sonnax unit. Still need to decide on that one….perhaps I’ll install the transgo first and see if I like it. I can always go back & put the sonnax in.

I did do the mods to the accumulator housing & plan on installing their plate….I had to get another plate because I made a mistake and drilled a hole in it when I was supposed to drill it in the smaller lower plate. Transgo is sending me a new one for free (which is why I have this time to get wisdom from all you transmission gurus).

I’m curious why some people like transgo & others don’t. Why do you think their plate is silly?
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.
ah ok, I understand. So my option is to use the stock pr valve plus transgo spring + shim, or the sonnax pr valve with stock spring, right? in that case, I’ll just go with the sonnax if it achieves the same thing.

also, what exactly is accomplished by reversing the hydraulics of the OD accumulator?
Ok okay! Thanks for clarifying. 👍

And is 75psi line pressure at idle the ideal? I bet I’ll have to go back in & adjust afterwards.

I decided to install everything per the instructions on the transgo kit except I didn’t drill the TC holes, or notch the body or grind the switch valve. I also installed all the sonnax parts I listed above.

I took it for a drive today & it drives pretty much like it did before. Perhaps a bit more crisp changing 1-2 gears but 3-4 feels the same. I was expecting something more exciting. But if it helps my transmission last longer, its all good.

I haven’t checked the line pressure yet. I’ll do that still.
Did you install the Sonnax manual valve?
I installed the sonnax manual & pr valve.
I did everything according to transgo instructions except for the holes for TC lockup, notch & switch valve grinding. I also opted to not install TV green spring, or the gold spacer.
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.
Cool. I guess I did things right then. I also installed the transgo tf-boost kit for worn boost bores, because the kit recommended it.

I just expected more of an improvement in shifting characteristics. 1-2 feels fine but 3-4 is still pretty mushy. 50mph + when the TC locks in is when it feels best.

What’s the best port to use to test line pressure? Rear servo, front servo, governor, accumulator or overdrive? I bought a kit to test the pressure so I might as well do it.
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.

Ok, I just checked it. In Drive or 1st or 2nd it’s at 67.5 psi. In N and reverse and P it’s at 0psi.

Is that what’s it’s supposed to be?

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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.
ok, I just took it for a drive with the pressure gauge attached and it went up to around 115psi. That’s driving normally, throttle about 50% up to 70mph.

I don’t think I can adjust the pressure adjustment screw anymore…it’s pretty much screwed in all the way.
Yeah, something is screwed up. That's a very low number, and you shouldn't have the PR adjuster screwed in at all.
The PR adjuster is adjusted according to the transgo instructions….with the spring adjuster flush against the inside edge of the retainer…which is basically screwed all the way in clockwise. Screwing it in takes pressure off the spring & screwing it out applies more pressure. So what direction increases line pressure?

Right now mine is just like in the picture from the instructions.
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Ok, so I have room to adjust, that’s good. Someone earlier said Transgo wants 75psi at idle which means I’m close at 67.5psi…. Maybe just turn the screw two turns counter clockwise?

I was expecting more like 80-90psi to be honest, since stock is 55-60. Maybe my valve body is worn out? It does have 260,000 miles on it.
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, I’m pretty sure I got everything back together properly. I went over it several times. Could it be a problem with the pump perhaps? I know this transmission was rebuilt right before I bought it. Since it’s shifting properly, is it really likely there’s a problem in the VB?
I went on another test drive. At WOT I’m getting 155psi

I’ll tear the VB down again I guess. What are the first things you’d look for?
I just pulled the pan and noticed something odd. My valve body has a 3rd gen governor pressure sensor on it. There is also an adapter from 4th gen plug to 3rd gen plug. I thought my model year is supposed to have the 4th gen? Take a look at the pic. I bought a new sensor, but it’s the 4th gen. Did some 2004.5 trucks come with the 3rd gen sensor?

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