What did you do to your NBS GMT800 Tahoe/Yukon Today?

[Fless]

From a 17 cruze. The usb port wasn't working so I replaced it with a new housing as it comes assembled already

Curious, @dszx13... where did you tap for the aux input and how do you switch the radio input to that (XM?).

Also, does the USB port work and, if so, for charging only? What powers that?

 

[dszx13]

Curious, @dszx13... where did you tap for the aux input and how do you switch the radio input to that (XM?).

Also, does the USB port work and, if so, for charging only? What powers that?

Usb isn't working. Was the reason it was replaced on the cruze. The first post with pics explains where and what was tapped into

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[Fless]

Yeah. Wasn't sure if the connections you mentioned were for the USB port or the audio. Which wire is which channel?

How do you switch to the audio on the radio?

 

[dszx13]

Yeah. Wasn't sure if the connections you mentioned were for the USB port or the audio. Which wire is which channel?

How do you switch to the audio on the radio?

It's for the aux port. Turn the radio to Sirius channel 0 which shows radio id.

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[TheAutumnWind]

Also, another tip that I have not seen many people mention. When reinstalling the servo cover, a lot of pressure needs to be applied to be able to get the snapring back into the groove around the cover. I ended up using a chunk of 2x4 wood about 6 inches long, and a long pry bar. I wedged the wood up against the transmission tunnel/floorboard of the truck just opposite of the servo cover, and positoned the prybar on the wood, to where it was just between the wood and the servo cover. I was able to flex the praybar enough to get the cover pressed in ALL the way so I could easily get the snapring back in. With the wood behind the prybar, that was just enough proper spacing for the prybar to get that cover pressed in perfectly. Plus my prybar ended up being just the right length that I was able to rest the handle behind the torsion bar, and that basically held the pry bar in position. That allowed me to use both hands to reinstall that PITA snapring on the cover. If you don't have a helper that can hold that prybar against the cover during re-install, I highly suggest getting some wood and a prybar to figure a way to have it hold itself in like I did.

I have a long prybar that i wedged in there between the body and the exhaust that held it all the way on. Could not have done it with one hand for sure.

 

[TheAutumnWind]

Did you get the longer pin and new spring? Cause I’ve been reading a lil about it and it’s recommended to replace the spring from years of use, same thing with the e-clip for the Servo pin and the longer pin is needed because it seems the stock pin doesn’t have the movement that’s needed with the new Servo


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My transmission was replaced in 2014 by the p.o. I assume the spring is new. E clip was in good shape. I think the shorter pins were only an issue in the earlier transmissions pre 03...

 

[TM98]

I have a long prybar that i wedged in there between the body and the exhaust that held it all the way on. Could not have done it with one hand for sure.

I had to get help with mine as the cover was a different shape because of the fourth gear servo. It was hard to figure out how far the cover needed to go in because of the shape. I had my son helping and we were finally able to get it held long enough to get the clip to hold.
I had installed just a corvette servo on a 700r4 a while back and taking it out, changing the parts, then reinstalling was fairly easy.

 

[inmypassatlife]

How about a hearse? Haven't seen an NBS one before
https://www.facebook.com/marketplace/item/993617097480350

 

[M1Gunner]

How about a hearse? Haven't seen an NBS one before
https://www.facebook.com/marketplace/item/993617097480350

I’m at a loss of words with this one lol

 

[Chubbs]

Finally got around to installing my corvette servo in the escalade. Only sat around in the garage for like a year.

Everyone should do this. Shifts are more positive, but not jarring. Trans temps stay a little lower and it reduces wear/increases service life thanks to less slipping

My issue isn't with the 1-2 shift. The 3-4 shift on my truck is really sketchy, espc the way I drive it. When I was putting together items for the 1st trans service, I had an old trans guy talk me out of replacing any hard parts so I figured next best scenario was have the parameters changed in the programming. I haven't gotten with a tuner yet but I'd still like to get 1st hand testimonials from a number of folks running a vette servo and more on the orig trans, attesting to any experience with component failure or degradation of useful service life.

This is (below) is what the old guy from the trans garage told me over the phone; about increasing pressure on parts that are 120,000 miles/15-years old. I wouldn't hesitate w a newly rebuilt/reman unit but you never know how long old shit is going to hold-up to performance mods. I'm not saying the servo is some 'wild mod' but these 4L6 trans aren't the most robust piece of equipment. as discussed below, the Sonnax piece is better designed to hold both 1st & 4th. From what I've read and experienced, that 4th apply is a much better target.


Michael Dose
The servo applies pressure on the band, not the clutches. The band is a weak point and the extra pressure is achieved by making the center section smaller, giving the apply piston more surface area. The band applies in 2nd and O.D. or 4th. Notice that the center section of the servo moves independently from the outer piston. The outer piston is located inside the cap that you see from the exterior of the trans. The outer piston applies pressure on the band when in fourth gear. When the user installed this set up he would be increasing pressure on second gear band apply only. Sonnax has a larger outer piston to increase pressure in fourth gear as well. I mention that because the band is a weak link and it can slip in fourth as well as second. Given the fluid color of this transmission I would say you may very well have some band slipping going on. Obviously it is best to make this mode before that begins to happen.

2 months ago•1

Furthermore, about that pin sometimes included with the servo setup, I couldn't get a straight answer on that in the time I had to put this together, which also gave me pause. I would certainly buy the kit with the pin, but everyone should do his own research instead of taking Joe-Blow advice. I had read mention of filing the new pin to fit, which means it may be needed to for clearance purposes in at least some cases depending on your own, specific unit. Unless you have extra 2k just burning a hole in your pocket, I suggest saving the trial & error for something less-critical, and much less expensive. The consequences of a mistake may not be immediately noticeable "DOHH!" Moment, but neglecting to utilize a replacement pin could very well be creating some adverse condition within the operation leading to an overall decrease of the orig unit service life which is my biggest hangup on this.

Upon further investigation, the Sonnax version of this 2nd gear upgrade (corvette) servo comes standard with a replacement pin, which they make to seem somewhat important. I think a lot of you guys installing the piston only without the new pin are neglecting necessary procedure, espc if working on high-mileage/orig trans.

https://www.sonnax.com/parts/2486-2nd-gear-super-hold-servo-kit

https://d2q1ebiag300ih.cloudfront.net/uploads/part/instructions/2486/77911-03K-IN.pdf?v=1495651615

I can't speak for everybody else but Sonnax has built an incredible rep in the world of aftermarket trans replace parts & upgrades. If their 2nd Servo comes with a pin, then by God you need to be getting a pin with your GM vette servo, as well. Has to be a reason for it.

The only reason I would have for replacing the servos is extending the service life of the orig trans that came in my truck from the factory. Wether or not the trans tech with 30-yr experience is correct about the advice given to me, it is still wise to expand on his theory, nonetheless. If anybody reads this and would like to comment on their experience with upgraded servo/s on the original transmission, I would certainly appreciate you dropping a line on the subject and helping build a case for any pros/cons in the long-term affects of this mod.