NSBU install tips?

[kanton1]

With all these switch failures, I have decided to go down to the local Allison dealer, pick up the new NSBU switch and install it myself hoping to avoid a hassle with the dealer and being out of my truck for a few days. For you fellas that have done your own swap, do you have any hints, tips, or suggestions for someone who is going to do this on there own?

Thanks in advance

[77TransAm]

Let's see....
- You'll be putting the truck in neutral, so make sure you take the appropriate precautions when you raise it (wheels blocked, etc).
- If the connectors don't pull off easily, take the hair dryer out and warm them up - the potting sometimes melts in the old style NSBU's and the heat will loosen it enough to get the connectors out.
- Disconnect the shift cable BEFORE you try to loosen the nut on the selector shaft - otherwise you're looking at a broken shift cable. No fun to change. smile.gif
- Once you have the nut and lever off the shaft, just pull the two bolts that hold the NSBU to the trans and finesse the NSBU off. It's a tight fit around the front driveshaft, but it will come out of there.
- Next, make sure the trans is in neutral (rotate the shaft all the way clockwise for park, then two clicks CCW for neutral. The flats on the shaft should line up with the little diagram cast into the trans).
- The new NSBU will have a small piece of stamped steel on it - that is to hold the switch in neutral. Leave that piece on the switch and install the switch onto the trans.
- Tighten the two bolts to 18-21 lb-ft, remove the stamped steel piece, install the new shield, the shift lever, and the nut.
- Tighten the nut to 15-20 lb-ft, install the cable, plug in the connectors, and you're done!

[txguppy]

I searched the NSBU threads on the DP. Questions arose. How do you know if it needs replacing? Why won't the "stealer" replace it, are these out of warranty? finally, my truck has NEVER shut off by turning the key off while in gear. Is this a switch failure? Thanks in advance. :confused:

txguppy

[Hound]

77TransAm,

When you say "- Disconnect the shift cable BEFORE you try to loosen the nut on the selector shaft -"
Where do you disconnect it from and how do you disconnect it? It's probably a really silly question that has a very obvious answer once you look at the thing but it's kind of dark and cold out there tonight. Thanks very much for the hints on how to replace the NSBU!

[BowTieDmax]

Well the new NSBU is on, and the truck is on the road. I highly recomend that anyone that has this "old" style to buy a new one and just replace it or atleast carry it in the truck.More so if you drive in the snow due to the salt and slush splashing up on the unit. Because I know I didnt heed the warning and it cost me 2 days without the truck, lost income plowing for the first snow of the season, the emparrsment of borrowing my dads car , plus everyone asking why my truck was sitting were it was.Plus reinstalling it in a 18 deg. snow storm in the dark. Then the lost time in the woods on opening day dear season to make phone calls to find the part. I got to hear the GM dealers go Daaaa whats a NSBU?? How do you know thats broke?? Of course no dealer stocks it and it could be 4 days to 4 weeks to get it. So I called the closest Allison dealer and they had 14 of them in stock. He said GM is supposed to warranty these but wont. So my wife drove the 120 mile round trip to get it ($50.32). He asked my wife how I knew this was it and she said because of this web site (thedieselpage) I belong to. I really got to thank all of you and this page because I could only imagine the hasel if I didnt know about this switch. My "service engine light" is still on. Does anyone know if I just just gotta get this cleared or what ?? Thanks ;)

[battmain]

BowTieDmax wrote:
"service engine light" is still on. Does anyone know if I just just gotta get this cleared or what ??"

You'll need a scan tool to get the code. I've heard that Autozone will check it for you for free with their scan tool. Then once you get the code, some folks here have access to the manuals and can tell you what to do. smile.gif

[77TransAm]

txguppy, you'll see a lot of symptoms of NSBU failure in some of the threads in this forum, but I think some of the common ones are flashing or no PRNDL indicator on the dash, failure to go into range, or stuck in third range. It is a warranty item, but a lot of the dealers seem to have trouble diagnosing it. My guess for that is that the 4L60E uses the same NSBU, but it does not serve as many functions in that application, and a failure won't cause the same symptoms as it will for the Allison.

Hound, the shift cable is connected to the selector lever on the trans with a plastic ball-and-socket type joint. It just pops off with gentle pressure from a screwdriver behind it.

[hjd3021]

Could someone confirm that the new NSBU switch part number is Allison 29540479?

[kanton1]

77transam,

Thank you for the tips. I'm just a little worrisome about the cable. I was looking at mdrag's photos and it appears he did not take the cable off the lever, is this not the correct way? link here: http://community.webshots.com/photo/55288748/55289083noDNRI

thanks for further clarification,
kyle

[Hound]

77TransAm,

Thanks for the info! Had I bothered to use my brain last night I would have thought to look at the service manual :rolleyes: I certainly appreciate you taking the time to respond though!!

Kanton1,

The service manual says what 77TA said.... remove the cable before trying to get the nut loose.

[ 12-03-2002: Message edited by: Hound ]</p>

[mdrag]

Hound,

You are correct. I did not remove the cable from the lever :eek: but after reading 77TransAm's comments about shift cable replacement - I will remove it if there is ever a second time...

I carefully held the shift lever with an adjustable wrench while loosening the nut holding on the shift lever - there was no movement or strain on the cable - but if something slipped you could damage the cable...This was the first NSBU switch that I've replaced. Even with the Helm's manuals - many of the instructions are vague and EXPERIENCED advice helps a lot. I was not aware that the cable could be removed easily as described above.

One other point that I did not see mentioned - the old NSBU switch was on the selector shaft tightly and needed firm coaxing to come off. The new one was also a tight fit going on and you have to make sure that the switch remains aligned with the shaft and doesn't rotate out of position....you CAN'T twist it into place. The metal 'neutral assurance bracket' helps you maintain the alignment and is removed after the switch is in position. The location prevents you from looking 'straight on' to confirm alignment of the switch with the selector shaft... Good luck.

[mdrag]

hjd3021,

Check the pics in my sig at the KD EXHAUST or BIG WHEELS link - the part number for the new Allison NSBU switch is clearly displayed.

[kanton1]

thanks for all the tips,

just installed the new switch. took about 1/2 hr. the most difficult part was getting the new switch onto the shaft, had to use some muscle to slide it on. $54 at the allison dealer and 1/2 hour of work, sure does beat having to haggle with the dealer and being out of my truck for a few days if the original switch failed.

thanks again
kyle

[tbrowne]

I just talked to my local Allison dealer and the tech advised to be careful not to force the new switch onto the shaft. He stated that most of the NSBU switch failures are the result of damage to the switch caused at the factory by forcing the switch onto the shaft. Excessive force can crack the plastic, which allows moisture to seep into the switch causing its demise. He advised to remove any burrs, bumps or blemishes on the shaft that make installation difficult. A little care here can ensure a good install.

[77TransAm]

tbrowne, good idea to watch the shaft for any imperfections (there is generally a burr where the shift lever bolts up to the selector shaft), but even on a brand new shaft the new NSBU is a very tight interference fit. It takes a fair amount of force to install the NSBU, but it takes a LOT of force to crack the case. At any rate, the main cause of failed old-style NSBUs was just leakage around the switch housing - it was a poor design and the new NSBU seems much more resistant to that type of failure.

[DonG]

77TransAm,
Do you know if the new 2003 trucks with Allison transmissions are coming out with the new design for the NSBU Switch???
Is there an easy way I can find out what is on my truck???
Thanks, Don

[mark45678]

If I understand my dealer there was a change on trucks built after 7/31/02 ?????? Mine was built 7/16/01.....guess where it it tonight? NSBU failed!35K on it..... most of the time was fine but if it gets above freezeing thats when its going haywire! OEM switch is made by lucus? Isnt this the same guy we named "MASTER OF BARKNESS" in the 70's because of alot of british cars???

[77TransAm]

Don G, I know that the early 2003's still have the old black switch (p/n 12450016). I haven't seen any recently built trucks to compare, but the easiest way to check is just to roll under and look. The NSBU is located on the driver's side of the trans, near the back, just above the oil pan gasket. It has two connectors going into it from the rear and the shift selector shaft going through it from the side. The old NSBU is black and the new design is tan in color.

mark45678, you are correct in your assumption of which Lucas corporation has their name stamped on the switch. Now you know why they have such a high failure rate! smile.gif

[pinehill]

And here I thought I had banished the "Prince of Darkness" (Lucas) from my garage by replacing most of the Lucas equipment on my 1956 Triumph Tiger 110 and my 1966 Triumph Bonneville. Please tell me that the tan NSBU is made by a more reputable company. :(

[ 12-05-2002: Message edited by: pinehill ]</p>

[conradv]

OK, I have the black switch on my 2003 GMC (took delivery in mid October 2002).

Do I have to pay to get a tan one, or is there a statement by Allison I can take in and complain?

I'm thinking the former rather than the latter... ;)

[ 12-16-2002: Message edited by: conradv ]</p>