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quadra trac VS selec trac


stokey
08-08-2004, 01:03 PM
what is the difference in the quadra trac and selec trac and which is better?

Dale Aeppli
08-08-2004, 01:15 PM
what is the difference in the quadra trac and selec trac and which is better?
HI, I'VE OWN CHEROKEES SINCE THEY CAME OUT HAD ONE WITH QUADRA-TRAC. IN MY OPINION WOULD NEVER BUY ANOTHER SELECT TRAC IS A GOOD SYSTEM DALE jeepman600@aol.com :smokin:

JDPascal
08-09-2004, 01:25 PM
The Quadratrac is a 4wd on demand system that uses a viscous coupler to drive the front axle when there is a difference in speed that will cause it to slip. When the coupler slips, the fluid in it heats up and makes a more positive drive connection.

Lots of people swears at them and lots of people swears by them. They would seem to require more attention to maintenance than you could probably get away with on a selectrac system. The weak spot most people complain about is the coupler, though there is no talk of the previous maintenance practices, tire selection, replacement and maintenance etc..

The selectrac has the 2wd/4hi/N/4lo selector and the driver picks his drive mode.

As to which is better, that is up to the users experience. Dale has his preference for some very good reasons - some operational, some repair related and some maintenance related no doubt.

Some of these reasons may not reveal themselves untill you actually own and use the system.

My Quadratrac has been good so far. No repairs - just change the oil both springs I've had it (now using synthetic) and go. It is good for my wife to drive in winter without worrying about shifting except for the transmission.

That said, I sure wouldn't turn down a Jeep model with selectrac either.

JD

ByronP
08-09-2004, 11:50 PM
I am most familiar with the 93-98 Grand Cherokees(ZJ). So depending on what year you are looking at some things may change. The 93-98 Grand Cherokees came with three t-case options - the NP231, the NP 242(Selec-Trac) and the NP 249(QuadraTrac). The NP 231 is considered the strongest of the three. It has 4HI, 4Low, N and 2HI. It is a traditional 4WD t-case. Very simple and not prone to many problems. It is also the least common case found in these years. The NP242 is the most common. Like JD said it has both the Full time 4WD and the part time options(4HI/4Low/2Hi) and you can select between them. This case offers more options based on how you want to drive. The NP249 is also common found, mostly on the V8 powered ZJs. The VC in the 93-94s is different than the 95-98s The newer model offers full lock-up in 4Low. And some claim smoother engagement. IMHO the NP 242 is the best all around case. I have the NP249 in my 93 and while my wife likes the fact that she doesn't have to think about the 4WD I would prefer to be able to lock in 4HI or 4Low when off-road. While the NP249 is fairly reliable the VCs are prone to failure which can be an expensive repair. Though, I haven't had any problems with my 249 (125K miles), if I did I would probably swap in the 242 or at least replace the VC with one from a 95-98. Hope this helps.
ByronP

CTCarpenter
12-11-2004, 09:36 PM
My Quadratrac has been good so far. No repairs - just change the oil both springs I've had it (now using synthetic) and go. It is good for my wife to drive in winter without worrying about shifting except for the transmission.


JD

Can you be more specific as to what oil you're using and what method you used to remove the old oil?
Thanks.

JDPascal
12-12-2004, 12:41 AM
Can you be more specific as to what oil you're using and what method you used to remove the old oil?
Thanks.

The transfer case has two large plugs on the back of the housing. They are almost in a verticle line about 6 inches apart at take a 1-1/16 wrench (I think) to remove. Top is fill and bottom is drain - of course.

I am currently using Amsoil ATF but any synthetic ATF will work. Mobil 1 synthetic ATF would be my other choice.

If you chose to use conventional ATF, I don't believe it would matter what type you used because there are no clutches and the Transfer Case should be a closed system where the oil can't migrate to the transmission.

I know that the T-case will run significantly cooler in the summer and have better cold weather lube in the winter. Thats a winner for the owner anyway you look at it.

It only takes 1-1/4 qts, so if you don't know when it was last changed, you could drain the old out and refill with new conventional ATF and run it for a few hundred miles then drain again and install the synthetic and you are good to go for another year or two.

Hope this helps some. Any other questions - ask away!!!

JD

CTCarpenter
12-12-2004, 07:39 AM
The transfer case has two large plugs on the back of the housing. They are almost in a verticle line about 6 inches apart at take a 1-1/16 wrench (I think) to remove. Top is fill and bottom is drain - of course.

I am currently using Amsoil ATF but any synthetic ATF will work. Mobil 1 synthetic ATF would be my other choice.

Hope this helps some. Any other questions - ask away!!!

JD

Thanks for the reply. I just bought this vehicle (1994 GC with quadratrac) I would like to help prevent VC problems, so I want to change the fuid in the differentials to synthetic as well. What fluid would you recommend and would you use the same method? Any other info is greatly appeciated.

dksob81
12-12-2004, 09:27 AM
well like everyone has mentioned Quadra-trac (NP249 Transfer Case) is all time 4wd, and Selec-Trac (NP242 Transfer Case) u can select between 2hi/4hi part time/4hi full time/Neutral/4lo.

The 249 does need more attention to maintenence. The VC has a tendency of oing bad and locking up (mostly on hot days in the summer while driving at high speeds) and this causes binding and hoping while turning, the best way to prevent this is to change the fluid on schedule and i recommend replacing with a Synthetic Fluid (Royal Purple), it will help displace the heat and keep the VC from locking-up when it's not suppose to. Most of the time when the VC locks up it's b/c the fluid in the TC has never been changed - so doing the schedule maintenence and switching to a synthetic fluid should keep the VC working for a long time.
Pros/Cons for the 242, umm there is none....lol. You can run it in 4wd full time in the winter and it acts like the 249 (w/out a VC tho) and then in the summer run it in 2HI - Better gas milage and a bit more power. and when off roading throw it in 4WD HI Part Time (this locks both axles for optimum traction- just like when the VC on the 249 is fully engaged - locked-up).

all-in-all the Selec-Trac (NP242) is better, but don't be discouraged the quadra-trac is a very good transfer case, but need more attention to the maintenece to keep it alive.

glennco1
12-12-2004, 11:20 AM
So let's include quadra-trac II in the mix, what is the difference between quadra-trac and quadra-trac II?

dksob81
12-12-2004, 12:28 PM
quadra-trac is 4WD all the time (70/30 split - meaning 70 power to the rear wheel and 30 to the front, then when the speed between the 2 axles change extremely - slip, the VC locks up giving 50/50 - 50% power to each axle), quadra-trac II (NV247 transfer Case) is 2WD and then when the rear wheel start to slip it engages the front wheels.

then you have quadra-drive, which is kinda like Quadra-Trac II except it can change power to each wheel, it can litteraly give all power to 1 wheel, if that wheel is not slipping - on dry land. if all wheels are slipping then power is equally distributed between each wheel.

a_alyte
12-12-2004, 12:48 PM
With the NP242 Transfer Case, could bad or worn front u-joints cause binding when turning in 4WD HI?

Also, I've always had a shop change my diff fluids but I plan to do it myself next time. I want to switch to synthetic but all I can find is 75W-90. The manual states to use 90W in the rear but I havn't seen any bottles of gear lube which read only "90W", is 75W-90 mobile 1 synthetic good for both axles?

JDPascal
12-12-2004, 10:19 PM
Thanks for the reply. I just bought this vehicle (1994 GC with quadratrac) I would like to help prevent VC problems, so I want to change the fuid in the differentials to synthetic as well. What fluid would you recommend and would you use the same method? Any other info is greatly appeciated.

To change the diff oil, just pull the covers off the axle center sections. You will need to catch about 3 quarts of oil when it drains. I use a squirt bottle to spray degreesing solvent around in the housing to flush out any extra crud that I can and then let it drain and dry it out as best I can.

Before you flush it with solvent, drag your finger across the bottom of the inside of the housing to check for metal chunks and wear materials.

You are bound to find some but not a gold or silver mine...........



This could be done the same as the T-case if you don't know when the last change was done or you find what you think is a slight excess of wear material - Install some lower cost conventional 80w90 gear oil and run it for a while and flush it again before you install the synthetic.

The gear oil's I've found have been 80w90 in the conventional oils and 75w90 in the synthetic. Both should work fine except if you are towing a trailer. Then the owners manual says that you should use 75w140 synthetic ONLY.

My preference runs to Mobil 1 but there are others that are as good (some may say better) but I won't argue the point.

I like the synthetic because in lowers the temp in warm weather and lubes better on startup in the cold weather.

OHYA!!! - To seal up the diff cover when you put things back together, I use the Blue RTV silicone. Not that the red or black won't work - just my preference.

To get the oil back into the diff, I use a pump made for filling the lower unit of an outboard motor. On some of the diff oil bottles the pump lid will fit the cap threads. Works great!!

If you did flush it, take it easy for the first couple a miles to let the oil get distributed back through the bearings.

And don't forget the 4 oz of mopar limited slip additive. Even if the diff oil container says the oil is for limited slip diffs, you still need it. It comes in an 8 oz bottle so you have enough for two changes. Only need it in the back end.

When I put it in my rear diff, all of the axle hop that had me concerned about my VC failing went away............. Took a couple of weeks but it worked for me and it is worth a try before some one puts out for a T-case repair.

This got a little long but hope it helps

JD

JDPascal
12-12-2004, 10:20 PM
Hi a_alyte

I hope what I wrote above answered your question. If not, let me know.......


JD

a_alyte
12-12-2004, 11:09 PM
Thanks JD,

You definitely supplied me with much needed info., this being my 1st Jeep & all.

I want to make sure that I'm clear on one thing! Are you stating that 75W-90 synthetic gear oil can be used in both diffs?

The Haynes manual states to use 90W in the rear, but all I see in the stores is the 75W-90!

This is where I'm confused, I don't want to put the 75W-90 synthetic in my rear diff if it will cause a problem!

Also, I planned on switching to synthetic by simply pumping the old oil out w/a suction pump. Is this not a good idea since I'm doing the switching?

JDPascal
12-13-2004, 12:09 AM
If I am right in assuming that this is the 98 JGC in your profile, then I believe the Haynes manual has a miss-print so far as the 90w oil is concerned.

The 75w90 definatly won't cause a problem an you should use it in both diff's.

I don't even know where you would get a 90w oil. If you check the oil companies websites, all you will find is the multigrade gear oils.

If you don't have an owners manual, you should still beable to get one from Chrysler. The 98 is still the same basic Jeep as my 96 if I remember right and the oils I mentioned are right out of my owners manual.

So far as sucking the old oil out with a suction gun goes, that would work too. You just wouldn't get as complete a cleanup as with the cover removal and I like to be able to see what is happening to the parts while I'm changing the oil too.

No problem there if that is how you want to do it - I've been told I'm on the extreme end of fussy when it comes to clean when I work on a vehicle so I've learned to make allowances when others want to do it their way (with some exceptions).

JD

a_alyte
12-13-2004, 12:30 AM
Thanks for clearing that up for me, JD.

That Haynes book is something else, I can't keep track of all the contradictions I noticed that book!

I know what you mean about being clean & thorough when working on your vehicles, I'm like that too when I can!

I probably should remove my diff covers when changing, especially on the front, it might give me a hint as to why my jeep is hard to turn after using 4WD HI!

JDPascal
12-13-2004, 12:35 AM
I have a chilton manual for my Jeep and a Haynes for the Cougar but when I get into some heavy stuff, I get info from the mitchell manuals we have at work.

Some times I wish I had a factory manual but the mitchell is second to none so far as aftermarket info goes.

JD

CTCarpenter
12-13-2004, 08:07 AM
Hi a_alyte

I hope what I wrote above answered your question. If not, let me know.......


JD

Answer was perfect, and I will be tackling this on my next day off. The things we do for our kids....

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