Transfer case.

[Hu Ryde]

Has anyone thought of putting a electronic transfer case in? I would like to be able to take it in and out of AWD without having to pull the propshaft. I did a search and not much came up. Also if this is a big No/No then is there anything I can do to beef up my existing one while it's out? I asked Brian and I got no comment. Does that mean they are good enough? Thanks

 

[nomoty]

Well i don't believe there is anything you can do to them thats why all the people runnin 9's are not AWD anymore. Now sytynut was runnin 10's on the sy AWD and i bought his spare t-case. Now I know why he sold it he is doing some other projects. anyway the only thing i can say is have your rebuilt which can cost a lot of money if the viscous coupling is fucked that alone is close to $1000. Normal rebuild will run around $800 to $2000 depending on whats wrong with it. I Have a TY of course anyway i am going to put his t-case on my TY and have the rear driveshaft modified to work on the sy t-case. SY and TY t-cases have different rear driveshafts and the only diff. on the t-case is the output shaft housing and the shaft itself. Now something else to consider is buy another t-case and take it in and have a good one built out of the too and then have the other one rebuilt or you could sell it in a rebuild condition for $100-$150. This is all my blabings and IMHO. OH and noone has done a 2wd - awd t-case as it can not shift on the fly which would be great but anyway.

 

[Tydriver]

YMMV but, from my experience on 4x4 cases. They only shift out of 4hi when theres not alot of load applied to them, ie when they are freewheeling or coasting. Almost ever 4x4 I've been in when its either switched out of 4wheel (either via lever or switch arangement) it doesnt actually occur until the drivetrain binding is removed (ie no throttle applied). As I mentioned, you may have similiar/different results but I dont think in this situation it would work. Unless of course you were to let up and allow the Xfer case to become unloaded therefore allowing it to disengage the Front axle.

 

[nomoty]

Yep i heard that to that reminded me of a previous post about this and why would you want to let off the gas then it wouldn't be racing!!! That was a comment from the last one.

 

[gooche26]

I understand why letting off the gas could be costly in a race, but if you could switch to RWD (I'm guessing RWD would be better for faster speeds) wouldn't the loss of the power going to all 4 tires and the gain of more power given to the rear tires offset letting off the gas?

Maybe I'm just looking at this in a wierd light. But this is what I'm getting at:
One would launch their truck in AWD and at a certain speed where AWD becomes a hinderance to acceleration the driver would let off the gas switch to RWD and keep going but with the benifits of RWD helping to push the car to higher speeds faster.

 

[tloof]

Hey guys,

Just use a '98-'01 OLDS Bravada transfer case in your Sy/Ty or 4x4 S10 to get the benefit of 2WD in normal driving, but with the flexibility of auto AWD when traction is lost. It even changes on its own back to 2WD while moving under acceleration when traction is regained. This transfer case has a stand alone ECM control module that runs an electric motor that tightens up the clutch discs in the viscous coupling that proportions power to the front & rear driveshafts, or to the rear alone depending on what the speed sensors on the transfer case see. This transfer case is a 4WD hi range case only that normally runs in 2WD mode, but pulls in the front wheels as well when rear traction is lost. It is only 2 pounds heavier than the Borg Warner AWD transfer case used in the SY/Ty's, and is based on the New Venture 4WD transfer case as used in full size pickups & SUV's, but without the lo range gearing (thus the reason for being much lighter in weight than a normal full hi/lo range 4WD transfer case). With this transfer case you literally get your cake and can eat too! (2WD efficiency with auto AWD flexibility when needed!).

 

[jwaller]

I would love to see somebody try this....BC its a great idea...but lets just say you do a boost launch....how long are the rears going to be burning down before it shifts into AWD.....?????

 

[protosy]

From what i have been reading, this seems like a pretty good solution. the t-case is supposed to apply clutches in a 1/4 second. and when slippage is for a period of time it is supposed to go to full lock so as to not wear the clutches out. The only questions I have are:

1) how durable are those clutches?

2) can you just select 2wd? if you wanted to do a nice burnout or something this would be kinda cool.

3) is the harness/ecu/tcase all you need? or does it interface with the DRAC(SP)/trans?

4) what is the rated torque capacity?

seems this is a winner over the NP8 tcase from the tahoe/yukon I was looking at. although I know that the NP8 can do just 2wd with no "automagic" 4wd. whatever the outcome, I am going to be using one of these two in my sy.

chad




<font size=-1>[ This Message was edited by: protosy on 2002-02-18 22:19 ]</font>

 

[tloof]

I picked up a 2000 model OLDS Bravada transfer case with ECU brain & wiring harness for $500 down in my home town of Houston, Tx. It only had 8,000 mi on it, and was wrecked due to the floods we had down here in Houston last year (although the vehicle itself was not flooded so all the components were still good!). I also had previously acquired a '94 Bravada transfer case for my swap, but when I discovered the capabilities of the newer generation Smartrac that the '98 up Bravada had I decided it was way more advanced with its 2WD mode, and so I had to get one (thats why I know the weight of the components in comparison).

One thing that I must point out though, in order to use this system you will have to use the vehicles main ECU as well because it downloads vehicle identification data to the transfer case module upon start-up (gear ratio, tire diameter, vehicle type...SUV, 4x4 truck, etc.). It also gives a trigger signal to the transfer case module (via a single multiplex wire connection) when the vehicle is below 5 mph and when the throttle position sensor pushed wide open, in order to instruct the transfer case module to pull in the front drive output to prevent wheelspin on initial acceleration from a dead stop (something that would be very benificial for our purposes I believe!). It is really very simple to wire up. The transfer case module only has 11 wires to attach up (7 wires go to the transfer case itself thru the special wiring harness that comes with the transfer case, the others are power, ground, and the communication multiplex connection). The main vehicle ECU can be reduced to only 8 to 9 wires itself for the functions required (3 wires to the TPS, 2 VSS input wires, 2 power wires, 1 ground, & the multiplex communication wire). I believe that the TPS connections might be able to be reduced to one using only the output voltage from the existing Sy/Ty's TPS, since the same TPS sensor is used on both the Sy/Ty and the '98 up Bravada's. I'm not sure yet if that will mess up the existing input for the Sy/Ty's ECU since current will be flowing to both ECU's, but if all the ECU is looking for is a certain voltage input & not a particular current flow, then it should work.

As far as the duribility of the clutches, I am not sure of that, but I must say that they don't really take that much of a load since all they do is apply a little resistance to the planetary gear unit in order to force the power load in proportion to front or rear. In otherwords, they don't actually transmit the power loading like an automatic transmissions clutch disks do, they only impose a resistance to the planetary/sun gear assembly to direct the power flow one way or the other, or a proportion of the two (just like the viscous coupling in the regular Sy/Ty transfer case does...except the Sy/Ty unit is fixed at 65% to the rear and 35% to the front).

Anyway, that is where I stand right now on my conversion issues with this type of transfer case!!

 

[Daron]

Lew and I tossed around the newer style, electrically actuated clutch transfer case idea. After looking into how the unit is constructed, Lew decided it wouldnt likely be able to withstand the torque numbers a mildly modded Sy would dish out, much less a big power ride.
Theory is nice, but I would love to see if it would survive a mid 12's Sy, just not brave enough to not listen to Lew's reasoning..

 

[JoeLutz]

tloof,
Let us know how it goes.

 

[tloof]

Daron,

What did Lew base his determination on that the newer style New Venture NV-136 Smartrac transfer case (in the '98 up OLDS Bravada) was not able to withstand the high torque ratings of the Sy/Ty's?

First of all, the case on the NV-136 is basically the same as the New Venture NV-233 electric shift full range hi/lo 4x4 transfer case (used in all '96 up 4x4 S10's) that has more than adequate bearing sizes to take the loading (and in fact is physically larger than the Borg Warner BW-4472 AWD transfer case used in the Sy/Ty).

Second, the planetary/sun gear unit used inside that transmits the actual engine power to both the front and rear is virtually the same planetary gear unit that is used in the Sy/Ty's Borg Warner BW-4472 AWD transfer case unit, and the BW unit has no problem taking the abuse. Of course instead of the viscous coupling, the NV-136 uses electrically applied clutch disks in oil (similiar to automatic transmissions) which allows the planetary/sun gear unit to proportion power to the rear only, or to both the front & rear. Granted the clutch discs do wear in the process, but they don't really take all that much of a load since they only apply the resistance neccessary to the planetary/sun gear unit in order to force the power load in proportion to front or rear. In otherwords, they don't actually transmit the power loading directly like an automatic transmission clutch disk pack does, they only impose a resistance to the planetary/sun gear assembly in order to cause the power flow to be directed one way or the other in proportion to either the front or rear output shafts.

Third, both the Sy/Ty's BW-4472 transfer case and the Bravada's NV-136 transfer case use a chain to transmit the power flow off of the planetary gear unit to the front output shaft. I don't know if the chain size is the same between both units, but my bet is that the NV-136 unit is at least equal (if not stronger) than the BW-4472 unit.

Fourth, the front driveshaft as used on the '98 up Bravada (and this front drive shaft is basically the same as all '96 up 4x4 S10's) has the same size CV joint as the Sy/Ty shaft uses, but it has eliminated the weak double cardin unit that so often breaks in the Sy/Ty, so in my opinion this later style front diveshaft is much stronger than the Sy/Ty's shaft.

With all of these features, what is it that Lew feels is the weak link in the NV-136 transfer case?

 

[protosy]

I think the ecu thing is going to pretty much be a show stopper to us sy/ty folks. I am going speedpro and would not want that obd2 ecu in my truck :smile:. Also, from what I understand that NV-136 tcase integrates with the abs unit as well.. and uses the wheel sensors to determine slippage, not a mechanical coupler. The NV-233 is about 4 lbs heavier than the NV-136. But I think it would probably be easier to integrate to sy/ty application since it is mechanical, as opposed to integrated.... but I could be wrong.

 

[tloof]

No, the transfer case module does not integrate with the ABS system. The transfer case is a stand alone mechanical coupler as far as applying power from rear to front & rear. The NV-136 transfer case does this by its dedicated speed sensors for the front & rear output shafts in order to detect rear wheel slippage.

By the way, the use of the OBD2 '98 up ECU would only be for the function of vehicle download data, and the TPS trigger input to the transfer case module, not to run anything else, although I am considering using it to operate the 4L60E auto trans as a stand alone controller as well for my purposes.

The NV-233 is about 20 pounds heavier than the NV-136 if I'm not mistaken, since it has an extra low range gear set, shift forks, etc. The same modifications will be required in order to convert to a NV-233 in a Sy/Ty as well, since the NV-233 uses a stand alone ECU module to run the electric shift motor. There is a special stand alone wiring harness and ECU that you could use from a '92-'94 Gen 1 S10 with the electric shift NV-233 transfer case. That is the wiring harness that I am using to adapt the NV-136 Bravada transfer case into my '93 4x4 S10 (I got it from a wrecking yard for $75). Also, you will still have to change out the front driveshaft to adapt to a NV-233 as well.

So personally, I think the '98 up Bravada NV-136 transfer case is the better way to go!

 

[75Monte]

tloof - it sounds like you know your stuff. Please take pictures of this process if you can. If you are successful, I'm sure more than a few people will want to duplicate your efforts. Do you have any current 1/4, 60ft, etc. stats (better yet, a Datamaster file) that you can compare to AFTER you get this Bravada transplant done?

 

[tloof]

Not at this time, since I am doing a complete ground up conversion of my '93 extended cab 4x4 S10 pickup with a 500 HP 406 ci SBC, 4l60E auto trans, and the Bravada transfer case system. I should have it done sometime late this Summer.

 

[charles]

Any more info on this project?

Did the xfer case bolt right up , etc?? Couldn't you just go slighty ghetto and just use a manual switch to change it from AWD to 2WD??

 

[7dhamper]

How bout a 2002 Escallade AWD T case? Or a 99+ S-10 4 door quad cab 4X4 set up? Both seem to be big improvements on previous model year components. Are they the same as the Smartrac from the Olds? What about the T case in the new straight 6 body style TrailBlazer, Envoy, and Bravado?

I'm building a drive train based on 3.73 front and 4.11 Dana 44 posi Vette independent rear gears. It is to have AWD on an 18" / 20" wheel combo That can take the HP of a twin turboed LS6 (475+ HP estimated). Transmitted through a built 700R4 auto. Once I get this drive train perfected on my '89 GMC Jimmy 4X4 I will adapt it, frame and all, to my '74 Oldsmobile Omega body, lose the cats once and for all, and murder every ricer on the street!