Docked Wage

I've finally started the conversion to my 1992 Jeep YJ. What I'm trying to accomplish is build a Jeep that is relatively tough but I don't need to do hardcore wheeling. I've been there and done the "drive it like you stole it" thing in Trucks, cars and boats. After many years of bleeding money I've calmed down a bit. Yes, I will off road it but if there's a chance of breaking a suspension piece, smashing the body or making mine ache more than it does already, I'll slow down or go back. Mainly this Jeep will be a daily driver in the summer and most of the off road it will see is on the sand. Oh yes and my wife will likely drive it more than me.

As far as the conversion goes, I'm going to try to do it as inexpensively as possible using standard stuff that anyone can find easily online, at a salvage yard or a local parts store. I hope to avoid welding anything except the Motor Mounts and the only thing I'd like to source is the fabrication of the exhaust. We'll see how that goes.

Right now I'm in the disassembly stage and part acquisition mode. As of today the Jeep trans and transfer case is out and since we are getting an Indian Summer around here I expect the front end and engine will be removed this weekend.

Here's a pic of what I'm starting with:



For parts, here's a list of what I've got so far:

From a 2005 Silverado 2WD with 24K

5.3 Flex Fuel Motor Complete Take Out
4L60E Transmission
PCM
The entire vehicle wire harness without one cut in it.
PDB
Gas Pedal

From a Late 80's to Mid 90's S10 4X4

NP231 C Transfer Case - Manual Shifter (get the shifter if you can)
Factory Transfer Case to Transmission Adapter

From a Ford Explorer Second Generation 1995-2001

Code D2 (on the door sticker) 8.8 Traction Lock Rear Axel with 4.10 and Disc Brakes. Hint: Usually found on the 2 door sport or Eddie Bauer package with the bigger 255/70/16 tires from the factory.

To try and keep myself on subject I'll change the font color on specific questions that pertain to this build. Any and all input is greatly appreciated. I'd rather not learn by having to do things twice or pay for it twice either. In return I'll list the part numbers that I end up using so that others can use this info down the road. I'll also detail any fabrication that is required as well as possible.

Docked Wage

So here's step one of my plan.....

Split the NP231 Chevy case and my stock NP231 Jeep case and use the Chevy front half and guts with the Jeep back half and output shaft.

From Jeepin1995 on Jeepforum.com here's how to make the hybrid case:

chevy front case half
chevy 4-lo planetaries (they have the correct splines for the chevy trans and have 6 sun gears, not 3 like the jeep case therefore they are stronger)
chevy chain and sprockets (on the main shaft and also the front output shaft) the chevy chain is wider/stronger


jeep rear case half
jeep mainshaft(so i can keep my jeep SYE)
jeep SYE, jeep speedo gear/setup

This hopefully allows me to retain the stock speedometer since the stock sender will still be in place.

I also hope to reuse my driveshafts as is. This means I'm thinking the transfer case will end up in the same position. As of now with a 4" lift and a 1" Tcase Plate drop I do not get any vibes at freeway speeds. I'm hoping that by not messing with the drivetrain angles and positions to much I can remain vibration free when done. Edit: I did not have to modify my driveshafts.

Since the transfer case will be a Chevy front half it will bolt right up to the 4L60E using the factory adapter that came with it. I have already changed the 2wd output shaft out of the donor trans and test fit the adapter and the Tcase and everything went together perfectly.

Docked Wage

Part two of my evil plan is to keep the factory gauges.

The dash in my Jeep has been completely restored and they work perfectly so I'd rather not toss them.

Here's what I think I've figured out:

Voltage Gauge - Gets it's signal from the Ignition circuit in the dash. Edit: Works perfectly

Speedometer - See post #2 on how I plan to keep the speedo reading by using the factory Jeep signal generator on the Transfer Case Output Shaft. Edit: This actually worked perfectly in a later post.

Fuel Gauge - Use Factory Level Sender (but change the pump) Edit: Worked Perfectly

Temp Gauge - Use the 12mm plug at the back of the pass side head and get an adapter so the factory sender can screw in. Edit: The factory Jeep Sender screwed in and this works perfectly.

Oil Pressure - Drill and Tap the Bypass Plug by the Oil Filter Base so Jeep factory sender can be screwed in. Edit: Worked perfectly.

Tachometer - Here's where I'm unsure.... I read that the tach output from the silverado's pcm is modulated like 4 cylinder. That's why there are issues driving V8 tachs from what I've read. Considering my Jeep is a 4 cylinder I'm thinking I'm all set to just hook it up and go. Could it be that easy? Edit: Nope not that easy. A Tach Adapter/pull-up is required.

Docked Wage

I have not settled on is how to deal with the VSS as it relates to using the 4X4 Low Range Gears in the transfercase. I've seen the Jags that Run system and the Advance Adapters setup. The AA setup solves the problem by putting a 40 tooth reluctor gear on the transmission output shaft and then drilling the Tcase Adapter Housing to hold the VSS. It's pretty clever and will solve the problem. Since my PCM has a 2wd tune with the VSS on the input side of the Tcase, it should care less what gear the t-case is in. I think....

Here's the link to part number 716073E. http://advanceadapters.com/product/6762/716073E.html

The alternative is the Jags that Run Kit and putting it on the Rear Output of the Transfer Case or the Rear Pinion Yoke. It is a lower cost option but then there's the low range issue. With this setup when in 4WD Low the PCM will see a very slow vehicle speed but high engine rpms. As a result I've heard of problems with erratic and sometimes violent shifts.

Edit: I used the Advance Adapters Kit and it works perfectly. See later posts.

Docked Wage

For the Fuel System I used a GSS 310 Walbro Pump and a Corvette Fuel Filter/Regulator

Docked Wage

For the Engine Mounts I'm looking at the Novak Mounts. Considering my engine will stay stock and I don't plan on beating on the rig....Edit: I Ended up using Advance Adapters Mounts.

For the Transmission Mount I'm planning to reuse the Jeep Factory Skidplate and machine new holes for the 4L60E mount based on where my current driveshafts put it. Edit: This could have worked see subsequent post.

For the Exhaust I'd like to use the factory manifolds from the truck. Edit: No way the Truck Manifolds will fit.

I've seen somewhere that if you fly-cut the manifold mount flange 7 degrees they end up tucked in toward the block like block hugger headers. I have cheap or free access to just about every machine ever made to chew on metal. I ended up using C6 Corvette manifolds. See subsequent posts.

LS1 TJ

Here's what I did. Not YJ but a TJ.

Novak adapter from the 4l60e to the 231. I've done a 6.0 and a LS6 with a 231 behind the 6.0 and a 241R behind the LS6.

For the PCM to read the vss correctly the novak adapter has the pick up on the 4l60e mainshaft.

The drive shafts front and rear need to be modified. Rear lengthed and the front shortened. Radiator from Novak a bolt in with a tranny cooler.

I ran the left side exhaust around the front of the oil pan and merged it with the right side. 3 inch all the way out the back.

Home built frame mounts and Speedway universal engine mounts. Cut off the jeep motor mounts.

I mounted a 255 walbro in the Jeep tank. Corvete fuel filter regulator. Had to use an Autometer tach. GM computer signal will not talk to the stock Jeep tach.

I did the 8.8 swap. Works great.

Howell harness for the LS6 and 6.0 and they are truly plug and play.

Runs great. Starts at -25 degrees at the turn of the key. Great plow jeep for the winter. See pics

Docked Wage

LS1 TJ,

Thanks for the reply. If I can ask, what was it that made the driveshaft mods a requirement?

Assuming the original (stock) position of the transfer case is the reference, it sounds like you ended up with the whole powertrain moved forward. Was there a clearance issue with the firewall?

As far as the tach goes, I may have it figured out. I ran into this same type of issue in a boat that I repowered recently. The EE's at work helped me figure it out. So now I need to pull the YJ tach and take it to the nerds at work and let them tell me what "language" the tach wants. From there we can build a circuit to translate what is coming out of the Chevy PCM into the language the tach can understand.

Regards,
Ken

LS1 TJ

The LS/4L60e moves the t/c case forward from the AX5 or AX15 location. Which is good . Helps with the rear drive shaft angle.

In regards to the tach. I don't have any IS wizards at my disposal. My tach sits right up behind the A pillar and unless you are looking it's not visible from the outside.

The good thing is I don't need low range to plow anymore!

Docked Wage

OK thanks for the info. I'll start looking for a good driveshaft shop around here.

For the Tach if all else fails I may just try to find a cluster out of a GM (LS based) vehicle that has the same scale and sweep angle as my stock one. From there I'll swap the tach guts into my cluster. That will definitely solve the problem.

LS1 TJ

By the way it does awesome donuts in the snow in 2 wheel drive!

markeheiden

On my Jeep I went thru a 3-month nightmare because I used a jags that run style VSS that plugs into the speedo output. What no one tells you is that there is a 3-1 reduction in in the speedo gear so your 8 pulse VSS acutally only puts out 2.7 pulses which is too weak and inconsistent for the TCM to read reliably.

Go with a 40 pulse kit or install an NP241 transfer case from a 90's suburban, blazer etc. that has a 40 pulse sensor where the speedo output is on your NP231. They made those transfer cases in passenger or driver side drop.

There are probably ways to figure out your speedometer signal but that is infinitely less important than getting the VSS signal to the computer to run the engine.

I used 2004 vette exhaust manifolds because they stayed close to the block and exit near the center giving more room to run a down pipe back to the mufflers. They have a strange (2-3/4") dia. flange that is impossible to find a mate for so I had to cut my own flange out of 1/2" Thick metal to weld the head pipes to.

I used an inline adapter for my temp gauge mounted in he upper radiator hose and tapped a second hole in the aluminum block for the "steam pipe" to connect to with small rubber hose.

I also used an external Walbro pump mounted just outside and below the tank. Works perfectly.

Docked Wage

Mark,

Was your Jeep Injected to start with? If so are you running 2 (in tank and in inline) pumps now?

Regarding the VSS and the Tcase I have pretty much settled on the kit from advance adapters. Their trigger wheel and sensor are before the t-case. That way I won't have to worry about the reduction factor and keep my 2wd trans tune.

Ken

davev78

I have a 5.3 in my 92 YJ, hope this helps your questions:

1. The Tach is a plug and play, ie: the GM output is standard 4cyl output that the YJ tach wants to see. When you get your PCM you can have the tach output programed to what ever cylinder output you want. The guy who had couldn't get it work had a TJ- totally different gauge design driven off the Jeep computer.

2. You are making the right call with ath AA VSS kit, that is the best way to make it work. Jeeps use a 3 wire VSS, were GM use 2 wire sensors. The signals are incompatable unless you use a signal converter like Dakota Digital makes. For your app I would use the Jeep VSS to drive your speedo only as it already there. The other option you have is to have the speedo output on the GM PCM tuned to your gear/tire ratio and output to run the Jeep Speedo. I have my YJ speedo run off the PCM speedo output.

3. I used corvette exhaust manifolds, as I could not get the truck manifolds to fit. My set up is custom as the engine is as high and as far back as possible so your results may vary. I also made custom motor mounts as the vette manifolds sort of cover the motor mounting pad on the block so there is no way the stock truck motor mounts would work with the vette manifolds.

Docked Wage

Dave,

You are my new best friend. You made my day with the tach answer.

If I may continue to pick your brain....

What did you use for your upper and lower radiator hoses?

What trans/transfer case did you use?

Did you need to change your driveshafts?

Thanks!

Ken

BOWTIECJ7

Not for nothing But in my 1985 CJ7 5.3L Swap I used Shorty Headers for a 2000 Camaro Fit real nice inside the frame. And I got some coated ones off Ebay pretty cheap. Also I used a VSS from Dakota digital and when I had the PCM Reprogramed They Worked out the details to make it work. I also used the Stock hoses just trimmed them to fit. The top one I cut just off the t stat housing used a plastic splice from the parts store and turned it up over the intake work out great.

Docked Wage

Thanks for the info. I'll track down a set of those headers.

Sort of slow on my end these days. I got distracted and pulled the body from the frame. The frame is out now getting blasted and painted. It should be back by the end of the week.

Ken

LS1 TJ

Just got the plow back on th TJ and plowed some snow. Sure is nice with the heat and radio on. I pulled the body off mine and sandblasted then powder coated the frame. Sure looks nice when their done.

Will you use the stock rear drive shaft? Most 8.8 conversions with SYE kit reccomend a CV joint rear drive shaft.

Docked Wage

I'm undecided on an SYE. My current setup never vibrated so I'm not sure I need to spend the extra $. At this time I'm thinking I'll set the motor between the rails 1" to the passenger side to deal with the additional offset of the 8.8. Hopefully I can just reuse the stock driveshafts.

BTW sweet picture of the working Jeep!

Where the heck is all that snow this early in the year?

Ken

Docked Wage

Got the frame back from the blaster yesterday and put on a coat of Satin Black Chassis Saver Epoxy today. I did most of the work with a brush and then used a HVLP touch up gun for the tight areas. I then turned the pressure down to about 20 psi at the gun to do a light stipple as the final coat. I'm really happy with the results.