Ya gotta have a plan if’n ya wanna do it right.
And, a plan means making decisions as to what engine, axles, etc to put into any project. Often, that is harder than actually doing the work. Well, that and writing the checks. That is hard too, but I digress.
So, I will ramble on a bit about how I came to the decisions I made on what will go under the covers of Project Blue Oval YJ. If you have all the answers, hit the back button and dive into the project pages as they are developed.
One thing I wanted to accomplish was to be lighter, lower, slicker and leaner than the Scout 800 I built last time. The Scout was outstanding on trail and it actually drove well on the road. But, it was not something I wanted to get in and drive to church just because it was a nice day. I wanted to be just above the typical trail Jeep but not so far above as to be a trailer queen. I seldom do Hammers level trails, but I really liked the 37” tires on the Scout. I wanted to be able to drive it to the next state if I wanted to, wheel it and then drive it home. This decision meant no full width axles, kind of required an OD tranny, and pointed to a powerful motor.
I also loved the wheelbase and interior room of the Scout 800. 100” is a good number for a wheelbase with a 37” tire. To get that on the Jeep meant a bit of surgery which I could handle by stretching the frame and body or moving the axles. The frame/body stretch meant a lot of body work…the frame is the easy part…but I did not want to get into a custom soft top. If I cared less about that factor, I would have sawed the woman in two and added about 10” to the Jeep right behind the doors. It would have given me the interior gain I would have loved to have, but I will stretch the wheelbase instead and live with the tiny back area in the YJ. 100” is the goal and a rear axle move of 6” will give me a great departure angle and help keep the front end down on steep climbs, the Jeeps nemesis. It will require a lot of gas tank mods, so one thing leads to another.
Motor: The heart of the beast.
Since it came to me motor-less and there was no way I wanted to put the factory 4 cyl back in, I had to wrassle with the powerplant decision. I needed to stay smog legal (California) so that required a modern motor with all the factory emissions stuff. No Caddy 500CI motors for this Jeep.
My considerations were –
The bad parts to the Ford stuff are no real good OD auto tranny that bolts up and that holds true for the 5 speed manuals too. Also, there is not as much aftermarket support for Jeep swaps like there is for the SBC. But the cool factor of having that 5.0 decal on the Jeep? Well worth it.
Tranny and t-case stuff: getting all those ponies divided up and organized.
I knew I wanted an overdrive tranny or some sort, either auto or manual. I won’t get into the auto VS. stick debate here, but when I decided on a manual, I had to look a bit to see what my options were behind the 302. If I could have settled for a 4 speed, I would have used an NP435 since it bolts up, is compact and is pretty much unbreakable. The granny low of the NP435 combined with a Ford Dana 20 (especially with Tera Low gears) or an Atlas, etc makes for a excellent trail combo and is short and strong, but I hate shifting those dump truck trannys on the road and I was not sure about the 302 pulling the gaps in the basically 3 speed tranny on the mountain passes I have to deal with. Also, no OD. This would have been the killer set-up for the money, however.
The Ford T-5 that comes in ‘Stangs is not considered a viable tranny to work with.
So, I ended up with an NV3550 out of a TJ that, with a simple adapter, will bolt up to a Ford truck bell housing and then to the 302 block. It is not quite that simple, but I will get into all the details in the build-up. The NV3550 has a somewhat checkered past for noisy-ness and finicky shifting, but is rated for the torque the 302 puts out and has a nice 4:1 1st gear. It was not cheap (even used, figure $500.00 - $800.00), but it should do the trick. This tranny in the GM version was placed behind small blocks in full size trucks as well.
Now that I had that figured out, I needed to get the low range I needed. I actually got more than I needed in the form of a Klune-V David 4:1 reduction box coupled to a Ford NP205. I sat for hours running numbers in the calculator and figuring the cost vs. performance. I wanted to get to around 100:1 at some point and this combo actually gives me around 150:1 in low/low/low. Overkill? Maybe. Greg Miller at Klune V says I will love it, so if not, I will blame him! Certainly not the cheap way to go, but I can choose the 2:1 NP205 (king of cheap and strong, but it is a big fella) , the 4:1 Klune and the 6:1 combo of both to get a ton of choices and with a manual tranny, choices are good. It was expensive, but as long as I can accommodate the length of the combo with careful axle and motor placement, I am set with a bulletproof t-case combo and the doubler will give the tranny a break by taking a lot of the shock loading off it.
Now, in retrospect, one thing I should have considered more was an NV4500 swap. It is huge and expensive but it would have given me a pretty good low even with a NP241 (2.72:1) behind it an overdrive 5th gear, and it would not be stressed at all by the little 302. However, I probably would have needed an Atlas t-case to get to at least 3:1 reduction (or the new Lo-Max gears for the NP205, or a 4:1 Dana 300, etc) and the cost of those two items would have been pretty steep as well.
As long as I can make it fit, I should be jazzed. If not, look for a sale on shiny expensive parts!
Axles: “Hello, …Dynatrack?” NOT!
The decisions for what axles to run are largely driven by tire size and driving style backed up by budget. I would be running 35” to 37” tires so I could not go too light weight. But, I wanted to stay away from 14 bolts and 60s, etc. I like the full width idea, but I needed to keep the wheels under the fenders for street use. As far as I am concerned, the closer it comes to bolt in, cheap and common the better it is.
Front axle -
Obviously the D35 had to go, but the D30 was a consideration for the front. Ultimately it was brakes, hubs, and steering that bumped me out of using the D30. It can be built to survive 35s but 37s are pretty much over the top. Since the cost to build it compared to a D44 is about equal, the best reason to keep it was that it is already in there. A D44 is just ‘more better’ when it comes to bigger brakes, better steering options, better hubs and such. I will spend the money on alloy axles and good u-joints to help the D44 survive.
Following the theme of Ford stuff, I wanted a HP D44 out of an F150 but I could not find one anywhere at a reasonable cost…actually any cost except full aftermarket. So, I settled on a Waggy driver’s side drop out of a late 80s full size Jeep. I will change the rotors/hubs to 5 on 5.5 and go to crossover steering.
Rear axle –
I really like junkyard options. As I said before, if it works for cheap and makes sense, I like it. So, along those lines….
The 8.8 is tough. Yeah, the c-clip thing is bad, BUT you have to break an axle shaft before it is an issue. Very few guys running these break ‘em, even with 35’s, 36’s etc and heavy throttle use. It comes with disc brakes in the correct years and is about the right width at 59.6” or so. It is also very garage ready as far as getting it into the Jeep. No narrowing, etc. The axle tubes have a tendency to spin in the housing, so some welding takes care of that. I will add 1” spacers to get to 5 on 5.5 to match the new front pattern (adding some width, too) and likely upgrade to some of the new through hardened alloy axles that are coming out soon. The cost of the alloys would have been duplicated in any other axle I would have used, but the length will be stock and easily replaced with a junkyard spare. By the time I am done I will be above junkyard cost due to the alloy axle gamble, but if pennies need to be pinched, I bet I could run the stock shafts and never have any issues.
Lockers: Getting it all to the ground
After project This Old Scout, I knew I wanted a selectable locker up front. I have always wanted to try the OX locker and when the company re-organized itself and refined the product, I ordered one for the Waggy 44 front axle. The full Detroit I had used in TOS was a real bear to steer and I do not run enough hard core stuff to want to be locked up all the time in front. I wanted a full case locker so the lunchbox stuff was out of the running. There is one other real contender here and that is ARB. It is a great choice but I liked the idea of the mechanical cable VS. the air supply and compressor set-up of the ARB. We shall see how that works out.
The rear will get a tried and true Detroit locker to replace the weak 8.8 carrier. If I ever have issues with the OX, I want one locker that I know will work all the time. I will put up with the handling quirks of the Detroit on the road although if this was a daily driver, I would have either run Ox’s at both ends or taken the plunge to ARBs.
Tires - I had really liked the Mickey Thompson Baja Claw radials I had on This Old Scout. But, I had always wanted to try the tried and true Goodyear MTR. Tire choice is very related to the terrain you wheel in and the balance of highway over pure off-road. The MTR is king in the West Coast desert conditions, especially if you require a tire with good road manners. That was an easy decision.
The size was much harder. A 35” tire on a Jeep is the upper limit to keeping things simple in my opinion. With a 35, the lift can be kept low-ish, the axles can be in the D44 range, the stock motor (6 cyl) is good, etc. Step over that and it gets iffy. A 37” tire nearly requires alloy shafts in a front 44. You are treading on thin ice with most ½ ton equipment. The lift requirements increase or careful trimming is required, etc. Still, even though I do not really do consistently hard rocks, and even though 35’s and lockers will go anywhere that I need to go, I still chose 37s following the theory that you should use the largest tire that does not completely cross over the line of practical use. This decision will cost me the upgrade to alloy axles front and rear. If I messed up, I can change to 35s from 37s easier than the other way around. Another thing is, the MTRs are relatively petite for a 37.
Suspension- SOA/ SUA, Links, Legos, or whatever?
Few arguments about 4x4 set-up get as much mileage as where to put the leaf springs or even to eliminate them completely. Spring under axle, spring over axle, shackle forward or not, is being discussed somewhere on a bulletin board or campfire near you at this very moment. The arguments are:
Spring Under Axle (SUA) –
Pros:
Keeps the lift low, usually 2-4”
Easy and cheap to install
Requires few steering mods
Tons of aftermarket choices in springs
Helps prevent axlewrap
Cons:
May not be enough lift for bigger tires
Ride can be rough due to increased arch in the springs
Limited axle travel (droop) due to arched spring
More hangy-down parts under the axle tubes to catch on rocks, etc
Spring Over Axle (SOA) –
Pros:
Approx 6” of lift built right in even with a flat spring
Good ride due to less arch in the spring pack for the equal amount of lift
Excellent axle travel
Often can use junkyard or OE springs
Cons:
May be more lift than you really want or need
Tends to increase axle wrap and may require anti-wrap bar
Requires expensive steering mods
May kill springs over time especially if the axle wrap is not controlled
I like leafs because I can understand them. I can work with them in my just above average garage. They work very well for 99% of trial and highway use that the typical Jeep sees. Maybe links will be in my future, but not for now.
I am going to try staying SUA front/rear with Skyjacker Rock Ready 4" lift double military wrapped springs. Hopefully this will allow for decent axle travel and stability and reduced axle wrap in the rear. We shall see how it works. I hope this will give me the low stance I covet, the reasonably compliant suspension that local trails require and an overall balanced ride. If not, there is always the torch and grinder.
Well, that is about all of the big decisions and how I looked at it. You will need to make your own decisions based on your fevered dreams and goals. Good luck to you. To see how my decisions turn out, follow along on the build-up pages.
Here are some links to read up on and think a bit:
