Pleeease Diagnose My Noise!
I have an ’04 Grand Cherokee Overland with Quadra-Drive and a 4.7 V-8 HO with 84,000 miles on it. I had synthetic fluid put in the differentials approximately two years ago at 73,000 miles. Previously I had changed the fluid with synthetic fluid in the diffs and transfer case at 29,000 miles. I have had a bad grinding or binding sound when I back out of the driveway or make a sharp turn out of a parking lot for the past year or more.
First, I’d start by checking the boots on your CV-style front axleshafts. If these are broken and grease has leaked out of the joint, you may hear sounds coming from the front axleshafts. But they usually make a clicking or a popping noise rather than a grinding noise when they are bad.
Next, I’d check the fluid in the front and rear axles and transfer case. If the fluids are low ,fill the part with the correct fluid. The NV247 transfer case (found in WJs with Quadra-Drive) uses Mopar Transfer Case Lubricant PN 05016796 (gold colored), while the NV242 transfer case (WJs with Selec-Trac) uses ATF-4 (red colored). If all are full, then you may have more of a problem. Sounds like this is very difficult to diagnose long distance, but here is what I would bet my money on if I were a betting man. If you only heard the grinding sound when turning, then it could be coming from one of your differentials. In that case, I’d say that one of your differentials had some damage. Your differentials allow differences in speed from the two axleshafts as the Jeep goes around corners. This is because the inside tires actually travel a shorter distance than the outside tires. But since you also have this grinding when you back out of the driveway, I’d bet that the sound is most likely coming from the transfer case. Since your Grand has full-time four-wheel drive when you go around a corner, the differential or viscous coupler in your transfer case has to compensate for differences in speed between the front and rear axles, much like the differentials in your axles do on a turn. Again, here the front axle is actually traveling a slightly larger distance than the rear axle that is following it. Because of this difference, the front driveshaft will turn a little bit more than the rear driveshaft. To allow this, your NV247 transfer case has a part like a differential called a viscous coupler. It sounds to me like this viscous coupler needs to be replaced. Also, as you back up the weight of the vehicle transfers forward and would cause slight speed differences between the front axle and rear, causing the grinding in the transfer case viscous coupler.
You can check this by chocking the front tires and jacking up the rear axle with the Jeep in park so that both rear tires are off the ground. Then turn one of the rear tires by hand. If you hear grinding coming from your rear differential, there is your problem. If not, lower the Jeep and with the front tires still chocked, shift the transmission into Neutral. Then jack up only one of the rear tires and rotate it by hand. If you hear grinding coming from the transfer case, you have located the problem. If not, put the Jeep back in park and chock the rear tires. Then jack up the front axle so both tires are off the ground and repeat the first test you performed on the rear axle. You should hear the grinding coming from your front axle’s differential if that’s where the failure is.
I have been reading Jp for a number of years now, and I always trust you guys for Jeep advice. I was hoping to get an update on the Shrink Ray TJ. Unless I missed something, I don’t think we have heard from you since Part 2, when you shrunk the rear. How is it working? Have you made any other upgrades? Would you do anything differently? Would you do it again? Can we expect to see a Shrink Ray Ray TJ: Part 3?
I am going to buy a TJ soon for my next project, but I am not sure whether to get a four-cylinder or the six. I like the concept of the Shrink Ray TJ, and want to use it as inspiration for my next project, but I just wanted to get an idea of how it is working out before I pull the trigger on a four-cylinder because most people would steer you away from it.
This is what I am looking to do: buy a stock, manual, early TJ and build it on a budget as a daily driver/ weekend warrior. My limited cash will force me to keep most of the original drivetrain, but I will add a mild lift to clear 33-inch tires. I will slap on upgrades as funds allow such as armor, lockers, winch, and so on until I have a decently capable Jeep that maintains good road manners. The question is should I get the 4.0L for power and build it heavy, or should I get the little four-banger and chop it down light? Any advice would be much appreciated. Keep up the great work over there at Jp!
The Shrink Ray TJ is doing well. I have been wheeling it pretty hard over the past year or so, and it’s about to go under the knife for a little more work and repair. I’ll get to that in a minute. First let me catch everyone up on what I have done with it since Shrink Ray Part 2. Keen readers will have seen the little TJ in “Clearance Clarence,” (Mar. ’13) where I installed a T&T Customs high-clearance center skidplate/T-case crossmember. At that time, the little TJ that can also got a cable shifter and slip-yoke eliminator kit from Advance Adapters. That required some Brown Dog 1-inch-lift motor mounts and a Tom Wood’s Custom driveshaft.
Since then I have added a set of old forged aluminum 5-on-51⁄2-inch 15x8 Weld wheels that I had been toting around the country for several years. These wheels were modified with lightweight OMF Beadlocks and wrapped in a set of 35x12.50R15 Explorer Pro Comp MT2s (“Tight as a Tick,” June ’13). I made the wheels fit the stock Dana 30 and 2WD V-6 Toyota Tacoma 8.25 bolt patterns by adding a pair of adapter/spacers from SpiderTrax and an old and well-used Dana 30 Warn locking hub conversion with Chromoly shafts and CTM U-joints from my pal, Trent McGee. I also added a junkyard fresh set of ZJ front coils (“Super Cheap,” Oct. ’13) to replace the sagged and beaten stock TJ front coils that were on Shrinky.
Since Part 2 appeared in the magazine, I have wheeled the little TJ all over Moab, a few trails and dunes out in Johnson Valley, and all over southern Arizona. With the addition of the larger tires, the combination of gearing of the AX5, NP231J and 4.88 axle gears is not quite low enough. I will be swapping the light duty AX5 for an old-school granny-geared manual, but I am not gonna give away which one just yet. Also the Jeep needs new lower front control arms, a timing chain, and some general loving. It’s next on the docket to spend time in the garage getting this trans and loving as soon as I can get some space cleared.
With the lighter weight and proper axle gears, this TJ feels pretty peppy despite the four-cylinder. If I had it to do over again, I might have held out for an ’03-or-newer TJ with the 2.4L, but in general I am pretty happy with the Jeep. Honestly, it works better than I expected. You could do a similar conversion with a 4.0L-powered TJ, only without moving the grille and radiator and you’d have a nice lightweight Jeep with some realistic horsepower. Of course you won’t get the same approach angle (which is definitely zero with the 35s) as I did with Shrinky, but you’d have more usable power. All in all, if you want to build it slowly and keep the Jeep ultra-light as I did, I would probably suggest a four-cylinder Jeep. Right out of the box with factory 4.10s in the axle, they crawl pretty well and are cheap. If you know your TJ is gonna end up heavy, go right for the 4.0L—unless you think you may swap engines some day, in which case the added cost of the 4.0L will be wasted.
If I have any regrets, it revolves around the grille and hood. I had and almost swapped on an old beat up M38A1 grille. I could have matched this with an M38A1 hood. I think that would have taken this build over the top. Can I go back and swap on a vintage grille and hood? Yeah, sure, but I probably won’t. It would be lots of work and undo lots of stuff I already did, and did well (if I do say so myself).
Bench Racing a ’55 Willys Wagon Build
My 15-year-old son recently purchased a ’55 Jeep Wagon that he just fell in love with. He bought it basically striped down to just the original frame with the original axles and body, which are in great condition. The engine, transmission, transfer case, and even steering components are missing.
His question is: What now, Dad? My question is what are other guys doing to make slight modifications, yet not turn these things into hardcore trail rigs?
Let me take a moment to give you an idea where we live and what we do and hope to do with the wagon. We’ve been to Moab a handful of times with our CJ-5s. He would love to take this rig down there, but only do the gentler-to-more-mild trails. We live in Southeast Wyoming ranch country and drive a great deal of two-tracks. Full-width trails sure are comfortable.
A few years ago, I rolled Mama’s ’76 CJ-5 a few times down I-25, just south of Buffalo, Wyoming, doing about 70 mph. The 3.54 gears were not the problem, but the front wheel bearings without grease were the problem. Would you like to see those pictures?
Anyway, we were able to salvage the 304c.i. V-8, T-150 trans and Dana 20 T-case. We don’t have a money tree for 40-inch tires and coil suspensions. We have good luck with 32 to 35-inch tires and leaf springs. We’d like to use the free to us 304 V-8, the T-150 and Dana 20. Is it possible to beef-up the axles and create a wider, more stable stance?
From here we are at a stand-still when it comes to springs and axles. We have looked for leaf-sprung suspension systems, but just have not found the right place that has the right answer. And like I said, he would like a different wheel and tire combination then what the original is. Seems like it will take a pretty good arch in the spring to even fit a 32-inch tire without rubbing the body and fenders?
Now you have a good picture in mind of what we’re up to. So, gentlemen of Jp, what would your recommendations be?
Well, Wilsons, this Jeep build sounds like it is right up our alley. Your long question is gonna require a bit of a long answer, but as I see it you have a couple of options to take for the Willys build. I like the idea of the 304 V-8, T-150 and Dana 20, that’s a good solid base for the Willys to start although you could at least contemplate a Ford T-18 or NP435 swap to get a little deeper gearing (via these transmissions granny geared First gear ratio). This is not necessary, but would only increase the crawling ability of the Wagon. You could also keep the T-150 and add low gears to your Dana 20 (either 3.15:1 TeraLow aftermarket or 2.61:1 Bronco).
As for the suspension and axles, I really like the simplicity of using YJ Wrangler leaf springs in a spring-under configuration. These springs are readily available and ride well. I think you wil want some 3- to 4-inch-lift YJ springs, and set them up spring-under just like I did on project Ground-Up. The YJ springs are wider and generally ride much better than early CJ and Willys 4x4 springs. You are also gonna want to swap to a frame-mounted Saginaw steering box. You can either dig up an old steering column for a Wagon (assuming you don’t have one) and modify it for a U-jointed shaft to run from the column to the box, or get a more-modern column from a J-truck, a Chevy, or aftermarket supplier. Again, you can have a look at the way I set up the steering in Ground Up, or have a look at “Steer It Right,” (July ’13).
As for adding width to the axle, you can add some spacers (about 11⁄2 inches per side) or wider wheels with less backspacing (like 3.75 inches) to your Wagons stock axles. Unfortunately, your narrow track axles from “Mama’s wrecked CJ” won’t be any wider than the axles the Jeep came with. They will be narrower and probably too narrow for you to use. I would run some 31s or 32s on your wagon with an 8- or 10-inch wide wheel, and the Willys should be pretty stable on-road and off. If you want to really increase the stability, look for some axles out of a wide-track CJ or a fullsize Wagoneer.
An SM420 and Buick Odd-fire Walk Into a Bar…
One of your editors wrote an article on bolting a SM420 trans to an odd-fire Buick 225 engine, and he said that you can’t use the aluminum bellhousing. He stated that you had to get a cast iron one and bore out the hole to 5.00 inches and turn the front cover of the transmission to 4.999-inch. I’ve looked all over the country and cannot find a cast iron bellhousing for the 225 odd-fire Buick that I have in my ’67 Commando. Can I get you to email me about this and suggest a place to look for the bellhousing, clutch arm, and throw-out bearing? I’m putting a Dana 300 behind the SM420. I’m hoping you can help.
You got it both right and wrong. For starters, you can’t use the factory one-piece aluminum bellhousing from a ’70-’71 Jeep with the T-14 and Buick 225. These bellhousings were designed specifically for Jeep to use the T14, and the tranny bolt pattern, throw-out bearing retainer bore, and stickout length aren’t correct for the GM SM420. However, the older ’66-’69 Jeeps used a stock GM bellhousing with a cast iron adapter to mate the T-86 or T-14 transmission (as the case may be). You can bolt an SM420 right up to the early bellhousing once the adapter is removed, so if your ’67 bellhousing has the adapter, you’re in luck.
That said, not quite as simple as bolting the two parts together, you do have to modify the bellhousing a touch. The modifications you need to make to the aluminum bellhousing include drilling out the lower two bell-to-transmission boltholes for clearance, since the SM420 has threaded lower bolt holes that must have the bolt enter from the clutch-side of the bellhousing. Also, a little clearance is necessary at the top of the transmission bolt pattern to clear one of the SM420’s shift rails. This clearance coincides with a vent hole in most of these Buick V-6 aluminum bells. Both of these things should be easy to do with a drill and a die grinder. As for the throw-out bearing and clutch arms, these parts are available from Novak Conversions (novak-adapt.com) and Advance Adapters (advanceadapters.com), as well as others.
As for the bellhousing machining work, that’s if you’re trying to mate an SM465 transmission to the engine using a standard GM 4.687-inch bearing retainer bellhousing. According to Novak, the best way to do this is to bore the bellhousing out to 5.00 inches and turn the tranny bearing retainer down to 4.995 inches.
Jeep Fashion Police
Your “Trendy in Utah” article caught my eye. I have noticed the seemingly very sensible trend towards lower, more stable off-road modified Jeeps and appreciate the performance and safety aspects of such. However, I do not enjoy your criticism of overly tall “monster” setups or chrome accessories. In the same article you mention how you can’t do a write up of every plain Jane Jeep out there. Well, Jeeping is about doing your own thing. I think they are all pretty cool, some cooler than others, but I don’t think we need the Jeep fashion police keeping us in line. Customization, and especially innovation, just don’t work that way.
Terry Donohue, Jr.
West Chester, Pennsylvania
OK, I’ll defend my opinions, but they are just that, and I could be wrong, but it’s unlikely. I think they are based in fact and experience of what works on trails in general around the country (not for the local Jeep show). But still, you don’t have to agree with me, or do what I do. That is where innovation comes from. Good ideas of how to do things differently. Unfortunately, not all ideas are good, and some that work, don’t work well. In general, I think I am very open minded when it comes to Jeeps as compared to other people I’ve known who have worked at Jp over the past 10-15 years (don’t ask me to print their names). I like all Jeeps that do what they are supposed to do well or can be modified to do so without taking out a second mortgage.
First, as I said in the article, I like chrome on a Jeep, but in moderation and when it makes sense. A chrome grille cover is right up my alley. I like that bling. Cheap chrome hinges that don’t fit well? No thanks. A chrome diff cover that is paper thin, warped from the manufacturer and no match for the smallest rocks on the trail is junk and a downgrade as compared to most stock diff covers. Most of us want to make our Jeeps better off-road, not more vulnerable. Use common sense. Spending $5,000 on chrome gadgets that don’t increase performance is a waste of money in my opinion. Spending $200 to make something look a bit better or more “yours” is fine.
As far as über-tall Jeeps, you are the second person to say I am wrong, but oddly, despite that, my opinion of comically tall Jeeps has not changed. For clarity, I feel that anyone should run the minimum amount of lift necessary to clear the tires they want as long as the rest of the Jeep can handle those big tires. If that means hacking sheetmetal, then you should do it (as long as it won’t cut a tire or a passerby when done). I’ll admit that if you are into mud running having a tall Jeep is good, but even that has its limits. An extra six inches or a foot of lift between tires and body is a waste even in the mud (and yeah, I have driven in it—a lot). If your unnecessarily tall mud truck rolls over when one tire drops into a deeper mud hole, you are as screwed as anyone who has ever flopped a rig anywhere.
A great example of a big tire’d Jeep that I like and works well is former Editor John Cappa’s ’73 J-truck. It was built around big tires, but was low and stable. (Although it rolled on its side at Top Truck Challenge in a mud hole. Oh, and once at Tierra Del Sol’s Desert Safari). If a similar truck had the same tires and axles but lacked the trimmed fenders and had a foot more lift to clear the tires it would be scary and dangerous. I would also be willing to bet that it would be no more capable than John’s truck even in deep mud. Don’t agree with me? Build a J-truck with a tired AMC V-8 on deuce-and-a-half axles and 46-inch tires with uncut fenders and show me. Then if you can’t follow me in a relatively stock Jeep wearing 32s to the grocery store, or over a fairly simple trail with off-camber sections, you lose and I win—even if I get stuck in the mud.
If your Jeep is extra tall for tall’s sake and is less stable on a side hill than a drunk monkey or in danger of rolling over at the entrance to a trail, you are not “customizing” or “innovating” correctly, you are going backward and making your Jeep less capable, less useful, and less of a Jeep.
Lastly, if you drive a “plain Jane” Jeep, I am down with that. Let’s go wheeling. I probably like your Jeep. Just don’t expect me to take photos of it for a four-page feature spread in the magazine. Why? Well because it’s a magazine and we are trying to keep the magazine growing, our hobby viable, and our jobs secure. The best way to do that is to cover unique Jeeps that reflect trends that make sense rather than supporting things that look cool, but are actually counterproductive to the end goal.
Socket to ’Em
I can’t seem to find the correct socket size for a ’78 CJ-7 front axle nut to be able to replace wheel bearings and do a brake job. Any assistance would be greatly appreciated.
It’s a 21⁄16-inch socket. Most auto parts stores should carry them or you can order it through Quadratec (www.quadratec.com).
Get It Set
I have a couple of quick questions regarding the steering shaft set screw recesses that you mentioned in “Ground Up: Part 2,” (April, ’12). Is there a specific drill bit that you would recommend for drilling the recesses? Is there a recommended recess depth?
That’s a great question. I would recommend using a drill bit that is the same diameter as the threads on the set screw. That way you will be sure that the set screw is actually recessed into the steering shaft. Also, get some good quality thread locking compound and use it liberally on the set screw and lock nut, and check the set screws frequently. You don’t want these things backing out.
Got a tech question you’re just itching to get answered? Send it on in to Jp Magazine, Your Jeep, 831 S. Douglas St., El Segundo, CA 90245, or e-mail it to firstname.lastname@example.org.