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re-gear for towing, easy SUA axle swap for 4x4?


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OK, so I know re-gearing is the primary response to many inquiries on power, I never concerned myself with it because I was happy with the AW4/4.0 HO/3.55 setup...until now. I have found myself in a predicament where I believe gearing will be my only answer, and of course cannot find the exact info I need, and doing a search gives me 167 hits, most of which are irrelevant for the info I need; maybe someone can give me a quick answer to save hours of searching.?.

 

My situation is with my MJ shortbed I did the 4.0 HO swap on. I have the 3.55 front axle in it; but have yet to put the matching 8.25 rear in it, so I am still suffering with the pathetic 3.07 as a 2wd truck only. Since I lifted it, I am planning on going with 31" tires. After the lift, it is still SUA, AND I WANT TO LEAVE IT THAT WAY!

 

The issue: I have a 2,200 lb 7x14 double axle enclosed trailer. After towing it (loaded with about 1,200lbs, totaling trailer weight at about 3,400 lbs, with my donor XJ before the swap, with the same 4.0 HO 3.55 axle as planned for my MJ), in the mountains 6,500+ ft elevation, I realized the jeep struggled a bit more than expected. That in mind, the trailer was a bit larger than I needed, so I had planned on selling it, and purchasing a smaller single axle 6x12. Unfortunately, since new a few months ago, I have used the trailer very little and had CRAP luck with it...it got paintballed on one side, puting about a dozed dents down it, then someone backed into it denting the rear door, then I loaned it to someone (I trusted), and they demolished the front by driving about 60 miles on a dirt road with a lifted truck putting countless dings on the front from rocks getting kicked up :fs1: I am stuck with it now as I REFUSE to take as much of a loss as I would have to in the short few months I have had it. I also do NOT want to buy a bigger truck. What must I do so my MJ can tow it with relative ease? I figure I can get away with only about 500-600lbs of load in the trailer most of the time, totaling the trailer weight less than 3,000lbs. I am holding onto the hope gearing may save my situation.

 

I just towed it with my MJ for the first time, with about 400 lbs in it (totaling about 2,600lbs) with my 3:07 rear and 30x9.5 tires up a 2,000 ft climb, 8 mile long grade. While the MJ wasn't happy about it, it gave its all @ full throttle and still held 45 mph in 2nd revving at 3,000 the whole way. It did OK on flat land. Sooo, needing a rear end AND matching axles, wanting a fairly quick and easy swap, DIRECT front swap and perch welding OK for the rear...hitting the wrecking yards, what am I looking for? running 31" tires and an HO motor, will the 4.10 gears be sufficient, or should I be looking for another ratio? I still want it to be practical for long distance highway driving unloaded. Once needed ratio is determined, what XJ's should I be looking for, for the axles I need (in other words, years/motor/trans setup?) I honestly don't NEED any rear axle in particular, sure I would like a d44, but I will take whatever I can get for now just to get it DONE as winter is around the corner and I need my 4x4 working SOON; then I can fine tune from there. Can anyone give me something to work with PLEASE? Thanks!

 

-James

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I believe 4.10 gears will be sufficient, and they can be found in most 4cyl Cherokees and Comanches. Front axle from either will be a direct bolt in, rear axle from a Cherokee would have to have the shock mount and perches cut off and new perches welded on. From a Comanche would of course be bolt in. I believe a front axle from a Grand Cherokee or TJ Wrangler will bolt in also, but rear axle has a *bunch* of stuff on it to cut off because they are a coil sprung 5 link, IIRC.

 

Don't waste your money on a D35, but instead get a 29 spline (97 and newer?) 8.25, or better yet if you can find a good deal, a D44. The 27 spline 8.25s use the same housing, so look identical on the outside, but the shafts are only marginally bigger than a D35.

 

A Ford 8.8 out of an Exploder is also an option, plenty strong enough, but it is a bit narrower than a Comanche or Cherokee axle, and you need to either adapt the flange plate on the axle, or the end of your drive shaft to hook one up to the other.

 

If you currently have a D35, be aware the nose on an 8.25" is an inch longer. Either get perches with multiple holes like from Ruffstuff Specialties to allow you to move the axle back if needed, or check your drive shaft engagement into the transfer case to make sure it can go in another inch without issues.

 

And if you don't already have them, get trailer brakes!

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Buy a full size truck. Just because you can pull something doesn't mean you should. Older single cab trucks are going for dirt because everybody wants four doors. You have a great looking MJ but I would think that trailer if loaded wanted to swerve left or right you would be along for the ride.

 

I guess I have nothing helpful as far as the gearing goes, My truck currently has 3.73 gears but also has a V8. It has tons of get up and go on the road, but am going to regear to something in the 4's when/if I find a Dana 44

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4.10s should work great for you. But in the interim, grabbing a 3.55 geared rear axle and throwing it in would still be better than it is now.

As mentioned, if they aren't there already trailer brakes should be on your to-do list. :thumbsup:

 

 

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Buy a full size truck. Just because you can pull something doesn't mean you should. Older single cab trucks are going for dirt because everybody wants four doors. You have a great looking MJ but I would think that trailer if loaded wanted to swerve left or right you would be along for the ride.

 

He is towing less than 4K. Properly set up his MJ will tow this fine. Plus he specifically stated that he does not want to get a bigger truck. Buying a bigger truck just to tow this little trailer is a waste. :fool:

 

4.10 gears should work pretty well for you. I'd look for a '97+ 8.25 and a '96 to '99 D30. The 8.25 will have larger shafts and the D30 will be high pinion and no CAD with larger axle shaft u-joints. Car-part.com should help you find a matching set in your area. Look for 2.5L XJs.

 

It is also very important that you get the proper drop hitch to get your front out of the air.

 

Willy

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His first post says he's currently running 30x9.50, but want to move to 31" tires.

Thanks, I missed that the first time around.

 

Fact (verifed by yours truly): 31x10.50 tires with 3.73 gears turn EXACTLY the same RPMs for a given speed as stock tires with 3.55 gears. EXACTLY the same. So consider if towing your intended trailer would be bearable with a stock truck with automatic, on stock tires. If so, then 3.73 gears would be okay and 4.10s would be a little better.

 

However, if your answer about a stock rig being bearable for your purposes is, "Heck no! No way, Jose!" ... then you move to 4.10s being the least gear you should consider, and 4.56s or even 4.88s being preferred.

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Thank you, thank you, thank you!!! This is the info I was looking for. I will be making a day of Junkyard hopping tomorrow, in search for 4 cyl XJ/MJ's with 4.10's front and rear jamminz.gif Unfortunately, I fear I may get stuck with a d35 rear, but whatever...so long as it will work for NOW, I'll take what I can get. I'll keep the Ford 8.8 in mind as a last resort...I want as simple of a swap as possible though to minimize complications and the need for too much work.

 

Looks like you are in luck. Check this out...

 

viewtopic.php?f=4&t=18775

 

Rob L. :brows:

HAHA, I saw that. Too bad its so far away :wall:

 

Buy a full size truck. Just because you can pull something doesn't mean you should. Older single cab trucks are going for dirt because everybody wants four doors. You have a great looking MJ but I would think that trailer if loaded wanted to swerve left or right you would be along for the ride.

I already tried that, and wound up screwing myself even more financially...Lesson learned; if you ever come across a great deal on a Ford with a 460 V-8, its not such a great deal: -Plan on stopping at EVERY gas station to top off, to be sure you make it to the next one. Then when you can no longer afford to fuel it, plan on selling it later for much less than you paid because seemingly EVERY potential buyer knows about their excessively thirsty nature, and their 1st question being "Does it have the 460?", followed by immediate disinterest. One cannot deny it will tow anything you put behind it though. The other issue, aside from additional insurance, is storage. Besides, my MJ was suprisingly stable towing it at 60 mph, more so than the XJ, but the slightly longer wheelbase might have something to do with that.?.

 

Anyway, 'nuff said. I don't doubt my MJ can handle that trailer, as long as I watch the weight of my loads and am selective on the mountain routes I drive to reduce drivetrain strain as much as possible. Ya, she's got a little tail squat with the trailer attatched...but it looks worse than it really is; I think those Hell Creek leaf packs are a little on the soft side(whick is nice driving unloaded) but remedies are available for that if it gets to me. Anyway, hopefully I'll come home tomorrow with some treasures. Oh ya, and trailer brakes are definately next on my list before I take that trailer anywhere else. Didn't wire them up for the last trip, because it was all up hill (for the most part). :chillin:

Thanks again :cheers:

 

-James

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Weight distributing hitches work great on flat terrain, but when going through a dip it wants to pull the rear wheels up off the pavement, when going over a hump it will make the rear squat as it tried to pull up the front wheels and trailer. I have seen a Silverado with a 26' camper and weight distributing hitch not be able to go over a raised rail road crossing because of this. The front wheels went up the hill, and then the rear wheels had no traction because there was no weight on them. The hitch tries to keep the truck and trailer level relative to each other no matter what, individual axle weight be damned.

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OK, so I did my Junkyard mission today. I am fortunate enough to have two pick-and-pulls within 40 miles of my house, so the plan was a big loop, I would first go to Carson City P-N-P, then the Reno one. It has been about a month since I had been to either one. I woke up feeling lazy, so I figured I would grab enough basic tools to pull a diff cover if I had to, to get gear ratio...and enough to get whatever else I couldn't live without and basically make a scouting mission of today, and go back tomorrow if I found what I needed.

Carson City P-N-P usually has about 8-10 XJ's on any given trip, but they are usually older, 80's models...its a score to find a early to mid 90's one. Well, I was FLOORED on this trip. I had completely forgotten about that whole C-4-C program. After walking through the cars to get to the small SUV's and trucks, I stopped in my tracks with the first two I came to. To my left was a MINT '99 Grand Limited, and to my right was a MINT '03 Grand Laredo :eek: As my eyes scanned the yard, all I saw was 97+ XJ's and tons of other late model Explorers, escapes, 4-runners...all late '90's and up in great shape :nuts: They had for the most part not been touched, so they must have rescently been put out. Once the shock had passed, I did briefly feel like shedding a tear for all AWESOME, well cared for rigs that ended up here...until the reality that all these XJ's had parts that were mine for the taking! HAHA, I must have looked like an overly hyper ADD kid in a candy store...running from XJ to XJ anxious to check out the next one. Carson City had 16 in all, 6 of which were '97+, and seemingly countless more in their holding yard (including an '05 liberty :nuts: ) Of course, of the 16, NOT ONE WAS A 4 CYL!!! :fs1:

Reno did have about as many XJ's out, mostly pre-'97, but once again, NO 4 CYL :fs1: :wall: They had so many C-4-C in their holding lot, they were double stacked! A '98 tacoma, on top of an '03 Suburban, in front of a '97 XJ, under a '98 Lexus, next to a '99 Durango...and on and on. ALL FLAWLESS!!! What a trip it is to see that. I did, however, see 1 MJ that fell victom to the C-4-C :(

So, a whole day devoted to this, and I didn't find any 4.10 axles, the closest I came was two sets of 3.73's in a couple V-6 2.8's. I didn't go home empty handed though!!! (its a good thing I only had limited tools on me, otherwise I would have spent ALL my $$$ on '97+ parts...plenty on perfect, complete '97+ doors out there :doh: ) I did get a '97+ front bumper though :yes: I got to go back for the OEM foglights for the bumper, they were on another painted bumper and I didn't have the tools with me to get those off. It appears as if I will be frequenting both p-n-p's now too see the latest additions from their holding lots :shake:

 

My new bumper :clapping: put it on, but have to fender trim tomorrow for the end caps to fit:

 

This one has got everything I would need for a complete '97+ conversion, everything is straight there and even the right color :wall:

 

And the one MJ I saw, RIP :( DEFINATELY going to keep my eye on this one to get into the yard for the tailgate and taillights as they looked great (the bed even looked nice):

 

Anyway, Raoden83, thanks for the reminder, I forgot about those guys. I already called a couple other full service JY's and only one had them, but wanted WAY too much $$$ for them, so I figure if it comes down to it, I will proceed with my current 8.25 (3.55) install just to get me through winter with 4x4, then proceed with my search for 4.10's.

 

-James

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