Ratio Change from 3.07 to 3.55

[flint54]

Would like to do this cheaply, but just once. My local

Jeep shop quoted me $850 labor and $600 parts to

swap the ring and pinion in both diffs (D30 and D35),

but I've located donor parts in the JY for <$100. Yes,

Ive been reading here long enough to know that the

D35 is weak and not worth working on, but I've not

been able to find a local D44 to swap in. Plus, I'm

not beating the h*ll out of this truck anyways. My

mechanical abilities are good, and I have a FSM, although

I've never done this particular job. My truck is 4.0 HO with

AX15, and I'm looking fir a bit more pulling power

without giving up too much highway use. Helpful

opinions and advice are welcomed. Should I be

leery of used gears (150K miles) if they look good?

Should I plan to re-use my young (~80K miles) bearings?

Thanks!

[tbrand]

Another option if a D44 is hard to find is a Chrysler 8.25. It's not quite a D44, but it's heftier than a D35, and loads of XJ's came with them.

[jimmy21669]

The 3:55 axles are FAR too common to spend money re-gearing 3.07's. Easier and cheaper to swap both axles, and as mentioned, you can upgrade to the 8.25.

 

Any automatic XJ with the 4.0 will have them.....

[mnkyboy]

A complete dana 30 with 3.55s is about $150-$200 and 3.55 geared dana 35s are even less. You could get both axles and swap them in a weekend

 

I could see regearing if you wanted an uncommon gear ratio but your after probably the most common ratio Jeep offered

[flint54]

I see the direction this is heading, however here are some of the factors that come into play:

Doing a rear swap now requires me to grind and reweld spring perches and I (don't have/am not)

a welder. It also would require changing U bolts due to larger tubes if using the Chrysler unit.

To me, one of the big D44 advantages is larger brakes the other swap options don't have.

The front swap drives me back to the alignment shop. Yes, the D30/D35 units are plentiful

but from a cost perspective it seems higher given the unit prices and the services I will need,

compared to just buying the 3.55 differentials (JY) plus I don't have to work with control arms,

springs, shocks, brakes, steering, etc. What would lean me towards swap for the rear is if I

could find a unit with disc brakes, but I haven't found one yet. I'm willing to drive up to 100

miles for the right unit, but, as you probably know, shipping is crazy costly. My affordable

ceiling for the whole swap is around $300. Beyond that I need to live with what I have. What

am I overlooking?

[MiNi Beast]

your overlooking your lack of potential.

front axle swap is straight forward unbolt everything and bolt it back up same way, and you alignment should not change unless you add a bigger lift in which would require to LCA and/or UCA. So buy a Haynes and follow it step by step to do swap.

 

The rear, again pretty straight forward as well. look for said axle of your desire, being a D35, 8.8 or 8.25 or D44, many to choose from all have their advantage, which should be chosen based on your overall goal as so your not spending money on same thing twice, save money in the long run, now leaf perches just cut them off, grind them smooth and I recommend buying a new set ($20) way easier to work with, then I cannot believe you don't know someone that has or can weld for you, perhaps for some beer and food on a sat or something, if all else they can be install at a local welding shop for like a $50 at most, then the rest u-bolts, well need new no matter what axle you get, so you have $40 into new set of grade 10 ones, so you have roughly $110+friend or weld shop labor+ a set of axles for about ($250/$300) = So about $410 +gas=$450 roughly which is way better then your $1400 you were quoted.

 

option as well is just buy a matching set of used gears and simply pay for the install kits and labor to have them installed, around here gear install goes for about $250 per axle, so gears be had for $100+$150(install kits)+$500(labor)= $750 still beats just the cost of labor you were quoted.

 

Are you sure you don't want 4.10's? What are your goals or what are you using the truck for? figure that and go from there.

[Pete M]

getting perches welded on can be as easy as driving to the local muffler shop and handing them 20 bucks. :thumbsup:

 

 

Do not spend anything on "upgrading" a Dana 35. no. no. no. no. no. no. :no:

[mkbruin]

Front:

Jack and support vehicle on jack stands.

Undo brake lines.

Undo tie rod ends from axle.

Undo front driveshat from axle, tape endcaps.

Undo track bar bracket from axle.

Undo upper control arms from axle.

Undo lower control arms from axle.

 

Install is reverse from above.

 

 

Rear:

Undo e-brake.

Undo brake lines.

Undo rear driveshaft, tape ends, bungee up and out of the way.

Remove u-bolts.

 

Install is reverse from above.

 

 

Axle choices:

Front 30 from TJ, XJ, MJ, or ZJ.

Rear: ZJ 44a, TJ 44, D35, Chry 8.25, MJ model 20.

 

All of the rears listed came in the correct width, and with the correct gearing (possibly).

You can get someone to weld perches for $20-$50, depending. Sometimes less. Find a local 4x4 board or a large board with people in your area (heck, post on craigslist...)

 

The ZJ 44a has a bad rep, but are still stronger than a c-clip 35 and are great if you truss. Their downfalls are lack of gearing (not a concern to you) and a center section that flexes if really beat on (hence, the truss).

 

Personally, I would go 8.25 and call it a day.

[richasco]

As others have said doing anything to a D35 is probably going to be a waist of your time and money. Putting 150k gears and bearings into your rear end is just asking to be left stranded somewhere. You mentioned reusing your low-mileage bearings, do you have the proper tools to do this? Have you read the articles at http://www.off-road.com ? If not, click the link and spend some time reading in the Jeep Tech section. If you want to learn to set up gears practice on a front axle first. The gear pattern is not as critical as the front axle gets less stress and use. From my own experience regearing a D30 is very easy. As others before me have found, the setup rarely needs to be changed when swapping gearsets between D30's. Good luck with which options you choose. I think you will love driving a 4.0l ax-15 with 3.55's.

[flint54]

Guys,

I got more than, and less than, I hoped for.

I don't need to hear about how to do a swap,

I know that. I also don't need to hear about

what vehicles are donors, I know that too.

Yes, I'm quite sure I don't want 4.10's as this

truck spends 90% of it's time at highway

speeds. I'm not climbing rock walls, I'm only

pulling an occasional trailer - not sure just how

much strength I really have to have (but I do

understand there's no such thing as too much)

Don't need a Haynes, I have the Jeep FSM.

Don't need to hear where to find a welder,

they're plentiful, but I like to do things myself

whenever possible (remembering the track bar).

Not sure why the risks would really be that

much different putting 150K mile gears in my

axle than swapping in a 150K mile unit, I must

have missed something. As I understand it,

axle bearings are all about measuring, shims,

and preload - doesn't sound too bad. I wonder

if I were asking about re-gearing a D44 as

opposed to a D35 if the answer would be same?

I think I'll just let this project simmer for a few

more months in the hopes that a D44 shows

up within my reach and budget. I really would prefer

to NOT keep the D35, just recognizing I may wait a

long time for the right D44 to come along. In the past

months of hunting I've found only one, and someone

had already pilfered the gears! Thanks for all

the feedback. BTW, I have yet to find an XJ/MJ/ZJ

in the boneyards with < 150K - most are over 200K

miles. I suspect the axles aren't the weak link for

the average XJ that hasn't been modified from stock.

[mnkyboy]

Problem with used gears is you are disturbing them and putting them into a different axle housing.

 

There are small difference between every axle so you figure the gears have been wearing a certain way for however miles then you take them out and put them in a different axle.

 

You take that versus a complete undisturbed axle and the risk is much less.

[ratrapp]

exactly.it's really hard to take used gears and swap them into another housing and not disturb the wear pattern.it can be done,but it is so much easier to swap the whole housing.my 35 rear axle has 180k miles on it and i replaced one wheel seal and bearing.i don't wheel the truck but when 4 wheel is needed it doesn't let me down.for normal use the 35 is a fine axle.

[A-man930]

swapping in a different assembly is 1000% easier than re-gearing. Even with welding in some new perches. I found an 8.25 with 3.54s and never looked back, so what if it has drum brakes? why do you want disc so bad? If its primarily a street truck then you don't have to worry about rocks/dirt/water collecting in the drums (the primary reason disc brakes are better for a trail rig.)

I've been guilty of over-thinking projects myself, as I believe you're doing. But it's better that than diving in without doing your research and knowing all your options well. I'd find a 8.25 and matching front D30, clean out the housings well, maybe replace the wheel seals and bearings on the rear, and get gone.

 

You will love the difference in how it drives :D

[flint54]

So yesterday I actually sat down and -read- the FSM section pertaining to diff rebuild, and have to

conclude the task is far more advanced than I'm qualified to perform - even if I had all the special

tools called for. My buddy says, just slap a set of gears in and go but that's not how I work. So

today I spent at the JY under a 2000 Cherokee Sport salvaging a 3.55 Chrysler 8.25 axle assembly

and had it off and loaded up in less than an hour. Too bad it's an open diff. but couldn't find any

posi's. It's going to take time getting it cleaned up and all the stuff ground off, and new perches

welded on. Price was right at $90, and the cover had never come off until I opened it up. Very

clean inside. I will convert to disc brakes before installing - better braking and easier to work on.

I'll install the rear axle when ready, and just wait (and stay in 2WD) until I can afford to swap out the

front. I also found a NP242J xfer case for another "rainy day" project but that's way downstream.

 

You guys were right - swapping is the smart way to go.

 

BTW, I need to find a pair of HD spring plates with shock mounts for the new larger 3" dia axle bolts.

I don't think my old 2.625" plates will work.

[Pete M]

I wallowed out my shock mount holes when I installed the 9" axle. I think (it's been a while) I used the 4" grinder. Doesn't have to be pretty. :D

 

But I built my U-bolt plates from scratch. I assume you didn't grab those from the XJ?

[btm24]

Just go back and get the plates that came off of the truck you got the axle out of. I think that should work

 

bRANDOND

[flint54]

I got the XJ plates and U bolts, but was surprised at how much lighter

they are then those on my MJ. Plus, they don't have shock mounts.

I'll go check the edge distance on my MJ plates and then will see

if those holes can be enlarged to accept the 3" bolts. I've got a set

of 2200# springs coming from HC and new 3# bolts with them.

[Eagle]

I wallowed out my shock mount holes when I installed the 9" axle. I think (it's been a while) I used the 4" grinder. Doesn't have to be pretty. :D

 

But I built my U-bolt plates from scratch. I assume you didn't grab those from the XJ?

The plates from the XJ wouldn't have the studs for the lower shock mount built in.

[HOrnbrod]

Getting back to spacers - I would not have used them if the rear disk brake caliper didn't rub on the inner wheel. So rather than grind material off the caliper, I installed SpiderTrax spacers and have had zero problems with them. Looks better too. :D

 

W/o Spacers

 

With Spacers

[Pete M]

I meant the thick u-bolt plates that are separate from the thin shock mount plates. They are separate in all my MJs, and I keep forgetting that I found them integrated together on that 92 MJ. I guess I'm assuming an XJ would have the thicker structural plates.