Best Rear End Swap Out For A Stock Dana 35 And Gears

[Biotex]

Make sure you have a shim kit.

[Bmoore2]

I am in the process of trying to buy all of this stuff not really knowing what to buy. Will you guys please help me with my shopping list for this swap. I am pretty sure i have the front down.

 

New carrier to support 4.56 gears

Spartan locker for 3.73 and higher

Shim kit

Ring and pinion 4.56

 

Now for the back is where I am a little lost and really need some help.

 

I know i need leaf pearches but i don't know which ones to buy. (Reminding that i am swaping over to a 8.25)  I looked at Rusty's but I have no clue which ones to buy.

 

I also need Shock plates???? Once again this is where i am lost. If anyone could give me a link or part number to search on so I make sure I get the right stuff I would really appreciate it.

 

And if there is anything else that I need to make this as smooth as possible would be really helpful as these guys doing the work like to get paid a boo-koo of money per hour. I just want to show up with everything that I am going to need and it be the correct stuff.

 

Thanks again guys for everything. If you need any information from me please just ask. I am ready to get this done!!!!!!!!

[Biotex]

Look at this site:

 

http://www.barnes4wd.com/Axle-Swap-Combo_c_39.html

 

They sell a kit with everything you need. If you know the OD of the 8.25 tubes, you can buy a kit to fit. Even if you source the parts somewhere else, you can look at the shopping list and know what you need. It doesn't include brake hoses and e brake hardware. Just the hard parts.

[Bmoore2]

Biotex :cheers:  you have been such a help..... Would love to buy you a beer if you every make it to Va or I come to Texas!!!!  Thank again bro for helping a rookie out.  :)

[Biotex]

Biotex :cheers:  you have been such a help..... Would love to buy you a beer if you every make it to Va or I come to Texas!!!!  Thank again bro for helping a rookie out.  :)

 

No problem. It's why most of us are on this forum. Get help when you need it, and give back to the community when possible..... Bud Light!  :banana:

[Mark Serva]

Happy New Year! I don't mean to steal this thread yet it's getting a liitle old so maybe you won't mind. 

 

Anyway, I am trying to figure out good rear ratios for a 2WD with the anemic 2.8 Chevy v6 and an A904 Trans. It really can't go much over 70 without overheating yet I'd still like it to go up hills. Am running pretty stock tires. As an 86 I wish I had the AMC rear in there yet it appears to be a Dana 35. I go up some gravelly roads okay when dry yet should get a LSD in there for wet days. Also, I'd like to upgrade to a 3.4 as the old oil sprayer is failing. 3.07 seems to tall yet I'd like the highway speed and MPG yet I'm not sure if I could get up a steep hill even with a peppier 3.4. And, I like the A904s, have an extra too, so I'm not swapping my automatic.

 

If anyone can share their experience with this situation I'd appreciate it mucho!

 

Happy motoring, Mark

[Marine1Texas]

Mark if I remember right that 904 is a 3 speed auto, so you should have at least a 3.55 in there. 70 is pushing the rpms on that thing with anything 3.55 and above. you should not be over heating that could be that sprayer and bad cooling flow. you would have to figure that out.

 

If you have 3.55 with say 225/75r15 your running 2950 rpms.

If you have 3.07 with say 225/75r15 your running 2550 rpms. However with a auto you going to loose big power on take off if you put 3.07 in there. no recommended.

 

With my 31's a 4.10 and standard 5  at 70 my rpms are 2450 however it is a 4.0 with much more torque then a 2.8 or a 3.4. 

 

I know you don't want to hear it, but if you want to cruise at 70 you need a over drive. If your upgrading engine, I would look for a cheap upgrade with a overdrive auto. maybe a wreck one that you can pull everything out of. Around here Comanche's are not common , however XJ's are all over the junk yards, and for sale. You can pick a running one up, wreck for 300 to 600 easy.

[Eagle]

I have to disagree with Noriyori. I don't think 3.55 gears is "pushing" anything. You probably already have either 3.55s or 3.73s, and before making any changes you need to determine for certain what you have now.

 

Unlike most of you grasshoppers, I'm old enough to remember when overdrive wasn't even a high-priced option in automobiles. Most vehicles back "in the day" were geared from the factory to run somewhere around 24 miles per hour per 1000 RPM. To put that in perspective, 60 MPH was 2500 RPM, and 3000 RPM was a comfortable 72 MPH cruise. The engines didn't burn up at those speeds -- after all, the redline was still 5,000 or 5,500 RPM, so 3000 RPM was well below the redline.

 

Your choice of axle ratio should be based on your tire size and the fastest speed you normally drive on the highway. If you'll be going to a 3.4L V6, I think using 3,000 RPM as your benchmark for highway cruise is a good starting point. Here's a link to the tire size and RPM spreadsheet I crated a number of years ago. Pick your tire size, then look down the table for that tire size to see what RPMs the engine will turn at each speed. For the A904 tranny, ignore the overdrive columns and use the 1:1 columns.

 

I don't know what "pretty stock" tires means, but let's assume you're rolling on 225/75-15s and your highway speed is 70 MPH. 3.45 gears will have the engine turning 3015 RPM at 70, 3.73 gears will raise that to 3177, and 4.10s will raise it to 3492. If you don't do a lot of high speed highway driving, 3.73s might be a good, all-around gear choice. for easy swaps, though, axles already set up with 4.10s may be easier to find. Again, if you don't do a lot of highway cruising 4.10s would probably be much nicer to drive around, and even 3500 RPM probably won't kill an engine for a long time.

 

Link: https://docs.google.com/spreadsheets/d/1pHFuhGgj6dQDfzyfFJH5z7NCDLW2KX3ABQgAJr3lBvM/pub?hl=en&hl=en&output=html

[Marine1Texas]

I was thinking he wanted better mpg, that is why I was shooting for lower Rpms. If one is fine at running 3k or slightly higher at 70 mph that is ok and yes it will not burn engine up, if everything is in good working condition. You should be able to find 4.10 very easy.

 

The 3.4 does have a good amount more of torque so you will have better PEP even staying at the 3.55 you have now.

 

Here in N.E. Texas 70mph is what you do on th 75, 35, or 635. You have to do 75 to 80 if your out of the city area or get run over even by the big rigs.

 

More info will get better answers of course. Area where you live. Here it is low altitude and pretty flat. Also looking for better mpg, and how often you drive highway.

 

Around here I spend 50% driving in low 2wd at 5 mph. 25% driving 55 mph local roads and 25% driving 80 mph on interstate.

 

Sent from my ASUS_Z00AD using Tapatalk

[Eagle]

There's a lot more to highway MPG than just RPM. My '88 Cherokee is a 4.0L 5-speed. Around here we don't have any 70+ MPH highways -- the fastest legal speed is 65 MPH, so that's what I drive. Can't afford tickets, or what they would do to my insurance premiums.

 

65 MPH in 5th (overdrive) is 1821 RPM. The same speed in 4th is 2428. I have run controlled tests. My gas mileage in 4th is the same as it is in 5th. The reality is that, overall, I would probably get better gas mileage with 3.55 gears or even 3.73s than I do with the factory 3.07s.

[FrankTheDog]

The 2.8 doesn't have enough power to be useful under 3,000 rpm you're going to have to spin it if you want to go anywhere especially uphill.

Listen to Eagle.

[Marine1Texas]

My 88 4.0 with 3.07 switched it to 3.55 and the mpg went down by 1 or two it not much difference same tires. Now on my 87 4.0 that had 3.31 went to 4.10 when chipped a tooth had 235's to 31 I have a lot of gunt now, however a loss of 4 mpg.

 

I know everyone is a expert, and everyone been doing everything for years, and master mechanics (sarcastic). These are what I have come to in the 6, 4.0's all non HO but renix, for here I need to be above 1850 and below 3000k to stay in half way mpg. I also am in a area that speeds are much fast, less stop and go, that is pretty flat.

 

I had a 1984 XJ 2.8L carbed and it was great at 55mph up hill or flat. it had the 3.55 with A904 and 215's standard from factory. However that $#!& engine blew up at 105k My Wife hated driving it, so slow. In those days the speed limit in Texas maxed at 65 during day 55 at night. 70 was the fastest that thing would go to the floor and it was screaming around the 3k rpms. I just wonder if that thing had a over drive it would of been able to handle 70 easy. since the highest of tq was at 2400 and it dropped off fast at 2800 rpms, the HP kept going all the way up to redline I think 4700 or so. Then again it really was only built to do 55 anyway.

 

 

I still waiting for the guy who was inquiring to give more updates.

[FrankTheDog]

I live in a very hilly area with very little open road driving.

That's probably why I get better mileage with 4.10's than 3.07's.

[Eagle]

It's not as hilly around me as it is around Frank the Dog, but it's not exactly "level," either. And while we have some 65 MPH highways, we have more 55 MPH highways around here. With a Renix 4.0L and 3.07 gears, 5th gear is useless under 55 MPH so anywhere but on the highway (and even there to go up some hills) 4th gear is what sees the most use. 3.55s or 3.73s would allow more use of 5th gear and that would probably help the overall fuel economy more than it hurts.

 

Everyone's driving conditions are style are different. Gear choice is not a one-size-fits-all proposition.

[Marine1Texas]

If your hilly yes a 4.10 would be a good choice. I like the 4.10 all the way around anyway. The one reason I went with 4.10 even on a flat area, it added back what got taken away with the 31's. Are you going to get a d35 with 4.10 or you going to regear? A lot of people are against regearing, since the dana 35 is considered weaker and not worth it. One can make a case either way. If you have the 3.55 in there you can get new ring and pinion gear and bump it up. I think if you can find a dana 35 or maybe even a dana 44 for a good price it will be well worth it, then doing a regear. Not everyone is skilled even who do diffs for a living.

 

I have regeared both of my d30 and d60. My 87 had the d44 from factory, so I just went with a thick gear on it. Took me 5 days to get it just right, so no whiney noise. My 88 had the d35 and we searched for a d44 for 4 months. The 88 has the 4.6 in it so I was for sure not going with another d35. That truck I use to pull trailer with 10 feet tall hay bales from the back up to staging area.

 

If you do have a regear and not a axle swap, Find some one with a good long record at doing jeep diffs. If it is not right, you can get a chipped tooth before you know it, or it can be very noisy.

 

If you plan on regearing try out RWKHausSupply.com. Robert runs it and can get you a good deal. He knows all you will need to know about regearing it.

[Wiggilez]

If you can find a Dana 44 from another Comanche (with the correct gears to make it easy, assuming yours is 4WD), then that is your best bet. You can still find a D44 with non-matching gears if you can't get one with the correct gears, but you'll have to bring it to a shop to swap gears, which usually isn't cheap. On the flip side, a F8.8 isn't cheap either, but for different reasons. You'd have to weld on new leaf spring perches and get a yoke adapter to mate it with your driveshaft. But, a F8.8 can be found from a '96 or newer Explorer with disc brakes and trac-lok if you are so lucky. Sometimes even with 4.10 gearing.

 

Other options, you can try finding a D44 from an XJ/Wagoneer (rare, also) but again, leaf spring perches need to be welded bottom side if you're keeping the stock, spring under axle (SUA) configuration.

 

My suggestion... find yourself a Chrysler 8.25 axle from a '97-01 XJ (those are 29 spline shafts) and have a shop cut off the SOA leaf perches and weld on some SUA ones. These axles have a strength near D44 (not as beefy as an 8.8) but can be had for reasonable prices and they are a dime-a-dozen. I believe some '91-92 MJ's used these axles also (the 27 spline version) and those would be a direct bolt in. Keep in mind though that if you go the C8.25 route (either from a XJ or MJ), you will need larger U-bolts (3 inch diameter) and the MJ plates/shock mounts to make the swap.

 

One last thing about the C8.25 option... if you wish to have disc-brakes later on, you can get rear discs components for a KJ/Liberty and those are direct bolt on with no modification.

 

I'm pretty sure the MJ only got the D44 all the way to the end, so no MJ 8.25s.

[Mark Serva]

Wow that's some great feedback and thank you for the tire calculator as well. I know, this is something of a feel it in the pants sort of experience. I really just putter around locally with the occassional trip to the Appalacians. A girlfriend used to push on my leg to go faster so yes, I'm that old guy slowing you down--sorry:)

 

And I'm running 235 75 15s yet will go smaller when they wear out. Otherwise, everything is stock 2.8, 2WD and A904. Have added a couple of electric fans to the radiator and have a flex fan too. Only overheats in the summer or over 75mph.  I understand it's geared for the oil embargo for around 55. Runs hot in town too and suffers from vapor lock often. Mostly, I believe due to aftermarket exhaust downpipe running about a half inch from the stainless fuel line. Plan to reroute fuel line in Spring before our hot and humid Summer. 

 

I've driven lots of old cars and am used to using the temp guage for speeed instead of the speedometer so that's not so much a problem. However, since I'm doing these swaps in pieces would like to get it set up to use the 3.4 at optimum RPMs for puttering around town, getting up some grades and maintaining 75 for about 2 hours. Otherwise, the average speed where I live (the worst traffic in the USA) is probably about 20mph so it's generally faster to bicycle.

 

Was thinking the 307 rear might work because the 904 seems to be geared so low. Zippy from 0 to 30 and nothing after that. Forgot to count my gears last time I changed gaskets yet I guess a 3.55 was pretty stock with the 904 and 2.8s. And, thinking the 3.4 to come, if I can find one, has about 60 more horses and torque so I might get an okay start with a better finish. 75 is all I need to not get run over on the highway. 

 

Thanks again for all the feedback yet hoping somebody had done the same and might share their success for failure before I follow them. Meanwhile, I'll start looking for some of those elusive Danas and Fords people recommend. There's a real shortage of junk yards around here so they get away with some crazy prices for the unknown. I really appreciate all the help and feedback!!!

 

Happy motoring, Mark

[vandior2001]

i have been looking  for a dana 44 for a few months and haven't had luck. :(

 

so i will start looking for a 8.25

 

the question i have is this

 

i have 286\65R18 tires now ( 2 sets really ) that's about 32x11 or so. my goal is 35's one day.

what's the best gears for that size range? i live in KY so i don't think there is a flat spot in the whole state.

the people i talk to locally say 4.10's are good even for 35's. i have a friend that's a jeep \ off road nut, he's telling me 4.56 is the way to go.

what's everyone thing? i would like to get muddy but i want to upgrade and regear frist.

 

also will my rear drive shaft still work with a 8.25? i have 4.0 5 spd short bed

 

thanks for any help!   

[onlyinajeep726]

 

If you can find a Dana 44 from another Comanche (with the correct gears to make it easy, assuming yours is 4WD), then that is your best bet. You can still find a D44 with non-matching gears if you can't get one with the correct gears, but you'll have to bring it to a shop to swap gears, which usually isn't cheap. On the flip side, a F8.8 isn't cheap either, but for different reasons. You'd have to weld on new leaf spring perches and get a yoke adapter to mate it with your driveshaft. But, a F8.8 can be found from a '96 or newer Explorer with disc brakes and trac-lok if you are so lucky. Sometimes even with 4.10 gearing.

 

Other options, you can try finding a D44 from an XJ/Wagoneer (rare, also) but again, leaf spring perches need to be welded bottom side if you're keeping the stock, spring under axle (SUA) configuration.

 

My suggestion... find yourself a Chrysler 8.25 axle from a '97-01 XJ (those are 29 spline shafts) and have a shop cut off the SOA leaf perches and weld on some SUA ones. These axles have a strength near D44 (not as beefy as an 8.8) but can be had for reasonable prices and they are a dime-a-dozen. I believe some '91-92 MJ's used these axles also (the 27 spline version) and those would be a direct bolt in. Keep in mind though that if you go the C8.25 route (either from a XJ or MJ), you will need larger U-bolts (3 inch diameter) and the MJ plates/shock mounts to make the swap.

 

One last thing about the C8.25 option... if you wish to have disc-brakes later on, you can get rear discs components for a KJ/Liberty and those are direct bolt on with no modification.

 

I'm pretty sure the MJ only got the D44 all the way to the end, so no MJ 8.25s.

 

 

Yes, you're correct... As you can see, this was nearly four years ago when I was fairly new to MJs and was basing my "facts" from stuff I had seen in junkyards and other places.  I've learned a great deal about them since then, and know now that 8.25s were never standard in an MJ. :thumbsup:

[75sv1]

• Might also look at the Ford 8.8. Fairly common with 3.73 and 4.10s. Also disk brakes on most of them.