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rear end change


tinlizzy

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4 minutes ago, CO54 said:

Spicer (Dana) 44 is the way to go, just check years to ensure the right bolt pattern if coming off a Jeep. 

 

yes Jeep ....this will be my first attempt at doing something like this ,Trying to find the closest possible match ......Thanks Steve

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38 minutes ago, 5027 steve said:

yes Jeep ....this will be my first attempt at doing something like this ,Trying to find the closest possible match ......Thanks Steve

Jeep used the Dana 44 front and rear on, 93-98 Cherokee, Grand Cherokee, and Wranglers, however during the same time they also used a Dana 35 rear with a Dana 30 front.

These where all on a 5 x 4.5 bolt pattern. 

GC from 99-04 flipped to the Aluminum Dana 44 with 5 x 5 bolt pattern. 

Wranglers stayed on 5 x 4.5 until 2007, when they flipped to 5 x 5. 

Jeep stopped using Dana 35's with the end of 2006

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7 minutes ago, 5027 steve said:

So i want the 5 on 4.5 correct??? my truck is in the shop up north at the cabin so I cant go out and measure it ...Thanks 

Provided you have a 1/2 ton, yes, 3/4 ton use a 5x5.  

There was some good references in the "51 B3B build after all these years" started by bkahler.   Pages 9-11 if memory works correctly. 

 

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2 hours ago, 5027 steve said:

Ok so I just went to our local junk yard to try and find a rear end ......... used the listings i found here and the only thing they could tell me is they had a Spicer 35 or a spicer 44 out of a Cherokee..... I guess i'm looking for advise please ....Thanks Steve

 

Steve,

 

I can give you this much.  I just bought an axle out of a 1997 Jeep Grand Cherokee.  It was a 3.73 with no ABS and no traction control.  I've been told it is a Dana 44 axle.  It has disc brakes and an aluminum center section.  As near as I can tell it's going to be a bolt in once I weld the new spring perches to the axle tubes.  It is shorter by one inch on each side so I bought wheel spacers to make up the difference.

 

In 1998 Jeep changed the axle width and they are about 2-1/2" wider per side so you need to keep that in mind when searching.  In my opinion the 1997 is good for 1/2 ton trucks and the later axle are good for the 3/4 ton trucks.

 

Brad

 

I just saw that Eric already covered this!  :)

 

Edited by bkahler
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On 1/13/2020 at 10:57 AM, Bobacuda said:

ARGH!

 

Tooljunkie - My most humble apologies, I meant to say '69 Sweptline, NOT '79 Sweptline

I also apologize to anyone and everyone that felt I was wasting their time and efforts.  I make typos, but that was ridiculous.

 

OK, I am sufficiently red-faced.

Bob

No worries, i figured it out straight away. 

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Sorry if it seems i hijacked this post..Just trying to sort things out.....OK went to local junk yard they have two dana 44's in stock,One with 3.73 ration and one with 3.55 ratio....this is where i don't have any knowledge on the matter ,I retro fitted a new world T5 trany into my truck, I don't know which ratio to choose ....Anything will be better than the stock 4.10 ratio ....they want $300 for complete rear end including disc brake set-ups..... does that seem about the correct price ?????? Thanks Steve...

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15 minutes ago, 5027 steve said:

Sorry if it seems i hijacked this post..Just trying to sort things out.....OK went to local junk yard they have two dana 44's in stock,One with 3.73 ration and one with 3.55 ratio....this is where i don't have any knowledge on the matter ,I retro fitted a new world T5 trany into my truck, I don't know which ratio to choose ....Anything will be better than the stock 4.10 ratio ....they want $300 for complete rear end including disc brake set-ups..... does that seem about the correct price ?????? Thanks Steve...

 

I don't have an answer for you on which ratio to choose, hopefully Jeff Balazs will chime in shortly.  He commented to me about a 3.73 might be more appropriate for my 218 powered 1/2 ton.  He runs a 230 in his 3/4 ton and has a 3.55 installed.

 

As far as price, I paid $315 for mine shipped from Michigan to Kentucky but it was missing all of the brake parts except for the backing plates.  I wasn't aware the brake parts were missing when I bought it so that was a price adder I wasn't expecting.  To be fair I would likely have replaced the rotors and calipers anyway just so I could start out with new parts.

 

Brad

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1 hour ago, 5027 steve said:

Sorry if it seems i hijacked this post..Just trying to sort things out.....OK went to local junk yard they have two dana 44's in stock,One with 3.73 ration and one with 3.55 ratio....this is where i don't have any knowledge on the matter ,I retro fitted a new world T5 trany into my truck, I don't know which ratio to choose ....Anything will be better than the stock 4.10 ratio ....they want $300 for complete rear end including disc brake set-ups..... does that seem about the correct price ?????? Thanks Steve...

A couple questions to answer your ratio question:

Still running the 218?

What is the final output of high gear in the T5? 

Do you live in a hilly area or at altitude?

What are your average speeds going to be?

 

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I've been pondering the rear axle change for years, and from what I've read from various sources, the Dodge Truck flathead torque curve delivers the best balance of pulling power and highway speeds with a 3.73 rear axle ratio on transmissions with a 1:1 top gear.  The 4.1 does well in all transmission gears at speeds up to 55mph, beyond that is pushing your luck...3.55 does very well at cruising 55-70, but seems gutless at lower speeds.  Originally, these rear axle ratios were engineered as part of the powertrain to maximize torque throughout the transmission range, so engine-transmission-axle configurations vary with torque curves and gear ratios...what may fit on the chassis may or may not deliver the best performance :cool:

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19 minutes ago, JBNeal said:

I've been pondering the rear axle change for years, and from what I've read from various sources, the Dodge Truck flathead torque curve delivers the best balance of pulling power and highway speeds with a 3.73 rear axle ratio on transmissions with a 1:1 top gear.  The 4.1 does well in all transmission gears at speeds up to 55mph, beyond that is pushing your luck...3.55 does very well at cruising 55-70, but seems gutless at lower speeds.  Originally, these rear axle ratios were engineered as part of the powertrain to maximize torque throughout the transmission range, so engine-transmission-axle configurations vary with torque curves and gear ratios...what may fit on the chassis may or may not deliver the best performance :cool:

Outstanding info 

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I have a Ford 3.7ish rear in my Studebaker half ton with 235 75 15 rear tires. It runs through a 700r4 auto with a .7 something top gear.  It runs down the road 2200 to 2500 at 60 65mph. The only problem I have cruising the empty truck is first gear is very low it's done at about 20 mph. But I am running a 259 v8 so you flathead might be ok with the t5 first. Second and third are fine. Not sure how the ratios compare between the manual and the auto but I wouldn't first and second are in the same neighborhood.  

 

Put your ratios in the linked calculator with some different rear ends and tire diameters for a illustration of how things work together.  

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

 

My P15 with OD, 4.11 and 28 3/4 inch rear tires is quite happy on the highway.  The OD makes the rear end think it's a 2.8 something, knocks down rpms by nearly 1000.  62 used to to run 3300 with OD it's 2400 and change. 

Unless your are going to never climb hills haul a load or town anything I would recommend the 3.7 ish rear gears.

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On 2/5/2020 at 6:47 PM, JBNeal said:

I've been pondering the rear axle change for years, and from what I've read from various sources, the Dodge Truck flathead torque curve delivers the best balance of pulling power and highway speeds with a 3.73 rear axle ratio on transmissions with a 1:1 top gear.  The 4.1 does well in all transmission gears at speeds up to 55mph, beyond that is pushing your luck...3.55 does very well at cruising 55-70, but seems gutless at lower speeds.  Originally, these rear axle ratios were engineered as part of the powertrain to maximize torque throughout the transmission range, so engine-transmission-axle configurations vary with torque curves and gear ratios...what may fit on the chassis may or may not deliver the best performance :cool:

Well stated. 

 

I would add that tire diameter is also an important variable to consider in the mix.  As a general rule, the taller the tire the deeper the gearing needed.  I have also found that lower power engines (like four bangers or flatheads) seem to have better pep when leaning a little lower rather than a little higher with final drive ratios.  If the math comes out for a rear end ratio that is in between what's available, choose the lower (higher numerically) option.  

 

I  believe if you've got an OD trans don't be afraid to go deep in the rear end.  Many people are surprised by how low they can go and keep reasonable highway cruising RPM.   

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9 minutes ago, 5027 steve said:

Has anyone found Correct spring perches to use when installing a new rear end ???? Thanks Steve

Steve,

 

I bought these spring perches from Amazon for my Axle.  The springs are 1-3/4" wide on my B3B and I would assume they would be the same for your B2.

 

I finished welding them on just last week.

 

Brad

 

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