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considering IRS yes or no?


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I'm considering ripping the Indepentent rear suspension off of a first generation Ford Escape which has a rear wheel width of 70.1 opposed to the Pathfinder's 66.5 so it will be really close, and looking under my aunts Escape the way the frame rises and lowers in the rear is actually pretty similar to the Pathfinder's frame as well so the mount wouldn't be too difficult either. I'm planning to be able to do coilovers front and rear, even though her set up is struts I would be plugging those holes with a custom made bracket to then be able to mount the lower of the coilover to. Then following the swap I would custom fabricate some upper and lower arms to allow me to lift the front and rear to accommodate for 35" tires along with cutting the fenders to flow with the bumper ill be making as well. I need opinions on this, do's and don'ts, pros and cons of this idea. My reasoning for all of this is to be able to have the smoothest possible ride for 4-wheeling and off road use. Any suggestions will be taken into consideration and before any of you tell me to go SAS this is just experiment and for uniqueness, and because out of all the swaps I've seen I've never seen an IRS on a first gen pathy plus I like the difficulty ill have. and when I have spare $1,500 I'm picking up another 88 pathy to do a SAS to.

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There is a company called "Cornay" who make high angle drive shafts and cv axles I think they cost a fair bit but it might help to get some more flex without busting your cvs.

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I woukdnt be concerned with flex that's for the other pathfinder getting straight axled this would be mainly for if I have to ever drive fast off-road possibly to pass by all the jeeps and chevys and Ford's with straight axles and they have to drive slow through ruts. Thanks for the input so far all three of you, is still like some more input from other members, yes the all wheel alignment will be a task but I think if I get my welds right and those custom control arms right, all ill have to worry about is mainly camber angle, ill also have the task of converting from a 5 lug to 6 with those cv shafts but hopefully when the money comes ill be able to get some beefier hopefully a bit longer ones too

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That could work too but I would have to have it on an allignment rack while I make my welds to ensure that its gonna drive perfectly straight and have no rear steer, and I don't know anyone that will let me use their allignment rack while welding on it.

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Well when I get the 35s I'm thinking about doing 5.13 front and rear or maybe 4.10 and keep my top speed a little higher but right now the escape is at a 3.77 gear ratio which is higher than what my front and rear are right now

Edited by Cory74700
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Yes but the 4.10 will not only bring the rpms back closer to normal opposed to my current 2.20somethin but will also allow me to still have a good top speed, right now I max out just over 180mph on a dyno, which I know is unnecessary, and I know you don't believe me as didn't anyone else so ill post that pic right now

 

http://i699.photobucket.com/albums/vv352/cory9999/dynospeednumberone-20130116-234303.jpg

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True and my on road top speed well that's unknown because my speedometer stops at 105 at about 3800 rpms in 4th gear but back to the topic, I was doing some more thinking and what would be better for off-road and on road combo use, coilovers or some high spec struts??

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I understand why you'd want to weld in a complete rear end. The trouble will lie in finding a body-on-frame car with IRS, a compatible gear ratio, and the proper lug pattern. The Escape is unibody, so I suspect you'd have a hell of a time moving its components over to the body-on-frame Pathy without an alignment jig, even if you can match the diffs.

 

The 180 mph makes me :lol: I had mine up to about 75 once on the highway, and that was enough. The higher gear ratios are really more for fuel economy than for speed.

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That bit about gear ratios vs. mileage kinda depends. A 10% throttle opening at 3,500RPM is a lot more efficient than a 30% throttle opening at 2,500RPM. The engine being near it's torque peak is the most efficient.

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Have you looked at an escape rear drive line? It's designed to take a maximum of 50% of the total torque from a front wheel drive 4 cylinder engine with no low range. You'll shred the thing the first time you use the truck for anything other than mall crawling. You have more power, more weight, and your rwd!! The cvs are waaay smaller then our front ones...and the diff is puny.

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The escape does have a frame under it that's the reason I am choosing to go with an escape rather than like a Nissan armada which is way wider anyhow, and why neither for coilovers vs struts??

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The escape has a 3.1L v6 with slightly less horsepower and torque I'm sitting at almost 190 Hp and about 220 lb ft of torque so yes the CVS would snap that's why I'd beef them up a bit and convert to 6 lug

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But again, its FWD and is using AWD designed for snow. You want to use it for a RWD application - so double the torque there (AWD vehicles typically can only send 50% to the none primary drive axle, some can do 100% but only for short periods of time) - and then you have low range, so now your talking possibly 4x the torque loads that the thing is designed for. its going to snap like toothpicks.

 

I'm not just talking drive train here, your talking bushings diameter/loading, bolt load- wheel bearing loads, tensile strength of the steel used in the construction, A-arm wall thickness etc.

 

I really like the IRS idea, but I think the Escape is a poor option. Get the IRS out of a R51 Pathfinder, or any number of Truck based RWD SUV's in the last 10 years....

 

These will be designed to handle the torque loads that you will put on it with a 4x4 with low range.

Edited by Inyourface1650
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Well what would be a good option to look for?? The ford escape was the first one I found to be almost exact to the width of the pathfinder rear end so I kinds liked that idea, I don't think Chevy or jeep did an IRS , I know the ford expedition did it in the newer models but that's way wider than the pathfinder, I mean it won't really matter too much because I'd like to have a wider wheelbase for stability reasons and cornering and all, but I haven't really found a suitable option yet.

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Like Inyourface said you might measure the R51 Pathfinder IRS and see if it would fit. The lug pattern is different (dunno why but Nissan went from one 5-lug spacing to another, point is WD21 and R51 wheels won't interchange) and Wikipedia says it's six inches wider (the whole car, dunno about wheel to wheel). You might check out some of the 90s Nissan Z cars, IIRC they used R200 diffs (like your front diff) in the back so gear matching at least would be easy. The R200A probably isn't as strong as the H233B but then this isn't a towing capability build... pretty sure the Z cars are unibody though so you're right back at needing some kind of jig.

 

I dunno what to tell you, except that you won't find a 'direct drop in' arrangement.

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I wasn't planning on having this be an easy task, as I said, SAS is easy, and I enjoy a challenge, I like making new things and custom parts to make things work, I think ill go to to the pick n pull today and take a peek under some cars, I know the camaro of the 80s had a frame under It and still had the IRS on some models maybe I can look there because I know that's a rear end that will hold up to all the power that my engine has

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Later Model "truck" Explorers use IRS and use the Ford 8.8"

 

Probably your best bet is a custom frame with a IRS Ford 9" or something (they make them for drag cars) and custom A-arms with coils.

 

I've always thought the R51 with an armada swap front and rear ( so it would be long travel front and rear) would be a wicked (cheapish) high speed desert truck...

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I wasn't planning on having this be an easy task, as I said, SAS is easy, and I enjoy a challenge, I like making new things and custom parts to make things work, I think ill go to to the pick n pull today and take a peek under some cars, I know the camaro of the 80s had a frame under It and still had the IRS on some models maybe I can look there because I know that's a rear end that will hold up to all the power that my engine has

You ain't thinking of a Camaro, they have been unibody since day 1 in the 60s... Corvette might be what was on your mind though they were/are full framed and have IRS (well from the 60s on at least). No matter what way you swing though if you do try, that alignment rack you don't want to/can't use is going to be a major asset in trying to make it right

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