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Discussion Starter · #1 ·
Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I am planning a 9" swap and since some people have done it I am wondering if the low pinion is as big of a deal as some might want youto think. I like the 20 minute 3rd member swap, large aftermarket axle support all the way to 40 spline axles, etc. Any comment?
Aaron
 

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Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

The low pinion is one problem. The thing that comes to mind with me is driveshaft length. I'm having trouble with d/s length in a relatively stock CJ5. If I was to swap in a 9", I'd have to go with a HIGH pinion. The stock 9" hog's head is huge compared to my AMC20.

IN2DEEP 78 CJ5 302 FORD T176/D300 35" BFGS
 
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Discussion Starter · #3 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I have a TJ so I am not as bad off as a CJ5. I know poeple have done it on YJs with out too much trouble. I would never spend the insane amount of $$ for a high pinion 9".
Aaron
 

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Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I would like to hear more opinions on this topic...

I have a set of early bronco axles at my disposal, and I was considering them for a rock climber...

I have virtually no experience with 4X4 suspension or dirvetrains past the transmission tail shaft, I'd like to hear the pros and cons...

"I Have The Body Of A God... Buddha"
 

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Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I have a freind who swapped in the full width F-9", and D 44 from a Ford 1/2 ton onto his 95 YJ. He is a cappable driver and as far as strength, it is a rock solid set up. But he is constantly fighting with clearance problems,in the rocks, which is what he built it for. He is seriousely rethinking his choice of both the 9" low clearance and the full size width. Ive never driven it, but he does struggle, where he used to shine.

Jeff
89 Wrangler
If at first you dont succeed, your replacement will try and try again.
 
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Discussion Starter · #6 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I don't think the low pinion will be that big of a deal with a CV driveshaft. It will basically keep the business end pointed up. I know people that have 9"ers in XJs with standard driveshafts and they never hit their pinion in the rocks. I guess I will do it anyway and see what happens.
Aaron
 
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Discussion Starter · #7 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

My buddy John did a D44 full width onto his CJ7, and is running 38.5" Super Swampers .. he doesn't seem to have any problems ..

Take a look at his "Orange Crush" at members.home.com/jeeps

Laters!

Vance - Calgary, Alberta, Canada
1985 4x4 S-10 and 1988 Jeep YJ
 
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Discussion Starter · #8 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I can see where tight woods trails could make it a pain if you were really wide.
Aaron
 

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Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I like 9", strong rear with easy access, "fairly" easy to find discs on 'em. The low pinion COULD cause a problem on some setups. A CV joint on the front of the rear driveshaft is MANDATORY, in my opinion, on a jeep with a standard 9". This is the stock setup on the EB's. Gears / parts are cheap and available for them too.

/wwwthreads_images/icons/cool.gif Big Ed
'88 YJ, 4" susp,3" body,33's,283 Chevy V8,TH350,4.11's,D30,D35c
 
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Discussion Starter · #10 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

Yeah that's my point. Gears are $115. A whole 3rd member with a spool is only $425. Axles range from $125 to $185 with bearings, studs, seals, and all. Disc brake setups are easy to do AND you can swap the gears on the trail in 20 minutes if you have a spare 3rd member with you. It is like having an entire spare rear end that is easy to swap broken parts out of. Of course the pinion is low but I don't think it is that bad. The high pinion 8.8s pinion sticks out farther than the 9" and it is supposedly 3 3/4"s higher. What does that equate to angle wise. I would like to see some figures because I don't see how it could be that bad. Early Broncos put 6"s of suspension lift on and don't need CV shafts. They have a little better wheelbase but still. I don't see how a 4" lift on a TJ with CV shafts and a SYE kit could be all bad. Oh and remember that Currie used to run regular 9"ers in their awesome YJs and they were the cream of the crop for driveable rock crawlers.
Aaron
 
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Discussion Starter · #11 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

Why not go with the Ford 8.8 rear from an Explorer. Later versions have factory discs. There are threads here that cover the conversion.
 
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Discussion Starter · #12 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

"Early Broncos put 6"s of suspension lift on and don't need CV shafts. "

My '74 Early Bronco had stock CV shafts front and rear.
 
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Discussion Starter · #13 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

The 8.8" is a good choice but I would rather have the versatility of the 9". The EB I looked at the other day didn't have a rear CV shaft and he said it wasn't a problem at all. He said it was stock. I wonder if it had been changed somewhere along the way. He said it didn't vibe at all though.
Aaron
 
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Discussion Starter · #14 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

the 9in is an excellent swap for any jeep. yes the pinion is low, but it is shorter than most, so you may have to lengthen your driveshaft. they are strong, have great parts availability, which makes them less expensive to work on. if set up properly, they are as strong as a dana 60 (i know this is subjective, but the 9in pinion at lower ratios is larger and better supported) and much lighter (up to 300 lbs).

dan
Good things come to those who do research!!
 
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Discussion Starter · #15 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I was planning a SYE kit when I did the swap but now I am actually considering an Atlas tcase so I would need new shafts anyway. I'd like to have shafts done only once. I think the pinion position isn't as important for diveline angles as it is for vulnerability. The shaft will be longer than with a high pinion so the result of the standard 9" should be a marginal disadvantage. Yeah I would say 40 spline axles are stronger than a D60s 35 spline axles. Of course I will only use the common 31 spline axles but the possibilities are there. Lighter is an understatement. I ordered a big bearing 9" housing yesterday for $125 and was expecting truck freight with at least $100 for shipping. UPS for $20 is what it ended up being. The housing only weighs 40 pounds. People say it is super strong and now I see light too. Of course 3rd member and axles will add to that but not likely near a 500 pound rear end. I like the fact that the pinion is supported on the front and not just the shaft. I doubt it will affect me much but in high horsepower situations I could see where the pinion could move under torque and cause trouble. Maybe that's why R&Ps bust on other rear ends when you bounce them. Maybe that pinion pivots from the torque.
Aaron
 
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Discussion Starter · #16 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

Wow! Geometry is actually going to come in handy!

I have never even seen a Ford 9", but I can run the approxomite numbers.
For my CJ7 withy T-4/d300 and AMC 20, my driveshaft length is 23.19" at ride height.


Let's say I have a 4" lift: I will have a 24.04" long driveshaft at ride height.
Now, I am going to start estimating. If I have a 9", At my stock height I will have a 23.34" long shaft at ride height. I am assuming that the pinion is one inch lower.
If I have a 4" lift and a 9" I will have a 24.35" long drive shaft at ride height.
Now If I have a 4" lift and an 8.8" I will have a 23.22" long drivesahft at ride height.

Now the length Doesn't realy chage that much. But none of my calculations acount for articulation.

Now what is really imprtant is the angle at the t-case yoke.
Logic says that as the vertical distance between the two yokes increases, so does the angle. That angle is what causes vibrations. The benifit of the 8.8" is not so much the driveshaft length, but the driveshaft angle.
Let's do some real math! Let's call the angle of the driveshat at the t-case yoke X. The sinX=23/23.19 which means X=82.66 degrees off of vertical or 7.33 degrees off of horizontal.
With the Ford 9" and 4" of lift it will be sinX=23/24.35 which means that the angle is 70.83 degrees off of vertical and 19.16 degrees off of horizontal.
with the 8.8 it will be sinX=23/23.22 or 82.1 off of vertical or 7.89 off of horizontal.

All of these numbers are made up except for the Stock lengths. I did not compensate for pinion to yoke length changes.

I hope all of this helped.

Ed

I live, I breath, I Jeep
 
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Discussion Starter · #17 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I can't draw at all!

Ed

I live, I breath, I Jeep
 

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Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

Drive line angles on a CJ5 with a lift are always going to be a concern regardless of tranny axle combos. Obviously there will be combinations that will cause extreme angles requiring careful planning. Low pinion angles will add to the equation. Keep in mind that the use of a CV shaft is NOT a fix all solution. I'm not very familiar with the Ford 9 and things such as pinion bearing lubrication. The AMC 20 pinion bearing is basically oiled from the Ring gear slinging oil forward. This action is not much impeded at increased angles. Therefore, a CV shaft works well when the spring perches are rolled to zero the pinion ujoint angle. You may want to look into this in relation to the 9". Check out Tom Woods Driveshafts for some more details. Also I believe Randys ring & pinion has some info as well.

RocknCJ /wwwthreads_images/icons/cool.gif
Good judgment comes from bad experiences, bad experiences comes from bad judgment.
 

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Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I put a 9" from an Early Bronco in my CJ7 a couple of years ago. TeamRush, you wanted the info on the swap so here's how I didi it. The swap went pretty easy, as the new spring perches ended up being located right under the stock ones (77 CJ7, 74 Bronco 9"). I left the perches there in case I ever want to do a spring-over. Since I needed to weld on the spring perches, I could "aim" the pinion the way it needed to be for proper driveshaft angle. What you need to do is, using an angle-finder, measure the angle of the yoke at the output of the transfer case with the jeep on its wheels and the driveshaft off. Put the tranny in neutral and turn the yoke until it's vertical. Then jack up the jeep, pull out the AMC 20, slide in the 9" and the spring perches, kind of eyeball the yoke as to where the yoke was from the old one and tighten up the u-bolts. Put the wheels back on and set the jeep down. Measure the angle across the pinion yoke with the angle finder, figure out about how much you need to move it in which direction. Jack it up again. loosen up the u-bolts (you do't need to take the tires off) and twist the whole assembly. Tighten the u-bolts, lower and re-measure. After a couple of times, you'll get them to match. Tack weld the perches and jack it up, take the tires off and take the u-bolts off. Lay in your best weld.

When I put mine in, I also relocated the shock mounts to the axle tube and got rid of the whole spring hanger. I kept bending the studs for the shocks on them anyway. I used the spring plate from the Bronco. The biggest problem was that the 9" is a whole lot shorter than the AMC 20. I was running the stock T150, and I ended up with a new driveshaft. A year later, when I swapped in the T18 (I'm turning my CJ7 into a Feep) I was able to re-use the origional rear driveshaft. I never ran one with a CV joint, probably because I got the angles to match. I have never had a problem with the low pinion causing vibration problems or clearance problems. Here in Wisconsin, we have mud, stumps, branches, logs and occasional loose rocks that grab things that hang too low (thus my bent shock mounts on the spring hangers). I don't see any drawbacks to the conversion. Disc brakes are right around the corner for me, and I put a spool in 2 weeks ago (only took a couple of hours) for the ultimate in traction. Funny, it squeals now every time I go around a corner.
 
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Discussion Starter · #20 ·
Re: Is a ford 9\" in a SWB Jeep as bad as some people lead on?????

I am doing the same swap,check out the jeep tech at offroad.com there is a article there about EB axle swaps
that will probably help.I agree with some the lower pinion may drag some rocks,call james duff and buy a skidplate
as far as driveline angles set it up properly run a cv driveshaft and you should be fine.I am doing a spring over with 2 1/2"
pro comp leaves with a 44 front 9" rear and it will work flawless.the 9' rear is good to about 5-600 hp,massive torque
and remember even most full size broncos that you see with 6-8"s of lift have a 9" with a cv and run 38" tires
all I can say is strong rear end,the 9" even has a pocket bearing on the pinion to eliminate gear deflection,does a dana 60
have anything like that?no and your true in saying the curries ran stock third members for years,no bare third member is worth a grand!!!
 
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