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Old 08-21-2011, 07:23 PM   #1
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Need fresh perspective on 8.8 pinion angle...

I don't think I have posted this to this audience, so here goes.

I recently received my Ford 8.8 brackets from Iron Rock. Nice. Currently, I am in sort of a mock-up mode, checking measurements against stock, etc. My biggest problem is my pinion angle. All my reading/research points to something like a 15 or 17 degree angle. Mine is much more shallow...

When I attach a looped string around my existing axle and run it up to the output shaft of my transfer case--and measure same--I get 8 degrees. That tells me I need to set the pinion angle of my 8.8 to 8. I'm running an OME Ultimate lift that is something like 3 inches or so. 33" tires. I do plan on installing a SYE/CV drive shaft when I hook up the 8.8.

Anticipating the possibility of 35's down the (long and winding) road, I magically arrived at a pinion angle of 11 degrees. Figuring adjustable upper and lower control arms would afford me some degree of adjustment (I could go down to 7 or up to 15, etc.) I think (thought) this was a good angle to set everything at.

I guess I am looking for suggestions on a pinion angle. I can't get close to the 15 degree angle so many texts suggest. Maybe I am being too anal-itical about is. Or am I missing something critical. How much adjustment can be made before trouble crops up? If I set at 11 and have to drop to 7, will this create issues?

?

CG

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Old 08-24-2011, 08:29 PM   #2
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A follow up question...

Is there anyone out there running a standard NP231 and a slip yoke eliminator kit (AA, Rough County, etc.) than can crawl under and measure the distance from the back of the transfer case (or even from the end of the new housing--assuming it is identical to the stock one) to the center of the output shaft? I need this measurement for work in my laboratory while exploring pinion angles. Does this make sense? Thanks!

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Old 08-24-2011, 08:43 PM   #3
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Hey Splinkr. I'm running a 231 with a JB Conversions standard SYE. I have a Rokmen TT skid and upper adjustable control arms in the rear. My 8.8 was built by ECGS, and you're welcome to take a look at it in person anytime we can get together. PM me your phone # if you wish and we can discuss what you want to know. I'll be happy to help you out if I can.
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Old 08-24-2011, 08:45 PM   #4
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As far as pinion angle...



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Old 08-24-2011, 08:51 PM   #5
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These 17 degree angles perplex me. I am getting 8 to 10 in my tests... I shall PM...
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Old 08-24-2011, 09:00 PM   #6
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I think I just realized what's confusing you. You have the standard (factory) driveshaft right now, correct?
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Old 08-24-2011, 09:05 PM   #7
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So, right now the factory driveshaft has angle on both ends. When you put in a Double Cardan (commonly, and incorrecctly called a "CV") driveshaft, The universal joint at the pinion end is not supposed to have any angle relative to the pinion. That's what I'm comparing in the two photos above. One is on the pinion and the other is on the shaft. See what I mean? ↓↓↓ This is why the pinion angle is so high compared to what you're seeing right now.



You should read my build thread HERE. I cover my 8.8 install in it.
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Old 08-24-2011, 09:47 PM   #8
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So I just looked through your 8.8 gallery. My thoughts so far are as follows.

Never heard of the tone ring mod. I deleted my ABS, as it has scared the crap out of me on the trail more times than it has assisted me on the road. Also, I didn't have much choice because the folks at ECGS removed it along with the stock carrier when they built the axle with the ARB locker I asked for. I hope it works for you though.

While you're welding, weld the tubes to the center section, as it is known to spin the tubes. If you don't trust your skills, or the flux core wire, have someone else do it. Just make sure it's done when you install it.

As far as C-clips go... I don't like them either, but you will really have to beat on that axle with 33's to break it, and if you do, the axle still won't fall out because it has disc brakes, so the caliper will keep the axle from running out. Not an ideal situation, but breaking an axle is never going to be an ideal situation. C-clip eliminator kit is redundant.
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Old 08-24-2011, 09:57 PM   #9
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Also AS's angle is going to be higher than yours even though you have the same lift. Reason...he has a tummy tuck.
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Old 08-24-2011, 10:49 PM   #10
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The exact pinion angle in degrees is a 100% non-issue. Stop worrying about its angle in degrees, there is no need to.

And since the correct pinion angle varies by both the suspension lift height and the distance to the t-case output shaft, there is no single correct pinion shaft angle so stop asking others what their angles are.

The only thing you need to worry about is the pinion shaft's angle in relationship to the driveshaft angle. That is it. The pinion shaft angle can be absolutely no higher than the driveshaft. The pinion shaft actually needs to point directly (!) at the CV joint itself at the forward end of the driveshaft. Ideally the pinion angle is from 1-2 degrees under that of a direct line to the CV joint to pointing directly at it... but no higher.

This is how it should look.
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Old 08-25-2011, 06:12 AM   #11
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Thanks to all. This is very informative. Ageless, I'd love to crawl under your Jeep with a ruler! Jerry, thanks again. I guess I am trying to be too precise in my measurements, but was only concerned that what I have measure under my Jeep was half of that seems to the "the range". The reason I need the length of the SYE output shaft is so I can mock-up my 8.8 (using your diagram above) set the proper angles on all my soon-to-be-welded brackets. Maybe even this is overkill and I should just go with my estimate. I am sure I can adjust out any variances with the adjustable U/LCA's.....
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Old 08-25-2011, 06:19 AM   #12
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Like I said before, you're welcome to check mine out any time we can get together. I'm actually suprised that we haven't ran into each other at Turkey Bay yet.
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Old 08-28-2011, 06:57 PM   #13
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Well, I did it: welded up my brackets today. Er, that is, had them welded! This linky probably won't work...



After much deliberation, measuring, mapping, checking, and re-checking, we welded them up based explicitly on the instructions. Hopefully, all will be well as they sure ain't coming off! I have a high confidence level it will bolt up.

Next, comes prettying it up, priming and painting, brake lines, new calipers, ,drums, adjustable arms, SYE, new shaft........

I decided on a pinion angle of 8 degrees based on numerous tests and mock-up. We shall see if this is correct...

The Ford 8.8 link in my sig has all the pics.

Thanks again.

CG
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Old 08-28-2011, 09:32 PM   #14
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Do you not have adjustable upper control arms? When setting up your brackets the pinion angle should only be a general guess, it's just to reduce the amount you have to adjust your control arms out. Your final pinion angle should always be dialed in through adjusting the control arms.

8* sounds really shallow considering ecgs sends all their axles out at around the 17 degree mark.
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Old 08-29-2011, 06:24 AM   #15
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I will have both upper and lower adjustable control arms. Based on my lift, 8 degrees is what the pinion angle worked out to be. This points the pinion straight at the end of the Tcase output shaft. Of this I am sure...
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Old 08-29-2011, 09:03 AM   #16
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I am running 19 Degrees on mine. As stated above when you add a SYE and CV shaft that changes the recommended pinion angle. The 19 degrees I have is just right with 3.5" springs and a tummytuck.
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Old 08-29-2011, 09:03 AM   #17
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Also if you have any other ? about welding up your 8.8 feel free to ask I have done a few of them now
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Old 08-29-2011, 12:05 PM   #18
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Glad you nailed it down.
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Old 09-04-2011, 10:47 PM   #19
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OK. So, my 8.8 is all welded up. Can I go ahead and swap out my D35, add adjustable control arms to level the pinion, regear the D30 to match, and use my existing rear drive shaft--cut down or otherwise modified to fit--and add a SYE/CV later on?
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Old 09-04-2011, 10:56 PM   #20
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Probably not. even if you get the correct pinion angle for a non CV shaft you still have the offset diff to deal with. The center section (diff) of the 8.8 is off center. It sits 3" over to the passenger side. This will put extra strain on your non cv set up as well. If you go for it any way you will also need to trim the cast ears off of the diff that protect the factory speed sensor and trim the extra cast next to the pinion when the ford stabilizer shock mount to the diff otherwise your rear sway bar will not fit.
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Old 09-05-2011, 03:01 PM   #21
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Thanks. I'll wait. Does anyone make an aftermarket sway bar that does fit? I plan on retaining the ABS in this axle if possible.
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Old 09-05-2011, 03:07 PM   #22
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Quote:
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Probably not. even if you get the correct pinion angle for a non CV shaft you still have the offset diff to deal with. The center section (diff) of the 8.8 is off center. It sits 3" over to the passenger side. This will put extra strain on your non cv set up as well. If you go for it any way you will also need to trim the cast ears off of the diff that protect the factory speed sensor and trim the extra cast next to the pinion when the ford stabilizer shock mount to the diff otherwise your rear sway bar will not fit.
I didn't know this to be a fact, but I had noticed that my driveshaft was angled to the side a bit. Nice to get factual confirmation.
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Old 09-05-2011, 03:35 PM   #23
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Thanks. I'll wait. Does anyone make an aftermarket sway bar that does fit? I plan on retaining the ABS in this axle if possible.
Its easy to just cut the housing. It can be done with a sawzall and only takes a few minutes.
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Old 09-05-2011, 03:37 PM   #24
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Quote:
Originally Posted by Ageless Stranger View Post
I didn't know this to be a fact, but I had noticed that my driveshaft was angled to the side a bit. Nice to get factual confirmation.
Notice the gap between the upper control arm mounts to the diff on either side.

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