8.8 swap question...need to understand something

[Toddmac]

Im getting ready to do my 8.8 swap this week and have a question on the pinion angle. Im looking at every write-up known to man kind and something is not making sense to me, probably a simple misunderstanding on my part.

These guys all take the pinion angle measurements from the old housing which in my case is a D35...that 8.8 is not going to have the same spots on it to duplicate this measurement at all.

Why cant I put an angle finder on the drive shaft with the stock diff in it and then put in the new rear diff, rotate it with a jack to that same angle and tack my perches in?? To me if its (just throwing this # out) 15 degrees on the shaft with stock diff and I put the other one in and achive the same 15 degrees, have I not acomplished exactly what I need?

In my tiny brain, this would be the most accurate way to achive the duplicate angle, so what am I missing here? To me this would compensate for the longer 8.8 pinion snout and also for all the descrepancies between the two housings as far as measurement locations.

Any of you 8.8 swappers got any input on this or perhaps can share where you took your angles from on old and new diffs? Im on vacation this week and the new brackets will be here tomorrow so I want to get this project done so I can spend the rest of my week eating pain meds and crying to the wife about how bad my back hurts!

Thanks as always gang, always helpful!!

[spunebil]

I always thought you point it 2 to 3 degrees bellow transfer case yoke.
That way when you accellerate it should only rotate to maybe 2 to3 degrees above t/c yoke.
Does that make sence ?

[Guest]

Spune that's if you are running a CV driveshaft. In an ideal world with a standard driveshaft the transfercase yoke and the rear axle yoke would be parallel at ride height. So if your tcase is at 5 degrees then your pinion would be at 5 degrees. Depending on your particular situation if you can deal with more vibrations or have alot of lift that just may not work.

[Toddmac]

Right now it has 4" of suspension lift and 1" transfer case drop. It has no vibration at all running the stock drive shaft with 35s.

[Grumpy Dwarf]

You will most likely get vibrations once you install the 8.8 because of it's longer snout which in turn makes your DS shorter. Now there are always exceptions because each jeep is different even if they are the same model but with your lift it will most likely happen. If you haven't changed the DS u-joints in the past few months then I would replace them as well because they will probably wear out quicker because of the change in your drive-line angles.
As far as your angles go it's just like inphobic says, just make sure they are parallel. Seems to me it would be easier to figure it with the new diff in there rather than off the old diff.

[spunebil]

I just figured he had a cv joint up front.

I forgot that some still run stock shaft with 4" lift .

[Toddmac]

I put the angle finder on the drive shaft and its at 13 degrees, the pinion yoke is sitting at 12 degrees. I didn't get the yoke angle at the transfer case but I will check that tomorrow. I talked to a guy earlier and he said as long as the yokes aren't pointed right at each other then I shouldn't have vibration, but when looking at it now, they pretty much are and no vibrations. I swear I have read they should point at each other somewhere and I think with what you guys are saying in being "parallel" that is what you mean as well isn't it?
I noticed with the lift that my shaft is about an inch out (towards the axle) on the output shaft of the transfer. I was hoping the longer snout on the 8.8 would return it back to where it was and that would be a plus but it sounds like that may or may not be true.

[Toddmac]

I just figured he had a cv joint up front.

I forgot that some still run stock shaft with 4" lift .

I do for now, I will prob end up switching it to a double cardigan shaft but for the time being it's the stock one but it does have the larger U-joint. 1330 Spicer.

[Grumpy Dwarf]

Here is what is meant by parallel:
http://www.4x4wire.com/tech/pinionangle/stdgd.gif
This is not my drawing by the way. The thing in black is your pinion and the thing in brown is your t-case output shaft, the orange lines show how they are parallel.
Now if it was a cardan DS then you would want the pinion to point almost directly at the t-case output shaft.

[Toddmac]

Interesting...my current setup has the transfer case pointing downward somewhat and the rearend is pointing up at it, I have never shimed or moved the rearend, its totally stock. I think Im slowly getting the handle on this from more reading, I do still run across totally contrary ideas everywhere still. LOL....sure makes it a pain in the @ss to sort out.

I was hoping to catch Wally or one of the local folks to me to put an extra eyeball on this before I take it out but tomorrow is the day and I haven't found anyone handy to me to see what they think.

[spunebil]

T/c. Can point down slightly and pinion up as long as the pinion shaft and t/c output shaft are par.allel.

[Guest]

My experience putting a D44 (has 1" longer snout) in a lifted YJ was that setting the perches at the factory angle and using the wedges from the lift caused perfect alignment with no vibrations.

As you noted, your driveshaft is pulled out from the t-case about 1". Having a longer snout just pushes it back in, just as you have speculated.

No guarantees, but that is my real-world experience putting an axle with a 1" longer snout into a YJ without a slip-yoke eliminator.

[Guest]

We put an 8.8 in Mike Morans TJ and he runs a factory shaft with the explorer flange on the rear. It seems to work fine when he not destroying it with rocks and the massive power of the 4 cyl.

[jagular7]

We put an 8.8 in Mike Morans TJ and he runs a factory shaft with the explorer flange on the rear. It seems to work fine when he not destroying it with rocks and the massive power of the 4 cyl.

2 shafts in 7 yrs....slip yoke broke apart and a rock point slit tube in half.
I do have adjustable control arms (TJ) and have adjusted the pinion to point back to the bottom of the tcase at the output. Didn't figure out anything. Drove 35k miles this way over the years.

I do have a brand new rear ds with new joints and 8.8 adapter for sale.....got 1 more wheeling trip before I pull tranny/tcase out for better things.....I can measure the ds if you like. I know the tube section is 10.5" long.

[Toddmac]

So far the project is moving right along. I have set everything and welded the perches and shock mounts on. Need to do a lot of cleaning on the housing tomorrow and paint it, put it back in and then start the fun of brake lines and e-cables. Everything looks ok as far as the drive shaft length etc, looks like Im gonna be very close to where it sat before as far as how far the yoke it out of the TC.
I got to say, if anyone is looking into this soon, be sure and check out Ruffstuffs swap kit. It's cheaper than MORE and it is **** for stout. Not fitment issues at all with the brackets. Hopefully by tomorrow at this time, it will be done and I will see how well or how bad I did. LOL.