8.8 pinion depth starting with zero reference

Hey guys in a bind (pun intended ). Searched the whole site for a "like" thread and came up empty handed. Also, I have read just about every 8.8 rear end setup guide out there and they all pretty much say the same thing "Measure your previous pinion and go from there". The problem as you can see in my build thread is the previous pinion got DESTROYED



The top of it is not round enough or straight enough to take a good measurement.

So I need a little guidance on how to start from zero. I have a brand new FRP 4.56 Ring and pinion to go in. And the rear end is now disassembled, cleaned, and even repainted. Just dont know how to start with nothing

It is a process shimming it correct it looks like you need a complete set of bearings pull the bearing off the old pinion and use the shim that is there install a new bearing on the pinion and install it in the housing without the crush sleeve and get the preload correct. Install the new bearings on the carrier and install it with the proper preload on those bearings as well and confirm the gear lash is correct and check the wear pattern and ring gear run out. Then you can adjust the pinion depth according to wear pattern until you get it right. You need the correct tools and alot of patience four things have to be correct ring gear run out, wear pattern, gear lash and bearing preloads. Install the crush washer, wheel bearings and seals get the pinion preload correct with the crush washer somewhere around 160 ft lbs then install the axels. With the proper tools you can preset the pinion depth and get close but still may need to reshim the pinion I will see if I can find the link that gives the pinoin measurement.

thanks for the help.. yah I have it all apart housing is clean and repainted.. Just was trying to find the exact measurement to start at when you have no reference.

Use the existing shim as your starting point you may get lucky. If you damage the shim you can measure it with a caliper.

Holy SHIT!!! Epic failure there... Good luck w/ the rebuild. Definitely start with your initial shims and go from there.

I would not have searched for that. I don't think that has happened before.

http://www.fordracingparts.com/download/instructionsheets/FordInstShtM-4209-8.pdf Good stuff here.

brinker88 said:

Holy SHIT!!! Epic failure there... Good luck w/ the rebuild. Definitely start with your initial shims and go from there.

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Most info shows that there should be .008 to .015 inches of clearance between the pinion gear teeth and the ring gear teeth once the carrier is shimmed correctly & bolted in place in place.

I reused the same shims when I rebuilt my 7.5 rear end.......

It was within .017 inches of clearance.....which is actually too much....

there is a more noticeable "clunk" sound from the rear end when the trans is put in Drive.....

I will reshim it to .012 inches (closer together) one day....LOL!

ok guys need more assistance on "guessing" since this is my first time.. finally was able to beat the remaining gear teeth back far enough to press the bearing off the old pinion.. The shim is damaged "go figure lol" it reads between 31.5 and 34 taken from many many reference points.. I am going to go out on a limb and guess it might of been a 32 mostly because of all the build threads I have read but whats your take?

Also there are numbers on the end of the new pinion.. the ones I dont understand are the 6 and C stamp.. Anyone know what that signifies see below for pics.



Thanks again for all the replies hopefully have it back to cruising altitude again soon.

kimcrwbr1 said:

http://www.fordracingparts.com/download/instructionsheets/FordInstShtM-4209-8.pdf Good stuff here.

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Thanks for that find kimcrwbr1.. That is an excellent document I hadnt run across yet much appreciated

adsm08 said:

I would not have searched for that. I don't think that has happened before.

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HAHA yah I dont think the PO had any clue what they were doing at all and that is why this gear looks like it does.. Everything in there looks like it was newew 500 miles ago.. But has been in a brownie easybake oven since day one lol

brinker88 said:

Holy SHIT!!! Epic failure there... Good luck w/ the rebuild. Definitely start with your initial shims and go from there.

Click to expand...

Yah I think I am going to need a little luck and a whole lot of paitience to figure this one out. Last rear end I re-built I didnt search for anything, just took out all the old parts put new ones and drove it till I sold it. That was some 20 years ago and last I heard (7 or so years ago) it was still on the road so I got lucky there.

In that exact situation I would remove the "Dead" pinion
and being careful not to rease the paint marks on the shank

Typically +2, +1, 0, -1 or -2 would set up the new pinion according to the original

Replacement bearings are so close (a matter of a few ten thousanths) as
to not matter.

THE thing to worry about is getting the pinion bearing races completely seated, which is a bitchy job on the best of days.

I keep in mind the fact that ANY foreign material being present while seating the races is "bad", and I have the purpose made tool to install the bearing races.

Even so on axles I'm assembling for my own truck I put the races and the bearing race seating tool in the deep freezer and I literally put a fire under the center housing, I literally put a coleman stove under the housing and heat it to 250-300degrees. doing this the races practically fall in, but I use that big race press tool to clamp them in place, with the center bolt tightened down and leave it overnight to cool.

The next step to "make sure" is to take a pinion (with good bearings) that I use as a tool and "install" it in the housing, this is basically used as a tension device

The pinion without a crush collar is mounted, a pinion flange and oil slinger are installed and a pinion nut that has been "circumcised" (the crimp collar has been removed and a tap has been run through it to make it a "free running" nut)
and this nut is tightened to 250ftlbs and the shaft is turned with a large electric drill motor (I have a socket spud and a 1/2" drive 27mm socket) and rotated at high 1500rpm for a minute and the nut retightened again and the process repeated as required (until it doesn't slack off)

This is all just to verify that the races are COMPLETELY seated.


The point is that if the big bearing race isn't seated the pinion will
walk forward. If the front race isn't seated the pinion bearing preload
will disappear, and in either case the pinion will start walking forward
and back in service and unwanted slack in the axle lets the pieces beat
each other to death...

the next step is to re-establish proper ring gear backlash.

I shoot for 0.0135" ring gear backlash, and I'm patient and OCD enough to
achieve it before I run an axle in my personal vehicle.

it is very rare that I will build an axle for someone else who isn't a
close friend first.

If you haven't bought me a Christmas present or an unsolicited bottle of
bourbon previously I'd probably tell you to do something more difficult that shoving a cooked piece of spagettti up a wildcat's a$$ using a cattle prod as a ram-rod... likely to attempt the spagetti-wildcat trick just to annoy the cat then try to shove the previously pissed-off wildcat up your own a$$

BTW, before anyone asks I have never done an aluminum case dana "chunk"
I run them as pulled from junkyard donors, because in a part-time 4x4 they rarely get run enough to worry about them a typical junkyard 4x4 truck
with 250k miles on it probably has less than 5000-10,000 miles on the
front diff and most of that driving around in winter conditions with the hubs locked and the T-case in 2wd

All the above information is GREAT. If you can understand that (minus the spegetti/wildcat tangent, lmao) you should be set.

FYI, 0.013 backlash WILL seem extremely "loose" to a novice (for example, a D44's baclash should be set to 0.006-0.010) but it's what evenyone recomends.

For some other good information, look at Yukons online installation manual on ringpinion.com

LINK

THanks AlanD and Brinker88.. Appreciate all the input.. I ended up having to delay the rebuild until this coming Saturday.. Hopefully I will be able to post a success story