Front Diff Reinforcement Collar

Ed · **Posted:** Tue Jan 24, 2006 8:18 pm

greiswig wrote:

Are we pretty sure about this measurement? Getting it right is obviously important. The 3 9/16" measurement is suspiciously close to a 90mm OD, and with so many other things on the Jeep being metric, I wonder...

I'm not sure the outside of a diff case is likely to exactly conform to any standard size. It's not like it's a proper shaft that Jeep are expecting us to wrap anything around. The input shaft and the bearing it sits in will obviously be either a standard imperial or metric size, but the aluminium casing that wraps around it is just going to be "some" thickness that the designers thought would be strong enough, I doubt they specifically picked the thickness to give us a nice standard outside diameter. But I could be wrong.

I agree about getting the measurement right, but I'm pretty confident in Eddo's 3-9/16", I'll try and get a more accurate version of my measurement in less adverse conditions. Also like Eddo says, the diff's probably almost strong enough as it is, so as long as the collar's snug (i.e. it's not rattling about loose!) I would think it would provide enough extra strength, but then I'm no expert!

Eddo · **Joined:** Thu Jul 07, 2005 7:01 pm **Posts:** 1214

Well it is pretty darn close to 3 9/16" I went under there with a very accurate digital caliper. It came out to 3.56 something which is just as close as you are going to measure to 3 9/16" on a rough surface like that. I measured it multiple times from different angles to make sure I got it correct.

The sanding off 1/32 on each side is pretty easy. You can use a dremel tool with a sanding cylinder, but that will take some time on hard steel. I would probably recommend something like a variable speed drill with some sort of sanding cylinder/disk then smooth it up w/ the dremel. It was actually easier then I though it would be.

Ed · **Posted:** Tue Jan 24, 2006 10:18 pm

Sounds good enough for me!

Hopefully my tame engineer buddy with a CNC machine will save me from any sort of sanding shenanigans.

ctemple · **Posted:** Mon Feb 06, 2006 9:13 am

pixeldzn wrote:

I found some in a 3 9/16 inner diameter. Problem is they are $80 a piece, vs $20 a piece for the 3 1/2 diamater from the same company.

Thier website is at www.staffordmfg.com and the part number is 8L309. I called direct and they told me a better price is available from local distributors. Local Distributer in Wood Dale, IL quoted me the $80 price. I might just go with his 3 1/2 version and sand it - still cheaper than McMaster Carr.

In any case, it seems a perfect size is available, we just have to find out where to get em cheaper. Anyone have contacts in this industry? JeepinAl?

Very interesting discussion and thoughtful potential solution to reinforcing this potential problem area.

Has anyone bought and installed the 3 9/16 ID Stafford Manufacturing collar referenced by pixeldzn? If so, I'd be interested in any comments...I'm trying to stay away from attacking a perfectly good 3 1/2 collar with my Dremel.

Thanks and regards.

MTN GTO · **Posted:** Tue Feb 07, 2006 6:53 pm

Get them in stainless steel- they'll last longer, s.s. is a lot stronger than the aluminum ones.
Stainless steel= $71.02 ea.
Aluminum=$43.40 ea.

pixeldzn · **Posted:** Tue Feb 07, 2006 8:18 pm

ctemple wrote:

pixeldzn wrote:

I found some in a 3 9/16 inner diameter. Problem is they are $80 a piece, vs $20 a piece for the 3 1/2 diamater from the same company.

Thier website is at www.staffordmfg.com and the part number is 8L309. I called direct and they told me a better price is available from local distributors. Local Distributer in Wood Dale, IL quoted me the $80 price. I might just go with his 3 1/2 version and sand it - still cheaper than McMaster Carr.

In any case, it seems a perfect size is available, we just have to find out where to get em cheaper. Anyone have contacts in this industry? JeepinAl?

Very interesting discussion and thoughtful potential solution to reinforcing this potential problem area.

Has anyone bought and installed the 3 9/16 ID Stafford Manufacturing collar referenced by pixeldzn? If so, I'd be interested in any comments...I'm trying to stay away from attacking a perfectly good 3 1/2 collar with my Dremel.

Thanks and regards.

I might need to reming JeepinAl to look into this again for me. I think he forgot.

Tokyojoe · **Posted:** Tue Feb 21, 2006 9:31 am

That company (McMaster-Carr) is located in several cities. If anyone living in the cities they are in, is going to Moab, perhaps we could do a group buy for those going to Moab and the individuals in those cities can buy them and bring them to Moab. Save in shipping (though not a lot, but saving a penny is always worth it).

Atlanta
Chicago
Cleveland
Los Angeles
New York City-Philadelphia

http://www.mcmaster.com/

Also, could do a mass dstributing. People in an area can give their request and money to someone going to Moab and that person could pick up all of the collars and then take them back to all of those people.

Just a thought.

vxla · **Posted:** Tue Feb 21, 2006 12:45 pm

Can you get to this area with a tranny skidplate on? I've got a skid row plate and I'm curious if I'll need to take it off. If not, I'll throw one on!

Guyute1210 · **Posted:** Tue Feb 21, 2006 1:04 pm

Tokyojoe wrote:

That company (McMaster-Carr) is located in several cities. If anyone living in the cities they are in, is going to Moab, perhaps we could do a group buy for those going to Moab and the individuals in those cities can buy them and bring them to Moab. Save in shipping (though not a lot, but saving a penny is always worth it).

Atlanta
Chicago
Cleveland
Los Angeles
New York City-Philadelphia

http://www.mcmaster.com/

Also, could do a mass dstributing. People in an area can give their request and money to someone going to Moab and that person could pick up all of the collars and then take them back to all of those people.

Just a thought.

Lemme know. I know Jeepin' Al will be coming less than 5 miles past my house on his way to and fro MOAB (I live off I-80) and I bet if I ask him real nice, he would meet me with a set.

XJMA · **Posted:** Tue Feb 21, 2006 7:31 pm

Forgive my ignorance, but I'm straining my eyes here and really can't see the crack!! Is it that slightly moist spot near where the joint is from where they cast it?

Also, under what conditions did this fail? What size tires, lift, etc? Did you bang the jeep hard off of something?

Also, I'm not seeing how this part could crack. Heat? What would put so much force right there that it would crack? The pinion torquing in it's bearings? Strange.

Ed · **Posted:** Tue Feb 21, 2006 9:35 pm

Quote:

Forgive my ignorance, but I'm straining my eyes here and really can't see the crack!! Is it that slightly moist spot near where the joint is from where they cast it?

Also, under what conditions did this fail? What size tires, lift, etc? Did you bang the jeep hard off of something?

Also, I'm not seeing how this part could crack. Heat? What would put so much force right there that it would crack? The pinion torquing in it's bearings? Strange.

Here's a broken one.

The pictures at the start of the thread are of an intact diff. Once it's broken it's too late to do anything except replace the whole diff casing. The collar is (possibly) a preventative measure, not a fix.

As posted in the other threads on this subject, it seems that it happens when your wheels are freely spinning and suddenly grip. Like if you get airbourne!

Jeepin Al · **Posted:** Wed Feb 22, 2006 9:08 am

Ok guys I dropped the ball on this one. Pixeldzn Don asked me to look into getting something made up. I have been so busy with the new job, my Big Al's 5 inch lift, and getting my welder to build more a-arms I just haven't had the time to really look into this.

I had a buddy of mine machine a alum. collar for the pinion gear and we welded it to the pinion support, increasing the thickness from around .25 inches to almost an .5 of an inch. Than I asked him to make an alum. plate that looks like the drivers side mount . We took this plate and welded it to the right side of the diff, opposite of the mounting plate on the left. I am hoping that this will support the diff casting.

Mechanic Mike, can your machine shop take some of those ready made collars and bore them out to the correct diameter, we need. I think this would be the simplest way to go. To hand grind the collars will be difficult, you may leave high spots, and once installed this cause more stress on the little alum lip around the pinion. Getting professionally machined would be the way to go.

Al

EagleVT94 · **Joined:** Thu Jul 07, 2005 9:52 pm **Posts:** 64

It's been years since my engineering materials science courses! Does a collar really help? It sounds like these are failing due to interior stress/heat as opposed to external contact. It seems like a collar may make the crack smaller, but wouldn't due much for hairline fractures and impending doom. I left the engineering world for medicine, but I'll chat with some friends on this one.

Jeepin Al · **Posted:** Wed Feb 22, 2006 9:47 am

The alum, can not be stressed as steel can, especiallyif it cast allum. It does fatigue, and will eventually break. I seen this in the old motorcycle engines I played with when I was younger. Due to the oils and heat, they get brittle. Next comes the action of the gears. When the power is aplied to the gear set, the pinion wants to back off the ring gear. The ring gear is held fast by two very large bearing (compared to the pinion) and doesn't move. Most of us believe that the pinion gear backs out against the thin area holding the bearing pushing the pinion shaft and bearing outwards towards the rear of the housing cracking the housing thru the thin tail section. Once this happens, a repeted load will crack it further, as seen in the picture.

The collar should prevent the intial crack from forming, hopefully.

I am still working on getting a front diff from a new Grand. It has a steel pumpkin. Its not a Dana product. I was told by a Jeep Mechanic its a 800mm american gear (?) the company MOPAR uses to make the 8.25 which he told me is really 8 3/8 or 850mm ring gear or something like that. Next question is, can I get a locker and 4.10's for the new axel?

Al

Ed · **Posted:** Wed Feb 22, 2006 9:49 am

Quote:

It sounds like these are failing due to interior stress/heat as opposed to external contact.

My take is that it's simply the input shaft levering itself out of the end of the diff casing. Probably the diff casing is almost strong enough as it is, so a steel collar tightly clamped around the point it's failing (where the input shaft goes in) might provide enough additional strength to stop it failing.

[edit]Err, yeah. Like Al said while I was typing this![/edit]

Of course when someone splits a diff with a collar on we'll know they're not effective, but until then they can't do any harm!

EagleVT94 · **Joined:** Thu Jul 07, 2005 9:52 pm **Posts:** 64

That makes sense. So many places to armor and reinforce! I'll just be keeping my fingers crossed for mine...

AZScout · **Posted:** Wed Feb 22, 2006 3:23 pm

Supposedly Jeep was to add another rib right where we are talking about adding a collar. That's the rumor from a year ago...

0311_DoC · **Posted:** Wed Feb 22, 2006 4:21 pm

Jeepin Al wrote:

Ok guys I dropped the ball on this one. Pixeldzn Don asked me to look into getting something made up. I have been so busy with the new job, my Big Al's 5 inch lift, and getting my welder to build more a-arms I just haven't had the time to really look into this.Al

I would like to hear more about this lift.. :twisted:

Or is still a work in progress. I guess im also wondering if it will work on a CRD if and when its finished.
Or is it just something your fabbing up for your own KJ?

Jeepin Al · **Posted:** Wed Feb 22, 2006 5:33 pm

I am hoping to introduce the lift to Moab in April. Many pictures etc will be posted after the ride. If it breaks, there will be no pictures just a lot of "I don't know what happen! What lift?"

Al

Tokyojoe · **Posted:** Wed Feb 22, 2006 8:43 pm

Al,

I think it will be more like " Someone hand me the Winchester, I think ol' Bessie has had it. Time to put her out of her misery. Everyone, please look away as I do this." Then sneak away as they look away. hahaha!

Front Diff Reinforcement Collar

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