How tough is the stock 9 inch do I need to go to the Daytona pinion

[spap]

Hey.
I‘m redoing my 77 nine inch
bronco has 35s , will be 4.56 gears Detroit true trac 31 spline axles and under 300 horsepower, 4r70w. Mild dessert trails some tough stuff but Nothing crazy.

it’s not that much more to have a Currie drop out built with a modular case and a Daytona pinion support. But do I need it . Or is the stock 3 rd member rebuilt with the 4.56 gears and a true trac non nodular case still pretty strong for what I’m doing. About 400 bucks more for Currie or vendors
I hear a lot about cracking of pinion support, but I’m not that crazy in what I do. Just wondering if it’s a real concern. Or save the money for something else
thanks

 

[Yeller]

If your not pushing things off road or abusive on road strength isn’t an issue. However….. spend much time at interstate speeds? The inner pinion bearing will begin to hate you and tell you about it. Daytona suport corrects that issue. In bronco’s specifically pinion bearings have been the most common failure I’ve observed, all on trucks with deep gears, overdrive, big tires and lots of freeway miles.

 

[Rustytruck]

get rid of the crush sleeve and go to solid spacer between the pinion bearings. weld a skid plate under the center housing. 1/4" plate will do.

 

[toddz69]

I was in your situation years ago and went ahead and had them do a nodular housing, Daytona pinion support, solid spacer and billet yoke. I figured it couldn't hurt to have all those extra good parts for not a huge amount of extra $$. I do a lot of freeway miles in mine so hopefully the Daytona helps it in that regard too as Yeller notes.

Todd Z.

 

[spap]

Thanks Im thinking that way, do it once and forget it,
sounds like getting rid of the crush sleeve helps a lot

 

[Rustytruck]

it sure does especially if you have to replace a leaky pinion seal.

 

[jamesroney]

get rid of the crush sleeve and go to solid spacer between the pinion bearings. weld a skid plate under the center housing. 1/4" plate will do.

Hi Rustytruck,

Can you please explain why you recommend the crush sleeve eliminator? I have heard that is a "can do" a "should do" and a "must do." I still don't understand the fundamental benefit.

The crush sleeve resides between the two tapered roller cones. If you could accurately secure the pinion nut...you wouldn't need a crush sleeve at all. Front wheel bearings do not use a crush sleeve. It seems that once your pre-load is set...then the crush sleeve does nothing. The only way to overcrush the crush sleeve is to overtighten the pinion nut. All of the bearing loads are directly on the cone and cup. So I'm puzzled by the value of the shim pack.

The GM 14 bolt is a crush sleeve, and the Dana Super 44 and all Dana 60's are now crush sleeve. I think every pinion in every light duty truck today uses a crush sleeve.

I have always recommended the Daytona pinion support, and the solid spacer. But now having built at least 50 of the 9 inch, and a couple hundred Dana 25's, 27's, 30's, 35's, 41's, 44's 50's, 53's 60's 61's and 70's...I am starting to ask "why?"

My last 9 inch that I built (for myself...) I re-used an old crush sleeve, and just added a new .010 shim under it. It worked great. I'm also starting to doubt the validity of not re-using TTY (torque to yield) fasteners. This Mechanical Engineering Degree is going to get me in trouble...

Would appreciate some insight.

 

[DirtDonk]

Looking forward to hearing more details about that as well.
When Ford built these originally did they use a crush sleeve, or a solid spacer?

And what are the issues associated with high rotational speeds and the pinion bearings? My 71 spent a lot of time above 3000 RPM on the highways and I didn’t have any ill affects luckily.
I wonder if there is a relationship between a possible lubrication issue and the pinion angle?

 

[Rustytruck]

as far as I know ford built all of them with crush sleeve. solid spacers came about when the drag racers were blowing up ring and pinions because of hard launches.

 

[nvrstuk]

Do the Daytona upgrade.

I know guys totally stock who have wasted OE pinions.

I've grenaded a few myself.

 

[spap]

I was thinking that too paul
if you run a lift and 6 degree shims, it looks like you will be putting in less gear oil in the axle because of the angle, the oil will leak out or be level with the fill hole earlier. Unless you put more oil in before You put the axle in.

 

[Broncobowsher]

The spacer is a more precise way of keeping the bearing preload. The crush sleeve is a mass production compromise. When you are trying to make enough gear setup for as little labor as possible, a little extra engineering into making a one size fits all crush sleeve saves labor costs when building millions of gear sets. For general use they have proven to work. For hard work, they have been known to not work so good. As far as setting preload compared to a wheel bearing, this is where things get strange. I have asked some good engineers, old time machinists, nobody can answer this for sure. Wheel bearings you set with a little free play, don't want to run them too tight. But a rear end you want preload, the opposite side of zero play. I have found bearing numbers for the same bearing used in a rear end as a wheel bearing, so the bearing isn't different. Speeds are not different. Lubrication, full floater axles run in gear oil so I am going to say that isn't it either. A differential needs to hold things in just the right spot for the gear meshing to be correct is the only thing I can think of.

Now the Daytona support. The name says a lot. It was developed for NASCAR running sustained high power levels at Daytona. The pinion bearings were getting destroyed holding high HP for long times. So they put a bigger bearing in that can take the loads. Back in the 90's and early 2000s GM trucks were real bad about burning up pinion bearings when towing. The little 10 bolt axles just didn't have enough pinion bearing. They went back and redid the housing to make a super 10 bolt. Basically a bigger pinion bearing. Consider the aero drag of a Bronco, a bronco running tall tires, loads are like that of towing a trailer. Maybe not running the Coca Cola 600 with a Boss 429 at full song in 1969, but getting surprisingly close at todays highway speeds.

As for the nodular case. The big benefit I see is a better pinion support. The 3rd bearing. In stock housings they are known to fail. Worse with deep gearing. and clearance with deep gearing often means having to grind clearance into them. Making them weaker.

So even with your relatively mild build, all the above are good ideas. As you state, they don't cost much. They all help protect the rear end for a long life. Except for the solid shims they are all upgrades that Ford did back in the day to make a 9" that would work hard and life in production form. The local Tucson axle shop won't build a 9" with a crush sleeve. They will only do solid spacers. That is the standard these days on a performance 9".

 

[spap]

Thanks all for the input , funny this all started because Currie which is kinda close to me, won’t rebuild your carriers anymore due to liability challenges. Started as a $1100 dollar rebuild at the beginning of COVID , finally got around to pulling everything, (44 year old bearings were going south) opened the rear end and it all original. Local rebuilds unitrax , T&J in so cal wanted $ 1,680 to rebuild with a truetrac bit for everything brand new it’s about $1,950 from Currie. That’s a small difference for a nodular carrier and a Daytona set up. I just don’t and prob won’t have tons of power, so thought I could get by. With 35 and the 4.56 s I want def go with the nodular set up. Seems like it will be bullet prof for my set up

 

[ntsqd]

One significant difference between wheel bearings and pinion bearings is the directions and magnitudes of the loads and impulses. And who says wheel bearings don't have spacers? Most street vehicles are lacking them, but racers have known for years that making a wheel bearing spacer increases the strength of the whole design. Not to mention that the tolerances on bearings are such that they are directly interchangeable. So if you hurt a bearing in a properly set up spacer system you can simply replace that bearing without having reset the spacer's length to again have the desired preload. On something like an Endurance racer this is important because the bearing pre-load was set by the person who set up the spacer and won't be affected by how tight the tired & bleary eyed crew member who replaced a bearing at 3AM got the spindle nut.

Remember that Strengths of Materials class exercise where you looked at the bending of just a tube vs. the bending of a tube with a tension member down the center of it? Add a bearing spacer and you turn the spindle or the pinion shaft into that center tension member making the bending strength of the whole thing a LOT higher.

 

[nvrstuk]

Totally agree TS. I think I slept in on the day my Strengths of Materials instructor reviewed that tho... lol

Overfill the diff. This is what I was told to do with my first doubler build back in the '90's when I had to rotate the pinion up for the corrrect angle. 20 1/2" long rear DS. I think I was running about 12+deg on my 9". I was concerned about it, so me being me I called several shops that did custom off road 4x4 builds and they all said to overfill the diff (whatever the amount was-can't remember) and add 1/2 cup of auto trans fluid to the mix. Solved any/all issues. Must have put 50K miles on the next couple years without any issues. I checked pinion brg heat with my infared.... not an issue.

Now, is this the best fix? No idea but it never caused an issue.

 

[jamesroney]

One significant difference between wheel bearings and pinion bearings is the directions and magnitudes of the loads and impulses. And who says wheel bearings don't have spacers? Most street vehicles are lacking them, but racers have known for years that making a wheel bearing spacer increases the strength of the whole design. Not to mention that the tolerances on bearings are such that they are directly interchangeable. So if you hurt a bearing in a properly set up spacer system you can simply replace that bearing without having reset the spacer's length to again have the desired preload.

Remember that Strengths of Materials class exercise where you looked at the bending of just a tube vs. the bending of a tube with a tension member down the center of it? Add a bearing spacer and you turn the spindle or the pinion shaft into that center tension member making the bending strength of the whole thing a LOT higher.

..."you can simply replace that bearing without having reset the spacer's length to again have the desired preload." 100% agree.

I remember in Strength of Materials that the bending of a tube versus the bending of a tube with a tension memeber resulted in greater resistance to bending when the material is anisotropic. So yes, a pre-stressed concrete beam has increased resistance to bending. But I'm not so sure about a pre-stressed carbon steel pinion.

But that's kind of moot since the pinion nut torque and clamp load is the same for both crush collar and shim, and therefore the tensile stress is identical for both.

What am I missing?

 

[Slednut10]

..."you can simply replace that bearing without having reset the spacer's length to again have the desired preload." 100% agree.

I remember in Strength of Materials that the bending of a tube versus the bending of a tube with a tension memeber resulted in greater resistance to bending when the material is anisotropic. So yes, a pre-stressed concrete beam has increased resistance to bending. But I'm not so sure about a pre-stressed carbon steel pinion.

But that's kind of moot since the pinion nut torque and clamp load is the same for both crush collar and shim, and therefore the tensile stress is identical for both.

What am I missing?

What you’re missing is that the crush sleeve technically only works once. Once you remove the pinion nut, you are theoretically supposed to use a new crush sleeve. Yes, lots of us have successfully reused them when replacing a pinion seal, but it wouldn’t take much to overtighten the nut and mess up the preload.

 

[jamesroney]

What you’re missing is that the crush sleeve technically only works once. Once you remove the pinion nut, you are theoretically supposed to use a new crush sleeve. Yes, lots of us have successfully reused them when replacing a pinion seal, but it wouldn’t take much to overtighten the nut and mess up the preload.

I'm going to agree to disagree. I have been pondering this one for a while. It goes back to my skepticism of TTY fasterners. Same concept except tension vs compression.

The crush sleeve deforms when it is crushed, but as soon as you remove the load on it...it immediately goes back into an elastic regime. The strain recovery results in a modulus that approximates the original modulus. Once you remove the pinion nut, the people that profit by selling you a crush sleeve tell you that you need a new crush sleeve. Also, it is always "safe" to always use a new sleeve. BUT, if I am replacing a pinion seal, I don't install a new crush sleeve. However, if I replaced a pinion gear...I would always replace the crush sleeve. WHY? It's nonsense. As long as the distance necessary to maintain proper bearing preload keeps me in the elastic region of the crush sleeve...I am fine. How do I KNOW that I'm in the elastic regime? That's the magic. The crush sleeve is constrained to be in the elastic regime, just under the yield limit because it deforms to get there. But a used crush sleeve has no such reference. So you need to make sure that your used crush sleeve is always just a little taller than you need, so it can crush again to establish a new reference.

I've convinced myself that I'm not wrong. But most wrong people think that.

 

[Rustytruck]

your forgetting once the crush sleeve is set it stays the ring and pinion wears as it wears it looses preload. now disassemble the yolk and replace the seal and re-tork the pinion nut. that action will take out the wear factor between the gears and the pinion and ring gear ride in a new location. accelerating wear. with a solid spacer the torque stays the same between the cones and doesnt change preload so wear between the gears ride in the same spot as you took it apart. is it better or worse who knows.

 

[DirtDonk]

I wonder how many people have actually checked the gear pattern and clearances after reusing an existing sleeve of either type?

Paul