Is there room to press 2 bearings onto this shaft? One just doesn't seem to be enough...
8.75 rear axle - room for 2 bearings?
- Thread starter MoPar~Man
- Start date
RemCharger
Well-Known Member
No, but you could get a full floater D60 out of a 1 ton.
This is a job that I think I'm going to tackle next year, I've never seen the inside of the axle tube yet myself, but it sure looks like the shaft would take a second bearing:
This is I think a fresh install of a green bearing, which is maybe a little wider than a tapered roller? It looks like there's room enough to put a second bearing there with the collar pushed out a little to the right. There'd have to be room enough in the axle tube for that, and the inner oil seal.
This is I think a fresh install of a green bearing, which is maybe a little wider than a tapered roller? It looks like there's room enough to put a second bearing there with the collar pushed out a little to the right. There'd have to be room enough in the axle tube for that, and the inner oil seal.
RemCharger
Well-Known Member
In a nut shell.. no, you can't. No, there has never been a reason to contemplate it.
68SportFuryAz
New Member
I'm really curious about why you'd want two bearings when ma-mopar built hundreds of thousands, possibly millions globally, of 8.75 rear ends and while they continuously improved the axles, splines, tapers, diameter etc and changed third members, gears sets, sure grip but never added 2 bearings. Even in the factory drag cars there aren't 2 bearings.
Well, the fronts have 2 bearings. I know it's the only practical way for the front hub is to have a pair of bearings. So why not do the same on the rears - spread the load? If the room isin't there, ok fine. But if it is?
68SportFuryAz
New Member
There are 2 bearings in the rear, where the torsional and fritional pressures exist. One in the carrier where gear torque is initiated and one at the flange plate where traction forces are imparted. The space in between doesnt need more bearings. And adding one would add extra expense with little improvement. If the flange side bearing failed and you have pressed one inboard of it you'd have to replace both. They dont unpress. The front hub bearings are only so close together because of their mounting structure. Unless we're talking a 4x4 which would also be different depending on fixed axle vs independent.
Just Carbs
Senior Member
I see no benefit for another bearing. To the contrary, because 4 bearings instead of two would increase the likelihood (chipping) of a bearing failure. And then they would both require replacement if either one fails. Parts left out cost no money and cause no problems, according to that GM president of long ago.
On the other hand, I do see the benefit of another retaining collar. I did lose an axle shaft out of a Dodge 1/2-ton small plow truck.
The shaft, wheel and tire traveled about 100 yards into the median when they left the truck that was traveling at about 50 mph in a straight line. No warning. It doesn't come out slow with some time to stop either. Just gone, bouncing end over end. Snow emergency in effect at the time. No cars on the road at 2am, no other damage. Fun night.
I gave that shaft a double dose of collars after that beautiful dry, starry full moon night.
On the other hand, I do see the benefit of another retaining collar. I did lose an axle shaft out of a Dodge 1/2-ton small plow truck.
The shaft, wheel and tire traveled about 100 yards into the median when they left the truck that was traveling at about 50 mph in a straight line. No warning. It doesn't come out slow with some time to stop either. Just gone, bouncing end over end. Snow emergency in effect at the time. No cars on the road at 2am, no other damage. Fun night.
I gave that shaft a double dose of collars after that beautiful dry, starry full moon night.
Well, you cant really compare the two like that. In reality there are already 4 bearings in the front from side to side of the entire vehicle, AND 4 IN THE REAR AS WELL. What the OP is describing would make 6 in the rear. Are we forgetting that there are bearings carrying the other end of that long axle at the carrier end of it???
Do the carrier bearings experience road force, braking force and carry vehicle weight like the 2 (per wheel) front bearings do?
volksworld
Well-Known Member
no...that's why heavy duty applications use full floater rears...trucks, oval track race cars, etc...inner and outer bearing on both sides,not relying on a pressed on bearing or a circlip to hold an axle in...stuff designed for passenger cars is only good to a point
68SportFuryAz
New Member
To clarify, I was only describing one axle assembly from carrier to the outer flange in my comments above, not the entire driveline. And also only the 8.75 rear end which was the quesion. During the design phase all road forces are considered and supported by the entirety of the driveline and its suspension all the way to sidewall height of the tire and the negative impacts made by other forces. When we add more torque, better traction, larger wheels, heavier tires we impact the assembly in ways it was not originally designed to support. These design decisions are why there are 8.25 rear ends, 8.75 rear ends, 9.25 rear ends all the way up to 11.5s.
The front bearings have different loads on them. You have side load from turning the wheels and the front of the car is heavier. The fronts also have larger brakes and the front will also have weight transfer under braking. So, 2 bearings make sense, especially since they are tapered bearings with a fairly steep angle to take the left to right side loads while turning.
Go to the rear and you don't have the same amount of side load and the weight is lighter. This is why the "green bearings" can work.
There's one other factor.... The rear bearings are substantially larger and if you were to compare apples to apples, one front bearing to one rear bearing, the rear bearings will actually take more load. So, 2 bearings per side on the front and 1 outer bearing and 1 inner carrier bearing. The inner bearing doesn't directly support the car like the outer bearing does, but they are on the end of an ~ 30" axle and that can create some load when the axle moves, pivoting around the outer bearing.
But, if you want to increase the load capacity of the outer wheel bearing, and you are using "green bearings", the obvious choice would be to find a similar sized roller bearing with no taper that would carry more load than the "Green" ball bearings. I don't think it's needed but that's the way to do it.
IMHO, the stock tapered rear bearings are the way to go. They last a long time and (again IMHO) the bearings seem to fail from lack of lubrication rather than failing due to overload. When these cars were new(er) and we drove and beat the snot out of them, you never heard of needing to change rear axle bearings, including on high mileage cars. What I think happens is the grease hardens with age and/or it gets washed away from the inner seal hardening and failing, letting the gear oil into the bearings washing away the grease. The outer seals also harden and fail with age and that lets dirt and brake dust filter into the bearings too. On the cars I've had to change axle bearings, the grease (or actually lack of it) on the old bearings confirms my opinion.
USSMOPAR
Active Member
What???? Same post on every mopar site? Has the solution arrived? Are you JCC under a new name?
This is absurd
This is absurd
This is bench racing at it's finest, but the race is going to be DNS once the OP finds out there's nowhere to put that 2nd bearing race, regardless of all that extra room on the axle shaft for the bearing itself.
No idea what any of that means.
Turbo301
Active Member
If you did put two bearings, wouldn't the inner one block lubrication re-fresh (via the axle fluid) of the outer one? If the bearing that's there is rated for the load you're applying, might as well not over-think it.
RemCharger
Well-Known Member
The bearings are greased and divorced by inner seal.
The 2 bearing theory cannot work with that style of adjustable taper rollers.
furyusvip
Member
Honestly, that's an interesting question, and very much in the 'bench-racing' vibe that is/was/should be a part of hotrodding.
If one is worried about using Green Bearings or just wants a substantially bigger axle bearing, one could cut of the standard Mopar housing ends and install Late Big Ford (LBF) housing ends. Yes, you would have to factor in the new axle offset, but it would allow you to use ANY aftermarket brake kit designed for a LBF housing.
When I did this on the Dana 60 I built for my 70 Sport Fury back in the mid 90's. I used the (then) very popular Ford Explorer disc brake kit and it worked really well.
Housing Ends Late Big Ford - Strange Engineering
OR Strange Engineering also offers a larger Mopar housing end that accepts a much larger (3.150 OD vs 2.875 OD stock) unit bearing.
Housing Ends Mopar - Special 3.150" Bore - Strange Engineering
Hope this helps...
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