9" rear axle conversion?

(On topic) - Much better than bearings wearing on 8.8" shafts!

Not to get off topic, but the 9" Ford rear has the bearings pressed on to the axle shafts to retain them vs. C clips in the 8.8" rear.
Can you safely run 9" style pressed on bearings in a 4,400 lb car on a road course?....:dunno:
A 4,400 lb car with good tires and suspension can generate some huge side loads on the axles/bearings.

(On topic):

The typical "big Ford" 9" axle shaft wheel bearing is from the F150, and is a wet tapered roller bearing (I think they are rated #3800). There are also other optional bearings. I am planning to go with NASCAR floating axles, which have opposed taper roller bearings - 3/4 ton/1 ton F250/F350 hubs.

===
 
My Bad!

If you want to be extra safe just don't race. I have seen thousands of races and I have over 260 in the MM with an 8.8. I have seen dozens of wrecks and none due to a snapped rear axle. The axles that I have seen snap do so on launch with no subsequent wreck.
Money would be better spent on a quality helmet, racing seat with harness and a cage.


OK, sailsman, I must defer to your vast experience & knowledge. But, don't you think a helmet, racing seat, harness, & cage is a waste of time & money, also?

These examples must be a 1-in-a-million occurrence? ...

http://www.youtube.com/watch?v=ST6FQV2GBIk

"Just like it says I've been on 31 spline axles for way to long now, a little tire shake and boom. They are 35 spline now" ...
http://www.youtube.com/watch?v=4XwDW7CdvTE

Wheel passes car:
http://www.youtube.com/watch?v=UguuAiVex7E

http://www.youtube.com/watch?v=ZuEthx26Pkg

http://www.youtube.com/watch?v=8F4BL2CM5cU
 
Please read my post -" I have seen dozens of wrecks and none due to a snapped rear axle. The axles that I have seen snap do so on launch with no subsequent wreck.
Money would be better spent on a quality helmet, racing seat with harness and a cage."

It's your money spend it how you please.

I strongly disagree with your statement - "A #4400 car with slicks and over 500 horsepower needs 1.5" axle shafts. If you think smaller diameter shafts are OK, you are not very concerned with safety."- based on actual real World experience and the opinions of some of those who have far more expertise than myself.
 
Last edited:
I very much appreciate the strength, reliability and near-zero maintenance of proper tapered roller bearings and floating axles. This is absolutely how it should have been done from the beginning. I hate axle designs that roll the bearing directly on the axle and transfer side loads to the diff through C-clips.

That said, there are probably not too many of us with enough power to justify the cost. But it is a cool idea.
 
No 9" now ...

We decided the 9" is out - too many problems to make it work.

Looks like we will go with a bolt-in modified stock/OEM 8.8".

The details:
Detroit Truetrac 33 spline (Eaton)

Moser Hobby Stock Circle Track Axle Package (forged ends, 5/8” studs, 45mm bearings)

Girdle cover + axle braces

Explorer or Wilwood disc brakes

Welded axle tubes

My used 3.27 ring & pinion, or a new 3.08​
 
Moser Hobby Stock Circle Track Axle Package

Do you still get tapered rollers? Floating axles?
I'm sure they are tapered, they are larger than the F150 (5/8 ton) rear wheel bearings - semi floating:

Moser "Hobby Stock Circle Track Axle Package" ...

SKU: CTHOBBYSTKPKG Availability: In stock.
$695.00Quick Overview
MADE THE AMERICAN WAY IN THE USA!
*This item will ship two business days after online transaction is completed.
Product Description

We offer the strongest Hobby Stock flanged axle on the market! These custom alloy axles feature a giant 1.774" bearing seat for use with a 45mm bearing plus 1/2" thick axle flange and a larger radius to greatly lower the risk of flange breakage.
Sure you can find a cheaper axle in the junkyard or imported from overseas, but remember...You get what you pay for. And in this case, you're going to get much more than you've paid for.
This package includes the axles, 45mm Timken bearings and seals, heavy duty retainer plates, 5/8" circle track studs and our weld-on forged housing ends, specially bored for the 45mm bearings.

Not enough room from the lower control arm bracket to the outside of the hub to keep the tires inside the wheel well. They would be wider by 1 3/4" on each side with floating hubs (even with a 9", a 3 1/2" wider rear track
in total).

=====
 
I can see where a true floating axle would require extra space to fit the flange and spindle. A good oversize axle and bearings should work nicely. And you'll keep the extra HP that would be lost to the draggy 9".
 
2 Month Update

I picked up my rebuilt 8.8" two days ago. My builder had a few minor problems that held up his work. As you all may be aware "Nothing is really a 'bolt-on'"!

Parking brake with the Wilwood iron rotors wouldn't clear the 5/8-18 studs, so we saved some money and went without the p-brake. The aluminum hat 12.2" diameter 13/16" thick iron vented Wilwood rotors required safety wiring the retainer cap screws.

The O.D. flange taper of the shafts required more machining, and the index center of the flange needed turning to fit the Wilwood hat.

I would like to paint it "Hot" pink, but will probably go with "Rustoleum Cold Galvanize".

Adapting the hydraulic lines should be easy, but since I am losing the ABS function, I may remove all the ABS hardware, and need to add a proportioning valve. Perhaps a new master cylinder is also in order. Might need to disable the ABS light somehow?

The calipers are 4 piston, and will clear 15" wheels. But I now have the problem of finding wheels to fit. I want 10" wide, to fit the 5 on 4.5" pattern and the 5/8" studs. The center hole is over 3" diameter, and wheels need to be 45 degree taper lug seats.


8_8Rebuild_011.jpg




8_8Rebuild_009.jpg




8_8Rebuild_008.jpg




8_8Rebuild_007.jpg




8_8Rebuild_006.jpg




8_8Rebuild_004.jpg




8_8Rebuild_001.jpg

 
Any update on how this axle bearing and other upgrade worked out? My rebuilt rear end is starting to howl 30K miles after a complete rebuild (except ring and pinion). It would be really nice to have proper tapered roller bearings that could actually hold up to a few thousand miles of use.
 
Well

Any update on how this axle bearing and other upgrade worked out? My rebuilt rear end is starting to howl 30K miles after a complete rebuild (except ring and pinion). It would be really nice to have proper tapered roller bearings that could actually hold up to a few thousand miles of use.

If you have a 2003 or newer, it is complicated to weld on tapered bearing 9" ends, (as far as I know, no one has done it) and retain ABS. I deleted the ABS function by converting to the 33 spline Moser Hobby Stock axle shafts when we went with the 9" bearing ends on my pre-2003 housing.

Only 30K on a complete rebuild means a component failure or improper repair/rebuild. I would expect 100K at a minimum.

==
 
These axles should make it to 100K in theory, but examples of earlier failure are numerous and the aftermarket is awash in axles heat-treated by morons who don't know what they're doing.

I jacked up the car today to confirm the problem is play in the axle/bearing interface. I noted the ABS sensor is very close to the axle tube. So a 9" (or floating) axle end retrofit would at a minimum require larger ABS tone rings to move the sensor further radially from it's current location.

Nothing is ever easy. But I am convinced this axle/bearing thing is futile and I don't want to keep revisiting it.
 
These axles should make it to 100K in theory, but examples of earlier failure are numerous and the aftermarket is awash in axles heat-treated by morons who don't know what they're doing.

I jacked up the car today to confirm the problem is play in the axle/bearing interface. I noted the ABS sensor is very close to the axle tube. So a 9" (or floating) axle end retrofit would at a minimum require larger ABS tone rings to move the sensor further radially from it's current location.

Nothing is ever easy. But I am convinced this axle/bearing thing is futile and I don't want to keep revisiting it.

You can't lump all bearing failures with improper axle contact surface heat treating. I'm sure that many failures are caused by a repeat failure from improper cleaning of a contaminated housing. It happened to me.

Replacing the OEM housing ends requires a degree of re-engineering. A few questions come to mind:

1) Is there space for replacing the ends, and still maintain the same track width?

2) Is there space to narrow the housing, avoid tire/shock damper interference, and allow a wider wheel?

3) Can replacement axles shafts with 9" tapered bearings be equipped with OEM 8.8" ABS rings (9" 31 spline shafts are the same o.d. as 8.8" 31 spline shafts)?

4) Can the tooth counting pick-up sensor be properly located to where the rings turn on new shafts?

5) Do you want to delete ABS, or adapt it to new shafts?

6) Is deleting the parking brake acceptable (I deleted it on my 2000 CVPI)?

7) Would it be practical to use a Sterling axle replacement, in order to retain the Watts link, ABS, and gain 3/4 ton bearings?

I'm sure that a solution can be fabricated, but at what expense, and with how many compromises?
 
You can't lump all bearing failures with improper axle contact surface heat treating. I'm sure that many failures are caused by a repeat failure from improper cleaning of a contaminated housing. It happened to me.

Sure, I just consider it a likely possibility. The rear end and axles were not destroyed and filled with metal when rebuilt. Anything is possible, however.

Replacing the OEM housing ends requires a degree of re-engineering. A few questions come to mind:

1) Is there space for replacing the ends, and still maintain the same track width?

I did not see any width issues, plenty of tube length between the CA brackets and bearings

2) Is there space to narrow the housing, avoid tire/shock damper interference, and allow a wider wheel?

tire/shock clearance is dictated by the CA bracket location. The goal would be to retain factory track width.

3) Cn replacement axles shafts with 9" tapered bearings be equipped with OEM 8.8" ABS rings (9" 31 spline shafts are the same o.d. as 8.8" 31 spline shafts)?

Pretty sure new ABS rings would be needed due to the location of the ABS sensor needing to move outward radially to accommodate the larger bearings. Not to mention axle shaft diameter would be unlikely to match the 31 spline shaft. Likely a custom fabrication, but not an unreasonable part to fab.

4) Can the tooth counting pick-up sensor be properly located to where the rings turn on new shafts?

I think so, new mounting hole location would be needed.

5) Do you want to delete ABS, or adapt it to new shafts?

I want to keep it of course.

6) Is deleting the parking brake acceptable (I deleted it on my 2000 CVPI)?

I would like to keep it, but this seems the most difficult as the larger 9" style end likely could not match the backing plate holes. Maybe a disc brake parking brake, or something similar. Driveline yoke PB? This could be a headache.

7) Would it be practical to use a Sterling axle replacement, in order to retain the Watts link, ABS, and gain 3/4 ton bearings?

Don't know what this is. I was actually planning on looking into floating hubs for race cars.

I'm sure that a solution can be fabricated, but at what expense, and with how many compromises?

I guess I'll find out . . .

Here is a floating hub with the correct bolt pattern. Need to find out more about the required axles and mounting required to implement it.
 
Back
Top