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69chevyguy

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Discussion starter · #1 ·
Problem - while replacing wheel bearings I've discovered that the spindle has developed a "lip" on the underside of the outer bearing surface. That is the bottom most surface of the spindle that would carry the vehicle wieght to the bearing inner race has a lip too small to see with the eye but big enough to feel (and big enough to cause interference when sliding the outer bearing onto the end of the spindle). This only exists on the bottom edge and there is no other damage or even wear anywhere on the spindle that I can find. It appears the inner race has spun on the spindle and created this lip where the weight is focussed.

Question - $20 bucks says buffing with a fine emery cloth will get rid of this lip. But what I don't know is tolerance of the bearing inner race to the spindle, and if when this lip was created it would sufficiently make the race mounting surface out-of-round to matter for bearing adjustment and performance. Any ideas?

The Kicker: This is a '69 Impala with factory disc brakes. No aftermarket spindles exist. Rather rare option also, very rare to come accross used ones anywhere, and when you do, well they're used...so often not in any better shape. Replacing it is not really an option...
 
Any reputable machine shop should be able to weld or build up the surface and machine it back down to perfectly fit the bearings.
 
Discussion starter · #4 ·
Thanks guys...nobody has any specs on clearance of bearings to the spindle should be do they? Manual says 0.008" end play with zero pre-load (no real idea what that means...) but when I slide on the outer bearing it seems to go on fine without any slopply movement...but at the same time I wouldn't say it's snug. I did emery cloth the spindle and it did take down that lip I described, but now I'm probably just paranoid that fit won't be perfect and I'll blow out this same bearing in the near future or cause more spindle damage!
 
I doubt the wear is a problem regarding 'strength' of the spindle, but . you DO have to do something to prevent the race from spinning. 'shade tree's idea? or even better.. see if a machine shop can knurl the portion of the spindle where the race sits?
 
Imho, the bearing should slide on w/ no "wiggle" or "teeter-totter" slop and the .008" is "in and out" slop of the mounted wheel assembly so that it can expand once it's ran and gets warm running down the road.

No in and out slop and it will get hot and expand and maybe even lock a bearing and really screw everything up!

Maybe I'm off on the .008" b/c that seem's like a bit more than just adjusting the castle lock cap a notch or two to create the in and out slop??

It's been years??

pdq67
 
Timken P/N LM67048.

Nominal bore dia. = 1.250"

Shaft diameter for outer ring rotation/normal loading and axial displacement possible= 0/-0.00051"

This is for a Camaro inner bearing. If the Impala runs the next size up then the tolerance is still the same. Inch series TRB's shaft size tolerance for the above is the same all the way up to about 3" diameter.

I do not recommend knurling and/or dimpling in this application. Adding in additional stress concentrations on one of the most life-critical components of the car is not sound practice. Either blend in the step with emery cloth and run it, or have it welded up and reground. kI won't go into how knurling and dimpling wreak havoc on bearing loading and overall life.
 
Discussion starter · #9 ·
Shaft diameter for outer ring rotation/normal loading and axial displacement possible= 0/-0.00051"
Carl, where'd you get that data from? Mine's a Timken M12649 (cone) and for reference the cup is M12610..and I'm talking about the outer bearing. Is that shaft diameter info from their website?
 
That is a standard tolerance range for inch-series TRB applications that have outer ring (cup) rotation and must have axial movement possible on the inner ring (cone.) Inch-series TRB's have a different tolerance range than other bearing types.

There is likely some sort of fit calculator on Timken's website. For sure there is something in their catalog.

The actual that may have been speicifed by GM at the time of manufacture may have been different, but not by more than a few 0.0001".
 
Discussion starter · #12 ·
Thanks Carl!

I've also done some more research...it would appear (I need to verify it though) that Corvettes used the exact same spindle on all 1969 - 1982 applications. It may also be true that the full sized used it in other years after 1970 also. I don't have the parts manuals to verify it (my parts manual ends at 1970 and is for full size only) but the spindle P/N is 3953416
 
Discussion starter · #15 ·
Thanks for the info 1stGenLvr.....by chance does anyone reading this have a parts manual for full size from 1971 up? Just curious now if they have the same 3953416 spindles and if so, I think I may have a pair in a '71 Impala sedan not too far away...
 
The 71 and above spindle is different in that it has a cast 1-piece caliper bracket and use different ball joints. However I don't know if the ball joint stud dia is the same or not. The bearing size is the same. If the studs are the same dia/pitch you could take both sides and swap.
 
Robert and Matt Weller,

You guys know what forged spindle GM modified and how and then used on the '65 Z-16 BB 11" four wheel drum braked Chevelle?

I can't get ANYBODY to tell me b/c it's always, "Well, this one and they did that to it to make it fit"????

I ask b/c I only went w/ my "pdqCBB" front set-up w/ 13" rotors b/c I could NOT find out how to modify any existing GM forged big-car spindles to fit my '67 1st Gen. Camaro Car like was installed on the Z-16!!

I liked my small drums until they got hot and flat went straight to h*ll so I figured the Z-16, 11" front drums should be right "up down town" vs the hassle of installing discs all the way around since 12-bolts did come stock w/ 11" drums.

pdq67

PS., and fwiw, my car now has on it 13", 1988 'Vette front rotors and big single piston calipers using homemade caliper brackets and 11.75" 1989 Camaro rear discs and homemade caliper brackets that mount 1980 Cad. Seville e-brake calipers for the CHEAPEST big 4-wheel disc brake system going, imho!!

AND only b/c I couldn't find out how to mount the Z-16 Chevelle's 11" drums all the way around on my car!!!
 
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