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Quote:

Originally Posted by Vince@MSperfab (Post 552687)

The GM outer bearings are just tiny, I remember a thread with forces listed. I cannot find it now. I believe it was when Pozzi was addressing the short spindle failures.

Greg, I remember the thread and Rons listing for brake forces. I think it was Rons thread.

Hey Guys,

A post I did on bearing thrust load capacities is here.

A post showing my new Track-Star hubs & the bearing size differences start on THIS PAGE. Be sure to read from post #427 to post #438.

The size & mass of the bearings define their ability to handle thrust loads ... and heat. A front hub bearing is a lot like a brake rotor. The larger it is the better its mass can handle the heat generated. The smaller it is, the higher the temps get & you get grease burn out.

The photos below show the sizes of bearings for reference.

Far left: Timken LM11949 rated at 917# thrust load. (Most GM 58-78, Ford 55-69 & Chrysler 55-72)
2nd from left: Timken LM12748 or LM12749 rated at 922# thrust load. (GM 82+, Ford 70-89)
3rd from left: Timken LM12649 rated at 1130# thrust load. (GM B-body & 1/2T trucks & Ford some HD apps 63-72)
Far right: Timken 2687 rated at 1800# thrust load. (Road Course & Oval Race Cars)

Quote:

Originally Posted by GregWeld (Post 552674)

Do either one have a car? Been so long I've forgotten....

We're expecting a celebrity guest appearance too! :D

Never thought I'd ever have BEARING ENVY...

I will upgrade to all this stuff on the Mustang after the August Sonoma event... that way Ron Sutton (I have to include his name lest you guys think I'm taking Ron in So Cals advice for something... hahahahahaha) will have had a chance to really look see at the underpinnings in case there's anything else that should be done.

Again - since lots of people read this stuff..... There's nothing "wrong" with the Mustang the way it is... BUT!! As Ron helps me dial this car in - the speeds and corner loads increase.... and I'm no engineer - but I think they probably grow A LOT as you increase the speeds. I'm going to ASSume that the braking loads increase - as you go deeper into a corner at a higher speed -- which is going to ADD HEAT to the equation... and as I go faster / harder - then the tires start to heat up and on and on. So what's good at one/some point -- it becomes a liability at another.

We all love to buy parts! And we all want to have bragging rights for this wheel or this tire - or this big brake kit..... I've just never given any thoughts to the other little parts that might actually matter. Bearing failure in a high speed corner is not an option!

Thanks for the info Ron. :thumbsup:

Quote:

Originally Posted by GregWeld (Post 552757)

I guess you will have to see if it needs an upgrade or not. I'm not sure how many options you have for larger capacity hubs but the nice thing is it will warn you, you just have to know what to watch for.

Thanks Ron,
I will continue to monitor Gaetanos bearing packs. If I see any signs of abnormal wearing or grease failure we will look at a different hub and or spindle.

Quote:

Originally Posted by Ron Sutton (Post 552743)

Hey Guys, A front hub bearing is a lot like a brake rotor. The larger it is the better its mass can handle the heat generated. The smaller it is, the higher the temps get & you get grease burn out.

Exhibit B:

https://scontent-b-sea.xx.fbcdn.net/...75362442_o.jpg

Quote:

Originally Posted by Vince@MSperfab (Post 552775)

Hey Vince & G ... and anyone running fast at track days on a budget ... the best advice I have for you is "clean, inspect, grease & replace often." Vince is already on this, but I don't want anyone following along to not understand how key that is.

Replace the outer bearings often ... they're cheap ... and when you replace them, make damn sure you're buying Timken & not some import bearing made with inferior steel. There is a difference in the quality of Timken steel. If Timken's bearing is rated at 917# ... what is a $7.99 china bearing made out of pot metal rated at? :confused59:

For reference, I raced in an oval track series (West Coast NASCAR Modifieds) that required stock spindles & hubs (rules to control costs - LOL). These cars were light ... 2550# & ran 8" slicks of moderate hard compound ... on short tracks where cornering speeds were 50-55 mph. So less car weight, less grip & less load forces than we see with big tired PT cars at road course track days.

When we ran Granada hubs (2nd bearing from the left) we replaced the outer bearings after every 2-day event. When we stepped up to the Impala hubs (3rd bearing from the left) we replaced them after every 2nd event. The reason is, these bearings are not rated for the loads they are seeing.

On the stock cars ... with softer, bigger 10" slicks ... more weight 3100-3400# ... ran on bigger tracks with higher corner speeds & g-forces ... we run the bearings on the far right. We run the car all season & only replace the bearings after a full season of 25-30 events. They last, because we're within the load window the bearings were designed for.

Guys, my recommendation is, to those of us building these cars to be fast like race cars, driving them fast on race tracks ... we also build in safety like race cars ... AND ... service & maintain them often like race teams do ... to prevent bearing & other part failures that cause crashes.

:cheers:

Ron, Where does the C5/C6/Z06 Etc. sealed bearing assembly fit into this equation? The GM guys have the luxury of going with a ATS spindle that utilizes a c6 bearing pack. I know mine were still tight when I sold my car. Not that much road racing time, however.

Quote:

Originally Posted by Sieg (Post 552777)

Exhibit B:

https://scontent-b-sea.xx.fbcdn.net/...75362442_o.jpg

I saw that in person Saturday night and it was IMPRESSIVE!!!

Just the fact that we're having a discussion about bearings -- and temperatures -- and service items...

Makes me wonder how many guys haven't checked this stuff at all - let alone after really pushing their cars hard.

I know for me -- I have a pretty decent shop and tons of time... so it's pretty easy for me to put this stuff up on the hoist and go over stuff. But I know if I had kids at home - and work - and house stuff to attend to - the car might just get parked in the garage and forgotten about until it's time to run again.