83 Crossfire TA

iTrader: (2)

I know that the 1LE cars used a larger outside bearing, is there any real advantage to it (I guess GM thought there was)?

I've owned a few of these cars going back to the early 90's, even autoX'ed fairly seriously for maybe 15 years and I've never roached a front bearing. Has anyone had a good reason to go with the larger front bearings? Heck, I'm betting that between all the 3rd gen f-bodies I've owned I've driven them between 350 and 450K miles and I've only replaced one set of front bearings, and that was on my first one and I'm pretty sure they weren't worn out, just "while I'm doing this I'll replace these, this will make the car better somehow..." (I was like 20 and was in "I'm going to F with everything," mode)

I'm doing a homebrew front brake swap, I've already machined a set of front rotors into hubs, but I've been looking and the larger bearings are cheap and it doesn't look like the pockets in the hubs would be hard to machine to fit a larger bearing, so I'm debating if this is a "while I'm at it I should do this," or "skip it, it's a waste of time and you have other things to do."

scooter

iTrader: (11)

If you can do it, why not? I think the only real risk is that you're machining a cast hub and there will be less material at the end. I know people have problems with the rotors cracking around the stud hole after they are machined down

//<86TA>\\

iTrader: (14)

I believe BigbrakeUpgrade does similar to standard hubs as the 1le is harder to source.

TTOP350

iTrader: (8)

Not sure bearing failures were an issue in auto x but I have read that road course failures did happen and that was the reason for the larger outer bearing.
Of course that could all be magazine bs and they used the bigger bearing because it was what was already spec'd for the larger cars 12" rotor.

91 1LE

iTrader: (1)

This is what I've read. They only had to redrill the stud holes to use the Caprice rotors.

83 Crossfire TA

iTrader: (2)

Well, 2 reasons:
- first my projects tend to snowball with little things like this until what I thought was going to take me like 2 weeks is something that I'm still working on 2 years later... really not exagerating
- not sure that I'm not setting myself up for bigger problems like the hub cracking because it has a thinner wall, there's way more meat around the studs when machined to spec then there is around the bearing.

Yea, that's the second part of my concern: fixing something that is not a problem, that I've never even worn out one of the stock bearings and I haven't heard of any one having problems with them, and maybe GM did it for another reason like just using an existing part designed for a much heavier car that was also sold for HD use (police and cab) and I didn't know if there was any overlap with those parts for 2wd fullsize trucks that used the same bolt pattern.

BBU.COM

Exactly.. GM used an early model rotor to graft the C4 calipers to the camaro. The set 3 cup and cone has a part number starting with "M" which equals medium while the set 34 has the "LM" which is light medium, this prefix refers to duty.

Set 34 static load max 7650 lbf
Set 3 static load max 9780 lbf

There is also other factors, bearing size- smaller diameter roller equals faster speeds, larger diameter rollers equal lower speeds. Set 3 has less larger rollers, set 34 has more smaller rollers. So bearing life and grease break down / operating temps will differ depending on usage. One more slight advantage that you can compare is roller length, the set 3 has roughly about .070 more length to its rollers. When you bore for the set 3 in place of the set 34 deepen the pocket by .100 and widen to 1.965-66 and press both hub and race at room temp with light oil. Generally that bore in a stock rotor (1.781) will leave .188-.220 depending on the rotor casting used, .200 is what connects the ring to the hub on a new rotor for reference

I do offer that cast hub with the larger bearing in the stock offset and if you look enough you will see GM did also.

I`d say if you have been OK with the 34`s there's no reason to abandon them and delay your progress, you can always do them later if you want..or need. If load ratings remained stock (245 50 16) on the chassis those should be adequate, these guys running 18/19/20 inch wheels with large adapters,heavier rotating mass... they are applying more load..how much is the only question but none of the set 3 bearing upgrade hubs have suffered a failure that has been reported to me at least. If you need anything related to boring the hub just let me know!