safemode

iTrader: (1)

I've asked and looked around on and off over the course of over a year. I've yet to find any definitive answer.

Apparently, some people have confirmed that there existed 10.5" rotors with larger outer bearings that were put in some third gens. I have these rotors in my 92RS. They take SET3 outer bearings, yet use the regular delco iron brakes. It may be that someone put Z28 rotors on my RS, so these may be wrong for my car, but other people have stated that Z28's at some points did come with these rotors.

So, some people say ILE use SET3, everything else SET34, stores say all Z28 use SET3, RS uses SET34. Obviously both are wrong, because a lot of Z28's use SET34, and obviously, some 10.5" rotors use SET3.

So the question is, what RPO actually gives you the performance bearings, or is it more than one RPO over the years, or is it simply the luck of the draw with some years making them standard on Z28's, others not?

I dont think i'd be able to convince autozone to recategorize them, but at least we could refer to them by a more accurate title other than ILE/Non-ILE.

Guest

It would have to be a year related thing. If I found the right part numbers, the main difference in the 3 and 34 is the OD of the cup. Likely the rollers are in a different location too, but the ID's are the same. They are:
Set 3 cup which is actually LM12610: 1.9687" OD
Set 34 cup which is actually LM12710: 1.7810" OD

safemode

iTrader: (1)

why is it that gmpartsdirect never has any part numbers quoted on here as being GM part numbers? what site do you goto to look up these part numbers? google is showing nothing on either one but returns for what rotors certain ball bearings can fit in.

is the LM12610 and LM12710 the 10.5" rotors with set3 and set34 outer bearings? Or are those the gm bearing part numbers?

Guest

Those are the numbers you'll find on the bearing cup itself. Its not GM's number, its likely either from Timken or BCA. All of GM's numbers are 7 or 8 digit numeric and if gmpartsdirect doesnt list it, they dont carry it or its been superceded. Anyway, that should help identify what is really in there, if someone pops the dust cap and looks they'll see either LM12649 (thats the set 3 cone) or LM12748 (set 34 cone). You should see those numbers on your old ones.

Set 3 and Set 34 are Timken's creation for part numbers.
Set 3 is (if my reference is correct)
LM12610 and LM12649
Set 34 is
LM12710 and LM12748

The first number is the cup, thats the outer part that is inside the rotor. The second number is the cone, thats the part with the rollers and cage. Just FYI for anyone reading this, when you replace bearings make sure you replace both pieces, no sense using an old worn out cup or dealing with production tolerances from one brand to another... and believe me there are differences.

Apeiron

The rotors are all the same, the cups pressed in to the rotor are different.

safemode

iTrader: (1)

That tells you the cup... but the crux of the problem is determining either what years or what option actually gave you a 10.5" rotor with SET3 bearings. Every online store and real store i've found simply call it ILE/performance/Z28 bearings and i dont think anyone lists a 10.5" rotor for our cars that take a SET3 bearing.

So unless you can use a part number to track back to a certain year or option either via gmpartsdirect or some other way, i'm not sure picking out the bearing cup numbers is gonna lead us to the answer.


EDIT: Oh you dont just mean the cap (cup as i was thinking), you're talking about everything in the center of the rotor. that changes things. So how do we track that since the rotor and cup were probably never listed apart?

Apeiron

Why does it matter? If you're replacing the rotor, you're replacing the bearings.

safemode

iTrader: (1)

You want people to throw out what amounts to about a 50-60 dollar piece that has no moving parts, gets no direct contact with anything really (thus i dont see how it can really wear out unless you call pressing races into it as wear), every time they change out bearings, which do see regular heavy stress wear. I dont see the logic in that at all.

That's like saying everytime you change bushings you should also replace what you're putting the bushing into. At least that's what it sounds like to me.

Edit again:

The reason being, everyone usually says SET3 is ILE only, and stores usually say SET3 is Z28. Both are wrong, because both non-ILE Z28's have had them, and obviously, some have not had them. So apparently something else determines what cars got SET3 bearings. I just want to find out what.
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Who's replacing the rotor? This thread isn't about figuring out what part you need to get or how to find what rotor you need to handle SET3 bearings in a 10.5" rotor.

The thread is supposed to be about finding out what factory cars got 10.5" rotors with SET3 bearings and if it was an option (rpo) that caused it, or if it was just by year and what year.

Apeiron

No, you throw out what amounts to about a $3 part that's pressed into the rotor.

Sure we can look up what cars come with a Set 3 bearing, but why does it matter what cars came with a Set 3? When you replace a bearing, you always leave the store with something that works, whether it's a Set 3 or a Set 34.

safemode

iTrader: (1)

So this 3 dollar part is what makes the Z28 rotor over 50 bucks more expensive than the RS?

I still dont see why you would spend the time to press it out and press a new one in since the bearings spin on the race, not the inner walls of the cup. What's getting worn?

ADDON:

It matters because both the stores and the general consensus on sites like this one state that the bearings are found in this or that car, when they're not. So you goto the store, and unless you've already done the job before, your bearing is not going to be what their computer tells you, and it wont be what you've read on here that it should be necessarily.

So i was trying to find out what really determines it. It's not ILE/NON-ILE and it's not Z28/RS. It's gotta be either a specific set of years along with some combination of RPO codes.

Apeiron

A Z28 and an RS have the same rotor.

It's a tapered bearing. The rollers roll on the inside of the cup.

But you leave the store with a bearing and a cup, so regardless of what you have on your car, and what's in the computer, you have everything you need.

safemode

iTrader: (1)

I dont know what you're talking about. The bearings roll on the race that you press into the hub. The race gets pressed in and removed with the bearings.

RacerX13

Welcome to the modern auto parts store! The applications they have on their computers are often inaccurate, and confusing. Most likely it is a late production thing. Those rotors were used on other cars too ( G body, S10 ) and they could have changed it to make them all use common parts. The lesson is to always check your parts against the ones you took off and don't assume that the parts store is right.

safemode

iTrader: (1)

I still want to know what you're referring to when you say "cup" Are you referring to the bearing race that comes with bearings when you buy them? Are you referring to the hub? Are you referring to the grease cap at the end of the hub?

If "cup" == hub then how is that getting worn? And how is the bearing contacting it when the bearing sits between the race and the spindle. Unless you're pressing and pulling bearing races out like nobody's business, i dont see what's getting worn here.

if "cup" == grease cap, why are we talking about grease caps?

if "cup" == bearing race, who doesn't get one along with the bearing? Though i doubt this is possible, since the races wont fit in the both hubs, only the one that fits them.

Edit:

in reference to the bearing race, I dont know how they do it in other countries. In the north east US, the races come with the bearings in the same package, the outer diameter of the race is not something you can specify. Thus, if your hub is supposed to get SET3 sized bearings and race, then it will be too big for the race that comes with the SET34 bearing, and vice versa. So you can leave the store with the wrong bearing, because all they use to identify what you need is the car model, or ILE option... both of which have been proven wrong to determine the outer bearing size for some unknown subset of cars.

Guest

When you buy a bearing, usually you get both of these pieces. You should replace both when you're doing the work. They do in fact sell them separately, but most places will not sell them that way.

Guest

They cant be, if in fact there are 10.5" rotors with "set 3" and "set 34" bearings. The OD is different. 1.9687" OD vs 1.7810" OD

I just checked a few websites, and as you said the rotors are the same PN no matter what year I put in so... that'd make the original poster's rotors off of something else, most likely.

safemode

iTrader: (1)

Ok, so the "cup" a few people were referring to is the bearing race then? That makes some sense.

Now we just have to figure out if people are differentiating the hub from the rotor, and leading them to say "all the rotors are the same".

Basically, my statement is this. There were 2 different hubs given to 10.5" rotors. One hub accepts SET34 sized bearings. One hub accepts SET3 sized bearings.

So we have the following thirdgen setup.

10.5" rotor with SET34 bearings. (all models except ILE and whatever we find out determines the next group)
10.5" rotor with SET3 bearings (what i'm trying to find out)
12" rotor with SET3 bearings (ILE only)

Apeiron

Our fronts are integral hub and rotor, cast as a single piece.

If I had my Parts & Illustration Manual here, I'd look it all up in a minute. Unfortunately it's in a container somewhere in the Pacific between Vancouver and Puntarenas.

safemode

iTrader: (1)

ok, so then the statement that "rotors are all the same only the cup is different" makes no sense to me at all unless somewhere you can buy a bearing race that's very thick to make a SET34 bearing fit in an SET3 sized hub. Why you would do that is beyond me, but that's the only way i could see that statement being made without being totally ignorant to the fact that you could get a 10.5" rotor with different outer bearing sizes, totally separate to the ILE 12" rotor.

So then, since the hub and rotor are one piece on our cars (which i originally was under that assumption but willing to believe i was wrong), then the statement many people seem to want to make :
"The rotors are all the same, the cups pressed in to the rotor are different"

Is false.

The statement that all the rotors except ILE got SET34 outter bearings is false.

There are two different 10.5" rotors for our cars (one has a hub which is too small to accept a SET3 outter bearing, one that does accept one), and a 12" found on ILE optioned cars. The goal is still to find out what determined the use of the higher performance 10.5" rotor.

Apeiron

Not according to GM:


82-87 F .................... 15606249 ROTOR, W/HUB & BOLTS FRT WHL (PG6-3,25)
88-92 F (EXC (1LE) ......... 15606249 ROTOR, FRT BRK (W/HUB & BOLTS) (PG6-3,25)
88-92 F (1LE) .............. 18016035 ROTOR, FRT BRK (INCL HUB)(06.307)(PG6-3,25)


Give me a minute and I'll find the bearings.

Apeiron

Alright, now to make things as clear as mud:

82-87 F .................... 14066918 BEARING, FRT WHL OTR (PG6-3,24)
88-92 F (1LE)............... 457049 BEARING, FRT WHL OTR (PG6-3,24)
88-92 F (EXC 1LE)........... 14066918 BEARING, FRT WHL OTR (PG6-3,24)

So according to GM, there was only one outer front wheel bearing ever used.

Ordinarily I'd be willing to assume that it was possible that GM had used different bearings in production, but started using a single bearing as a service item by the time my P&IM was printed in 1991. However, in about 2001 I bought new wheel bearings from the dealer parts counter for my 84, and I distinctly remember the computer specifically listing different parts for RPO Z28 then. It couldn't have been a 1LE thing, since the 1LE wasn't available in 84. I could be remembering wrong, of course.

safemode

iTrader: (1)

This isn't a matter of GM simply using a different bearing. You can't just swap in a SET3 bearing into a rotor that accepts a SET34 bearing.

What i have is a 10.5" rotor that accepts a SET3 bearing. Such a combination doesn't exist according to what you just posted. Others have said that they've seen such rotors on some Z28's. That's what led me to question whether it's true that the rotors for all non-ILE cars were the same.

So, either everyone who has said that they've seen such rotors on other Z28's and me are all using a rotor from a different car (which car would be nice to know), or the documents there are missing information.

GM says you have 2 possible combinations, either you're ILE and you have a 12" rotor with SET3 outter bearings or you have a 10.5" rotor with SET34 outter bearings. I'm just trying to find out where this third combination (10.5" with SET3) comes from.

Guest

The GM part numbers indicate the same thing to me the aftermarket does. If you have a 82-92 F-body the 1LE rotors you have a 'set3' bearing, if you dont have 1LE rotors, you have 'set34'. If you have a combination of both, your rotor didn't come off of a thirdgen Camaro, originally. That'd be my guess. I was thinking newer but maybe I went the wrong way... they might actually be off of an older GM of some sort that just so happens to fit.

safemode

iTrader: (1)

Certainly possible, though, other people have said that they've seen other thirdgens with this setup before. Unfortunately, it's nearly impossible to search for parts in any way other than by car model/make, and most places dont tell you any specifications on the part, so it's extremely hard to pin down what car this rotor was initially intended for.

1979 camaro had an 11" with set3 bearings. It'll be fun trying to track down the model car that had this rotor setup.

jwscab

So the rotor you have in your possession has a larger bearing in it?

if so, maybe it's an early malibu/el camino/regal/etc that used the same 10.5" brakes. maybe something to do with a diesel option for a heavier spindle?

or possibly an S10? also 10.5"

by any chance do you know if the lugs are definitely metric?

otherwise, I'd say they are maybe aftermarket with an odd bearing size?

just checked rockauto....lists 1981 grand prix with diesel as set 3 with pn 5038 rotor. 1988 camaro uses set34 with a differnt rotor pn. same 10.5" rotors that are interchangeable.....

safemode

iTrader: (1)

Lugs were the same as stock. Though it's not hard to put lugs in, so if we're going with that this rotor came with a different car, there's no telling that the lug bolts are original to the rotor. (they've since been replaced by me, as they were rusted to crap, but they had the original lug nuts).

I'd say it's a pretty cheap upgrade if you dont want to spend all the money on special aftermarket rotors/hubs or move to a 12" brake setup. Much stronger bearing setup anyway.

iansane

iTrader: (1)

The bearings aren't the issue with our front suspension setups; it's the ridiculously small 10.5" rotors for the weight of our cars.

BADCAM70

This might be a longshot but i recollect reading on Camarosource that cars equipped with option N96(16inch alu wheels only aviable to Irocs)also recieved a bigger bearing in the hub.

regards Mats

safemode

iTrader: (1)

The hub itself would also have to be different. But yea, i'm pretty sure i have that rpo, just can't remember the image name on my webserver of my rpo sheet. :-/ I know i came with 16" alu wheels.

Argh. I thought i linked my rpo sheet somewhere before but google and search show up nothing. Oh well. Will have to wait until i get home.

Guest

I seriously doubt there's a single group of cars out there with no GM part numbers to back up a different rotor. Camarosource doesnt show anything like that either.

I know a few people who had problems with their front outer bearings over long abusive trips so I can see a benefit to a larger bearing, if you're stuck for some odd reason with going with tiny rotors instead of upgrading everything.

safemode

iTrader: (1)

it's likely an older rotor/hub assembly from an older car. Which older car, who knows. I guess. It's a 10" rotor with stock sized inner bearings but ILE sized outter.

I really have to start making a list of all the non-stock parts this car has, and which cars i have to tell autozone and the like i have in order for them to find the correct replacement part number.

iansane

iTrader: (1)

Sounds like a caprice rotor or something.

Welcome to the club.

I've never had any issues with roadtrips. Last year I drove to Utah from Washington (averaging ~85-90 most of the way) and even through the 100* heat, high speeds and heavy c6 Z06 brake setup I had no issues with bearings. I use Timken bearings and Mobil1 grease.

safemode

iTrader: (1)

you saying with 12" rotors you still have those rinky dink tiny outter bearings?

iansane

iTrader: (1)

No. Not at all.

I'm saying with 14" rotors that weigh ~25lbs a piece I've never had any issue with those "rinky dink tiny" bearings. I daily drive my car. I beat the hell out my car. I put ~15k on my c5 z06 brakes and well over 20k on my c6 z06 brakes and all of it using the same bearings, just new grease eat time I yanked the brakes. Maybe I'm just lucky?

Guest

A road trip isnt going to put much heat into a wheel bearing. Go race it, see how long it lasts and where its breaking point is, and try with the bigger bearing.

iansane

iTrader: (1)

So to clarify, you're under the impression that I think the smaller stock style bearing that came on every production non-1le car is just as strong as the larger one, correct? Obviously bending the laws of physics is a bad idea. I think it's obvious the larger bearing is going to hold up longer. I was merely pointing out that my track driven, street driven, cruised, road tripped trans am has seen quite a bit of bearing load and the one bearing has not been an issue. I can see if there was improper installation, over torquing, improper lubing etc then you might have an issue but if that one bearing was an achilles heel of our cars but wouldn't you then see people posting problems all the time?

EDIT:

Which is it?

safemode

iTrader: (1)

the smaller bearings will be spinning faster than the larger bearings. This then would insinuate that the breaking point is sustained high speed. Basically, how long before the bearing begins to take damage doing > 90mph. The smaller bearing will build more heat, but just how much heat until it becomes damaged and how that equates to either single long duration runs or multiple short duration runs at high speed is anyone's guess.

Guest

Whats your purpose here, to start arguments?

Which is it? Reading comprehension 101:
A long trip driving across interstates at steady speeds of 80MPH is hardly abusive. Canyon carving at those speeds is, and I know people who have lost bearings doing just that. You haven't? Wonderful, you're special. I know people that have. I guess they aren't special.

As far as what you think or know, why dont you say so? I'm not a mindreader, but you said
"The bearings aren't the issue with our front suspension setups"
I know someone who used to post here and was a maintenance mechanic for buses (read:not an idiot who cant properly lube and tighten tapered roller bearings, nor did he neglect maintenance) who lost one of these perfectly ok bearings that are not an issue while running the backroads one day near his house. All he found was a toasted bearing, and nothing else. And I heard that story more than once, not to mention mine dont look too happy. But hey, your car never does it, so it must be user error, right?

iansane

iTrader: (1)

In no way shape or form. You come at me saying our bearings are too small. I've never heard of this issue. Which is why I countered saying I hadn't had or heard of this which seemed odd that there were not postings or rumors or suggestions all over the suspension or brake boards about upgrading to larger bearings.
I'd hardly call that reding comprehension 101. You don't specific that either is a different "trip". Maybe I'm just assuming that all trips are abusing because mine are?
I don't know if you've seen that mountainous roads through the pacific northwest or not so I'll just presume that you haven't. I tried to imply the abuse and mileage my car had received in multiple ways but it seems only one specific type of mileage stuck out in your mind. Again, I'm not saying that it doesn't happen, just that I, as well as others have beat on their cars and not had a problem issue. Sucks that you're friends seem to be having bearing problems.
I'm not a mindreader either, which is why I was trying ask how you were interpretting my comments and to clarify the confusion. Don't take offense to me trying to figure out how I'm wording myself incorrectly. What I meant with that phrase was we have other issues with our suspensions that people try to solve first before a bearing issue comes into play. I would've figured I'd find bearing topics quite regularly on boards like ffrax.com, corner-carvers.com etc but I haven't? I wasn't try to say that your friends are crazy nutjobs that don't know what they're talking about. I'm just trying to establish there are always going to be other causes to a certain problem.

Just being inquisitive here; You said your friend, the bus mechanic, lost a bearing on a canyon road. What happened? It started making noise? It seized?
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Now that the issue is brought up it seems almost obvious that if you're upgrading brakes you might as well upgrade the bearings and just figure in the cost of a 1LE style rotor to machine down into the price of an upgrade. Honestly, it never crossed my mind before because I didn't think we had a problem to contend with. But if you're there you might as well, right?

jwscab

I don't believe a 1LE rotor would work as you stated above because they place the wheel in a different place than the stock rotor turned into a hub. the face of the rotor has a different offset. (track width changes)

now, what you could do, is to order the rotors with the bigger outer bearing, and use that as a donor for a hub.

it seems like you guys didn't pick up on the info I posted earlier, these rotors seem to be a heavy duty rotor for the diesel g-bodies, not special heavy duty f-body or caprice (b-body) parts.