C6 rear hub vs front hub.

[keithq69]

I was wondering what the difference is between the front and rear hubs for the C6 Corvette spindle.
I know the rear has the internal spline for the drive but since the front and rear knuckle is the same (they just go on the opposite side of the car) can you use a rear hub on the front?
The rear hub is less than half the price of the front.

Thanks.

[andrewb70]

I was wondering what the difference is between the front and rear hubs for the C6 Corvette spindle.
I know the rear has the internal spline for the drive but since the front and rear knuckle is the same (they just go on the opposite side of the car) can you use a rear hub on the front?
The rear hub is less than half the price of the front.

Thanks.

I do believe that there is a difference. There are different part numbers for a reason.

Andrew

[keithq69]

Well the rear has an internal spline for the axle to fit so that portion is different.
I'm just wondering if there is a difference in the bearing of the hub.
I can buy two rear hubs for the price of one front.

[Ron.in.SoCal]

Is there a difference in the SKF ZR1 hubs? I noticed they are all splined and only one P/N on LG's site...

[Motorcitydak]

From what I have read, no one will give you a straight answer on that. Some people will say that the CV needs to be in there to hold the bearings together and others will say you are fine. I think it will depend on who makes it and what they are built for. I wish I could tell you more but I never got a definite answer.

I am almost positive that the ZR1 hubs are 33 spline vs the c6 30 spliners

[Ppd1979]

Saw on a previous thread, zr1 are the same part number front to rear.
Older hubs with splines need to be kept in rear or the come apart. Will try to find the thread
With it in it.

[jtomas801]

Saw on a previous thread, zr1 are the same part number front to rear.
Older hubs with splines need to be kept in rear or the come apart. Will try to find the thread
With it in it.

I hope not, that's what was supplied to me with my front sub frame.

Please, post a link to the thread if you find it.



Well you got me curious, here is the only thread I have found showing a Failure of the rear stock hub:
http://forums.corvetteforum.com/c6-tech-performance/2758200-differences-between-front-and-rear-hubs.html

Seems weird to me, that it would break where it did.

Thanks,
Jon

[coolwelder62]

Have not had any problem's running rear hubs on the frt.My Gm part's guy has been suppling them race team's.It's a good idea to check them over after track outing's.

[jtomas801]

Hey Scott, I think you are right. I did a little more searching and it looks like the corvette racers were having problems with stock front hubs (and a couple of rear hubs) breaking. Their theory is the combination of large sticky tires (Hoosiers A6 or R6) and massive amounts of heat transfer from the front brakes. The hubs would get weak from the heat and then the high, repeated, lateral-g's would do them in.

Thanks,
Jon

[Motorcitydak]

I agree with what you guys are saying but I have heard stories of GM rear hubs being put on the front of 2wd vehicles and the tire falls off after 20 yards. I would not trust anyones advise unless it came directly from the manufacturer. I know the answer that you want to hear but it would be dangerous for anyone to just say YES you can run them. At minimum, try to call SKF and ask them directly or use the exact same hubs that the vette guys are beating to death

[BADDRIDE II]

ZR1 front/rear are one in the same. As for the standard C5/6 units I personally "IMO" would run rear splined units in rear only, and fronts units in front.

This is some additional info about these hubs I thought some may find interesting:

Simply grab a new one (take your pick, stock C5/6 or even ZR1) and rotate it by hand and you will find they ALL are in great bind and will barely rotate.

Why is this? It is due to the way they are assembled and lack of hand fitment that is required to get correct tolerances/fitment (no bind).

While the two hub halves are being pressed together, the angular race surfaces are loading down on the steel ball bearings, which is why they do not rotate freely as a ball bearing design is capable of. Not to mention the heat that is created by this type fitment…..lots of friction!

Between the angular race surfaces that capture the steel ball bearings and the press operation that binds the two halves…..ideal tolerances are impossible for this type assembly process to hold. The tolerance stacking of all the “meshing surfaces” has proven to be too much for any type of precision by this type assembly process.

Anything that rotates at high speeds and is under this kind of metal on metal bind is bound to create extra heat that is NOT good.

Jason (GMR) and I have been deep inside these hub units, and funny enough find that it is not the hub body material, bearing count, bearing spread, etc. that leads these hub units to fail prematurely as much as it is there poor fitment/tolerances. As in any product….if you have poor fitment/tolerances, you will see less than stellar performance/longevity.

I/we (GMR) are currently working on putting the “GMR” touch on these stock type hub units. If you are in the market for the SKF/ZR1 hub and requiring more than a season of serious track abuse from this substantial type investment…. don’t buy just yet as I think you will like what is coming. Stay tuned for some seriously cool stuff!

Jay (NEW GMR teammate) “official” GMR intro coming soon:)

[jtomas801]

ZR1 front/rear are one in the same. As for the standard C5/6 units I personally "IMO" would run rear splined units in rear only, and fronts units in front.

This is some additional info about these hubs I thought some may find interesting:

Simply grab a new one (take your pick, stock C5/6 or even ZR1) and rotate it by hand and you will find they ALL are in great bind and will barely rotate.

Why is this? It is due to the way they are assembled and lack of hand fitment that is required to get correct tolerances/fitment (no bind).

While the two hub halves are being pressed together, the angular race surfaces are loading down on the steel ball bearings, which is why they do not rotate freely as a ball bearing design is capable of. Not to mention the heat that is created by this type fitment…..lots of friction!

Between the angular race surfaces that capture the steel ball bearings and the press operation that binds the two halves…..ideal tolerances are impossible for this type assembly process to hold. The tolerance stacking of all the “meshing surfaces” has proven to be too much for any type of precision by this type assembly process.

Anything that rotates at high speeds and is under this kind of metal on metal bind is bound to create extra heat that is NOT good.

Jason (GMR) and I have been deep inside these hub units, and funny enough find that it is not the hub body material, bearing count, bearing spread, etc. that leads these hub units to fail prematurely as much as it is there poor fitment/tolerances. As in any product….if you have poor fitment/tolerances, you will see less than stellar performance/longevity.

I/we (GMR) are currently working on putting the “GMR” touch on these stock type hub units. If you are in the market for the SKF/ZR1 hub and requiring more than a season of serious track abuse from this substantial type investment…. don’t buy just yet as I think you will like what is coming. Stay tuned for some seriously cool stuff!

Jay (NEW GMR teammate) “official” GMR intro coming soon:)


Okay, so you must be the "Jay" that Jason wanted to give my contact info to regarding the c5 service-able hubs, now I have to wait to see if these GMR stock hubs will fit my needs better.

Thanks,
Jon

[Motorcitydak]

Hello Jay, I also have been emailing with you or Jason about those service-able hubs. Looking forward to hearing from you about what you guys will be coming out with. Its nice to get input from someone who has been intimately involved with these hubs

[keithq69]

Thanks for all the replies.

I have no problem spending the extra money on the front hub if it is indeed different than the back other than the lack of spline.
I just didn't want to spend money I didn't have to if the rears work well.

I'm still not exactly clear about the stock hubs. I know there are failures because of the assembly tolerances but does the apply to the front and rear equally? If I am going to run a stock hub am I at as much risk with a front hub as I am with a rear? Is there something about the rear in particular?

thanks

Keith

[killer69]

Is there a difference in the SKF ZR1 hubs? I noticed they are all splined and only one P/N on LG's site...

yes the ZR1 hub has more BALLS, and more splines! it is a 33 spline as opposed to 30 on the c6, and yea only 1 part # front and rear.

[silver69camaro]

Simply grab a new one (take your pick, stock C5/6 or even ZR1) and rotate it by hand and you will find they ALL are in great bind and will barely rotate.

Why is this? It is due to the way they are assembled and lack of hand fitment that is required to get correct tolerances/fitment (no bind).



Jay, I agree with most of your post, but you must keep in mind that much of that friction comes from the grease inside the bearings. A hot hub spins pretty freely as the lube thins out, at least in my experience.

[BADDRIDE II]

Okay, so you must be the "Jay" that Jason wanted to give my contact info to regarding the c5 service-able hubs, now I have to wait to see if these GMR stock hubs will fit my needs better.

Thanks,
Jon

Sorry for throwing a curve ball out there Jon, but I will let you know this offering is in the very early stages (although we are moving forward), and from initial investigating will most likely not be any less $ than our current "servicable" C5 hubs if that helps. It will simply be an option for those die hards that want to stick with OEM type parts that want to squeek every benefits they can from these OEM units. Thanks for your interest!


Hello Jay, I also have been emailing with you or Jason about those service-able hubs. Looking forward to hearing from you about what you guys will be coming out with. Its nice to get input from someone who has been intimately involved with these hubs

Thanks, we do see a niche market for these GMR/ZR1 "modified hubs" but as I just mentioned above it will come at a cost. We feel there is definately room for improvement from what we have seen internally, although the current stock ZR1 hubs seem to do pretty well. We just want to make them better if possible and keep feeding you guys cool options. Thanks for your interest!


Jay, I agree with most of your post, but you must keep in mind that much of that friction comes from the grease inside the bearings. A hot hub spins pretty freely as the lube thins out, at least in my experience.

Good point Matt, but it is my opinion that the "cold grease" only slightly slows the rotation......similar to how the seals also create slight drag, but the "friction" is most definately coming from ball bearing to race contact surface. It seems to me that it is this friction that is putting heat into the hub body allowing the hub body/race to expand which does allow it to then rotate more freely. But it is also my thinking that if the hub body/race is expanding enough to free it up....that tollerance between bearing and race has loosened up and will translate to wheel flange deflection when you least need it.....high speeds or cornering.

Now I know that these ZR1 hubs are being used everyday street/track and work great fo the most part, but I also know that at a competative level of race they typically do not go more than a season, and in some cases only a few races. So it is that competative type customer that wants that "edge" and only wants OEM style hubs that will benefit. For the other majority the stock ZR1/SKF hub would be fine IMO and would last long enough to see the value from their investment. Our hopeful new product lines are just simply options and hope most will approve of our constant desire to come out with over the top offerings :rolleyes:

[Ron.in.SoCal]

Hey Jay/JSM/BadrideII - nice work. In partnership w Jason I think you two will make some great products. I'll be interested in your field test results. Priced right and if it lives longer/performs you might have a hit on your hands. If you need a test mule let me know :D

Keep going man...

EDIT: Although a good theory, I'm not sure about heat induced deflection on these units though. Not trying to challenge you at all, just doesn't compute in my mind. And the Vette guys (Pfadt/LG) have never mentioned it before like they have on the front bushings. Maybe a call into your SKF engineer friend can clarify how much stress the part can take and if heat has anything to do with it?

[The GMR]

Hey Jay/JSM/BadrideII - nice work. In partnership w Jason I think you two will make some great products. I'll be interested in your field test results. Priced right and if it lives longer/performs you might have a hit on your hands. If you need a test mule let me know :D

Keep going man...

EDIT: Although a good theory, I'm not sure about heat induced deflection on these units though. Not trying to challenge you at all, just doesn't compute in my mind. And the Vette guys (Pfadt/LG) have never mentioned it before like they have on the front bushings. Maybe a call into your SKF engineer friend can clarify how much stress the part can take and if heat has anything to do with it?

Haha, I tried to reply yo you earlier but your mail box was full! :)


Part of the Site being down is that we are making changes to the back end and system, new emails and hosting ect.. Jay will be taking over the majority if inquiries, the fact is simple. I'm completely overwhelmed and need to focus on what i'm best at. After long debates and discussions Jay and myself have figured out a perfect fit that will not only allow GMR to grow but also provide even better service to our rapidly increasing list of clients. So, as of a little while ago everything was decided on and Jay is now officially the other half of GMR, but don't worry he has agreed to be on his best behavior :spank2: from here on out! haha. People ask me about him sometimes and the reality is that some may think he is a little abrasive... I call it passion. This industry is starving for more individuals with his mindset! He truly is more then just an enthusiast, the words "good" or "good enough" are not apart of his vocabulary and thus I see him as a great fit for GMR. He has a serious passion for an unrelenting pursuit of continuous improvement. The bottom line is, I'm shooting for the stars and his mindset is on the same path! We have only just begun...

jason

[The GMR]

On a side note, Funny this thread comes up... I just shot a little video on our front hubs a few days back. Please don't be too impressed with my on camera skills! :)


http://www.youtube.com/watch?v=LfIOdK2vhlY

[BADDRIDE II]

Hey Jay/JSM/BadrideII - nice work. In partnership w Jason I think you two will make some great products. I'll be interested in your field test results. Priced right and if it lives longer/performs you might have a hit on your hands. If you need a test mule let me know :D

Keep going man...

EDIT: Although a good theory, I'm not sure about heat induced deflection on these units though. Not trying to challenge you at all, just doesn't compute in my mind. And the Vette guys (Pfadt/LG) have never mentioned it before like they have on the front bushings. Maybe a call into your SKF engineer friend can clarify how much stress the part can take and if heat has anything to do with it?


Hello Ron/Flash911/Ron.in.SoCal :lmao:

Sorry, perhaps I did not explain very clear. The deflection I speak of at the WMS is not coming from wheel flange flex itself from elevated hub temps as I think you understood it. The deflection at WMS I am referring to is due to the poor tolerances in the bearing/race/hub body meshing surfaces from which friction is created. As soon as you have ANY slop in these hub units…you will see deflection/erratic camber changes that are quite significant at the wheel.

I am currently working with one of the race industry’s top bearing specialist that IS currently outfitting many of the top NHRA,IHRA,SCCA, Bonneville, and NASCAR cars (did I mention he also owns/auto-x's a C6 as well?). This technology we are going to offer for the ZR1 hub is not new by any means and is currently being utilized by competitive Corvettes & Vipers looking for that edge (you just don’t normally hear about it because these are race secrets utilized by people that are willing to break away from the masses and think outside the box for that winning edge). But many, as I do to put much emphasis on proven technology so figured I would let you know I was not single handedly tackling this project. So stay tuned Ron and we will get you some solid proof that you need.

Again, these carefully “blue printed” hubs with upgraded ceramic bearings that we are working on are not for everybody…...for most, the stock offered ZR1 hubs will suffice. We just wanted to outfit these for the most serious of enthusiast requiring (or think they require) the best in OEM packaging. So if I know you Ron….you will be wanting a set! :cheers:

[Ron.in.SoCal]

Haha, I tried to reply yo you earlier but your mail box was full! :)


Part of the Site being down is that we are making changes to the back end and system, new emails and hosting ect.. Jay will be taking over the majority if inquiries, the fact is simple. I'm completely overwhelmed and need to focus on what i'm best at. After long debates and discussions Jay and myself have figured out a perfect fit that will not only allow GMR to grow but also provide even better service to our rapidly increasing list of clients. So, as of a little while ago everything was decided on and Jay is now officially the other half of GMR, but don't worry he has agreed to be on his best behavior :spank2: from here on out! haha. People ask me about him sometimes and the reality is that some may think he is a little abrasive... I call it passion. This industry is starving for more individuals with his mindset! He truly is more then just an enthusiast, the words "good" or "good enough" are not apart of his vocabulary and thus I see him as a great fit for GMR. He has a serious passion for an unrelenting pursuit of continuous improvement. The bottom line is, I'm shooting for the stars and his mindset is on the same path! We have only just begun...

jason

Sorry Jase...mbox fills up sometimes. I think you guys are a great fit and a 'kinder, gentler, verndor voice of reason' Jay will reach a much wider audience on this site than he has in the past. Personally I like the guy and have no prob w him stirring the pot, but sooner or later the thread runs out of steam. As I said, you two will make a great team. I even accused him of having an equity stake before, so what better person to partner with? Plus, edgy fits in the GMR employee handbook :lol:

I was five feet from you guys at Del Mar. Sorry, was engrossed in tech talk at the time but will say hi next time...:cheers:


On a side note, Funny this thread comes up... I just shot a little video on our front hubs a few days back. Please don't be too impressed with my on camera skills! :)

http://www.youtube.com/watch?v=LfIOdK2vhlY

Vid was killer. Question for you - it looks like the backside of the hub sits deeper on the spindle mount face. Will this change the WMS dimensions? Also, dig the SS studs, but I think ARP would be the ticket - brand recognition and a failure will not prevent someone from sourcing it anywhere. Also, dig the tech on the ceramic bearings, but the other Timken's have been around for a long time. Why not Set 20s?

[Ron.in.SoCal]

Hello Ron/Flash911/Ron.in.SoCal :lmao:

Sorry, perhaps I did not explain very clear. The deflection I speak of at the WMS is not coming from wheel flange flex itself from elevated hub temps as I think you understood it. The deflection at WMS I am referring to is due to the poor tolerances in the bearing/race/hub body meshing surfaces from which friction is created. As soon as you have ANY slop in these hub units…you will see deflection/erratic camber changes that are quite significant at the wheel.

I am currently working with one of the race industry’s top bearing specialist that IS currently outfitting many of the top NHRA,IHRA,SCCA, Bonneville, and NASCAR cars (did I mention he also owns/auto-x's a C6 as well?). This technology we are going to offer for the ZR1 hub is not new by any means and is currently being utilized by competitive Corvettes & Vipers looking for that edge (you just don’t normally hear about it because these are race secrets utilized by people that are willing to break away from the masses and think outside the box for that winning edge). But many, as I do to put much emphasis on proven technology so figured I would let you know I was not single handedly tackling this project. So stay tuned Ron and we will get you some solid proof that you need.

Again, these carefully “blue printed” hubs with upgraded ceramic bearings that we are working on are not for everybody…...for most, the stock offered ZR1 hubs will suffice. We just wanted to outfit these for the most serious of enthusiast requiring (or think they require) the best in OEM packaging. So if I know you Ron….you will be wanting a set! :cheers:

Jay you missed 'Ron in Socal' on the other site :) (no dots in between, gotta fix that!). So if I'm reading you right, deflection comes about the time that the part would require replacement anyway if the bearing is in fail mode.

I'm all for getting smart people on the team and you are doing just that. Definatley admire that! And d*mn, I just bought a couple more SKFs and received them this week! Mule offer still stands...:cheers: Bro!

[BADDRIDE II]

Vid was killer. Question for you - it looks like the backside of the hub sits deeper on the spindle mount face. Will this change the WMS dimensions? Also, dig the SS studs, but I think ARP would be the ticket - brand recognition and a failure will not prevent someone from sourcing it anywhere. Also, dig the tech on the ceramic bearings, but the other Timken's have been around for a long time. Why not Set 20s?

Ron, although there are many variables and lots of tunability with our setup, the simplest answer is: our WMS is approx. +.125" (1/8") in comparison to a stock C5/6 setup per side.

Keep in mind though that a stock type hub unit utilizes a "hat" style rotor adaptor that slides over wheel studs and onto WMS which will close this gap so to speek that you are talking about. Now of course every brake manufacturer has their own thickness hat/rotor adaptor. I believe BAER's C5/6 hat is approx. .300" as were Wilwoods C5/6 hat is approx. .360". So you will see that when compared to a Wilwood kit (if that is what a guy is currently running) We now would be within approx. +1/16" of an inch. or so.

So all in all we are within 1/8" or less of what most are currently running as to keep your current wheel/tire package as close as to what it was in relation to frame/wheel well/etc. Now as if that isnt complicated enough, we have many other ways of tuning this setup in or out to customize it right were one may need it. I truly believe there will be very few setups that we cannot outfit. I encourage everyone to give us a call if you need help figuring out if this setup will fit your application.

*While reading above keep in mind that GMR's rotor adapter presses on from the back side for a precisely located hub centric fit and will not ad to the WMS.

Glad to see you like the 17-4 SS wheel studs...we use only US made 17-4 to guarantee only the best quality! This is a MAJOR improvement over the stock offerings that seem to work fine for most all. So you can only imagine what it would take to break one of these 1/2"-20 bad boys....not gonna happen! Nothing wrong with ARP, but we have our own specifications here at GMR and feel our studs are second to none.

As for our ceramic offerings, this is an option for the extreme user that just plain wants the best. Our standard kit still will come with the tapered rollers as does our rear floater kit and are plenty strong. I will save all the advantages of the ceramics though for another thread we will start soon as there is a lot to tell. Give me a call and we can go into further detail or answer any additional questions you may have.

Thanks, Jay

[ace_xp2]

Not well substantiated, but I've read one poster noting a bearing life increase with the addition of front ducting (and thus a presumed decrease in bearing temp):
http://forums.corvetteforum.com/autocrossing-and-roadracing/2605670-c5-wheel-bearing-noise-2.html
Post 25.

Post 26 also mentions that running in the bearings with some street miles seems to help a little.

[killer69]

I watched the video nice part. One question what is the increased track width measurement? looking at the two side by side I am guessing at .500 + per side?
just something people need to know as it may also require new wheels??

[killer69]

I watched the video nice part. One question what is the increased track width measurement? looking at the two side by side I am guessing at .500 + per side?
just something people need to know as it may also require new wheels??

[Jay@GMR]

I watched the video nice part. One question what is the increased track width measurement? looking at the two side by side I am guessing at .500 + per side?
just something people need to know as it may also require new wheels??

Blake,

Check out post #24 above. Ron was asking the same thing. If this does not make sense just let me know and I can give you a call. But all in all .....will work on most all existing wheel/tire packages.

Jay