Front Wheel bearings

Post Reply
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Front Wheel bearings

Post by BLS »

I've searched and come up with some guidance, but nothing I consider definitive...

I have ball bearings both inner and outer (FAG) that are like new. I am using Palermo bushings. With no grease and end play set at close to 3 thou, I can spin the drum and it will rotate for a long time. Now when I have it all assembled with redline grease and endplay set at the 3 thou, with a wheel and tire mounted it will spin for 50-60 seconds with a moderate push. Cold garage around 45 - 50F, so the grease is pretty thick. The seals are new with springs removed and a little grease on the running surface. I greased the bearings by filling the cage and adding grease to the race but the wheel cavity is empty save a coating to inhibit corrosion. When I raced many moons ago I would use a mixture of a lithium grease and STP. Always worked well but my memory seems to be a lot longer rotation time. But maybe it was at 90F or maybe my memory is bad.

My dilemma, when reading through the comments here and when reading internet searched literature about bearings, it is still unclear to me what the clearance (axial or thrust) should be for ball bearings. With the 3 thou (+-1), I can grasp the tire on each side and wiggle a bit feeling the play. I put a dial gauge on the wheel rim at the horozontal centerline and observe somewhere between 15 and 20 thou of movement as I wiggle. Seems to be a minimum of 15 and max of 20. Not sure exactly as at some point I may move the whole assembly thus the wide range there. I can see the drum Vs the backing plate movement. Since there is some radial clearance to a ball bearing, even with zero axial clearance there should be some wiggle i'm guessing. All the internet literature seems to be for a cartridge ball bearing, not the type we have although the data should be similar. Preload, no preload? When I used to set these things I used the old standard of tightening up and then backing off until the thrust washer was just loose enough to move. That would imply some axial clearance.

So, if you have ball bearings and bushings, what clearance (or not) do you use? If the answer is zero or preload, how do you determine the amount of preload?

Thanks,
Barry
SR Racing
Posts: 1205
Joined: June 24th, 2006, 1:58 pm

Re: Front Wheel bearings

Post by SR Racing »

Wow Barry, you are really into the details. :lol:

I simply preload them to make sure they are set and then back them off till I can just move the trust washer. They spin fine and I have never lost a wheel bearing (or axle). We check the wheel movement after a session. Frankly with all the slop in a link pin setup it would take a long time to precisely measure everything.
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Re: Front Wheel bearings

Post by BLS »

Thanks Jim.

With the spindle bushings I can't use the standard thrush washer test. The only way I can see is to measure the end play, but not sure what it should be for ball bearings.
Barry
Old Zink FV,
'87 Citation
SR Racing
Posts: 1205
Joined: June 24th, 2006, 1:58 pm

Re: Front Wheel bearings

Post by SR Racing »

I would just tighten to insure the seating and then back off till you feel ANY play. Even 1/8 of a turn on the axle nut will introduce plenty of play.
FV80
Site Admin
Posts: 1195
Joined: June 27th, 2006, 9:07 am

Re: Front Wheel bearings

Post by FV80 »

You can't "back off" anything using the spindle bushings. I don't measure my free play other than 'by hand and eye'. I have thinnest shims (the link pin shims ground down at the perimeter) and remove them till I feel drag with a tight nut - then add a shim and live with it. As Jim indicates, I never had any issues after "quite a few years" of running .. with the spindle bushings. I CAN feel definite rock by hand - it always SEEMS like too much play, but it works! :)

Steve, FV80
The Racer's Wedge and now a Vortech, FV80
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Re: Front Wheel bearings

Post by BLS »

Jim, Steve, thanks!

The "rocking motion" was probably my main concern. I don't really remember it but it doesn't mean it wasn't always present. That's why I measured it. The VW book calls for .001 to .003 end play, which is what I have, but I wanted to be sure it was the right number. It feels good so I'll just call it Good and move to the next thing.

Thanks,
Barry
Barry
Old Zink FV,
'87 Citation
smsazzy
Posts: 703
Joined: June 24th, 2006, 5:56 pm

Re: Front Wheel bearings

Post by smsazzy »

If you get the right combo of shims you can get rid of the rocking motion. Just make sure it does not drag, or you are giving up speed.

Mike includes a set of shims of varying thicknesses. If you can rock it top to bottom, try taking out two thin and insert one of the thicker ones. If that doesn't work, go the other way. It takes a while to get right, but once you get it right it should be good.

Don't be afraid to put more grease on those bearings. The redline stuff has very low drag once hot and is much better than the old stuff you used to use.
Stephen Saslow
FV 09 NWR
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Re: Front Wheel bearings

Post by BLS »

Thanks Stephen.

I seem to have it about as loose as I can get it without a lot of motion. I played around with the shims, some shims the same specified thickness are slightly different due to the tolerance, and I have it at around 1 to 2 thou end play on both sides. Going to more end play does not seem to free it up but going less seems to tighten it up a bit. Mike provides 0.1 and 0.2 mm shims (approx 4 and 8 thousands) and I also purchased some more including 0.5mm. Since they come in packs of 25 I'm shim rich 8)

Good point on the grease. Thanks.

I appreciate everbodys help. Some of it may seem trivial but I'm re-learning most of this stuff.

Regards,
Barry
Barry
Old Zink FV,
'87 Citation
brian
Posts: 1348
Joined: June 26th, 2006, 12:31 pm

Re: Front Wheel bearings

Post by brian »

There's a major distinction between ball bearings and tapered roller bearings in that the tapered rollers require some preload to center the rollers and minimize roller slip against the race. Heavy duty applications like trucks, can require as much as 40lbs. of torque preload. But in our case, I do not suggest preload in either case, but I NEVER run any wiggle or free play. Remember with the small amount of toe in we run, a loose wheel bearing can ruin your alignment with unregulated movement.

Like Stephen says, you really can't run too much grease. Whatever the bearing doesn't need will be extruded into the hub. I do recommend checking the wheel bearings after each session. They may free up after the first session after a repack, but if they go free after a few sessions, they need to be looked at just to make sure nothing has gone south. In either style take a good look at the races If they are changing color something may be happening. If the race goes dull silver, the hard coating is wearing thin and the race is getting old. If the race shows any pitting, the hard coating is gone and it's time for replacement. If the race is browning or worse yet, getting a blue tinge, it's time for discovery and replacement. If a bearing is too tight or lacking in grease, they'll get really hot fast.

One final thought, if you have done everything correctly, like BLS has, and the wheel doesn't feel free enough you may have a slightly bent spindle preventing the two races from running true parallel. It's a hard thing to see and measure, but look carefully at the spindle to see if there are any tiny edges where the races sit. If there is a small lip on the spindle right at the edge of the race, it may be bent.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
hardingfv32-1
Posts: 1014
Joined: December 1st, 2006, 8:01 pm

Re: Front Wheel bearings

Post by hardingfv32-1 »

smsazzy wrote:If you get the right combo of shims you can get rid of the rocking motion. Just make sure it does not drag, or you are giving up speed....
1) Why is it that all bearing manufacturers specify bearing pre-load with such bearing setups? Why is it that NASCAR teams send all their hubs to Timken to have the pre-load set? Why is it that my NOS F1 rear upright can barely be rotated by hand? "Make sure it does not drag", just another ignorant FV myth?

2) "The redline stuff has very low drag once hot", are you sure about that? Have you evaluated it's Kinematic Viscosity values? There seems to be only one grade available which must cover GT1/NASCAR to FF/FV. Could this product provide 'just a little' more oil film strength than is required by of the FV front wheel bearings? Do the front wheel bearings require a better oil film strength than the rear wheel bearings? How do the Kinematic Viscosity values of the trans gear oil compare to the wheel bearing grease? Time for a little homework?

Brian
tiagosantos
Posts: 389
Joined: June 20th, 2010, 12:10 am

Re: Front Wheel bearings

Post by tiagosantos »

Slow day at the office, Brian?
hardingfv32-1
Posts: 1014
Joined: December 1st, 2006, 8:01 pm

Re: Front Wheel bearings

Post by hardingfv32-1 »

Yes, boring day in the shop..... Just proposing some questions to test the quality of babble that was being posted.

Brian
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Re: Front Wheel bearings

Post by BLS »

Hello Brian,

When searching I found some of your comments regarding preload (or not). What do you recommend for the ball bearings? Preload, no preload? And if it is preload, do you set it by torque?

From my reading, it seems that preload is often called for on roller bearings, but it is unclear (to me) if preload is called for on ball bearings. The VW manual, written for ball bearings I believe, calls for 1 to 3 thousands end play.

With respect to the redline, I have no idea other than it has been recommended. If you read my opening question you will note we used to mix grease and STP to get a mixture that would stay in place for at least a weekend. Not sure how many people did that but I got it from someone else. It worked, at least I never had a bearing go bad and it *seemed" pretty free. Oil, like the rear, would work just fine I'm sure, if we could keep it in place...

Of course, I have no way of making rolling resistance measurements under load. The only means I have to test is apply a spin and time it. Not very scientific.

Hope your well. It's been a while.

Regards,
Barry
Barry
Old Zink FV,
'87 Citation
brian
Posts: 1348
Joined: June 26th, 2006, 12:31 pm

Re: Front Wheel bearings

Post by brian »

Because ball bearings inherently center them selves, they don't require a preload. No free play and no load it's kinda a feel thing. Remember always keep the drum spinning and go back and forth with the axle nut. You can feel it in the wrench.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
hardingfv32-1
Posts: 1014
Joined: December 1st, 2006, 8:01 pm

Re: Front Wheel bearings

Post by hardingfv32-1 »

BLS wrote: If you read my opening question you will note we used to mix grease and STP to get a mixture that would stay in place for at least a weekend. Not sure how many people did that but I got it from someone else. It worked, at least I never had a bearing go bad and it *seemed" pretty free. Oil, like the rear, would work just fine I'm sure, if we could keep it in place...
Just so I can understand your thinking.... What led you to think that anything other then OEM front disc wheel bearing grease was required? What do you expect functioning grease to look like on the bearings when you disassemble them?

The grease group number tells you the temp range that a grease is going to stay a solid. The thickness of a grease (Group #) has very little effect on the bearing drag numbers. Grease turns from a solid to a liquid at the bearing contact point and then back to a grease after leaving the contact point. It is the viscosity in the liquid state that determines drag. That is why you investigate the Kinematic Viscosity values. I pointed out the use of the Kinematic Viscosity values of the trans oil as way for you to see how low these values can get without bearing failure in the rear. Could those values then be applied to the front bearings?

Bearing pre-load... Again simply pointing out that 'no pre-load' is not considered optimum for bearing performance in the engineering or motor sports community. I spent a lot of time and many sets of front ball bearing to find the correct pre-load and grease combination. I have no need to share that knowledge. Obviously, no one in FV lost a front wheel bearing using a no pre-load setup, maybe that is good enough for most of the FV competitors.

Brian
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Re: Front Wheel bearings

Post by BLS »

Brian,

Regarding the grease: It was felt the standard grease of the day of the day was too thick (1970's), increasing the rolling resistance over a thinner grease mixture. You could certainly tell a difference with the free rolling test, but I have no idea if it was effective under load. I didn't "invent" the idea of reducing the viscosity of the grease, it was a standard practice of many FV's at the front. Right or wrong I cannot say. That experience is where I start from. I can say that I found it to make a much smaller difference when tested hot Vs cold. Hot as in coming in from a session. So, one might infer the kinematic viscosity at running temperature was not that great from the standard grease product to the mixture.

What should it look like? My experience is the color doesn't change very much if not overheated. On the bearing itself I don't know as the appearance changes when dis-assembled.

I am unable to find the kinematic viscosity value for the redline products, it doesn't seem to be published, only the viscosity index and CCS. I would agree that it could be a much lower value on the front with the loading and speed we see in FV. I am not sure how to get lower without a mixture, or if it would have any real world effect anyway.

I appreciate your comment about the bearing preload. It's something I will have to consider, later. At this point I'll be looking for seconds of laptime, tenths will come later I hope.

Thanks for the enlightenment,
Barry

PS, my thinking is usually pretty muddled these days...
Barry
Old Zink FV,
'87 Citation
brian
Posts: 1348
Joined: June 26th, 2006, 12:31 pm

Re: Front Wheel bearings

Post by brian »

Thanks Barry. I'm not a chemist or grease specialist, contrary to what my clothes look like, but I don't think the viscosity is that big an issue and we can be mislead by a static test (spinning a wheel) vs. what may be happening in a loaded, on track situation. I would think a critical behavior is the ability for the grease to stay attached and provide film strength under load and heat. There used to be a grease we used in our shop called Mystic M-6. I don't know if it's still made, but the stuff was great for film strength and slipperiness. Matter of fact, you couldn't wash the dang stuff off your hands! Like oil, it's probably more important to change grease more often than the brand or type you use.

I find that brake dust migrates into the grease and darkens it quite quickly and have gone back to leaving the spring in the seal. I like using a red grease to be able to watch for color change. Remember that dust is quite fibrous and will contaminate the grease. Since the "spring removal secret" is so nebulous in performance, I don't do it anymore. A complete washing in solvent and a hot water rinse is the only way to completely clean a bearing. Solvent residues will contaminate grease and reduce it's efficiency.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
hardingfv32-1
Posts: 1014
Joined: December 1st, 2006, 8:01 pm

Re: Front Wheel bearings

Post by hardingfv32-1 »

BLS wrote:I am unable to find the kinematic viscosity value for the redline products, it doesn't seem to be published, only the viscosity index and CCS. I would agree that it could be a much lower value on the front with the loading and speed we see in FV. I am not sure how to get lower without a mixture, or if it would have any real world effect anyway.
Yes, the data is had to find with some manufactures, so disregard their products. A little homework is required. First start with greases that you can actually buy in reasonable quantities. Some solutions are not available to the retail customer. Next gather the viscosity data and plot it on a graph.

You have to make some inference about products like Redline. Can we assume that the Redline grease is a racing grease? Could/should it have data similar to Timken's Performance Racing Grease which has very good data available? If so, you will see that it's viscosity is too thick for our application.

My test of a grease system is how fast the shinny bearing surfaces 'grey up' or micro pit.

Also note the too much grease packed in also causes drag.

Again, you are not going to see the kind performance gains from this bearing/grease effort as you will from say, using one of the new large manifolds. It is simply an effort to get the most from the car at every step of preparation. If you derive no pleasure from accumulating all of these small improvements in performance then don't bother.

Brian
Bob Posner
Posts: 70
Joined: January 23rd, 2008, 7:35 pm

Re: Front Wheel bearings

Post by Bob Posner »

Les Wildgoose developed a bearing lube system in 1983 using sewing machine oil and found that his car speed increased markedly, but only under braking when the light oil soaked his linings.
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Re: Front Wheel bearings

Post by BLS »

Brian M,

I used to have the car apart at least every two races so never allowed the grease to get very comtaminated. As I recall and I'm not positive, the end play would go down once the bearings were up to temp. I'll have to check after I get this thing on the track. For years I had my old race notes but they dissapeared sometime along the way...

Brian H,

These bearings probably have 8-10 weekends (the old style weekends, one race, couple of practice sessions, one qualifier) and remain very shiny. That would have been with my grease STP mixture. I'll keep a check on them.

I realize the gain is slight, but it is "free", unlike a new manifold... But, I do like working on the small things, both as an effort to understand the nature of the beast and to find those little improvements.

Well, on to other stuff like building a new support for my steering shaft. As with so many FV things, nothing fits my body length, but I'm getting close. I finished the welding for the new support a few minutes ago. I think that is the last of the fit refinements except for building a new lower seat to fit the new floorpan.

Everything takes about three times as long as I think it will.

I really do appreciate the help. I'll get this thing done soon.

Barry
Barry
Old Zink FV,
'87 Citation
tiagosantos
Posts: 389
Joined: June 20th, 2010, 12:10 am

Re: Front Wheel bearings

Post by tiagosantos »

Bob Posner wrote:Les Wildgoose developed a bearing lube system in 1983 using sewing machine oil and found that his car speed increased markedly, but only under braking when the light oil soaked his linings.
:shock:

:lol: :lol: :lol: :lol: :lol:
smsazzy
Posts: 703
Joined: June 24th, 2006, 5:56 pm

Re: Front Wheel bearings

Post by smsazzy »

Bob Posner wrote:Les Wildgoose developed a bearing lube system in 1983 using sewing machine oil and found that his car speed increased markedly, but only under braking when the light oil soaked his linings.
Which then caused soiling of his inner linings.
Stephen Saslow
FV 09 NWR
sharplikestump
Posts: 183
Joined: January 12th, 2009, 2:28 pm

Re: Front Wheel bearings

Post by sharplikestump »

Great discussion.............and then along came Bob (I'm still laughing).
Just wanted to mention, irregardless of how much endplay you personally desire, if you find that you cannot achieve it with the shims furnished, simply go with the shims combo that gives you slightly more endplay than you wish, and carefully lap either end of the bushing to decrease the freeplay or increase the preload.
Mike Palermo Jr.
BLS
Posts: 441
Joined: May 11th, 2011, 7:52 pm

Re: Front Wheel bearings

Post by BLS »

and carefully lap either end of the bushing
Hello Mike,

Missed you at the 50th...

Thanks for the tip. Never thought about that. I am close to what I *think* I should be. I'm going to check after it gets hot and see where it goes. As I recall it tightens up a bit...

Now, if I could just create a ten day week, maybe I could find more time to work on the important stuff instead of the stuff that pays the bills.
Barry
Old Zink FV,
'87 Citation
sharplikestump
Posts: 183
Joined: January 12th, 2009, 2:28 pm

Re: Front Wheel bearings

Post by sharplikestump »

BLS wrote:
and carefully lap either end of the bushing
Hello Mike,

Missed you at the 50th...

Thanks for the tip. Never thought about that. I am close to what I *think* I should be. I'm going to check after it gets hot and see where it goes. As I recall it tightens up a bit...

Now, if I could just create a ten day week, maybe I could find more time to work on the important stuff instead of the stuff that pays the bills.
Hey Barry,
The only regret I have pertaining to the "50th", was not getting to visit with everyone I wanted to. What a great time! Can't wait for the "100th"! :lol:
Post Reply