Adjusting SPF wheel bearings.

[Jac Mac]

Rereading my post I realize I probably should be referring to 'hub shafts' instead of 'stub axles'.

Dont panic, Im getting fairly good at deciphering terminology...

If it was my car I would be making up holders for the outer seal & machining the upright to accept that plus accomodate an inner seal, Then I would fabricate a solid spacer that would fit between the two cones on the stub shaft - this would be made slightly oversize so it could be selectively fitted to get the ideal bearing preload to each hub assy , now you could tighten the bearing retainer nut to a much higher torque amount, [The same way that we convert most 9" Diff pinions from the collapsable factory spacer to a solid one, then you can tighten the pinion nut to a torque figure that wont come loose].
Those 'dust slingers' appear to either have a rubber ring bonded on or possibly a mark where they are deforming slightly & allowing the bearing preload to reduce in service, if its a rubber ring this must play havoc during the set up procedure & if its the latter & deforming then it is simply not suitable in this application & could be the factor that is allowing this noise to occur/happen.
Hope thats all slightly clearer than mud, If not I will do a drawing in an attempt to further de-confuse..

 

[Richard]

Jac this was the side where the bearing were a slight interference fit. The upper spot you point to is where I nicked the radius while removing the outside bearing. The lower is where the inside bearing sits. It wasn't that hard to remove so I'm not sure why it ended up galled. Crocus cloth cleaned up both spots. On the other side both bearing were firm but did just slide on. I would think that’s the way you would want them to go on. Removing the outside (outside in relation to the car) bearing was a pain in the ass as they don’t leave you anywhere to get in under the bearing without destroying the shield. I had to use a knife and a small hammer to get things moving. It also required the removal of the rotor which was also a pain because of the use of soft flathead Allen bolts. Grrrrrrrrr

 

[Seymour Snerd]

If it was my car I would be making up holders for the outer seal & machining the upright to accept that plus accomodate an inner seal, ....Hope thats all slightly clearer than mud, If not I will do a drawing in an attempt to further de-confuse..

That's what I would like to do but I was having a hard time imagining where on the axle to find the space for the lip of the seal. For example it appears that the inner race of one of the bearings is right up against the threads. So where does the lip of the seal go? On the other end I could imagine there being room for a seal. IAE if you feel like drawing that I would love to see it.

 

[Jac Mac]

You guys are posting faster than I can Draw!!

I wonder if the particular bearings used in these cars has a 'marine' or industrial equivalent that has a rubber seal bonded to the inner race for use on boat trailers or machinery, that would make life real simple, plus I notice in one post that the bearing retainer nut/threads had deformed or worn, are L/R/ threads 'handed' or do they use say RH thread for both sides, in which case the solid spacer idea I mention above is the only way you will cure the problem.

 

[Seymour Snerd]

Actually if we went with the solid spacer could we not then switch to sealed bearings?

 

[Jac Mac]

Actually if we went with the solid spacer could we not then switch to sealed bearings?

Yes, that would be the easy way out, but if not then you will have to do something along these lines..

Damn, hope you can enlarge it, forgot to reset my dwg program from last night...

 

[Seymour Snerd]

Yes, that would be the easy way out, but if not then you will have to do something along these lines..

Damn, hope you can enlarge it, forgot to reset my dwg program from last night...

Quite readable. Thank you. What would the tolerance on the spacer be and what (roughly) is the process for establishing its length?

 

[Jac Mac]

Quite readable. Thank you. What would the tolerance on the spacer be and what (roughly) is the process for establishing its length?

Easiest way to establish approximate length would be to have a dummy shaft with minimal flange & retainer nut heights etc & simply fit bearings to upright, measure bearing cone faces, then subtract the two bearing cone widths from that measurement. Make your spacer to that dimension plus say 0.005" then still using your dummy shaft shorten the spacer 0.001" at a time [ a piece of emery tape on a glass surface is fine for this ] until you get the required 'feel' or preload on the bearings..... that will take a bit of experimentation & you might have to allow a bit for expansion of the alloy upright etc.

Another perhaps 'better way would be to have the spacers made to a set length & then use pinion spacer shims if you can find them in an appropriate size, but really once you set the bearings up in this manner I doubt you would need to service them again for a long time, & even if you do it should only be a matter of shortening the spacer by a very small amount to do so..

PS, I would envisage that the spacer would need to be made from say 0.125 wall 4130 tube or more as it must resist any tendency to crush when retainer nut is torqued..

 

[Seymour Snerd]

Those 'dust slingers' appear to either have a rubber ring bonded on or possibly a mark where they are deforming slightly & allowing the bearing preload to reduce in service, if its a rubber ring this must play havoc during the set up procedure & if its the latter & deforming then it is simply not suitable in this application & could be the factor that is allowing this noise to occur/happen.

Is it possible those "dust slingers" are in fact Nilos seals? Carroll Smith mentions them in "Prepare to Win" p. 91 as being probably the best way to seal tapered hub bearings.

See: Maryland Metrics: Introduction to Nilos Rings and http://mdmetric.com/prod/nilos/nilos.htm

 

[DaveM]

Is it possible those "dust slingers" are in fact Nilos seals? Carroll Smith mentions them in "Prepare to Win" p. 91 as being probably the best way to seal tapered hub bearings.

See: Maryland Metrics: Introduction to Nilos Rings and Maryland Metrics: NILOS Rings

Yes they are. Since Smith was one of the engineers on the Shelby GT40's race team I assume the Nilos seals were on the originals for him to make that quote. For race use with frequent disassembly and relubrication it probably worked fine. For longer term use they're not as sanitary as rubber seals, but I don't see an easy way to modify the uprights for that. I figure we live with the original design and regrease the bearings every year or two.

 

[Seymour Snerd]

. I figure we live with the original design and regrease the bearings every year or two.

Yes, to be clear Smith's books are all about race preparation, not street cars. Even so it is a different reality from the "we don't have seals" thinking we did earlier. I don't expect the car to be as environmentally bulletproof as my Land Rover, nor to be as low maintenance as the Rover is (supposed to be). :lipsrsealed:

As for achieving a completely sealed hub environment (if anyone cares) it looks to me like the way to do so would be to switch to sealed deep-groove ball bearings.

By the way from a historical perspective Smith was writing in 1975 or so and makes the comment that by then most of the major race teams had moved on from tapered bearings to either deep-groove ball bearings or to a combination of ball bearing and needle bearing for axial and radial loads, respectively.

Richard -- can you make out any identifying information on those seal/slinger parts? If so I'd like to research them I bit.

 

[Richard]

No markings and I don't think they are Niols. They are simply dust shields. I've seen bearing like you're talking about and these are not it. Very crude. I still have one out of the car some I'll see if I can't get a picture of the other side.

 

[Rick Muck- Mark IV]

Yes they are. Since Smith was one of the engineers on the Shelby GT40's race team I assume the Nilos seals were on the originals for him to make that quote. For race use with frequent disassembly and relubrication it probably worked fine. For longer term use they're not as sanitary as rubber seals, but I don't see an easy way to modify the uprights for that. I figure we live with the original design and regrease the bearings every year or two.

Agreed. And I have it on VERY good source that they are Nilos seals from Germany. As said, these are "race cars" that happen to be streetable and so they carry some quirks that one must live with. Rather like a Derby winner is probably not the best choice for plowing a field, a GT40 is not the best choice for fording a muddy creek crossing the road.

We may endevour to make the cars more liveable and better sealed, but they are still 1963 racing technology.

 

[Seymour Snerd]

(after reading a bunch of Nilos literature) Nilos seals are interesting. If I understand the sealing mechanism correctly, when new the axial edge of the seal bears against the side of the bearing outer race with a carefully designed force. During a break-in period the seal grinds a groove into side of the outer bearing race and since the seal is initially filled with grease (I hope), after the groove is formed the sealing action is created by the "labyrinth" (U-shaped path) of grease formed by the seal running in the groove.

Ideally the break-in period occurs under 6 M/s relative speed between race and seal, so if I assume a 3" outer race and 26" dia. tires corresponds to about 52 M/s vehicles speed or 187 Km/hr. They imply that the break-in process takes 24 hrs, I assume at that speed (the document is translated from German and a little hard for me to interpret precisely). At a more typical average speed of (say) 45 Km/hr for "driving around" that implies 1080 km of break-in period. (this assumes the break-in process is a linear function of "travel" but I don't know that velocity is not a component).

So I guess that means that for the first ~600 mi/1000 km of driving our new GT40s we should keep the speed below ~115 mph/190 km/hr while tring to avoid parking in water deeper than 11.5".

Seriously, this does mean that when reassembling the hubs you probably want to clean that groove area and reapply grease, and that the seal itself must be treated with great care so its lip is not damaged nor the seal distorted since it depends entirely on retaining its original shape to match the groove it previously formed.

PS: they also mentioned somewhere that it's generally fine to use the same grease on the seal as you use for the bearings, but if you are really concerned about water entry you can use water-repelling grease on the seal. I assume that refers to "marine" grease (the blue stuff?).

 

[Kirby Schrader]

(Next step. Try a different browser, I guess....)
That cured it... Sorry about that.

Kirby

 

[Jac Mac]

Alan, that theory from Nilos is all very well, but if you look closely at the pics in Richards post#70 above its evident from the wear on the inner portion of the nilos seal that it has not been 'clamped' between the bearings & shoulders of the hub/or retaining nut. ie insufficient preload..... this might actually be the source of the 'creaking' sound that I think Richard & Kevin have been trying to pin down as the nilos seal instead of having the OD spin against the outer race as per the literature, it is virtually 'locked' there @ the OD & spinning on the shaft...... again converting to a solid spacer between the bearings would make the 'nilos seal work as intended, might not be what SPF designed/copied, but seems the logical way to an immediate fix, albeit for all the extra hassle I would rather run a 'proper seal'.

 

[Seymour Snerd]

.... this might actually be the source of the 'creaking' sound that I think Richard & Kevin have been trying to pin down as the nilos seal instead of having the OD spin against the outer race as per the literature, .

Interesting. Of the two variants intended for use with tapered bearings the AK versions has "nibs" intended to interlock with the locking ring to prevent rotation. However I see no evidence of that in Richard's pictures so we probably have type AV. I don't quite understand how that version is guaranteed to spin, because the catalog makes it quite clear that you are allowed to have play and the whole system works. I suppose they could think the friction between locking ring and ID of the seal is guaranteed to be greater than that between outer edge and outer race. So yes, I'm mystified and this could easily be the source of some noise, not to mention ineffective sealing.

The catalog is located at http://www2.nilos-ring.de/DWD/_111327/upload/media_4190.pdf and the discussion of mounting AV and AK seals is on page 17. I'd love to hear anyone elses insight into how this seal is supposed to work with tapered bearings that do not use a center spacer and high locking torque.

If I had mine apart today I'd be tempted to replace the seals and take some measure to guarantee they rotate with the axle, although I'm not sure what that would be; probably a dimple in seal and locking ring, or switch to type AK. Or install a center spacer.

OTOH if you look at the picture of Richard's outer race (http://www.gt40s.com/forum/attachment.php?attachmentid=53703&d=1309324110), there does seem to be a nice neat groove carved into the race, right where I would expect the seal to create it, although somewhat obscured by all the silver stuff (anti-seize?)

 

[Jac Mac]

Right, read most of that, I would suggest that the type that is stationary @ the OD & seals against the ID of the bearing would be more suitable in your application, rather than having the seal spin with the axle shaft which tends to sling the grease/lubricant outwards, but the Upright casting would need to be modified to accomodate that.

 

[Seymour Snerd]

Right, read most of that, I would suggest that the type that is stationary @ the OD & seals against the ID of the bearing would be more suitable in your application, rather than having the seal spin with the axle shaft which tends to sling the grease/lubricant outwards, but the Upright casting would need to be modified to accomodate that.

Yes, in fact they say that the "inside seal" type is always preferred.

 

[Richard]

If you look at page 8 and the drawing of the AK seal it looks to me like SPF only used the right most seal, the one that seals against the casting. There isn't one that seals against the outer bearing race. In fact the outer bearing race is to thin at that point to even have one. I'm now going to have to pull the side I have finished back apart to make sure there is grease in the groves.

This poses another problem, if the outer bearing is a press fit removing the bearing without damaging the seal would be difficult at best. Not understanding how this whole thing works is a problem and again points out the need for a "Real" shop manual. While I had it apart I should have ground a few spots around the backside edge of outer most spacer so it has a place to pry against.

Question, the bolts holding the caliper and the ones on the CV joint are all 10mm, I torqued them to 45ft/lbs. What should they be torqued to?