Slip fit spindles on a 1970

[Alex McDaniel]

When removing the rear wheel assemblies, and the spindle nut and flanges, the spindles just slid right out of the the support/bearing housings. I took them to Vansteel in Clearwater Fl and learned that the previous owner may have 'turned' them into "slip fit" spindles commonly used for racing. He also said that they were useless now and would require new ones for bearings to be pressed onto. He did a micron measurement, the the figure was -----.4 (all I remember off hand). He said they needed to be at least .7 to be able to be used.

Has anyone had any experiences with "slip fit" spindles? What the pros vs the cons are to having them?

Also upon inspecting the bearings the only damage was a barley perceivable brown 'burn' streak on the inner races of the outer bearings. Is this a sign they were close to failing?

Thanks
Alex

[Terry F.]

Re: Slip fit spindles on a 1970

It would be interesting to know what the grease looked like and what amount of play was detectable in the bearing with regard to that brown streak. If set up correctly the bearings will last a long time. The fact that you are in there again and the indications that someone has been in their before is sort of the answer to your question.

Bottom line...I don't think they will give you any type of guarantee without returning to the press fit application. I would follow their recommendation even though it will cost you new spindles. They will set them up right and you will not have to deal with them again in your life time.

Just my opinion. Terry

[Don H.]

Re: Slip fit spindles on a 1970

I have used a "slip fit" on multiple cars for many miles and no trouble. I put the spinle in a lathe and use emery clothe, checking with a micrometer very closely. To remove the spindle after installation, I use a spindle knocker (sold by Corvette suppliers) and pound it out with ease. I believe this fit is fine for normal driving. I would not use it for stressed (racing) applications. Don H.

[Jim T.]

Re: Slip fit spindles on a 1970

Alex when the 1963 Corvettes were built in St Louis they had slip fit bearings on the rear spindles. From what I have read, during the model year due to 1963 Corvettes used in racing/competition driving encounterd rear spindle bearing problems and production was changed to interference fit of the bearings on the rear spindle. There are many Corvettes that the owners have optioned for having their rear spindles turned to a slip fit to make it easier to repack/change the rear bearings. Do not have my 63 service manual handy right now, but I believe the torque for the 63 rear spindle was just 50 foot pounds. I don't know when the change was to 100 foot pounds. Having a slip fit on a original spindle where the brake disc is still rivetted to the spindle an owner with a dial indicator can set up the bearing clearance when servicing the rear wheel bearings. Another advantage of the slip fit will allow the installer to set up the bearing clearance with out installing the outer bearing seal until the bearing clearance has been established. With exact bearing clearance and a true 100 foot pounds of torque on the spindle nut, you may not have any problems with your slip fit spindles. I don't think anyone can guarantee that you will have a problem if the unit is properly set up.

[Wayne W.]

Re: Slip fit spindles on a 1970

If a frog had wings he wouldnt bump his butt on the ground.

Nuff Said.

http://www.members.aol.com/wombvette/AxleFail

[Terry F.]

Re: Slip fit spindles on a 1970

Very impressive. It turned into a lathe. The twisting of that one axel suggests a lot of heat was generated. Wow! The only thing keeping the wheel on after that is the caliper.

Terry

[bruce11495]

Re: Slip fit spindles on a 1970

Warren...Do you think this was caused by slip fit bearings? The one on the right looks more like that wheel got "loaded" on a right turn, both wheels slipping and that one wheel got good traction and twisted the splines. I would bet that the twisted spline is off the drivers side, I've seen that symptom numerous times with BB/SB and slip/non-slip bearings.
The one on the left could have been bad bearings and /or lack of lube.
That's my .02 cents worth

[Wayne W.]

Re: Slip fit spindles on a 1970

Whether caused by slip fit or not is not the major issue here. Fact is, this is what you effectively have with slip fit. And if for some reason you loose the nut or the rest of the shaft, out comes the axle. Brake calipers will not necessarily hold when this happens. Both of theses resulted in the Frog bumping his butt on the road.

[Michael H.]

Previous discussion on Slip Fit Brngs

63 rear wheel bearings

63 rear wheel bearings
Ray Carney -- Monday, 4 April 2005, at 6:12 p.m.

When did the assembly procedure change on the rear wheel bearing for the C-2? The 65 bearings had to be pressed off and on and I believe that the 63 bearings were just a slip fit. Could someone please educate me on the differences of the rear wheel bearings?

Thanks for any help!
Ray #36314

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Re: 63 rear wheel bearings
Mike McCagh #14 -- Monday, 4 April 2005, at 7:43 p.m.

slip fit to press fit spindle bearing change occured in about dec of 62. either will work. i prefer slip fit and modify all my post 63 midyears to slip fit by turning the spindles. makes for easier disassembly to re-lubricate every 25 k miles. mike

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Re: 63 rear wheel bearings
Duke Williams -- Monday, 4 April 2005, at 7:53 p.m.

I don't have first hand knowledge, but the early slip fit design must have caused problems early on. Otherwise they would not have changed the design.

The good news is that with the press fit design, the 30K mile service interval was eliminated! Since drum brakes have a higher thermal resistance path to the hub, if you overhaul the pack and use a high quality synthetic wheel bearing grease, current owners will likely never have to do any more work on them in our lifetimes.

Duke

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Re: 63 rear wheel bearings
Michael Hanson -- Monday, 4 April 2005, at 8:21 p.m.

Duke,

There were actually two revisions for this bearing in early 63, both of which increased the press fit of the bearing on the spindle. The entire original design system was off the design paper and into production when someone in engineering had a horrible vision. What if one of the spindle flanges cracked and eventually came apart at speed? (likely in drag racing) It suddenly occured to him that the flange alone was responsible for keeping the rear wheels from departing the vehicle. Soon after (very soon) the press fit was introduced. About a month later, the specs were changed again to increase the press fit.

This wouldn't be nearly as serious a problem on 65 and later with disc brakes as the rotor in the caliper would prevent the assy from coming out but the press fit bearing was still used as a precaution.

Other than the safety factor in the event of a broken flange, I know of no reason why the bearings would have to be press fit. Their exactly the same as a front wheel bearing on any pass car and these have been slip fit for decades without any problem.

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Re: 63 rear wheel bearings
Duke Williams -- Monday, 4 April 2005, at 8:55 p.m.

The entire design and production configuration history is detailed in a TSB that I have and detailed in previous posts some time ago. There were actually IIRC two interim designs implemented on the line in November before the final design went into production on Dec. 1.

Do you know for a fact that the design change was motivated purely by this "horrible vision" or was it really motivated by a high failure rate? I don't see this "horrible vision". On both the floating and press fit designs the axle nut is torqued and cotter pinned to the axle, so the likelyhood of the axle nut departing allowing the axle to float out is nil if it's properly assembled. On the front end the nut is only held on by the cotter key, but the nut does not see hub torque because it is a dead axle not a live axle like the rear, which does see both brake and drive torque. They are different design architectures - dead and live axle.

If the stub axle breaks or the hub breaks off the axle the wheel will depart the vehicle with either design - just like all GM live axles used on cars.

I'm not aware that GM issued a recall (rare to non-existant in those days). They probably just repaired failures as they occured under warranty.

Duke

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Re: 63 rear wheel bearings
Michael Hanson -- Monday, 4 April 2005, at 9:25 p.m.

There may have actually been more than two design changes. I know there were at least two, both of which had to do with bearing press fit and wheel/tire assy retention. I don't remember for sure if it was the spindle OD that increased in size or the bearing ID that decreased. (most likely spindle OD) If the flange disintragated, which is not at all uncommon, there would be nothing left to retain the spindle assy. The nut would be retaining nothing and the entire assy could leave the vehicle. With a press fit bearing, at least the bearing would retain the assy. If I remember correctly, the flange was redesigned about that time also. I think the flange went through a few design changes over the next year to elimiate breakage. There may have been, as you mentioned, several different rasons why the bearing clearance/press fit was changed but I know for sure that wheel/assy loss was one and I'd have to guess it was probably the most important one. I suppose the nut and cotter pin were a factor also as they could have had the same result on wheel assy loss. Either way, it wouldn't have been a pretty picture. Can you imagine Dr. Thompson or Doug Hooper loosing a complete wheel/tire assy at one of the first road racing events for the new 63 Corvette? Bet there wasn't a lot of time that passed between the initial ECR release and the actual change in production.

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Re: 63 rear wheel bearings
Wayne Womble -- Monday, 4 April 2005, at 10:44 p.m.

We have had long discussions on the merrits of slip fitting rear bearings. Personally I would never drive a vehicle that I knew had slip fit. Here are the reasons why. Both of these vehicles lost their wheels and axles and they are C3s and had disk brakes. So this is not just a drum brake issue.

http://www.members.aol.com/wombvette/AxleFail

There is another reason not to slip fit. The bearing race surfaces are not intended to run loose and wear occurs where they slip. This wear makes it impossible to hold the bearing tolerances to specification and you get considerable play in the axle. Here is a picture of that occurance.

http://www.members.aol.com/wombvette/AxleFail3

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Re: 63 rear wheel bearings
Dick Whittington -- Tuesday, 5 April 2005, at 12:06 a.m.

Just my two cents worth. I have seen two spindles that all that was holding the nuts on were the cotter keys. Apparently someone in a prior repair had overtightend the nut and stripped the threads. Scary thought on a slip fit.

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Picture really is worth 1000 words.....
Michael Hanson -- Tuesday, 5 April 2005, at 7:05 a.m.

Thanks Wayne. I guess that pic says it all.

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Re: 63 rear wheel bearings
Michael Hanson -- Tuesday, 5 April 2005, at 7:07 a.m.

Dick,

I think I know the mechanic that did that. He worked on my x girlfriends car a few months ago. Same outstanding quality.

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Re: 63 rear wheel bearings
Dick Whittington -- Tuesday, 5 April 2005, at 7:09 a.m.

Livin' proof that Bubba is alive and well.

[bruce11495]

Re: Previous discussion on Slip Fit Brngs

I believe that John Greenwood used slip fit axles on his Vettes. The outer bearing should be installed with Loctite to combat the spinning on the axle...........

[Joe L.]

Re: Slip fit spindles on a 1970

Alex-----

I do not recommend the use of slip-fit rear spindles. I have never used such spindles, do not use them now, and won't be using them in the future, either.

Keep this in mind: the change to the press fit design spindle had to have been a greatly costly one for GM. It greatly complicated their component assembly and field service. You don't think that GM went to all this trouble and expense because the slip fit design worked just as well, do you?

I agree that it SEEMS like the slip fit design should work just fine. However, I think that's jst how it is. It SEEMS like it should work just as well.

[bruce11495]

Re: Slip fit spindles on a 1970

Joe...I don't know if we'll ever find out why GM changed from the slip fit to press fit. I just know that it works! I haven't seen a higher failure rate from the slip/press, but it is easier to check and to service. I raced Vettes hard with slip fit and had but one failure, a twisted spline. This was do to the one wheel getting traction, while it was heavily loaded. The racers all used it a that should be the ultimate test.............

[Joe L.]

Re: Slip fit spindles on a 1970

Bruce-----

I've heard of quite a few folks that have used the slip fit successfully. However, as I say, GM changed this design very early on. I can see no other reason for them doing this other than demonstrated problems in the field. Since the change was implemented "mid 1963 model year", the problems had to have surfaced VERY quickly, a design change had to have been worked out as to details very quickly, and a manufacturing change implemented very quickly.

This sort of situation "feels" to me like one where either there were a LOT of problems experienced in the field during the first few months or there were only a few problems but it was deemed to be a major safety issue. I can see no other reason for a change in design like this. Many Corvette problems of long standing took years to get finally corrected; this one took MONTHS.

As far as folks using slip fit and having no problems, I look at it this way: a lot of people went up in the space shuttle and returned with no problems, at all. Some didn't, though.

[bruce11495]

Re: Slip fit spindles on a 1970

Joe.... Point taken, but we're still speculating. The best answer would be from the 63 owners. Did they have any over abundance of of axle failures in their cars? That would give us more insight..........

[John H.]

Re: Slip fit spindles on a 1970

The change might also have come about as a result of a Proving Grounds failure; I worked at Chevrolet Engineering, and failures at Milford on production configurations got INSTANTANEOUS visibility and attention. This particular change (slip-fit to press-fit) also had a major impact on the assembly process, tooling, and productivity at Chevrolet-Warren, and that kind of a change wasn't undertaken "on the fly" without good reason. Would love to see the "Reason" and "Effective Point" boxes on the ECR that released the change.