Rear wheel bearing doubts

[miked]

Help appreciated.

I have just fitted rear spring platforms on an S4. Issue 18. Whilst there I checked the play in the bearings. They have covered about 10k miles and are RHP inner and NTN outer as I recall. I found slight amounts of play in both sides. Being a paranoid character about the alloy chapman strut and the hub shaft etc I stripped everything. Alloy still in good condition and loctite never moved. shafts in good condition and no spin on shaft to inner race. I split the bearings ( down to the balls) and they had clean grease (no rust) and no visible signs of any damage/ wear. I did all the careful cleaning etc etc and rebuilt everything with new SKF. Upon completion I checked before fitting the lot to the car. RH side no movement but some very slight play in the left. Thought it was me so carried on. Once the car was on the floor I swayed on the wheel and found that I could feel it more dramatically. More leaverage! I talked to SKF and they told me about clearance and manufacturing tolerence and upper and lower limts. Meaning that one might be at one end of the scale and the other at the opposite end. Only by random selection of a boat load of bearing would I find two at the close end??? Very confusing. Also some stuff about how the tightness to shaft fit on the inner race could influence play. I am no engineer but this sounded strange and of minute proportion if true.

I have another new set in boxes and upon feeling these the outside alway seem to have less end float than the big inside one. Am I loosing the plot and is this usual. I do have a thing about play. I know the front taper run with play and it is required but you would think that relatively big heavy ball bearings would be more exact than this.

I dont really want to do it all again for nothing and end up with some play. I do need to jack up and get under and try and determine the exact amount. Could I be swinging on the end float of the bearing and it is not really vertical play but horizontal end float. The racers out there must surely have experienced this and alawys be checking.



Thanks Mike

[GrUmPyBoDgEr]

Hi Mike,
I don't know who you spoke to at SKF, sounds a bit like a used car salesman. The sort of play you describe will not result from a sloppy new bearing, there is no such beast or you've got a real dud which could not normally pass through the manufacturing process without being picked up.
If there's no play between the shaft & the bearing or the bearing & the housing maybe the play is within the lower wishbone mountings. Have you tightened them up or waiting till the car sits on its wheels with the suspension loaded?
All bearings are classified in order to identify their internal "diametric clearance" :- 0 00 & 000
0 has the tightest diametric clearance. 000 has the greatest amount of clearance.
00 is the most commonly used clearance for ball bearings in general engineering; quote from "Newnes Engineer's Reference book" my copy is donkeys years old but these things don't change
More specific information on bearing selection can be obtained from bearing suppliers design aid books. Left mine lying somewhere in England years ago!
I hope you nail down the cause of the problem soon. With your experience you should know that you are living "the Lotus experience"
Cheers
John.

[types26/36]

Mike,
I also find the bearing explanation rather dubious, although you say there is no play between the bearing and caseing quote "loctite never moved" I would recheck that again but as John said check for play in other area's first, one possible source is the shock in its housing,make sure the top gland nut is thightened down particually if you have recently fitted shocks.

[steveww]

The big nut that holds the damper in the strut tube needs to be very tight. If you have fitted the TTR dampers they are shorter than the originals and thus require a spacer to be dropped down the strut before fitting the damper.

[david.g.chapman]

I fitted new rear bearings to my plus 2 two years ago, and felt some play in the rear wheels afterwards. There was no evidence of the bearings slipping, and I could not see anything actually moving about.

I but it down to play in the bearings- even though they were new.

After 10K miles the play has not increased, and my MOT tester says that the play is well within acceptable limits.

I am talking about play of 0.3 mm or less at the wheel rim - in other words too small to see, but you can feel it. Make sure the handbrake is off when you test.

If you are up to 1-2 mm, say, then that might be too much.

Dave Chapman.

[Hamish Coutts]

Mike,

There are many things that can cause play in the back end apart from bearings and outer driveshaft fit. I think the other guys in this thread have covered that well.
If I found any play in a rear hub bearing I would assume it was worn out and replace it. There should be no play in that type of bearing.

If bearings are a tight fit in the hub carrier and the outer drive shaft is a tight fit in the bearings then there could be play in the fit of the hub to the driveshaft. Is that torqued up properly?
Bt the way are you sure the outer shaft is a tight fit in the bearings? Are you testing this with the inner drive shaft disconnected? The rotoflex can exert quite a loading on the outer shaft and stop any movement you try to induce in your testing.

My rear uprights were in need of a bit of attention. I eventually fitted spyder uprights which use the large wheel bearing in both outer and inner positions. There is no play.
Any 'play' problems I have had at the rear were caused by the fit of the outer driveshaft into the wheel bearings.

Regards,

Hamish.

[miked]

Guys, thank for all your help.

This is were I am at:
I am on AVO normal length rear adjsutable shockers. Gland nuts were tight but I will double check. The car is back on the floor and I covered 200 mile last Sunday. I have doubled checed the "A" frame bolts. The bushes are poly and almost new.

I have done the TTR instruction for the Hubs with lapping paste etc and 3/16" drill check and making the roll pin key shorter and sitting it at the edge (to prevent fouling). I also did his instruction about keep driving and return to check the torque. I have the TTR UJ type sliding spline shafts so have no great forces.

Top nuts on the shock have been done twice. I can get flex movement from the top of the lotocone as you would except with some swinging, but no noise/play.

Tonight I will get it jacked up on to blocks under the whelels and get under to id were it is between. Get my boy to work it while I feel for the movement. Can even jack carefully under the "A" frame to remove the weight to see better. Also try to get a measurement. I will come back to the forum before ripping it apart.

Bearing guys was a bit of a waste of time. I have no experiece with deaing with this. Usually buy a bearing and fit it. No more movement.


Could I be doing something wrong with the fitting. I did all the Paul Robinsshw book stuff and used a nice piece of thick walled tube to drift the bearing on the shaft. Did all the cooling and slight heating buisness.

When putting the built up hub shaft into the case (with the front bearing inplace) I drifted that in with the copper hammer. No great brute force jus t decent tension. Put circips in& left o/night etc. thans Mike

[miked]

Outcome!

I set up the DTI against the side of the wheel rim with the car wheel off the ground. It was supported just under the "A" frame. It is hard not to shake the whole car. I believe that with very carful movement of the wheel and feeling the rear bearing play it showed about +/- 7-8 thou of an inch (total about 14 - 16). I also tried a pry bar under the Disc and flexed that up and down. There is some very very slight movement. This is were it orignates from. Other side has nothing.

I have decided to live with it. Whilst I can feel it (and my friend can as well) it seems a waste of effort to strip everything to fit more new SKF bearings. Car drives well with no noise. I will keep an eye on it.

One question though, for anybody who has done this lots of times. When you look at the two bearings the inside one definitly end floats more than the outside one. When assembling, should this be taken into account. Is it possible to to push one further against it's (end float) stop than the other, as when the hub shaft pushes in, the inner race of the outside brearing grips the shaft. I used a tad of loctite on the bearing to the shaft. Just a thought. This could make one slightly tighter than normal???
I am not sure not a mechanical man!


Mike