Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: stickandrudderman on April 07, 2015, 15:53:49
-
I have noticed over the last year or so that new bearings supplied both by MB and FAG (the original manufacturer) have excessive end float and I have been unhappy to fit them.
Now, I have been doing this a long time, long enough to know that you can never know everything, but I'm pretty certain that this never used to be the case and that the fitment of new bearings always used to eliminate the end float.
However, after trying three different bearings of the same spec, I tried an alternative recommended by my bearing supplier with the result that end float is eliminated whilst still having the necessary geometry to allow for angular movement.
the good news is that the bearing is also cheaper.
SKF 1208-ETN9 Self Aligning Bearing
And this is where you can buy them:
http://www.wychbearings.co.uk/1208-etn9_open_skf.html
It is for you to decide if there's any merit in my findings.
-
Yup, I tried that and was told in no uncetain terms by my bearing guy not to use that type of bearing - he's been selling bearings for a very long time ( well into his 80's ). The twin row ball bearing type is designed for high speed and the type that you need is designed for heavy load. So, I put the right one back in.
I imagine what you used would be OK for a whille but I wouldn't recomend it as a viable alternative.
-
Well Dan, it would seem that your bearing guy who has been doing it a long time and my bearing guy who has been doing it a long time have a difference of opinion.
I'm willing to bet that this replacement will be just fine but only time (and miles) will tell.
-
Just for the record, the load capacity of the original barrel bearing is 49,000 N while the load capacity of the dual race ball bearing is 34,500 N. The load capacity of the left bearing (6208) is 30,700 N. Know the numbers an make your choices.
-
Well Dan, it would seem that your bearing guy who has been doing it a long time and my bearing guy who has been doing it a long time have a difference of opinion.
I'm willing to bet that this replacement will be just fine but only time (and miles) will tell.
I can accept that. I don't change many of them so the extra exspense isn't that much of an issue.
-
Yes, I agree the extra expense is not a problem if you are not paying for it, it is very easy to spend someone else's money.
If the above company that Colin mentioned runs out Simply Bearings has them, I have used these with no problems, as yet.
-
Typically when engineers design something where weight is not a big issue they aim to have it built with a factor of safety of 3 meaning the part is normally 3 times the strength called for. Where weight is an issue as in an aircraft, this factor drops to 1.5. So the replacement part is probably okay. BUT, the engineers called for a specific part here-- that is a self aligning roller bearing and not a self aligning ball bearing. If it fails prematurely and the car was still under factory warrantee--I know that is not the case here but just for the sake of argument, my guess is MBs response would be, you did not use the part our engineers called for. Agree with Dan, the cost differential probably isn't worth the risk of having to back in there any time soon and replace it with the correct one.
-
The point is, the "correct" bearings currently being supplied are introducing excessive end float and are therefore unacceptable.
-
one of the next days, I will take a look at the specs of the bearings. I used to be a specialist in that field in machine construction.
You should be aware of the specs of the static and dynamic behaviour. If you use a to low dynamic figure, it will influence the life cycle.
But: the dynamic figure (Cdyn) in fact is defined as: 90 % of the bearings will last 5x the life expectancy out of the calculation. So you will be lucky the most of the time, by definition of this calculation, if you don't exaggerate.
-
The point is, the "correct" bearings currently being supplied are introducing excessive end float and are therefore unacceptable.
Your opinion is important. What do you think the problem is? Has the specification been changed (would require a different part number, or at least one with a different suffix, yes?) Or is it poor manufacture? Maybe the source of manufacture, like instead of Germany, maybe some 3rd world country?
These kinds of things always have me shaking my head...