1966 MB 230SL too-large-endplay issue

[dnadanny1]

HI there.

My 1966 230SL (Engine: M127.981) has too large end play at the crankshaft thrust bearing. And, I dont know where I can buy a thrust bearing with a oversize width 30.50mm, and the diameter of the bearing is 59.50mm.

I can find 59.50mm crankshaft bearing, but cant find thrust bearing with a oversize width 30.50mm at the same time.

Anyone knows where can I buy the correct-size bearing set?

Thanks a lot.

Regards,
Danny   

[Benz Dr.]

There was a time when MB sold thrust bearings separately but now they're all part of the thrust or locating bearing when you buy a set of main bearings. Generally, the crank is ground under size and the thrust journals are ground over size by the same amount. In other words, if a main crank journal is ground .25 mm under size, the thrust area of the crank journal is ground the same .25 mm over size.  New locating or thrust bearings are designed to fit with the correct crank end play.

[ja17]

Yes only the oversize bearings have a wider thrust these days. Just installing a new main thrust bearing (same size as your original), may cut down on your endplay if your original thrust bearing is worn. It is usually a combination of wear on the crank thrust surface combined with wear on the bearing thrust surface which causes the excessive play. It is risky just replacing bearings, since roughness, and wear may cause break-in problems if your crankshaft is worn.

[dnadanny1]

Thanks for your help.

What really confused me is that my old thrust bearing is with 59.75mm diameter and 30.5mm width , but my new bought is with 59.50mm with 30.10mm.

I think if i buy 59.50mm thrust bearing, the width of it will be greater. Instead of being greater, the width of my new bought bearing is smaller than the old one.

I cant find any thrust bearing online that fit exactly the diameter and width.

Any thought on this?

Regards
Danny

[ja17]

Check to see if your thust bearing is STD. diameter.

[dnadanny1]

Thanks for your help.

Even with extensive effort, I still cant find a thrust bearing with 59.50mm diameter and 30.75mm width.
Therefore, I gave it to the machine workshop to fill the end play with welding at the crankshaft. And, what he did is shown in the attached picture.

This final product worries me a lot. However, the machine workshop said there will be no contact with the back, because the crank shaft will move forward spontaneously.

Any thoughts on whether I should believe the machine workshop, and go ahead installing the thrust bearing. Most importantly, I hope I can buy a correct set of thrust bearing with 59.50mm diameter and 30.75mm width.

Thanks a lot.

Regards,
Danny

[Charles 230SL]

Hello Danny, I’d contact Metric Motors about the oversized main/thrust bearing. They’ve rebuilt enough M127 engines to know where to source the bearings - and whether they’re even available.

[Benz Dr.]

OHHHHHHhhhhh................ I don't like the looks of that at all.  Those little divots will likely chew up your bearing because you need full contact in order for the bearing to carry end thrust. The only thing I agree with is that the crank will move forward naturally as the engine is running.

You have a bit of a dilemma here. You have a crank journal that's at .50 mm under size and the width is .75 mm over size. The way to correct this is to grind the crank journal down to .75 mm under size so it matches the with of the main bearing. This is as small as you can go and the crank would probably have to be replaced if you ever need to rebuild again.

However, my question and problem with this '' repair '' is whether or not the hardness of the crank journal was affected during this welding process. It may need to be re-hardened and it might be easier just to get another crankshaft. I'm afraid to say this but I think you have a boat anchor now.     

[Mike Hughes]

When I saw that picture my response was unprintable.  That might have been a way to keep a Model A engine running a little longer during Dust Bowl times without having to re-babbit the mains, but...

[dnadanny1]

Thanks all for your help.

I am contacting Metric Motor to get a new oversize thrust bearing. And once I get the new bearing, I will machine all divots out and install the correct size bearing.

Thanks again.

Regards,
Danny

[ja17]

I do not think you will have the option of choosing the trust bearing oversize without also increasing the oversize of the bearing itself. most likely you will have to grind the entire crankshaft undersize.

[stickandrudderman]

After that crankshaft has been attacked with the welder, I would no longer have any confidence in it and would bin it. I am not a metallurgist but the effort and expense involved in finding out later that this crankshaft has been compromised by the welding process are far too great to warrant the risk of fitment IMHO.

[DaveB]

I am no metallurgist either but I would not expect it to be that bad - the crank is a massive heat sink.
That is a tricky situation though, no doubt the machine shop will say their solution is good enough. I hope they will work with you.

[dnadanny1]

Thank you all.

Given the comments from the majority, I am totally convinced that I should buy a brand new crank shaft at this point of time. So now, is anyone here has a credible source of suppliers who can provide me a set of new nice crank shaft with bearings included?

Thanks again.

Regards,
Danny

[dnadanny1]

I do not think you will have the option of choosing the trust bearing oversize without also increasing the oversize of the bearing itself. most likely you will have to grind the entire crankshaft undersize.

I understand what you mean. Do you have any source of oversize bearing that you can share with me?
If I can buy one over-sized, I will then definitely grind the entire crankshaft undersized.

Thanks for your reply.

Regards,
Danny

[ja17]

According to the "technical data booklet" , the width of the flange bearing increases from 30.000 mm to 30.700 mm with the fourth repair oversize. Less repair stages fall in-between. First I would have the crankshaft measured to make sure you have enough width to fall into the range. At that point you can figure out what size you need. Mercedes still supplies bearings for your engine. You can also find NOS sets on Ebay. Other vendors on this site can also supply bearings.