Thrust bearing question - PeachParts Mercedes-Benz Forum

t walgamuth · #1 06-12-2010, 12:22 PM

Over on the Miata forum a fellow has discovered he has excessive end play on the crank of his 99 Miata (a fairly common problem in a smallish number of 99s).

Another fellow is saying he can simply replace half the thrust bearing without removing the engine.

Does this seem practical to anybody here?

Seems unlikely to be a good idea to me.

Mike D · #2 06-12-2010, 12:46 PM

It all depends on the configuration of the bearing. If it's a standard type, the bearing surface is attached to a "shoulder" or "saddle", then it's a fairly straight forward procedure.

Drop the bearing cap, spin the old bearing out, slide in the new, replace the lower bearing half, button 'er up and away you go.

If it's a "shim" style with a locking ear then it's a whole different ball game.

Replacing half of a two piece bearing doesn't sound like very good work so I'd say, "no" it is not a practical or proper solution. Used car lot repair kind of "fix".

thorsen · #3 06-12-2010, 01:03 PM

I'm not familiar with the Miata but I replaced the thrust bearing in my MGB several times with the engine in situ.

http://mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36454#27

t walgamuth · #4 06-12-2010, 01:27 PM

I just read the haynes manual and it does look possible.

Thanks!

Chas H · #5 06-12-2010, 07:15 PM

Quote:

Originally Posted by t walgamuth

I just read the haynes manual and it does look possible.

Thanks!

Not only possible, I did this very thing to my Miata 20K miles ago. I sold the unused bearing-they are sold in pairs- to another Miata owner who then did the repair to his Miata. The factory has some wide tolerances for crankshaft endplay. I reduced the endplay from .0085" to .0035".

The Clk Man · #6 06-12-2010, 07:24 PM

Do all Miata owners have end play?

Chas H · #7 06-12-2010, 07:34 PM

Quote:

Originally Posted by The Clk Man

Do all Miata owners have end play?

You betcha.

The Clk Man · #8 06-12-2010, 08:13 PM

Quote:

Originally Posted by Chas H

You betcha.

Dude!!! that sounded gay.

Chas H · #9 06-12-2010, 08:20 PM

Quote:

Originally Posted by The Clk Man

Dude!!! that sounded gay.

Now how would you know that?

The Clk Man · #10 06-12-2010, 08:26 PM

Quote:

Originally Posted by Chas H

Now how would you know that?

MeltedPanda told me so.

Chas H · #11 06-12-2010, 08:32 PM

Quote:

Originally Posted by The Clk Man

MeltedPanda told me so.

AHA! I thought you two were up to something.

t walgamuth · #12 06-13-2010, 05:59 AM

Are you the same Chas H from the MIata forum?

Chas H · #13 06-13-2010, 02:48 PM

Quote:

Originally Posted by t walgamuth

Are you the same Chas H from the MIata forum?

But of course!

MS Fowler · #14 06-13-2010, 05:25 PM

Quote:

Originally Posted by t walgamuth

Over on the Miata forum a fellow has discovered he has excessive end play on the crank of his 99 Miata (a fairly common problem in a smallish number of 99s).

Another fellow is saying he can simply replace half the thrust bearing without removing the engine.

Does this seem practical to anybody here?

Seems unlikely to be a good idea to me.

I agree that its probably not the "best management procedure".
However, having half a thrust bearing will keep the end play under control, but for much less time than if the whole bearing were taking the load.
The crank will only rub on the half that is the larger. Remember, the thrust face on the CS is smooth, so its not like it hits something every half rev.

It might work for a weekend or two, but I'd be replacing it sooner rather than later.

Chas H · #15 06-13-2010, 05:36 PM

Quote:

Originally Posted by MS Fowler

I agree that its probably not the "best management procedure".
However, having half a thrust bearing will keep the end play under control, but for much less time than if the whole bearing were taking the load.
The crank will only rub on the half that is the larger. Remember, the thrust face on the CS is smooth, so its not like it hits something every half rev.

It might work for a weekend or two, but I'd be replacing it sooner rather than later.

Obviously you know as much about a Miata engine as the other respondants.
Here's photo of the thrust bearings, all and both of them.
http://www.google.com/imgres?imgurl=http://ecx.images-amazon.com/images/I/4146aaZtO7L._SL500_.jpg&imgrefurl=http://manualtransmissionparts.blogspot.com/2009/12/vandervell-thrust-bearing-set.html&usg=__yV2-69GYBAl_ESzQdoOe7k9ZQlo=&h=371&w=500&sz=17&hl=en&start=8&um=1&itbs=1&tbnid=5OFiU-_nlqz--M:&tbnh=96&tbnw=130&prev=/images%3Fq%3Dcrankshaft%2Bthrust%2Bbearing%26um%3D1%26hl%3Den%26sa%3DX%26tbs%3Disch:1