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XPAG Rear oil thrower and thrust bearing clearances

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XPAG Rear oil thrower and thrust bearing clearances
#1
jcimino Avatar
jcimino Jim Cimino
Dushore, PA, USA   USA
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I just got my parts back from the machine shop and have two questions. The new thrust beating is about .012 wider than the old one and I see that it will need to be sanded to get the proper end float. Tom Lange had stated that he sands the non thrust side…which side is that? Also after the line bore of the block, the rear oil thrower touches the scroll and has zero clearance on top and bottom. I know the suggestion is to keep it between .001-.002, how are you guys achieving that clearance?

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Re: XPAG Rear oil thrower and thrust bearing clearances
#2
Rob Z Avatar
Rob Z Silver Member Rob Zucca
Camarillo, CA, USA   USA
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1948 MG TC
1960 MG MGA
The rear side the thrust bearing is the non thrust side. When the clutch is depressed, it pushes the crankshaft forward. Although I did it, it’s said that sanding the thrust faces will embed particles. If it’s not too much, maybe it can be scraped. Again, if it’s not too much, try scraping the thrower.
I used the method described in the last entry on the attachment. Basically it’s renewing the original clearance between the scroll and thrower. After following these instructions using Teflon tape and JB weld, I used some bluing on the slinger face, reinstalled the crank, turned it by hand, removed the crank and scraped any areas that showed contact. Then did it again a few times until there were no marks in the bluing. It only leaks a couple drops after a run.

https://www.mg-cars.org.uk/imgytr/oilleaks.shtml


"Time flies like an arrow......Fruit flies like a banana"


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Re: XPAG Rear oil thrower and thrust bearing clearances
#3
DEC3 Gold Member Dana Cartwright
Syracuse, NY, USA   USA
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Rob, didn't you say that backwards, about which face of the center bearing is the thrust side? When you step on the clutch, the pressure plate tries to push the crank forward in the engine, and what resists that is the rear face of the center bearing. So to me, the rear side of the center bearing is the thrust side.

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Re: XPAG Rear oil thrower and thrust bearing clearances
#4
Rob Z Avatar
Rob Z Silver Member Rob Zucca
Camarillo, CA, USA   USA
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1948 MG TC
1960 MG MGA
Dana….you’re correct. Brain f@&t again. Thanks for the correction….cool smiley
Rob

In reply to # 4789808 by DEC3 Rob, didn't you say that backwards, about which face of the center bearing is the thrust side? When you step on the clutch, the pressure plate tries to push the crank forward in the engine, and what resists that is the rear face of the center bearing. So to me, the rear side of the center bearing is the thrust side.


"Time flies like an arrow......Fruit flies like a banana"

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Re: XPAG Rear oil thrower and thrust bearing clearances
#5
Mikelead Avatar
Mikelead Mike Leadbeater
York, Yorks, UK   GBR
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1953 MG TD
Personally I wouldn’t use sandpaper or similar abrasives on soft white metal, as you don’t want abrasive particles embedded in the metal .
A clean fine file or a scraper, checking parallel to the other side with calipers. Better still a milling machine. I would aim for an end float of around 4 thou.
A lathe would also suffice, you wold need to make a jig to hold the shells.
Mike

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Re: XPAG Rear oil thrower and thrust bearing clearances
#6
DrRichard Avatar
DrRichard Richard H
Derby, Derbyshire, UK   GBR
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If you have access to a lathe and/or are a skilled operator it is nice to mount the bearing shells in a chuck and turn off the required amount from the non-thrust side. Also an alternative method of getting the oil collector right up to the scroll is to turn up a mandrel from a piece of aluminium. Make it the exact diameter of the scroll and place it in the rear main bearing. It is then easier to adjust the position of the collector to get that minimal clearance before replacing the mandrel with the crank. Best to remove the two dowels while you do this as otherwise it is easy to break off the corners of the oil collector when you move it while they are in place. I had several oil collectors to choose from when I did mine and they all seemed to have the holes in slightly different positions. it is certainly possible to get minimal leakage this way.

Richard

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Re: XPAG Rear oil thrower and thrust bearing clearances
#7
jcimino Avatar
jcimino Jim Cimino
Dushore, PA, USA   USA
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Unfortunately I no longer have access to a lathe and I don’t know where the closest machine shop is at ( I live in the sticks, we only have one traffic light in the county �). My biggest problem seems to be that the scroll is touching the main cap since the engine was line-bored, now when I tighten the rear cap I can’t turn the crank and the bearing clearance is at .0015. The guy who did the machine work said the line-bore was in bad shape and he had to remove about .008 off the cap.

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Re: XPAG Rear oil thrower and thrust bearing clearances
#8
tdmidget Scott P
Tucson, USA   USA
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The problem is that your bore job is incomplete. The area around the scroll should have been bored also but that is a different diameter and most automotive line boring equipment isn't capable of 2 diameters in one set up. At this point you need someone who knows exactly what he is doing and why. It will be possible to hone it. This must be a Sunnen or other rigid hone, not a cheapy spring load thing. I would set it up with the block on a bench right side up with the cap on the scroll area. With the hone fairly loose in the bore stroke it withe weight on the cap. All material will need to come from the cap. I recommend getting someone experienced for this as a screw up will be expensive.

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