924Board.org

[MikeJinCO]

A cautionary note

While assembling my new motor we found that with the new made in China main bearings their was ZERO thrust clearance. This is a 931 block and crank. In fact the crank wouldn't even turn. The machinist had to rework the thrust bearings to get proper thrust clearance.

After rework all is well.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[ideola]

I doubt this is an issue with the bearings, as I have built multiple motors using them and have not experienced anything remotely close to this. Did you have your mains line-honed???
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erstwhile owner of just about every 924 variant ever made

[MikeJinCO]

Nope, not align honed. Checked with a borescope, but that's really a different subject. Align honing may well be necessary on these old blocks, we'll find out. My point is don't just chuck bearings into them and assume everything will be fine.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[Carrera RSR]

Surely you would check clearance with Plastigage first? Bearings are not a 'chuck them in and everything is fine' element of an engine build
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252

[Ian89C4]

Mine were OK. Plastigauged within specs and the crank turns nicely. Yes, assembly lube was used
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Ian Edgerly
North Carolina

Current:
1981 924 SCCA/ChampCar Weissach Race Car ("Serenity")
1987 924S ChampCar Endurance Car ("Der Weg")
1980 924 Euro ("Wahala")

[924RACR]

Mine were fine - in the '82 931 rebuild... Those were the King brand bearings from Ideola, is that the ones we're talking about? Been a while, I forget...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[MikeJinCO]

Mine came from EBS Racing in a unlabeled box so I assume the newest ones. We had no end play/thrust clearance with the crank sitting in the block and only the #1,3,5 top bearing shells in place without bearing caps and then locked tight with the center cap only, just barely snugged down. So this was well before getting to final assembly.

When this motor was taken apart the main bearings were almost reusable and the crank looked almost perfect. It did get polished and all reciprocating parts balanced.

My point is just be careful as there might be quite a bit of variation in this latest batch of bearings. The machinist has also remarked on how poorly many aftermarket parts are made these days. I spent 10 years working for TRW piston ring division(supplied Ford, GM, JD and Cat primarily, Chrysler wouldn't pay their bills)and knew how poor the quality control was on our aftermarket parts as compared to OE parts back then, We would go to the parts store to buy competitors to compare and theirs weren't any better. Unless you are someone like Total Seal who has the latest Japanese machinery the older equipment is used for the short run aftermarket stuff and the new, vastly improved, equipment is used for OE parts.
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Mike


'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

[CorsePerVita]

I rebuilt my last motor with king bearings and they've been great. Not sure though if i'd trust made in china bearings lol..
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- 1977 Porsche 924 2.0 N/A (Trackday Project)
- 1979 Porsche 924 2.0 N/A (The other daily)
- 1980 Porsche 931 (Daily)
- 1987 Lamborghini Jalpa
- 1999 Ducati 900SS