Euro951

Ok lets try to end the age old question for #2 Rod bearing. I am listing some info as I have been told but want knowledgable 1st hand information from people who race or have had this happen to them. I would also like to know what countermeasures people have done to stop this issue.

Some say rod bearings are spinning because

1.) lack of oil in the sump on sweeping turns. ( oil starvation )
2.) Crankshaft oil issue (not crossdrilled)
3.) Low oil in sump
4.) Lastly, I have heard the the crank girdle is only pinned in the rear and not towards the front. There was some discussion on another forum if the girdle was moving ever so slightly at high RPM causing increased wear on the bearings towards the front of the engine.

What are some solutions to stop or alleviate this issue?

Chris White

1) No
2) yes...but no
3) no
4) no

This has been covered quite a bit but heres my view again...
Problems -
The crankshaft has a very poor oiling passage design - there are 90degree corners in the oiling passages, a basic flaw for high performance cranks. Cross drilling does not fix this.
It is very easy to aerate the oil. The sump design has very little clearance between the crank and the sump in the front half of the pan – when you brake hard (you can get 1g on track tires) a lot of oil surges forward and comes in contract with a crank spinning at 6k rpm, this will aerate the oil. Foam is a crappy lubricant!
Oil pump cavitation – the stock oil pump is known to cavitate at higher rpm. This is made a lot worse by air bubbles in the oil aeration).
Hot oil – the stock system is not up to the task for track driving, oil temps get very high and this thins the oil.
Only one truly dependable fix – dry sumping.
Other intermediate fixes –
• Do not over fill the sump – up to the max line only
• Do not run at high rpms (over 6500)
• Add a good Oil cooler
• Adding a windage tray
• Bearing coatings – may provide that brief second.

savvas944

dry sump is the answer.Plus the extra horses.

savvas944

F1 circuit director.
---------------------
951 track car -86-89
968 road/Track car-92
NISSAN 240RS DRY SUMP-RED-83
NISSAN 240RS DRY SUMP-WHITE-84
ASTON MARTIN VIRAGE LEMANS- RED-94
MITSI EVO 8-06
LEXUS RX350-07
NISSAN XTRAIL-05
VOLVO 240GL -TURBO-92
SUNBEAM RAPIER HI20 - 3NOS.UNDER RESTORATION-72

M758

I have experienced rod bearing failures and have run for a long time without them.


My take is the oil flow to the #2 and #3 rod is weak to start with. The flow to the #1 an #4 are much better. Greg Fordhal (who is probably crew chief for a DP team at Daytona this week) has experinece on these cars and runs one. He did some crank testing and found #2 & #3 rods have low oil flow. This is supported by the age old questions of why #2?

So he suggests cross drilling #2 and #3 (second worsts flow) only . This helps balance the flow on all 4. Now this does not solve the issue as Chris mentions alot of good stuff. The situation is just that any disruption to the oil flow can cause the bearing to spin. So you need to focus on maintianing a strong supply for good cool, high quality oil to the bearings. This includes not foaming the oil, keeping temps inline, using high quality oil, changing it frequently and changing rod bearings as a maintance item and main bearings when doing rebuilds. The reason for bearings is older bearings can wear from start up and the larger the clearances they more oil is needed to float the bearing. Fresh bearing help restore clearances in most cases.

The only complete solution is dry sump, but that is not realistic on most cars. However you still can do alot to increase margins.

Do a search and you can fine 5-6 posts where I lay out many of the things you can do. One of the most important is keep oil level full, but not over full. I have seen cars spin bearings if on track with oil at the "low" mark. Also don't run 5-30 in race motor. That too will spin bearings as the oil is too thin at temp.

333pg333

???

lee101315

Hmm... Solution? A three piece subframe and crossover from Lindsey racing.

I change my rod bearings two or three times a year. If im winding the motor up to the other side of the tach at an autoX or during a mountain drive, I keep a close eye on the oil pressure gauge.

If I hear the knock knock knock, I call AAA, and have the car flatbedded to my shop. Total cost is about $130 between the rod bearings and the oil pan gasket.