Crank walk and what I've read via Magnus Motorsports

[daedalus]

There are a lot of posts, some odd 200+ pages. I would like people to know why crank walk happens and that balance shafts DO NOT cause it.

You can goto wikipedia look up the balance shafts. They're just to reduce vibration. Other than that no inherit effect.

As far as the crank walk. It's the oil squirters. They are actually ABS check valves. Magnus removes the squirters, welds the hole, and thus no more crank walk issue. The page will explain it in detail. But the basic is all because lack of oil pressure.

http://magnusmotorsports.com/?page_id=323

[Bill Hincher]

just drill the main bearing to route some oil on the thrust bearing on the clutch side, works great

[daedalus]

Huh, that's pretty interesting.

[Mr Hyde]

The theory is that the 7 bolt bearing cradle has some slop built into them.

This same cradle also sandwiches the bearings with the crank journals.
On startup the 7 bolt engine hasn't delivered a sufficient amoutn of oil to the bearings, coupled with the fact that alot of guys are installing high pressure clutches.

When the motor is started you press on the clutch peddle, the force from your clutch presses against the crank, and it MOVES because the bearing cradle is loose. The "walking" of the crank wears at the main thrust bearing. Once it has been worn out of spec, the crank now will "walk" back and forth.


It also happens with 2jz engines as well....

Hope this helps

[Bill Hincher]

that kinda makes sense but there aint a production car built that dont require holding the clutch down before the starter engages

that was the argument for STP ( 110 wt oil) it stays in the overheads longer overnight so no damage is done on start up

but the reality is , if you read the article mentioned at the end of this thread , it begins with THE MAIN BEARING DONT GET ENOUGH OIL
end of story

[jeffball610]

Or you could just disengage the clutch switch and start your car without the clutch in. Just make sure you take it out of gear first.

[OLDIE]

If you don't want rebuild the bottom endso you can drill the thrust bearing then you can use PRO MA MBL8 in your engine oil and it also eliminates lifter ticking if you don't have the later lifters
I use it in my DOHC 2323 cc stroker 6 bolt

[kuroi]

I'm all for the pre-oiler/accumulator, 60psi on startup is the way to go.

[biglady112]

A big thing people don't realize also is that on a 7 bolt there is an oil squirter extremely close to the thrust bearing. Not only is it close to the thrust bearing, it gets its oil from the same galley extremely close to the feed hole for the thrust bearing. So it reduces oil flow AND pressure to the thrust bearing. So that does not help at all.

We have made a few seven bolts live and have walked our fair share as well. Sometimes there just is nothing you can do. It just does it. Even if the motor went for ever and a day just fine. Then came out for a service and upon start up walk.

It is more common then people think. It is not mitsubishi related. My friend's honda prelude has walked twice. His motor is an H23 no vtec motor.

[Bill Hincher]

the clutchs are over sprung on race applications, the force to move the throw out bearing is too much, the EVO went to a pull style
The Japanese dont put any more strength then required to build thier stuff
If you wanna drag race use the auto trans option and aviod all that

I have heard all that oil squirter stuff, but in the end , if pressure is maintained behind the squirter, it doesnt change pressure or volume at the bearing , it only delays oil at the squirter and allows it to organize

I have heard a lot of numbers about oil pressure that are a concern too, guys running 80lbs of pressure dont make a lotta sense either, fliud under pressure builds heat, volume is what is needed not excessive pressure

[biglady112]

That is what I am telling you. The squirter is directly next to the hole for the bearing. It has no choice but to affect oil pressure and flow.

I feel with a proper clutch setup has no ill affect on end play wear regardless of clutch used. If it was specific to heavy clutches why do bone stock automatic DSMs walk?

And I feel exactly opposite about pressure. We run as much as we can get in our land speed cars. We run a full 5 miles flat out. In four years we have never had a bearing failure. We run as much as 120psi on start up. But the car also carries 7-8 quarts. I run 8-9 quarts in my colt. While temperature affects the oil, I highly doubt these walked cars are running 250* plus oil temps for ectended times.

And with everyone in our little world doing all that they can to reduce oil pressure, does not help at all. As I said, we runas much as we can and have NEVER had a bearing failure in a machined motor. Street car or race car.

[Bill Hincher]

what kind of filter sytem do you use?

[biglady112]

Stock mounted oil bracket. Wix brand Axsa RX-8 oil filters. Super tiny filters. Never had issues. The land speed car runs no oil cooler and a 3000GT filter, any bran he can find. He runs 20w50 racing oil. Up to this point I have run regular Valvoline 10w40 oil. People get way to involved with theories and recipes. KISS and just haul some ass.

[Bill Hincher]

yeah well, that dont work out, anytime you get over 100lbs on a stock oil filter they either split or blow the oil ring out because they are not torqued , only hand tightened, so they blow right off the housing at that kind of pressure, not to mention aint a performance move

at 218mph the math dont work out to the RPM's you would have to run, I am supried you didnt go to a dry sump system

[biglady112]

Well it has been working out for four years for his car. And 7 years for my car. And he made 18 runs last year in a single event. so 18x5=90 miles of wide open racing for a SINGLE event. And the oil filters ran just fine. Yep, that motor still runs and made it throught 4 LSR event in 2010. As well as some 1/4 mile testing, and around the block testing. In all, the car has over 425 miles of full throttle racing so far with nothing but tranny failures. Engines and filters never seem to have issues. Just some head gasket service and nothing more. Hmmm.

Again, Keep It Simple Stupid.

And I will just link you to our 214mph run from august. We went 218 in september and blew up some silicone parts we did not have spares for in october.

Oh, and this car run 218mph at 6700rpm. And we still have two more gears to install for more mph. Current rev limit is 9250rpm. So yea, if we had the aero and power, we have enough gear right now in our possession to do over 300mph. And that is no bs. But 250mph is a realistic goal for the ca in the next two years. We were 17mph faster this year than last. And just finally starting adding power in while we worked out the chassis, weight and aero.

209 run-
http://www.streetfire.net/video/209622m ... 051923.htm

214mph video in the video gallery
http://www.retributionlsr.com/

[Bill Hincher]

you must be running about a 30in diameter tire with about a 2:94 to 2:54 gear? whats the car weigh? must be around 1300 lbs? at 800hp?

[biglady112]

Wow, that is all I have to say.

4100lbs, 28" tires, stock FWD turbo mitsu tranny, AWD .666 5th gear, 625-650whp. Weight is 100% irrelevant on the salt. We have put 1100lbs in the car to get it to hook up.

Again keep it simple. We still have a .617 gear and .500 gear.

Everything you know about drag racing does not relate to bonneville. Took me a few years to learn that. They don't cross over.

[lsr mike]

Everything you know about drag racing does not relate to bonneville. Took me a few years to learn that. They don't cross over.

That is an absolute fact. the science is the same, the application is whole different beast.

It's about being Fast, Not Quick.