ACT extreme PP causing crankwalk??

[Insidious Surmiser]

feel like I'm getting paranoid here, but I'm reading that heavier PP's can cause crankwalk due to increased load on the thrust bearing on startup? I'm assuming an accusump would be a good precautionary measure here? :icon_neut just don't want this supra to take the route of most of the ones I've had in the past (#1 being the most god-awful piece of garbage I've ever encountered (sent to the junk yard), #2 blowing up tuned w/ SAFC, #3 and #4 meeting untimely ends due to unfortunate and unavoidable circumstances)

 

[Dirgle]

Bypass the neutral start switch and start the engine without having to push in the clutch. Allowing for minimal load on a dry thrust bearing.

 

[cal]

Where is this switch located? Do u just unhook it?

 

[Dirgle]

If you look at the clutch pedal you will see two switches. The neutral start switch is the lower one. It has a two pin connector that you disconnect and jumper the two pins to bypass the safety feature.

 

[Insidious Surmiser]

hrm... but a lot of guys that did this still got crankwalk (mostly mkiv guys from what I've seen) if an accusump will move oil to all the vital parts before startup, this should solve the issue I would think?

 

[Dirgle]

I did research into this when I did my 2JZ swap. The conclusion I reached was that the best thing to prevent crank-walk on a 2JZ was to disable the clutch start safety switch. This means that the pressure plate is creating less pressure than a factory pressure plate on startup.

So the failures that these people are experiencing are coming from using a higher clamping force pressure plate while operating, and can't be avoided without other changes. Startup isn't the issue for them.

I also noticed that most of them were running a higher than stock rev limit. So gear changes, and by association pressure plate actuation was occurring at a higher RPM. At a point which the lubrication system might not be able to keep up.

Remember, the thrust bearings are not really pressure feed like the mains and rods. They rely on spil off from the main bearing. And as you engage the pressure plate you put pressure on the forward thrust bearing. Due to that the tolerance on the rear thrust bearing the majority of the oil will be directed out this way. This coupled with the higher RPM means heats builds up faster and the bearing wears down quicker.

Now this is all for the 2JZ. The 7M has a far rarer occurrence of crank walk.
But if it worries you the here are some of your options.

1.Disable the neutral start safety switch. This will eliminate worries about cold start wear on the thrust bearing.

2.Move to a multi-plate clutch. These have much lower engagement pressures than the ACT extreme. So long term wear is reduced.

An accumulator is never a bad thing on a 7M. And if you're in a position to get one then do it. But I wouldn't get one to solve fears of crank-walk. Just disconnect your clutch start safety switch.

 

[Insidious Surmiser]

hrm... I responded to this a week ago, guess it never went through... anywho, thanks for taking the time to explain the finer details of the matter, between talking w/ you and my buddy that runs a tuning shop (mostly supras) I'm feeling much less paranoid 8)

 

[1986.5supra_kid]

still paranoid wish there was a gnome inside the motor that could measure the wear before it walks to far.