Why do you think you have crank walk?????

You do know the SVT is an IRON block not aluminum like most of the imports.

Call me later....

 

First time I've heard of anyone having this problem, but then again you're boosted...

I'm guessing new crank and bearings.

 

I doubt a new crank....

maybe just a good line bore and new bearings.

 

[][][][][]... I'm having DSM flashbacks right now..

 

If your having crank walk then you need to check the thrust on the crank and the bearings , It would be cheaper to get another crank if the thrust is wore then to repair the thrust , most cases the thrust bearing is worn

I am also curious why you think the crank is moving to far and how far is it moving ?

Tom

 

http://www.focusfanatics.com/forum/showthread.php?t=257407

 

wow saw your other post with the chewed up crank sensors, suck man maybe time for a rebuild on the bottom end and more boost.

 

Going through crank sensors pretty fast. On i think number 3 in like 6 months.

 

apparently John was the lucky one, not the car...

 

Ehhh its all good. He never really drove it enough to know bout the problem. Its goes a decent amount of time in between sensors. Just wanna get it fixed though. I can always tell when it goes out cause Ill park it and when I go to get in and start it the car gets no fuel and wont start. Has never failed while driving though.

 

Have you tryed shimming out the crank sensor ?

Tom

 

^^^ I've already suggested that the last time.... dont know if he listened or not.

 

Jim shimmed his crank sensor, but he wasn't chewing it up. He was just barely nicking his.

 

Yea I tried to shim it but the washer I had was to thick and the car wouldn't start. Went out and got sone thinner ones so I'll see what I can do

 

Small update......

Shaun called me last night and said he used a thinner washer.... And the car starts and runs better that it has since he bought it.

FWIW the last time I had the motor apart I checked the tolerance's and everything was in spec.

 

By crank walk, are you referring to movement front to rear? If yes, then if everything is in good shape, you can measure the gap between the crank and thrust bearings and get a new set of bearings that include oversize thrust bearings. If you have any scoring on your crank journals, you'll need to get it re-ground.

How many miles are on the current bearings? You may have just worn them out. Have you actually looked at the condition of your crank and piston bearings and journals? When I was an engine builder, occasionally an engine measured and looked fine and a new set of bearings was all that was needed.

A visual check will tell you a lot about crank wear. If you see any marks at all (usually in the form of a scratch that goes around the journal), get the crank reground and get new bearings based on the new size, .005" under to .020" in increments of .005".

 

So much for all these performance aftermarket clutches supposedly resolving crank walk issues. I've had a Clutch Master Stage 1 for two years and have replaced the crank sensor twice since then. Never replaced one with the stock clutch.

 

Yeah...... clutches have nothing to do with crank walk.

 

I have no friggin idea how a clutch would help with crank walk. That is preposterous.

 

That threw me for a loop, too... but it made me wonder if there were any issues aligning the output shaft during reinstall of the transaxle after the clutch swap.

 

Doubt it's the clutch. The car broke one sensor with a stage 4 and now there's a new stage 5 in so I don't think it's that.

 

Got the sensor shimmed our some so I'll see what happens from here. If I'm still having issues I'll prob take it apart when I go home

 

it being an svt i would just check the timing belt for piece of mind.

 

LMAO
You guys are funny.

No a 'clutch' does not have anything to do with crank-walk. But a pressure plate does. Think about the interaction between the PP, FW/crank and the IS. The design is to pull them together so they act as one. The heavier the PP the greater the pull. It's a repetitive stress disorder.

Also I'm not sure what you're running for a FW and PP, but it may be possible that the FW is bent some or flexing from the PP pressure. Possibly a combination of that and too much endplay. By the looks of the sensor this would be the most likely case. For the assy. to move that much and still run properly is unreal, looks like almost a 1/16th of an inch gone from the CKP.

So really I'd say you should be pulling the rotating assy. apart and checking it. Shimming the CKP is only a bandaid. Catastrophe is just round the corner.

 

Werd. Mine used to be boosted with an aftermarket clutch. The pressure plate clamping force is too great and the articulation of the plate pushes too hard on the fly. The only way to fix it is to beef up the thrust surface. Shimming your CKP is putting a band-aid on a gunshot wound. This is what happens when you make something do what it wasn't designed to do.

 

I would like to take a stab at making the interaction between the clutch assembly and crank walk a little clearer.

When you step on the clutch pedal it takes some level of force by the through out bearing to cause the pressure plate to separate from the clutch disk and flywheel. That same force is also trying to push the crank out the front of the block. To keep bad things from happening a thrust bearing is used to resist this force.

If you swap to a pressure plate that requires more force by the through out bearing you also apply more force to the thrust bearing.

An aftermarket clutch assembly that provides increased holding power (ie more HP) does not necessarily require more force at the through out bearing. Different leverage ratios in the pressure plate, use of centrifugal weights and/or improved friction materials in the disk can result in more power capacity without more force at the through out bearing.

One of the worst things you can due to a thrust bearing is to sit with the clutch pedal on the floor. This applies. A constant force on the bearing that accelerates it's wear.

 

Dgc is correct to a point , with all things working properly the thrust that is made into a main bearing gets oiled just like a main bearing does so you crank thrust hitting the thrust on the bearing should have a coating of oil and the crank thrust never should contact the bearing thrust

I dont know what clutch you have but ware on the thrust has nothing to do with the clamping power of the clutch just how much force it take on the PP fingers to release the PP that psi gets applied to the thrust but even then you shouldnt be getting thrust ware from any clutch made for the Focus

Tom

 

Correct I should have been more specific. The clamping force of the pp has no affect on the thrust surface but the force required to compress the bellville spring within the pp to disengage does. Generally, a pp with a greater clamping force will require greater compression force and therefore stress the thrust surface during disengagement.

I think the reason so many blown svts have this issue is due to the force provided by the aftermarket clutch and the force on the crank snout used to drive the blower. It just wasn't designed to withstand those longitudinal crank forces...