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Crank Walk Documentation

177K views 212 replies 106 participants last post by  cuemaster 
#1 · (Edited)
Crank Walk Documentation *mods please move to sticky in technical*

I am documenting my crank walk experience for you guys. I also have questions for you at the end of this thread.

v160
ACT Xtreme
GTE Bottom End

Occured after about two years of driving with this clutch. I tried to get it off the road in time but the last mile home was terrible. I also did not disable the clutch switch like I should have. Boy am I paying for that mistake..






My questions:
1. Aside from the damage to the block in picture two, there isn't much other visible damage to the block. The face of a few mains look a tad banged up. What should I be looking for also on the block? Will an experienced machine shop be able to give me an answer by visually inspecting the block and caps?
2. The crank is a major concern. It's very hard to see any damage on the journals of the crank, but there has to be some. When should I consider replacing it instead of having it fixed?
3. I noticed the rod bearings are a matte light blue. Is this normal or have I experienced actual bluing? The back of the bearings look normal.
4. There were shavings in the pickup. Can I clean it out sufficiently or do I need a new one?
5. After something like this, how trustworthy is even a well-fixed block? I spin this motor to 8600rpms.

I hope we can build on this thread.

Kill
 
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#2 ·
Sorry that I can't answer questions for you really...but if the crank journals have some damage, would it make sense to go with an sp 3.25 stroker motor? The reason I ask is because they machine your crank for the additional stroke. It's basically 6k and may take care of anything that was damaged. I apologize if this is getting off topic.
 
#6 · (Edited)
Been there done that :(

I lost 2 shorblocks in the exact same manner, one on the dyno in
Texas at that! The bottom line is, get a twin or triple. The plates are wayyy lighter, and the discs themselves do the bunt of the work. Every time we put clutches in supra's we disable that switch. A high mileage or hard starting car could die within weeks of installation.

You have to think, the thrust washers are not pressure fed , they simply rely on oil being splashed on them via the counterweight. So when your car hasnt run in a month, every drop of oil is sitting in that pan. For a few seconds, they are bone dry creating some metal/metal contact. Having that heavy plate smash them up against the main cap sure doesnt lessen the impact :)

On our blocks now, our machinist puts a little radial in the main cap , so oil is being squirted at the thrusts when there is pressure.


Josh@FSM


Ps: To answer all your questions in one shot: GET A NEW BLOCK & CRANK!! I dont care if someone as reputable as Jim Justice said you could re-use it, fuck that. Call it superstition, but I would never trust that block to be true. Im sure that has caused a gross misalignment in that main cap, and the mains will at least need to be honed. Then you will be using off the shelf bearings, band-aids, etc... Id man up and do the new SB from Elmhurst, and then go through it before putting it in the car. The pickup and pan need to be thoroughly cleaned as well as all the hardware in there.
 
#20 ·
Ps: To answer all your questions in one shot: GET A NEW BLOCK & CRANK!! I dont care if someone as reputable as Jim Justice said you could re-use it, fuck that. Call it superstition, but I would never trust that block to be true. Im sure that has caused a gross misalignment in that main cap, and the mains will at least need to be honed. Then you will be using off the shelf bearings, band-aids, etc... Id man up and do the new SB from Elmhurst, and then go through it before putting it in the car. The pickup and pan need to be thoroughly cleaned as well as all the hardware in there.

Agreed, reusing a walked block/crank is asking for problems down the road.
 
#7 ·
Why would disabling the clutch switch fix this problem ?
 
#8 ·
You're not using the clutch to start the car at the most critical time when oiling is at it's lowest.

Definitely get a new block and crank and multi-disk clutch. I've seen a few cars where they used the existing block and even put a new crank in along with all machine work, only to have the problem happen quite soon.
 
#9 ·
Instead of totally getting rid of the clutch switch, just move the switch somewhere off of the clutch.
I mounted mine elsewhere, its kind of like a theft deterrent thing of some sort.
sometimes I totally forget about it and I press the clutch and nothing happens then I am like, oh yea.
 
#22 · (Edited)
i crank walked just last summer, and that was two years after putting in a stage 2 rps blue clutch.
i do think it is caused by increased pressure plate pressure. i was wondering what clutch setups
would help this problem? also if an additive like this
http://www.bitrontech.com/
might stop the wear because the crushing force the crank puts on thse two cheap
shims would not be accompanied by heat and would be better lubed at all times?




also i did the clutch sw mod way back in 2001
 
#24 ·
This bitron is hard to believe. Anybody using this stuff?

i crank walked just last summer, and that was two years after putting in a stage 2 rps blue clutch.
i do think it is caused by increased pressure plate pressure. i was wondering what clutch setups
would help this problem? also if an additive like this
http://www.bitrontech.com/
might stop the wear because the crushing force the crank puts on thse two cheap
shims would not be accompanied by heat and would be better lubed at all times?
 
#27 ·
That sucks, you might be able to get a cheap Aristo SB instead of a new SB from Toyota.

Also if a R154 trans is used instead of the W58 or V series; would that reduce the chances of crank walk because of the pull clutch versus the push clutch?
 
#28 ·
Also if a R154 trans is used instead of the W58 or V series; would that reduce the chances of crank walk because of the pull clutch versus the push clutch?
No, because the presure plate still gets pushed forward to release the clutch disc.
 
#31 ·
Yea the TO bearing pushes in the fingers.

well here my story. i sent my car to 50-50 racing to put the 2jz in it. but the story is i bought a vvt-i 2jzgte motor and tranny from tiger motorsports in canada and shipped it down to 50-50 racing . and he calls me two weeks later saying my stck 2jzgte vvt-i motor with and auto tranny has crank walk. man that is such a line of bullshit
Did he send you photos ? How do you really know.
 
#30 ·
well here my story. i sent my car to 50-50 racing to put the 2jz in it. but the story is i bought a vvt-i 2jzgte motor and tranny from tiger motorsports in canada and shipped it down to 50-50 racing . and he calls me two weeks later saying my stck 2jzgte vvt-i motor with and auto tranny has crank walk. man that is such a line of bullshit
 
#34 ·
ive decided to use it in my new motor.
ive had a mkiv for 12 years now and this is the first crank walk and it pisses me off,
what a stupid design. if you think about it there is only one of those washers
involved with the motor, the other is just along for the ride.
 
#35 ·
Well I got a used SB from a yard with low milage. I pulled the motor apart and inspected the thrust washers. You can remove them with your finger. Granted the crank wasn't installed, it still seems too frail to me. I'd like to tack weld them in. They don't need to shift, do they? It's the high-rpm shifts that can rip them out, from what I have heard. Regarding the clutch, I'm getting a carbonetics CC which should solve the problem down the road.
 
#36 ·
Hmm, high RPM shifts. This is gonna suck. I actuall race the thing.

Does anyone know of any prep you can do to the new bottom end to possibly help prevent this?

I did the clutch switch bypass when the clutch was done but ended up with the crankwalk anyway. Made it about 7 weeks driving the car almost everyday.
 
#38 ·
Any fix for this weakness?

I'm currently waiting for new bottom-end parts (aftermarket pistons and rods) and will be putting the bottom end back together with new bearings etc.

I'd really like to know if someone has done something to fix this 2jz weakness alltogether! Anybody?
 
#39 ·
Haven't hear about crankwalk being a problem on any other car than the supra or cars with that particiular clutch setup.. Feels like toyota made a mistake here we just have to live with.. But I would think that the stiffer the pp is the more likely you are to crankwalk. So if Im putting in a new clutch on my supra it would be the double or triple RPS carbon carbon clutch, since pp is only 15% stiffer than stock.. Costs a lot, but might be cheap in the long run :p
 
#40 ·
Yep and that's sad! ;)

I drove 10 k miles after installing 40% stiffer pp than stock. After first 2k miles I modded the car so that I can start the car without depressing clutch pedal and ALWAYS started the car without applying clutch.

Now that I took the engine apart, I noticed that the front side thrust washer had started to wear out just a bit (the one that prevents crank from moving backward):



My quess, after reading quite a lot about crankwalk, is that it wore down in the beginning, when i used to depress the clutch when starting the car. There's no oil pressure when first starting the car and stiff pp will probably cause damage to the dry thrust washer as it presses the rotating crankshaft against it.. stock pp can also cause damage in the long run... or bad luck?

Thus, I also STRONGLY recommend anyone to start their car always in neutral and without applying clutch!!

And I can imagine that when the thrust washer wears down a bit, it will not last long at all as oil film between crankshaft and thrust washer will not be as "perfect" as it should...
 
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