will it ruin or can it ruin anything in the head.... ???

Crankwalk will not ruin your head. It will just totally buttfuk your bottom end.

No pun intended ;)

That definatlly is sumthing , it means that the thrust areas on yur middle crank bearing have worn out or fallen out , some , depending on the main bearing type some have "thrust washers" on teh center bearing and some center bearings are made with it , if yu have experianced crank walk well yeah the bottom end is screwed pretty much . The lower portion of the connecting rods will be damaged , thrust plate , oil pump housing , the block tho should have not really sunstained any real damage , , depending how much the engine was pushes but it can be seen if the pan and crank is removed and inspect the thrust area to see if the crank wore into this area alot.

I thought that i read somewhere that there is something you can do to prevent crankwalk on the 7 bolts... replacing somthing or other...... Can anyone verify that and tell me what exzctly it is?? Thanks..

(i am wondering becouse i have read if you run over 350hp on them no matter the milage they are prone to start walking.. )

What is crank walk?

Crankwalk applies merely to models with manual transmission . The input shaft has slight in and out play in teh transmission thus it affects the crankshaft travel over time on some engines. This is the reason that a "thrust bearing" is used specifically on these engines to to keep the crankshaft frum traveling back and forth when the clutch pedal is depressed and pressed. Most older 4G6 series i have seen "6 bolts" yu call them and all asian market 4G63 engines were built alot stronger in this area and also used 2 thrust main bearings , which the main bearing has a lip on teh sides of it , and it closes the clearance so there is no travel of the crankshaft . Older 4G6 engines used 2 (mainlly asian markets) and if there was not 2 it used Thrust Washers , which were not part of the main bearing itself but sat in the same area , they were also made of a diffrent material to maximize strength and not wear in cases of poor oil lubrication. Later model "7bolt" models used just one thrust bearing , in the center crankshaft main bearing caps , unfortunatly poor oil lubrication , prolonged oil change intervals etc cause them to wear down extremelly fast in manual transmission vehicles causing the crankshaft to travel excessivelly back and forth.

very good explination... but can anything be done to make sure when runnin more power it does not happen?

Hi! :)

I am interrested in the same question, I am to rebuild my 7bolt soon. Change bearings and internals..

does anyone know if they make a kit for it?

buy a performance rebuild kit

Yes there are kits for it , not really kits per say but there are high performance parts vendors that we get bearings frum like TOGA and RALLIART , J-EAST, etc that make higher performance rod and main bearings that are made for higher reving and durability . TOGA is one we use alot and J-EAST which also makes a really good bearing , they make the rod bearing our of an aluminum composite , so if like yur oil pan cracks or sum reason yu loose oil pressure the rod bearings will east up a bit til there is a bit of slack and it will not damage the crankshaft. and they have really strong main bearings with 2 and 3 oil whole position and a gulley for constant oil saturation on both sides and not just one like most bearings That may have just one oil hole and a oil gulley on just one of the bearings.

Actually... Was talking to a mits mechanic the other day and he explained to me the reason the 7 bolts walk is because mitsu designed the crank and rods as oil squirters instead of the pistons (like in the 7 bolt). As you drive the 7 bolt harder and harder, the crank and rods will literally over "squirt" oil and deprive the crank of the necessary oil... thus wearing your crank bearing, thrust bearing, and basically screwing over your bottom end in any other way possible.

If you wanna prevent crankwalk there are a number of things you can do.

1) get an auto tranny.
2) get better rods and pistons
3) best option IMO, 6 bolt swap

Forget Rebuilding a 7-bolt or making it stronger! Just buy a 6-bolt motor and drop it in. Its not easy but well worth it! And when you get the 6-bolt if your 7 has some life left in it then spend a little extra and bore it and get aftermarket rods and pistons. If your goin to swap might as well do a little work while the blocks down.

if your crank walks and destroys the bearings then little tiny pieces of metal will be sucked up into your oil. If you run it too long after the bearings fry then yes, you can ruin the head.

the easiest test for this is make a hard left hand turn and if your clutch pedal falls to the floor,,, don't run your car,, until you have rebuild the bottom end.

a good preventive measure: install new main and rod bearings. have a machine shop advise on a line bore and if it is necessary, they will tell you the bearing size you need.

if you have a dial gauge mount it to one of the brackets or the fram under the car and put the dial on the crank pulley. Yank back and forth on the crank pulley and if it moves more than .010"(can't remember exactly but this is alot) you will need new bearings soon

The Supra guys have come to the conclusion that it is the clutch switch. You know you have to push the clutch in to start the car.

I've heard more stories about an upgraded clutch and then crankwalk then a stock clutch and crank walk. Reason being the pressure plate and what not are up and sitting on the crank with no oil or lube for start up.

move the by pass switch somewhere else and don't use the clutch on start up and you will minimize your risk for crank walk.


Oh and the good news is Supras have crank walk too, even better, their AUTOs are not immune to it. The bad news is the percentage of affected 2JZEDETTs is much lower then the 4g63t's