Free Balance Shaft Removal

Free Balance Shaft Removal

This can be done with the engine in the car, Scroll to the bottom to see what you do different.

Parts needed: JB Weld (fast set type if you can't wait a day)
Frost Plug (40mm or slightly larger if you can only get imperial ones.)
Hacksaw
8X1.25 25mm bolt
8X1.25 tap

	Remove the oil pan
	Remove the pulleys and gears. Remove the engine cover
	Here's a couple photos from the bottom of the engine of the front and rear balance shafts in the engine still
	The rear balance shaft is part of the oil pump assembly. It can be removed from the oil pump assembly by opening the front cover of the oil pump and removing the bolt. The balance shaft should just pull out from the back of the oil pump once the engine cover is removed.
	You have to tap the threads in the end of the rear balance shaft to accept a longer bolt. Use a 8X1.25 tap and go about 1 cm deeper. This will seal the oil holes completely and keep the oil pressure up. Make sure to clean out the metal tap shavings so they don't go in the oil system. The second picture shows the top stock bolt that used to hold the pulley on the shaft. The lower bolt is the one that will replace it. (New bolt is 8X1.25 25mm long, stock one was 20mm long) (note: You won't see the pulley as in the pictures if you just remove the balance shaft from the oil pump without taking the oil pump apart which is the recommended way of doing it. Leave the oil pump intact so you don't have to replace the gasket.) Before reassembling make sure that the bolt when screwed in covers the oil holes. You need to leave the bolt out 1mm to compensate for the pulley if you didn't take the oil pump apart.
	Just cut the shaft off next to the oil pump. Takes 5 minutes with a hacksaw, be patient. You can put the balance shaft back in the oil pump assembly to keep it from rotating while cutting. If you're using a dremel or cut off saw just mark where the oil pump ends on the shaft and cut it off there.
	The front balance shaft seal hole needs to be filled so that the oil doesn't come out. The mitsu frost plug fits in the hole and a little of the JB weld keeps it in place (use the slow setting stuff if you can wait a day to put it back together, if you're in a real hurry then use the quick set type JB weld) Be sure to plug the bolt hole for the balance shaft pulley that you've removed. It's a nasty oil leak if you forget to plug it!!! You can just use a shorter bolt with a little gasket maker or thread lock on it to seal it.
	The front balance shaft has oil holes for the bearings. Pop the front one out with a large socket or a screwdriver but don't damage it (much). If you rotate the sleeve bearing 180 degrees the hole no longer lines up with the one in the block and keeps your oil pressure up. The bearing behind this one is a little more difficult to get at but here's the secret that only I will let you in on (all those $60 kits sell you the "specialty tool to remove it) if you turn the balance shaft around so that the end that the pulley use to go on goes into the block first, that outside diameter is the same as the outside diameter of the bearing sleeve. Hit the end of the balance shaft a couple times to knock out the sleeve bearing. Turn it as well 180 degrees and reinstall the bearing with the balance shaft as an install tool. (see photo below if you've never seen a balance shaft and I've lost you at this point. The shaft I'm talking about is the top one)
	Here are the shafts and pulleys removed. The shafts alone remove 6 lbs of rotating mass from the engine. "There is an average of 2.7 HP gained from every pound lost off the crank shaft." - Unorthodox Racing Given that the balance shafts are spinning at twice the crank rpm it has a potential of a 32hp gain! (I figure 15hp is realistic, Unorthodox ALWAYS exaggerates their claims. What more can you ask for from a free mod?

Removing Balance Shafts with the engine in the car

There's a few things to do differently if the engine is in the car. Leave the front balance shaft in the engine. You'll have to remove the front balance shaft gear to get the front engine cover off but without tilting the engine to a wicked angle it's next to impossible to knock the old front balance shaft bearings out and install the new ones. Just leave the shaft in so that it blocks the oil holes in the bearings. Removing the balance shaft belt will stop this shaft from rotating and to put things in perspective you're just leaving 2 lbs of dead weight in the engine, about the same weight as the build up of mud in your back bumper. Follow the same procedure as if the engine was out of the car for the rear balance shaft removal and don't forget to put a bolt in the hole where the balance shaft belt tensioner used to be. You'll have to put the front balance shaft pulley back on after the engine cover goes on to prevent oil leaks. You'll get the exact same results either way you do the balance shaft removal, the key is that you've reduced the engine rotating mass.

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This page was last edited July 31, 2001 10:36 PM