Balancer shaft deletion: what owners did on the Turbo and NA

The short version

• The balancer shafts are driven by the crank and spin to cancel engine vibration. An owner who had one out said the Turbo's weighed almost 6 kg. Others said about 4.5 kg, 4 kg or nearly 5 kg.
• On the Turbo, a kit from Courtenay Sport replaces the shaft unit. Owners did it with the engine in the car and the sump off.
• On the NA it is a different job and owners said it means taking the engine out.
• Owners who did it said the engine revs more freely. Most noticed little or no extra vibration. A few noticed a lumpier idle.
• Owners disagreed on whether it is worth the risk and whether the bottom end should be balanced at the same time.
• Do not just block the oil feeds and leave the shafts out. An owner warned the crank would "make a bid for freedom". Use the kit, or the equivalent parts.

What the balancer shafts do

Owners described them as contra-rotating weights that cancel vibration from the crank and moving parts. One said they turn at twice engine speed on the 2.2, another that a gear on the crank drives a pair of eccentric weights at double engine speed. They are driven off the crank like an alternator, so they take some power to turn. One owner said GM claimed about 5 bhp for each shaft on the 2.2, without saying at what rpm. Another owner thought the real loss was only bearing friction and was small. Nobody in these threads measured it.

The owners who argued for removal pointed out that the Turbo's predecessor, the X20XEV, had no balancer shafts, and that the Astra VXR's Z20LEH came without them from the factory. One said the strengthening ladder frame and splash panel in the kit come from the X20XEV. One owner added that engines from before 2000 (the X20XEV) and the Z20LEH have no drive gear on the crankshaft for them. Another pointed to the many other four-cylinder engines made without balancer shafts.

Turbo (Z20LET): the Courtenay Sport kit

What owners said it contains and costs

• A ladder frame that is an OEM part from an X20XEV-type engine, an oil pickup and baffle or splash cover, 8 bolts, blanking grub screws and a gasket.
• About £89.95 in 2009. A 2008 post said just under £90 and a reply in the same year said £100.
• In spring 2010 the kit was out of stock for some time. A customer who rang Courtenay Sport said the company that made the oil pickup pipe had gone bust and a new supplier was being found, with stock expected in two to three weeks. A later call in the same thread was told the kit was going through a re-design. The kit was available again later in the thread.
• Courtenay Sport's own words, as an owner quoted them: the kit is for the Z20LET, Z20LEL and Z20LER, reduces internal power losses and lets the engine rev more smoothly and briskly when the bottom end is lightened and balanced as part of a rebuild, and saves nearly 5 kg.
• A reply from them to a customer said the Turbo's shafts are gear driven, so the job is to remove them, blank the oil feeds to the shaft gears and fit the kit.

How owners fitted it (engine in the car)

This is one owner's 2011 write-up, with other owners' comments added. He said he had written it from memory and should have taken more photos.

1. Jack the car or use a ramp, and remove the undertray.
2. Drain the oil.
3. Remove the lower sump, which is about 15 bolts. Undo the two bolts holding the sensor in the lower sump and leave the sensor hanging.
4. Remove the upper sump. He called this the fiddly part because the exhaust gets in the way, especially a 3 inch one. There is an electrical plug above where the sensor hangs, and some bolts are horizontal as well as vertical. He took the downpipe off the turbo to get more room. Another owner said you drop both sumps, because the lower part has to come off to reach the upper sump bolts.
5. Remove the oil pickup pipe (4 bolts), then the bolts that hold the balancer shafts on.
6. Remove the crank bearing caps one at a time, so nothing gets mixed up. The two outer holes in each cap are drilled bigger to a set depth, then tapped, and grub screws are fitted with threadlock. The grub screws block the oil feeds that used to go to the balancer unit. He could not remember the drill size, depth or the cap torque. The kit's paperwork gives the sizes.
7. Fit the new ladder frame, oil pickup and splash cover.
8. Refit the sumps in the order they came off, using new gaskets. Reconnect the sensor and the plug, refit the exhaust and undertray, lower the car and refill with oil.

Other owners added the following:

• One owner had Courtenay Sport do it with the engine in the car. He said it took "a fair few hours" of labour, including removing the bearing shells to tap and block the feeds.
• Another had it done at a garage and suggested combining it with a service, because the oil comes out anyway. He also recommended fitting the underdrive alternator pulley at the same time.
• An owner who had done it himself reused the oil, which had only done a few hundred miles.
• If you do not want to drill the caps yourself, two owners suggested taking the bearing caps (one said "shell bearings") to an engineering shop. One said he would use the machine shop at work. Another did it with a hand-held electric drill and re-tapped the holes, and reported the engine fine after nearly two years.
• One owner said he had decided not to bother after reading the kit's fitting guide and finding out the caps had to be drilled.
• One owner removed the shafts and said to check the bearing caps for wear while they are out. His were fine.

The home-made version

In 2011 an owner said that you could make your own if you were prepared to. His steps were: get a ladder frame from an X20XEV (he was only 75% sure of that, and others asked to have it checked), tap and block the two oil feeds with grub screws and threadlock, make a baffle from sheet (not essential in his view, and he had none), and perhaps bend the old pickup pipe to clear the different-shaped X20XEV ladder, which would need welding or brazing. An owner listed GM part numbers for the pieces:

• 90610450: oil baffle plate bracket (X20XEV, Z20LEH)
• 90652279: oil baffle plate (Z20LEH)
• 90648384: oil pipe and filter head (Z20LEH)
• 90502090N: the sump gasket he thought was right (his link had died by the time a later poster looked)
• plus grub screws for the oil ways

A later poster rang Vauxhall about these and was told they might be old numbers, so check them with a parts counter before ordering. He then found the sump gaskets online by their numbers (in the parts list). Courtenay Sport's own parts came from the Z20LEH Astra VXR engine, according to an owner in 2008.

NA (Z22SE): a different job

The Turbo kit does not apply. Owners said it is an engine-out job. One thought the NA's shafts come out sideways, where the Turbo's sit under the crank as one unit. (An owner in 2008 first said the NA had no balance shafts, then explained he meant it does not have the same set-up as the Turbo kit. The NA does have them.)

The method owners used

As one owner described it, and others agreed it was nearly free:

1. Take the shafts and sprockets out and dismantle them.
2. Cut the counterweights off the shaft ends.
3. Knock the bearings further into the block so they cover the oil feed.
4. Refit what is left of the shafts to the sprockets and refit.

The shafts then act as idler gears for the chain. One owner said an owner in the USA had done well over 50,000 miles with idler gears, so he saw no long-term issue. Since the water pump is chain-driven, this keeps the chain and the pump turning (see Water pump replacement).

Other ideas that were discussed

• Just remove the chain. One owner suggested this as a reversible option. Another pointed out the chain drives the water pump, so the pump would not turn.
• A shorter chain straight from the crank to the pump. An owner posted a picture of a GM short-chain arrangement and another found a GM racing balance shaft elimination kit (XGH676). Owners who had looked into it said it needs the shafts and bearing housings removed completely, the oil channels sealed, and a new chain guide made because the standard ones do not fit. One owner said the chain guide would wear quickly because of the angle the chain takes around the crank sprocket. A Dutch Speedster mechanic had made his own guides and inserts but said the hard part was getting a shortened chain made, because no firm would do it reliably. An owner who asked an F1 team contact was told the gain over the idler gear method would be negligible, and the others agreed it was not worth the extra money.
• An electric water pump. Raised as a way to remove the chain completely. One owner thought another member had fitted one and had air-lock problems at first. Nobody in these threads confirmed a working conversion.

What owners noticed afterwards

• Revs and response. Most said the engine revved up faster, especially with a lightened flywheel, the underdrive pulley and short belt. One owner who did the NA with big cams said he could not tell the performance difference and thought it only revved slightly faster. See Lightened flywheel: daily driving, engine braking and what owners found.
• Vibration. Several said they noticed nothing. One said the NA ran smoother after removal with performance cams. Others felt a lumpier or slightly less even idle. One said it was a myth the engine becomes lumpy.
• Poly engine mounts. Several owners said uprated or poly mount inserts added far more cabin vibration than the deletion did. One owner with only the front uprated mount had a windscreen-shaking vibration at his natural idle speed, which went away at 75 to 100 rpm higher. See Engine mount failure noise.
• A rattle that went away. One owner got a rattle from the bottom of the engine after fitting the underdrive pulley, and it disappeared when he removed the balancer unit. He said he had heard of others with the same problem.
• Weight. Anything from about 4 kg to nearly 6 kg for the unit, depending on who was asked. Owners said other changes (lightened flywheel, removed ancillaries and sound proofing) added up to a car lighter than standard.
• Power. No dyno figures for the deletion alone appear in these threads. One owner repeated the GM figure for the 2.2, and another said removal mostly stops the engine losing power turning them rather than adding it.

The case for and against

Owners who thought it was safe

• One owner said that "dozens" of owners had removed them and he had heard of no ill effects. Several others said they had heard of no failures.
• One had run without for a year, another for over a year, with no problems. A 2.2 owner removed his a couple of years earlier, then had the bottom end balanced and found the crank was "spot on". Only the lightened flywheel needed rebalancing. His engine had steel rods and forged pistons.
• Another owner said technicians he knew at a Ferrari and Lamborghini garage said they would do it without question.
• When a poster on an Astra forum claimed that lots of VX owners who removed the shafts needed a rebuild every 6,000 miles, an owner who knew the cars dismissed it.

Owners who were cautious

• An owner advised having the crank balanced to tighter tolerances at the same time, or tiny vibrations could shorten the engine's life.
• A race-build owner's blog, quoted in 2009, tested a spare crank and found a 300 gram deficit on each crank counterbalance even with lighter pistons and rods, which he calculated as a 2 ton bending load between cylinders at 7,000 rpm. Another owner replied that the 2.2 is a different engine from the Z20LET, whose block he said dates back to the 1970s. A third said they balance the bottom end when removing them on a race car.
• Courtenay Sport told one owner it is only really needed on highly tuned cars (stage 4 or 5), according to that owner. The same owner was concerned about the balancing point above.
• An owner who did not do it said the benefit is tiny and the risk of removing and drilling main bearing caps is large, and suggested simpler mods instead.
• An NA owner who removed them said "personally wouldn't bother", as the idle was poor with performance cams and he could not tell any gain.
• The 2.2 was built for estate and rep cars, where smoothness matters, according to one owner. He said the VX is rough and ready, so it makes sense if the engine is out anyway.

Sump baffles (a related job)

An owner suggested adding a baffle or two to the sump if you track the car with sustained cornering. He knew someone who would weld them in for about £50. Another owner knew of no one who had baffled the standard Z20LET sump, but pointed to a member of another forum who had posted pictures of baffling a C20LET sump and offered a baffling service. The ladder frame from the kit also acts as a baffle.