After a Red Bull-fuelled start of epic proportions last issue, our Honda CR-X SiR project bangs on this month with the engine, gearbox and flywheel coming under examination.

FULL PHYSICAL

With some suspect moisture in the intake ports, things weren’t looking that flash for our B16A engine when we pulled it out of the car in Racer-X’s first installment last month. But before we peeled off a few red notes for a replacement, the build crew agreed it would be worth a second opinion after all, Honda motors have a reputation for being tough little buggers and hard to kill. For that opinion we put a call through to NZPC’s tech guru, Steve Murch, luring him into the workshop on a Sunday with the promise of his favourite beverage: a white chocolate mocha latte. (Er! sorry Steve; we agreed I was to say a crate of Hairy Man ale, didn’t we?) The wise one would bring in his leak-down testing device and give us a verdict on the B16A’s bill of health. It was a good plan.

The way the leak-down instrument works is by measuring how much leakage there is in each of the engine’s cylinders. For the most part this will show up leaks from around the valves (worn guides), from around the pistons (worn piston rings), and from the between the cylinder head and block (blown head gasket). Ultimately, you’re aiming for no leaks at all, which translates to an engine in perfect working condition. Considering our CR-X is 18 years old and has obviously led a bit of a tough life, it was hard to be optimistic.

The testing began by finding the cylinder firing order, which in the case of our B16A was 1,3,4,2. The number one cylinder spark plug was removed and Steve dropped a long screwdriver in the hole until it was sitting on the crown of the number one cylinder piston. Turning the engine over by the crank, we were able to see top dead centre (TDC) when the screwdriver lifted to its highest position.

Of course, it could have been bottom dead centre (BDC), as the piston rises to its highest position twice in one combustion cycle, but TDC was confirmed by the position of the distributor.

The reason you need to undertake the leak-down test at TDC is because at this point both the intake and exhaust ports are shut, and theoretically the cylinder should be airtight. If the valves are open you’re not going to get much of a result, for obvious reasons.

Once we had the internals where we needed them, one of the leak-down gauge’s hose ends was wound into the spark plug thread. A compressor attached to the hose at the other end of the gauge and was switched on, forcing air into the cylinder and immediately revealing any leak on the meter. There was bugger all. Sweet. One down, three to go.

As it so happens, there wasn’t much drama and cylinders number two and three showed the same result. Number four had a slight leak, showing approximately 10 per cent down on the gauge. This percentage is not indicative of a 10 per cent leak, however, and is well within acceptable tolerances. So basically, it’ll be good to go back in the hole once all our bolt-on performance parts and gearbox get re-attached. We’re pretty lucky, really.

BOX OF BITS

As mentioned last issue, one of the reasons for pulling the engine out was because we wanted to remove the gearbox, and it’s no more time consuming hoisting both out at once than getting the box out on its own. It also means there’ll be fewer skinned knuckles when we replace the cam belt and other bits, and we can give the engine bay a good clean up.

From previous driving experience we knew the CR-X’s factory Y1 5-speed box had a few issues, as the box does in many performance-spec cars; in this particular instance it’s one of the parts most prone to wearing out. We could have gone to a later model gearbox, but that would involve upgrading the CR-X’s cable clutch setup to a hydraulic arrangement, and then there would still be the same chance of being lumped with a dud box.

So the call was made to stick with what we had, and let the pros at The Gearbox Factory strip it down to the last bearing and tell us what we need to do to bring it back up to task. Its main issue prior to disassembly was crunchy gear engagement, especially on the downshift from third into second, and there was bit of a noise. It was also difficult to change up from second to third at speed, instead preferring to select fifth.

After only a couple of days at The Gearbox Factory, Keith, Chris and the man on the job, Paul, had the gearbox in pieces and laid out on the bench for us so we could come in and pretend to know what we were looking at.

There were a few obvious issues straight off. Most of the gears themselves had worn teeth, and their new shape reduced the chances of a clean engagement. There was also a lot of glazing on the gears, meaning that it’s harder for brass synchro rings to be slowed down, which doesn’t help the gear-changing cause either. Around half of the bearings looked like they needed replacing, including the big diff carrier bearing, which was well and truly knackered and most probably the cause of a lot of noise.

While it all sounds a bit bad, the problems aren’t major ones to fix, and according to Chris they’re just general issues that arrive with regular wear and tear.

The good news that came out of the initial strip-down was finding out that the diff is of the limited slip variety, and most likely an aftermarket addition. This is a big score, because if there’s one thing you need in a track-spec front-wheel-driver it’s an LSD.  We’ll have more on the gearbox, including the step-by-step rebuild, next issue.

LIGHT ’N’ TASTY

With plenty of slip in fourth and fifth gears, it was obvious that the clutch in the CR-X would need replacing. When we got it out it looked every bit as poked as we expected. Hiding behind the clutch, however, was a very nice 3.5kg (7.7lbs in the old money) Toda forged chrome-molybdenum steel flywheel. Although the flywheel had a few hard heat spots it appeared in good condition, and given our 'budget’ mantra for this build, we decided that it was well worth retaining.

Any time you replace a clutch it’s recommended you have the flywheel machined to suit, but in the case of our Toda item it wasn’t that straightforward. Because of the deep heat marks, regular lathe machining doesn’t have much effect, so the flywheel needed specialist treatment. For that task we handed it over to BNT, which has a machine geared for the job down at its Invercargill branch.

Measurements were taken, before the machine was turned on and a stone disc did its work, grinding the face of the flywheel down to a straight finish and ridding it of all the heat marks. Returned to its former glory, it’s now ready to be mated up to a new clutch.

Words: Brad Lord Photos: NZPC

This article is from Performance Car issue 151, click here to check it out.