Acura NSX Gets New Engine & Transmission Parts - Project NSX - Wrenchin'

NSX Drama
Look around and you'll find that early NA1 NSXs have at last transcended below that price point that many simply find unreasonable when considering a 15-plus-year-old Acura. It could be because of the economy, or perhaps it's the lack of interest in cars with two too many cylinders in this age of fuel efficiency awareness, but it doesn't matter. Honda's all-aluminum supercar is, at long last, affordable. Rejoice, but don't let the entry cost fool you. Owning and maintaining an NSX is never cheap and modifying one is even worse. Deep pockets are mandatory as is at least an inkling of mechanical know-how. For perspective, compare a mid-'90s Civic timing belt to the NSX's. The NSX belt is nearly four times more costly, yet it's made of the same material, by the same manufacturer, presumably at the same plant. It isn't gold-lined, and it won't make you any more popular. The clutch assembly is even more discouraging, with the NA1 NSX's OEM twin-disc setup retailing for roughly $1000 more than the Civic's. Installation costs are worse, as space is tight and many technicians prefer complete engine removal for otherwise routine maintenance. But with a little bit of dexterity and a whole lot of patience, the NSX can be relatively easy to work on and, if you've familiarized yourself with engines like Honda's B-series and chassis like mid-'90s Civics and Integras, you'll no doubt find yourself in familiar territory when tinkering with the NSX.

Recapping
Bolt-ons are nice but they often lead to bigger things. The story begins with a sub-$30K Berlina Black NSX, a few basic mods, like coilovers and rims, and an overzealous, anal-retentive owner. Project NSX--until now, a one-owner, high-mileage commuter car--fell into my hands in relatively good condition. Upon inspection, the chassis was straight--never so much as tapped--the interior was a 7 out of 10, and the suspension, brakes, and drivetrain were all met with a nod of approval. As such, there was little left to do except install a set of Buddy Club coilovers paired with 17- and 18-inch Enkei RPF1s matched with BFG tires. The engine was left untouched, but a few key brake upgrades were made along with an alarm and tracking system, and some basic, albeit expensive, interior trim pieces. Life was good...for about a week.

The Build
It's difficult for an honest enthusiast to leave something alone. Improvement is often unavoidable. Such was the case with Project NSX. The idea to freshen up the aging paint job soon led to a complete teardown and overhaul. The chassis was stripped of all four fenders, its hood, bumpers, trunk, doors, side sills, and wing, and the engine and transmission were pulled all in an effort to increase the car's longevity both inside and out. Similar to newer Hondas, the NSX's engine and transmission must be removed along with the car's rear subframe, which includes the rear brakes and suspension assembly. It really is one of the easiest engines to remove; of course, there are the routine engine-removal steps like disconnecting fuel and coolant hoses and throttle cables, but the axles can be left in and the engine can remain seated in its subframe by its front and rear mounts until it's pulled away from the chassis. Now was a good time to separate the engine from its transmission and get it up on an engine stand. Aside from any gaskets or seals that would be encountered once the cylinder heads were removed, every single gasket, hose, and o-ring known to Honda was ordered and thrown in the parts pile and eventually onto the engine. The opportunity was also taken to replace the transmission's input shaft bearing. Like the engine, even the NSX's transmission is eerily similar to its B-series Integra sibling and the process for replacing parts like bearings, synchros, and differentials isn't much different.

Cleaning an engine that's seen more than 100,000 miles isn't easy and involves several bottles of degreaser, multiple wire brushes, and stockpiles of rags. Once cleaned, the timing belt and water pump were replaced, camshaft seals were swapped, and the valves were adjusted. The valve adjustment procedure for C-series engines is similar to that of any other twin-cam Honda engine. When installing the timing belt, it's important to align the camshaft gears and to tension the belt exactly how Honda instructs you to. Also, notice that the C-series' camshaft gears are specific to each camshaft; don't mix these up. Failure to perform any of these steps the right way will most likely result in bent valves, nicked pistons, and a much smaller savings account. On a side note, it's extremely difficult to line up all four gears with the engine in the car. The process involves a couple of mirrors and lots of double-checking. Notice how the entire drive belt system looks similar to any other early- or mid-'90s Honda engine.

Since the tensioner should...        read full caption Since the tensioner should be replaced along with the timing belt, I opted for a locking one from CT Engineering. The tensioning procedure is a bit different than when using an OEM one, and you won't be able to adjust it once the covers are on--even though the CT one uses an OEM tensioner bearing--but a locking rod end bolts to the water pump housing, making sure the tensioner stays put.	All six fuel injectors were...        read full caption All six fuel injectors were dropped off at RC Engineering for a flow analysis and overhaul. RC charges $24 per injector to clean and calibrate most Honda ones and even includes a new set of o-rings. The process isn't a bad idea, especially when you're working with used injectors that you know nothing about. The NSX's weren't off by much, about five percent from best to worst.	As much work as possible was...        read full caption As much work as possible was done while the engine was on the stand, including the valve adjustment and fitting as many new hoses to the engine as possible.
NA1 NSXs with five-speed transmissions...        read full caption NA1 NSXs with five-speed transmissions are equipped with twin-disc clutches right from Honda. SPEC set me up with a single-disc clutch that's about 5 lbs lighter than the stock one. To accommodate the missing clutch disc, SPEC's setup is paired with an extra thick but lightened flywheel that spaces the single disc away from the engine block. This allows for the transmission's input shaft to reach and makes for an easy conversion.	I opted for a sprung-hub,...        read full caption I opted for a sprung-hub, single-disc setup for something that'll be easy on the foot. SPEC supplied everything from the clutch alignment tool to the pilot and throw-out bearings. Oh, did I mention that the entire setup is about half the price of a new OEM one? The SPEC pressure plate also features beefier straps and rivets, which means it'll last a bit longer too.	Unlike most other Honda clutch...        read full caption Unlike most other Honda clutch applications, the NSX's throw-out bearing fastens to the pressure plate. This makes installing the transmission a bit tricky since the clutch fork must be slid onto the bearing while the transmission is being pushed toward the bellhousing. It really does take two people to make this happen.
I also took the opportunity...        read full caption I also took the opportunity to replace the transmission's input shaft bearing, which contributed to the annoying knocking sounds at idle. The entire engine wiring harness was also stripped and re-loomed for a like-new appearance.	To properly paint a car like...        read full caption To properly paint a car like the NSX, you've really got to disassemble the entire thing. The guys at Downforce in nearby Anaheim, California know this. The car was completely taken apart--including everything from the doors to the bumpers, hood, trunk, side sills, and more. Each part was individually stripped, prepped, and painted. Downforce is a relatively small company, so the shop's manager, even its owner, had their hands on this thing and, at the very least, oversaw it from start to finish.	Sometimes the subtlest of...        read full caption Sometimes the subtlest of modifications are the most rewarding, like getting your ride-height just right, down to the last 1/8 inch, or sourcing a set of thin side moldings for your Civic that only you and a select group of enthusiasts will know are special. Such is the case with Project NSX. Dorky body add-ons and NSX-R wannabe nonsense was out of the question, but there are a couple of basic exterior mods I've addressed, despite how subtle they may be. For the most part, there are few differences between the JDM and USDM NA1 NSXs. Of course, the JDM version is RHD but almost everything else is the same. Almost. In the name of highway safety, the U.S. DOT requires automakers to do all sorts of silly things, one of which is to plaster a couple of huge sidemarker lights on both sides of cars like the NSX. Don't kid yourself, they look out of place and they've got to go. But despite how subtle the mod might be the solution is either really time-consuming or really expensive. I'm cheap so I took the time-consuming route. Remember, the NSX is rare and its fenders are made of aluminum, both factors that contribute to some expensive pieces of metal. It's not unheard of for a couple of fenders and rear quarter panels to go for the price of a clean DC2 Integra. With that in mind I decided to bust out the old TIG welder. The trick is to leave the fenders on the car while welding, do a bunch of periodic stitch welds, and keep the metal cool with a wet towel in between welds. Skip any of these steps and, like it or not, you'll have to forget about that DC2 you wanted and shell out for some new NSX hardware. Four precision-cut pieces of sheet aluminum, several dozen stitch welds, and a few hours later and I've got a complete set of make-shift, JDM fenders. Almost - the guys at Downforce still had to get their hands on them for a truly finished product.
Everything was torn apart....        read full caption Everything was torn apart. The mirrors were removed from the doors and disassembled as were the headlight housings, A-pillar covers, door trim pieces, and air ducts.	Downforce reassembled most...        read full caption Downforce reassembled most of the car for me since lining up NSX body panels is more of an art than it is a science. Despite the NSX's cost, exotic nature, and exclusivity, its construction is quite raw. The car has two strikes against it from the get-go: it's made of aluminum and it's hand-built. Both attributes make for a difficult reassembly process, one in which I struggled with for days. Mass-produced, stamped-steel body panels--like those for your Civic--are relatively easy to put back where they came from. It isn't terribly difficult to line up fenders, hoods, and bumpers as they pretty much go back on the way they came off. Aluminum parts like to re-shape themselves after sitting around getting painted, and NSX aluminum panels vary from one another. A lot. This is where shims come into play. You might not expect to hear the words shims and NSXs in the same sentence, but they play a vital role in assembling one. But the shims are not some body shop hack. No, NSXs were shipped directly from Honda this way, shims and all. You might find one nearly a quarter-inch thick behind the lower part of your driver-side fender, all in an effort to make the fender and door flush with one another. But don't expect to find a similar sized shim, if any, behind your buddy's NSX's fender. The whole process is quite random and, while a single shim might have worked in a certain spot before teardown, it's likely that it won't work there during assembly. The solution is to have a big bag of shims handy and plenty of spare time.	If you own an NSX, you know...        read full caption If you own an NSX, you know how much money you can save by repairing rather than replacing. Take the side air ducts for example. The aluminum housings cost more than $400 each. These ones were stripped, which meant the plastic vent covers couldn't be screwed back on. The solution involved a 3mm tap, $2 worth of hardware, and some very careful drilling and tapping.
When taking apart a 17-year-old...        read full caption When taking apart a 17-year-old car you can expect things like taillight gaskets to be destroyed. There are four pieces that need to be replaced. Nope, they aren't cheap.	Not having a lift doesn't...        read full caption Not having a lift doesn't just mean it's more difficult to get the engine in and out but there is a lot of time wasted here. The subframe and suspension has to come out in order to remove the engine and transmission but it's also got to go back on the car in order to move the car around.	Okay, I now have two sets...        read full caption Okay, I now have two sets of engine mounts. Of course, I only need one though. The ones on the left were fabricated by the guys at Downforce. They took the three factory aluminum mounts (the right side one is steel), and filled them with a higher density rubber. The Innovative Mounts set on the right was built form scratch and filled with similar rubber. The Innovative set is constructed of steel, but the company says it plans on producing a billet aluminum version in the near future.
Okay, I now have two sets...        read full caption Okay, I now have two sets of engine mounts. Of course, I only need one though. The ones on the left were fabricated by the guys at Downforce. They took the three factory aluminum mounts (the right side one is steel), and filled them with a higher density rubber. The Innovative Mounts set on the right was built form scratch and filled with similar rubber. The Innovative set is constructed of steel, but the company says it plans on producing a billet aluminum version in the near future.	If you follow the engine removal...        read full caption If you follow the engine removal procedure outlined in the 1991 Acura NSX service manual, you risk breaking the car's delicate yet expensive aluminum suspension components. And we aren't talking about sloppy, inexperienced home mechanics who have no business changing their own oil let alone swapping an engine--this was a problem that seasoned Honda- and Acura-authorized technicians experienced. As a result, the service manual was revised, instructing technicians to remove the entire subframe, suspension, and braking systems as a single unit, along with the drivetrain, just to eliminate the need to un-pop the suspension's ball joints. Under no circumstances should any of the NSX's ball joints be popped apart (unless you actually need to replace one), like you'd naturally assume to do when pulling most any other Honda engine from its chassis. All of this made me having to change my NSX's two rear, upper control arm ball joint covers all the more sketchy. The trick is to use the uber-expensive NSX-specific ball joint removal tool and to center it perfectly over the joint. If you don't, and pressure isn't applied evenly, very expensive aluminum pieces will crack. How expensive? Well, an NSX's rear upper control arm retails for just over $1100, it's knuckle about half that, and there is not an OEM-replacement ball joint offered by Honda since it's sold as part of the arm assembly. Needless to say, one false move and it's all over. With the suspension off the car, I could normally change two ball joints in no more than five or ten minutes. The NSX's took me about an hour...to do two, and that goes without mentioning the beads of sweat that dripped down my face and the trembling hands as I contemplated the likelihood of a several-thousand-dollar mistake.	If you follow the engine removal...        read full caption If you follow the engine removal procedure outlined in the 1991 Acura NSX service manual, you risk breaking the car's delicate yet expensive aluminum suspension components. And we aren't talking about sloppy, inexperienced home mechanics who have no business changing their own oil let alone swapping an engine--this was a problem that seasoned Honda- and Acura-authorized technicians experienced. As a result, the service manual was revised, instructing technicians to remove the entire subframe, suspension, and braking systems as a single unit, along with the drivetrain, just to eliminate the need to un-pop the suspension's ball joints. Under no circumstances should any of the NSX's ball joints be popped apart (unless you actually need to replace one), like you'd naturally assume to do when pulling most any other Honda engine from its chassis. All of this made me having to change my NSX's two rear, upper control arm ball joint covers all the more sketchy. The trick is to use the uber-expensive NSX-specific ball joint removal tool and to center it perfectly over the joint. If you don't, and pressure isn't applied evenly, very expensive aluminum pieces will crack. How expensive? Well, an NSX's rear upper control arm retails for just over $1100, it's knuckle about half that, and there is not an OEM-replacement ball joint offered by Honda since it's sold as part of the arm assembly. Needless to say, one false move and it's all over. With the suspension off the car, I could normally change two ball joints in no more than five or ten minutes. The NSX's took me about an hour...to do two, and that goes without mentioning the beads of sweat that dripped down my face and the trembling hands as I contemplated the likelihood of a several-thousand-dollar mistake.
With the drivetrain out, now...        read full caption With the drivetrain out, now was a good time to rebuild all four CV joints. They aren't terribly expensive and will save hours worth of work later on. Don't be cheap; do it now.	Not having a lift in your...        read full caption Not having a lift in your home garage means you'd better be creative or willing to take your car to a shop. I wasn't interested in towing my NSX back to one of my friends' shops to reinstall the drivetrain. Doing so would have meant loading and unloading my car onto a trailer and risk damaging it twice. I just replaced the AC condensers up front and wasn't about to risk damaging the new ones. I'm also not interested in leaving my car unattended at a shop for who knows how long at which time customers can take turns sitting in it while I'm not there. Besides, I work better alone, without distractions, which makes my garage the perfect place to get things done. But I still don't have a lift, which means I had to get creative. In short, I needed 27 inches of clearance out back in order to slide the drivetrain in place. The solution involved two ramps, four three-ton jack stands, two six-ton jack stands, two hydraulic floor jacks, and an engine hoist. Both bumpers also had to be removed, which wasn't really a big deal since they've only been held down by a couple of bolts since the car left the body shop. If not, the front bumper would've hit the ground when jacking up the rear so high and the rear bumper wouldn't have allowed the engine to slide in. The only downside to installing the engine this way is that the subframe must be installed separately, after the engine and transmission are hung in place by the two side mounts. One of the nice things about installing an NSX engine with a lift is that you can install the axles, assemble most of the suspension, connect the front and rear engine mounts, even fill the transmission with oil, all without having the car anywhere in sight. But doing it my way works too--and I didn't even need an expensive lift.	And then there's my Taitec...        read full caption And then there's my Taitec GT Lightweight exhaust and Random Technology cats. The combo sounds awesome...once you put the silencers in it. It also fits great and is much lighter than stock.