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Sport Compact Car - December '97

Project Sentra SE-R

By Dave Coleman

[Put into HTML format by Pat Griffith]

From used car blues to Type-R track manners in one easy session.

Photography: Les Bidrawn, Dave Colemandec8_small.jpg (51497 bytes)

In our test of the Integra Type R back in May, we were amazed by how well that car did just about everything, but the front driver's balanced cornering attitude really stood out. "Front-wheel drive cars," we stated, "absolutely always understeer. The Type-R just changed that." While we still stick by that statement, we have to add one more car to the list of exceptions. Our 1991 Sentra SE-R tackled the same tricky road course at the Streets of Willow Springs with the same balanced handling as the Type-R, albeit with a little less velocity. But we're getting ahead of ourselves, time to introduce our latest project.


Last month we got all teary-eyed about the spiritual connections between the Datsun 510 and the Sentra SE-R (see "Bloodlines", SCC Nov '97), so now that we have that out of our system we can spare you the history and get right into the project. First, we'll start by answering the question you are probably already asking, "Isn't there already a Project SE-R?" Indeed there is, but the 1995 200SX SE-R we've been working on is actually quite a different beast than the previous generation 1991-1994 Sentra SE-R. The Sentra SE-R carries a different version of Nissan's venerable SR20DE engine, a more sophisticated suspension, and has a very different feel right out of the box.

Nissan has a long, established pattern of introducing great cars and slowly watering them down over several years. The classic Datsun Roadster reached perfection in 1967, and slowly got taller and more awkward until it was replaced with the 240Z in 1970. The Z did the same thing, slowly morphing from an elegantly simple sports car to an obese boulevard cruiser until it was finally re-born as the fabulous-but-expensive 300ZX. The 240SX also began as a taut, if slightly underpowered sports car, and later gained weight and had its sports car aspirations diluted as it entered its second generation.

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Early (1991-1992) SE-R engines can be identified by their intake manifold which places the plenum and throttle body down low, behind the engine.
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Later (1993-present) SE-R engines have a different head and intake manifold that places the plenum and throttle body on top.

The SE-R has not completely escaped this fate. The '91-'92 Sentra SE-Rs had a superb cylinder head  with intake ports that entered high in the head and flow straight down into the cylinder with very little bend. These early engines are recognizable by their inverted intake manifold that places the plenum and throttle body down low behind the engine-much like the 1994-1997 Integra GS-R's B18C engine. 1993 and later SE-Rs have intake ports which enter lower in the head and have to bend more sharply to enter the cylinder, reducing flow at high-rpm. These have a more conventional-looking intake manifold with the plenum on top. The Sentra SE-Rs also had a relatively taut stock suspension designed to deliver  well-balanced handling at the expense of a slightly stiff ride. The 200SX SE-R, on the other hand, has much softer suspension tuning, and  replaces the Sentra's multi-link strut rear suspension with a well-located, but less capable multi-link beam. The newer rear suspension has no anti-roll bar, which means the balanced handling of the earlier car is lost. One look at our project 200SX SE-R and you can see that its not hopeless. A few well-applied tweaks still go a long way, it just takes a few more tweaks for the newer SE-Rs than it does for the old ones.


Used Car Blues
The hardest part about buying an early SE-R is finding one. They were not exactly the fastest selling cars of their time, and those who did buy them tended to be enthusiasts who liked them so much that they still aren't selling them. Finding our SE-R took months of searching, but what we finally turned up was a pristine black '91 with 75,000 miles. The car had an unknown number of previous owners, but whoever they were, they were thankfully quite anal retentive. Inside and out the car still looks brand new.

Just a few weeks after buying the car, though, things started going awry. Blasting down the freeway one day at full throttle in fith, the tranny suddenly popped out of gear. Over the next few weeks it began popping out of fifth gear on a regular basis. (After speaking with several SE-R enthusiasts, it seems that a worn out fifth gear is a relatively common problem on early SE-Rs.) To make matters worse, both CV joints started making noise, and both front tires started going bald at an alarming rate. Not wanting to tear into the transmission or get our hands dirty with the nasty goop they put in CV joints, we took the car in to our local Nissan dealer and started crossing our fingers that the previous owner's extended warrantee would transfer over to us.

In the end, we ended up needing a new fifth gear, a new shift fork, fifth gear synchros, and basically everything that touches fifth gear. While the transmission was out, we also decided to have the clutch replaced. Given the pristine condition of the car, (it looked like it had been cleaned daily with tweezers and a feather duster) it seemed like a good bet that the previous owner drove like a wuss. If so, it followed that the clutch was probably still original, and with 75,000 miles on it, that original clutch would inevitably need attention soon. With the car torn apart at a Nissan dealer already, the choice for a new clutch was obvious. Nissan Motorsports offers performance and racing parts for everything from Datsun Roadsters to 300ZXs. They also happen to carry Centerforce clutches for SE-Rs, and any Nissan dealer's parts department carries Nissan Motorsports parts. Our performance clutch upgrade consisted of telling the service manager "Put a Nissan Motorsports clutch in there while you're at it." What could be easier? We also considered switching to a lighter flywheel while we were in there, but the stock SE-R flywheel is exceptionally light already, so there is little to be gained by making it lighter.

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From inside the combustion chamber you can see how straight the intake ports are on the early SE-R heads. This head has been worked over by Dan Paramore Racing, so it's quite a bit cleaner than a stock head, but the basic port geometry is unchanged. Unfortunately this head is not going on our project car... yet.

In case you were wondering, the extended warrantee did end up paying for the transmission and CV joints, so the $1500+ bill for driveline repairs was avoided. Lucky for us--it would have been a little more difficult to argue the merits of building a 7-year old sport compact car instead of a new one if we had to shell out over a thousand dollars just to keep the car on the road. The new Centerforce clutch is firmer than stock, but still relatively light with a very smooth engagement. Interestingly, the slightly-heavier pedal and stronger engagement gives the whole car a tighter, more connected feel. It's an interesting psychological effect that a lot of manufacturers could learn from. Sporty cars that feel sporty even on that test drive with the white-knuckled salesman in the car should have better sales potential.


Making it handle
With the money we saved on the transmission repair, it was time to deal with the handling. Even with bald K-Mart tires and a bad alignment, the SE-R's stock handling was surprisingly well balanced and tossable. It also wallowed slightly thanks to the worn stock shocks. With a fundamentally well balanced chassis to start out with, our initial plan was to get new wheels and tires, lower the car slightly, firm up the springs and shocks, and probably add stiffer anti-roll bars with an adjustable bar in the rear so we could tune the handling balance ourselves.

After removing the stock struts we marked the orientation of the strut tops so we could re-assemble them properly dec13_small.jpg (9055 bytes)
A spring compressor is needed to remove the stock springs, and an impact wrench is needed to remove the nut on the end of the strut shaft, but beyond that, nothing beyond normal hand tools is needed. When re-assembling the struts, the Tokico springs are short enough to install without a spring compressor, but an impact wrench is still helpful when installing the top nut dec9_small.jpg (7775 bytes)

We wanted to use springs and shocks from the same manufacturer based on the possibly-erroneous assumption that they would have well matched spring and damping rates. Every spring manufacturer and every shock manufacturer will have different priorities when making a new high-performance spring or shock absorber. If you end up with springs that were biased to the extra-stiff side, and shocks that were designed to be cushy-soft, you could have a car that bounces down the road like a mini-truck with polyurethane bump stops, and handles much worse than a stock car. Of course, chances are that most manufacturers will have somewhat similar ideas of what performance suspension components should do, so the mismatch shouldn't be that bad, but it seemed safer to get springs and shocks from the same manufacturer. After our positive experience with the Tokico springs and shocks on Jackson Racing's Civic (SCC October, '97) we decided to give them a try on our SE-R.

Installation of the springs and shocks was about as simple as it gets. Since we didn't have a spring compressor handy, we simply removed all of the struts fully assembled, took them and the new springs and struts down to the Wheel Warehouse, the closest well-qualified suspension shop, and had them use their spring compressor to mount the new springs and shocks. If you're on a tight budget, this can be a great way to save a lot of the labor when getting new springs and shocks. The only unexpected complication removing the struts was removing the rear seat to access the tops of the rear struts. To remove the seat back, you first have to remove the bottom of the seat, which is held in with two hidden latches. If you feel along where the front of seat where it meets the carpet, you will find the secret latches, and everything will come apart easily after that.

Often it is necessary to trim the bump stops when lowering a car to prevent them from coming into play during hard cornering. Ideally, the bump stop should only come into play in extremely hard bumps; if the suspension hits the stops during hard cornering, the tires can suddenly loose grip. When Wheel Warehouse separated the springs and struts, we noticed that the front bump stops were extremely short already, and were also very soft. Soft enough that they could even be compressed by hand. Because they were so soft, if the suspension bottoms out in a corner, the change in spring rate (resulting from the added force of the bump stop) will be more gradual, and therefore less of a detriment to handling than if it were extremely hard. It also means that if we cut it, there might not be enough bump stop left to protect the strut from bottoming out internally. The rear bump stops were a different story. They are quite a bit longer than the fronts, and also qutie a bit stiffer, so we decided to trim them. Since the top of the bump stop fits into the strut top, and the bottom of the bump stop is moulded into the dust boot, we had to cut the middle section out of it, and re-install the bump stop as two pieces.

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The front bump stops are tiny and quite short, so we didn't have to shorten them.
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The rear bump stops are quite long, so we decided to trim them to prevent the suspension from bottoming out in normal hard driving conditions. Since both the top and bottom of the bump stop fit into the strut assembly, we had to cut the middle of the stop out.
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The Tokico front springs (on the left) are significantly shorter than their stock counterparts. The rears (on the right) look like they are about the same height, but the top three coils on the Tokico rear springs are so soft that they go solid when the car is sitting on it's suspension.

One final note on re-assembly of the suspension, the Tokico springs have just barely enough pre-load to stay seated in the spring seats when the suspension is unloaded. It's important, therefore to make sure the spring is properly seated before the car is placed back on the suspension. The plus side of this is that you don't need a spring compressor to put the new springs on the struts, but make no mistake, you definitely do need a spring compressor to remove the old springs!

For wheels and tires we wanted to run a 16-inch setup, but didn't want big heavy wheels slowing the car down, or adding unsprung weight to the suspension. The wheels we found, 16X7-inch Black Racing Phantom N-1s (available from AKY USA), weigh only 15 pounds, yet are strong enough to stand up to real world roads. We talked to John Norris who runs these exact same wheels on his 240SX that he races in the Professional Sports Car series. The Phantoms, he says, are 2-pounds lighter than the wheels his competitors are racing on, and, while his competitors repeatedly bend their wheels, he has never bent a wheel. The stock SE-R wheel has an offset of 38mm, while the Phantoms were 45mm; we ran a 5mm spacer to bring the offset back to 40mm, which is exactly close enough. With 205/45-R16 Nitto NT505s, the front tires clear the wheel wells just fine, while the rears would just barely rub on the rear fender lip on big bumps until we folded the lip in slightly.

With the suspension installed, we took the car back to Wheel Warehouse for an alignment. The SE-R is adjustable for camber and toe at both the front and rear, so no elaborate camber plates or special camber-adjusting parts are necessary.   As we expected, the alignment was well out of spec.

With just the springs and shocks in place, we took the SE-R out to the Streets of Willow Springs, the small, tight road course adjacent to Willow Springs International Raceway. We were shocked at the handling! On the street the ride was firm, but not punishing, but it did seem like it bounced a little on sharp bumps, making the suspension seem slightly under damped. We feared that on the track this might translate into an inability to maintain grip on anything but the smoothest corner. (Tokico's Illumina 5-way adjustable shocks aren't available for the Sentra, so we were stuck using their non-adjustable shocks, otherwise we might have tried dialing out the bounce.) All our doubts about the suspension vanished when we reached the track, though. At speed, the suspension enters it's element; no matter what bumps it encountered on the track, the suspension always settled right back into position. Around corners, the car turned in incredibly well, could actually be induced into slight oversteer under hard trail braking, and would power out of corners in an easy four-wheel drift. (The SE-R's stock limited slip differential proved indispensable when powering out of corners.) It only took a few laps for us to give up on the idea of adding an adjustable rear anti-roll bar. The car was perfectly balanced with the stock bars. (That last statement should be a hint to owners of non SE-R Sentras. The suspensions are the same on all 1991-1994 Sentras, so with the same Tokico springs and shocks we used and the stock SE-R sway bars, any Sentra will handle like this. The front SE-R anti-roll bar is Nissan part number 54611 69Y11, and the bushings are part number 54612 58Y10. The rear SE-R anti-roll bar is part number 56230 69Y00 and the rear bushings are 56243 69Y10. You need two bushings for each bar, and the bars retail for about $100 for the front, and about $85 for the rear, much cheaper than most aftermarket bars.)

The Nitto tires, while not the stickiest tires available by a long shot, behaved quite well on the track. Their breakaway was smooth, consistent, and predictable, and a tire that breaks away smoothly and predictably will often allow you to drive faster than a tire with lots of grip that lets go suddenly.  More impressive was the fact that after nearly 50 miles of hard driving on the track  (broken up into several sessions where the car and tires were allowed to cool off) the tires showed very little wear, despite the fact that they were brand new and still had full tread depth. Many performance tires will start chunking if driven this hard will full tread depth, so we were happy to see that we wouldn't have this problem.

dec18_small.jpg (10890 bytes) On the rear strut, we found that it was easier to leave the anti-roll bar's end link attached to the strut when we removed it, and re-attach it to the new strut before re-installing it.
dec17_small.jpg (8343 bytes) The Tokico strut has the same brake hose support bracket as the stock strut, but is missing the bracket to support the ABS wire. If your car has ABS (this one didn't) you'll need to zip-tie the ABS wire to the strut housing to prevent it from getting snagged on any moving suspension parts
dec19_small.jpg (9084 bytes) When tightening the tops of the struts, push the top of the strut in toward the center of the car. This will give you a tiny bit more camber because of the small amount of slop in the strut top mounting holes. This is a common trick for SCCA Showroom Stock and Improved Touring racers to get the last possible bit of camber out of their stock suspensions. Of course, since the SE-R's camber is fully adjustable, this really isn't necessary, but it also takes next to no effort, so why not.


Reprinted with Permission