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View Full Version : S13/S14 Track width differences



djsilver
06-09-2007, 02:39 AM
Yes, I'm on night shift and bored..., Anyway, I have a 1990 coupe that I've built to run SCCA Solo and Track Trials in D-street prepared class. The rules are pretty funky but those that do it already know that :) In summary, I can mix and match suspension parts from the S13/S14 and I can use offset bushings & camber bolts but no adjustable LCA's/Tension Rods/ RUCA's, etc. Swaybars/Coilovers/wheels&tires are open.

I did the 5-lug swap up front by using an S14 ball joint in the S13 LCA and I've managed to work in some 16x8.5 300ZX wheels & 265/45/16 Kumhos without spacers by modifying my front strut mounts with longer mounting ears (and some neanderthal use of a fender roller!)

It all works very well but I was studying the FSM's for both vehicles for potential swap stuff and couldn't find any data on front/rear track width. Off to Yahoo and Google for a while and I came up with the following info;

S13; front 57.7"/ 1466mm
rear 57.5"/ 1461mm

S14; front 58.3"/ 1480mm
rear 57.5:/ 1470mm

So even though the S14 body is about 1.5" wider there's only about 1/2" difference in track width up front? The FSMs' respective body alignment diagrams show the hard points in that area to be the same, so is the difference is in the length of the LCAs? If that's the case the S14 LCA's may help me fit my next set of shoes (17x9 & 275/35/17) a little easier and increase my steering angle inclination at the same time. I'm curious about the differences in general on the S13/S14 front suspensions.

I also did the ghetto front sway bar upgrade by fitting a 27.2mm S14SE front sway bar. I had to use the stock S13 25mm bushings and brackets because the S14 brackets had different bolt spacing and the S14 bushings wouldn't fit the S13 brackets. It worked out OK except that the arms on the S14 bar were about 1" too long so the endlinks are currently angled back a bit :eek: (makes for another queston about S13/S14 suspension differences). It's a hollow sway bar so I can shorten the arms when it comes off for new poly bushings. ;)

So, who's already been through all this and knows all the answers?

J_Rho
06-09-2007, 04:49 AM
Sorry I can't help you on the track or arm length info djsilver, but I'm stoked to see someone giving the 240 a try in DSP. I think you're starting from the perfect 240 platform for such a beast - no DSP 240 will be as light as you'll be able to get your early coupe.

I see you're considering the 275/35-17 - might I suggest you consider instead the 285/30-18 all around, which is wider and shorter. They'd work great on 18x10's, which will fit fine under the rear with a strong roll, but will probably require a bit of flaring (perfectly legal for Street Prepared) in the front.

In the front, I think you'll be able to get things where you want 'em with camber plates alone. In autocross, you generally want to make the car as narrow as possible, and the 240 has lots of room to move the strut top inboard. If you're not happy with the alignment with camber plates alone, you can always do the offset bushings, and there's a lot of potential offset in an S13 LCA bushing. Problem is, displacing the lower ball joint outboard any further is going to just make the car wider and more likely to knock over cones.

I really like the Largus front bar on my S13 - it's a few pounds lighter than stock and quite a bit stiffer.

I think the 240 in DSP could be a lot of fun - a freshened DOHC motor with ITB's and custom header with no cat should net you 170+whp, with race weight at or under 2500 pounds. You'll be down about 30whp to the E36 BMW 328's, but you'll also be a smaller car and at least 200 pounds lighter, while getting to use the same tire. Could be a good combination at HPT, where nobody can put power down anyway....

djsilver
06-09-2007, 05:42 AM
I was hoping this would fish you out Jason! I've studied the 285/30/18 deal ad nauseum but I can't afford a set of 18x10 wheels that are light enough for the NA KA24DE to turn over. My short term deal with the 300zx wheels and Kumhos came from Ebay for $330 including shipping for all four:eek: . Since then I got a killer deal on some 17x9 Wedsport TC005's that weigh <16lbs each and will work around them. The main ingredient I'm missing is talent! My wife is marginally faster which puts me in the "mechanic and car developer" category but it's all fun nonetheless! We're in Savannah, Ga and just started with the 240 this spring after autocrossing a Ford Focus in H-stock and STS for 5 years. We did our first national this spring in Valdosta, Ga for a real learning experience. Among other things, we enjoyed watching the tire smoke from the 315's on the back of an S14 that was running in SM! I'll probably be fiddling with setup for the rest of this year and try to make all the SEDIV divisionals and a couple of nationals next year :D . Meanwhile we have Steve Hoelsher (CP), Chris Heisler(CSP), Jonathan Roberts (Pro-Solo) and Mike King(STS2), among others in our region for inspiration!

I have a freshened motor with no emissions stuff, .040 over pistons, S14 intake, hotshot header, random cat, 2.5" MR exhaust and a JWT ecu. I dynoed it with about 20 miles on the motor and had 153RWHP at 5500rpm and >150lb/ft torque from 2000-5800rpm with the stock intake/airbox/paper filter. I have a set of JWT cam gears but haven't decided yet where to start since I don't really want to give up much of that fat bottom end! I also have a spare S14 intake I've already cut off and a set of Hayabusa 46mm throttle bodies that I'm still studying :cool:. I also have another S13 intake to play with in case I want to try something crazy like what GunluvS14 was thinking about:p (you know!)

On the front suspension, I have camber plates already but I want to make the camber adjustments at the strut/knukle connection so I can rotate the camber plates and use them for playing with caster!:eek: What I'd really like to do is drill another mounting hole in the subframe to raise the LCA pivot about an inch but we all know that's not legal!:caged:

J_Rho
06-10-2007, 12:20 AM
Looks like you've got some talented people to run against, that's good. I narrowly beat Mike last year in STS - if he'd had a bit more seat time in that car I would've been in big trouble.

Tires are the single most important thing in car racing, and IMO going to the 285/30-18 will make more of a time improvement for you than just about every other mod you'll do. I know it probably seems too extreme or expensive or whatnot at this point, but you're really handicapping yourself, and your car, by not doing so. Buying 18's now may be more $ than buying 17's now, but it's cheaper than buying 17's now and 18's later, which you will, if you stick with it. You can keep the 16's for practices and local events and stuff, but I think you'll quickly find they're so much slower, they get relegated to rains or "drive these to the event" tires.

Any 18x10 in the neighborhood of 20lbs. is fine, and well worth it. The 240 in SP trim is a "momentum car", and speed through the corners will be the car's strong suit, not its power. The situation is similar in STS - the Civics could beat me in a straight line, but I could be just a bit better elsewhere.

You could try playing with some offset in the front TC rod bushing to adjust caster, but the 6 degrees I got with a non-offset bushing was pretty good. Much more than that, and the steering will have a hard time, especially in slaloms and othe steering-intensive elements. I don't trust any of those camber-bolt or slotted-strut solutions, I think they're just going to slip eventually and cause issues.

Some sort of revised intake manifold is good, if not for power, but for weight. Lots to be lost in making the mani smaller and removing all the emissions crap.