Icemark

All GXL models (86-90) had the same brakes as the Verts and T2 models, no matter what series.

All S5 coupes had the same suspension, except the GXL which came with the ride adjustable shocks (of course these shocks are pretty worn out by 60K+ miles, so there is no real advantage) and the T2 models built after VIN# 708021 (which got a heavier sway bar).

Only the S5 GTUs model and T2 model got a LSD.

The S5 'verts however did have the upgraded sway bar, bushings, and springs.

The 88 GTU, much like its direct predecessor (the 86-87 Sport) had the heavy duty suspension, but also had a LSD standard, and was replaced by the 89-90 GTUs model, however (again) the 89-90 GTU was the base model and replaced the 88 SE, with smaller single piston front brakes and solid rear rotors (instead of vented) and no real advantage to building a road racing car, unless your racing body sanctions swaping brakes and suspension parts.

And if you are convinced that the S5 NA car has an advantage over a S4 for engines, consider that the S5 NA cars only have 2 more ft/lbs of torque (138ft/lbs vs 140ft/lbs), which in a racing situation is minimal. Furthermore the S5 cars are typically 150 to 200 lbs heavier, even stripped (unless you remove the dash and substructures). Of course you can see that even 5 ft/lbs will not make a car 100 lbs heavier have any speed advantage.

JonEQuest

Sounds like you really know your sh*#.

What rear end did 88 verts come with?
John

Icemark

The 88 'verts came with a 3.9 ratio, open diff (Mazda was trying not to get the 88 CAFE penalty from having a gas guzzler, so you found the automatic tranny's 3.9 rear end on them so they could raise the Highway mileage).

Mykl

All 'verts have open diffs, even mine... I was wrong.

JonEQuest

So they are geared a little higher than desired for acceleration, I guess that is a good excuse for more power to be sought. BTW does open diff mean the `ol one wheel burnout? Not that I stupidly waste tires but that`s how we knew if you had posi in the old days.

Thanks for the info,
John

Mykl

Yep, one wheel burnouts.

heh, yeah my last set of Pirellis barely lasted me 10k miles... but I had discovered the two lane bootleg turn. I had worn my passenger side rear tire down to the belts while the rest of the tires looked fine.

Bruhman

The S5 GTU I'm looking at has five lug wheels, does that mean it's possible that it has the 4 piston brakes? Was that even a option?
The car is about 1 hour and 45 mins away from me and I haven't see it in person yet,( only a picture ). If it doesen't have 4 piston brakes it's not worth my time. I'll ask the owners to take off a wheel and see if it has the 4 pistons.

Thanks Brett

Icemark

#1 no it will not have the 4 piston brakes from the factory. The 89-90 GTU had 5 lug wheels, but only the heavy single piston front brakes.

#2 even if someone retrofited them, you can see the 4 piston brake calipers through the wheel opening, it will say MAZDA on them. Very easy to see, and no need to remove the wheel.

Rotorific

iTrader: (1)

I dont think it will be that easy with the revised pizza cutter wheels

jon88se

i don't understand somethin though, we all modify the cars and suspension components in the aftermarket are swappable for all FC's...so unless someones plannin to keep it stock (whos that!! ) then stock suspensions/models mean little. consider: power, weight, body

Jaxon

What 2nd gen model is the absolute lightest and where did those 200lb in the 89+ FCs come from? Seems like a lot of weight to add to a dash....does it add any kind of chassis reinforcement?

Evil Aviator

https://www.rx7club.com/forum/attach...postid=1118673

LI FC Greg

The S5 cars are not that much heavier than the S4 cars. The difference seems to get exaggerated more and more.

What's responsible for the weight difference? The auto seatbelts, a reinforced dashboard support, better quality interior materials and sound insulation for the most part.

Look at these numbers from Mazda sales brochures and from Road & Track magazine........

1987-88 Turbo=2850 (without PS & ABS)
1988 10AE Turbo=2900 (with PS & ABS)
1989-1991 Turbo = 2987(with PS & ABS)

1988 Convertible=3003
1989-90 Convertible=3045
1991 Convertible =3071

1986 Base=2625 (Totally stripped..no A/C, no PS, etc)
1986 GXL=2790 (R&T)
1987 Base=2700
1988 Base=2720
1988 GTU=2755 (with sunroof)
1989 GTUS=2775
1989-90 GTU=2800 (no sunroof)
1989-90 GXL=2881
1991 Coupe (no options)=2787

Look at all those numbers and you will see that a S5 is less than 100 pounds heavier than the comparable S4. Not much really.

JonEQuest

I now understand why my base 86 that I used to have blows my current 88vert. away, it was the lightest RX you could get. Man it flew. 125 one night on X....

....... don`t ask.

John

Icemark

Those number are fine and dandy, but if you looked at the actual window stickers for the actual cars you would see the difference.

For example most of the non-leather 86-87 GXL models were actually 2680 according to the window sticker when they landed in Long beach.

While the 90 GXL was 2880 according to the window sticker...

That is 200 lbs between the S4 and S5 version.

Heck even my old 87 Sport weighed only 2623 (with AC/PS/Radio/Cruise/Etc) according to the window sticker, yet your figures suggest that only a stripped base could weigh that.

The weight from the S5 cars comes from a revised dash support, larger gas tank, but also revised body panels. A couple of the body panels got thicker and heavier, (most notibly the A pillar and A pillar to B piller support as well as the B-pillar) and also lame stuff like Mazda stopped putting in the ultra light weight german jack and tool kit (to save costs, but still the light jack alone was 3lbs lighter) and added the much heavier mouse belts and other accessories like that.

See on the S4 coupes Mazda had to have the weight under 2875 or they would go into the CAFE gas guzzler charges (about an extra $1100 USD per car), so the had to get the weight down. On the S5 cars the weight limit [for cars getting 21 combined City/Highway] had changed to 3100 lbs and the cars weight went up because of it. Why do you think that the S4 verts didn't come from the factory with a auto tranny or Turbo??? because they would have failed the gas guzzler restrictions.

JonEQuest

Damn the EPA!!!!!! I wanted a turbo in my 88 vert. I feel like renting a Ryder truck and going down there and.......

..........oops...... uh,..... I was just joking, hehe

Icemark

Well he mentioned Road racing, which suggests that he will be racing with a sanctioning body. Most racing clubs don't allow moding the suspension or other parts of the car without changing classes. That upgraded class is generally 'vettes and 944S/Turbos, whcih a NA car would not have the ***** to compete with.

and see my mentions of the weight above. Even stripping out the entire interior (including the dash board and support) the S5 car is still gonna be heavier than the comparible S4 car because of increased structural metal and the gas tank.

Icemark

So swap in a Turbo motor... the 88 'verts are the easiest to swap... heck you can even keep your same ECU.

luv'n my 7

overall i would have to say that the gtu is a better road handeler, just on the fact that it's lighter. I have a gxl and it handels pretty good. But with the gtu having the same setup and being what? a hundred pounds lighter or so really makes a difference!

Evil Aviator

Yes, but some racing classes do not allow turbos, in which case he must race an NA. For example, SCCA IT and EP racing, which are good entry-level classes, do not allow turbocharged RX-7's. Also note that racing a TII means faster cars on the track, which means more expensive performance and safety modifications, faster parts wear, and more skill required of the driver.

I don't think that it's such a good idea to use the NA ECU. Besides, standalones are only $1,000 - $1,500 now.

Icemark

Actually the 88 'verts came with the N338 ECU which runs either a NA or a 13BT. As far as I know it is the only year and model that can do that.

Evil Aviator

What about the harness?

Icemark

you gotta modify or replace the harness, there are pins used for a NA engine that are not used for a 13BT and visa versa.

Unless you are electrically minded and skilled, swap the harnesses.

Evil Aviator

Unless you make minimum wage, install a standalone EMS.

That's nice info to know, but I still don't think it's worth the time and effort just to have the crummy 80's technology non-programmable S4 16k 8-bit ECU with its old, crusty wiring harness. I guess everyone has their own definition of "upgrade".

Icemark

in my case was, that I rather spent the money on a FMIC than a stand alone.

Not saying that I won't do a stand alone down the road, but the 338 works fine for now