BrewerBob

What is the difference between a base model, GSL and GSL-SE?

Yes, I've searched. And I've seen this page...http://www.rx7.org/public/1st-gen.html

But I haven't seen the difference. I have a '85 12A and I want a LSD and rear disks. What are my options?

Spieder

If you have a GSL then why isnt it limited slip and rear disc? Or do you have a stock 12a and are looking for a GSL or GSL-SE to put in there?

Oh by the way. My first car was a 12a stock 1984. A one leggar with drum. My new car is a GSL with disc and limited. To be honest. It makes no diffrence at all. As a matter of fact, you wet handling ability goes all to **** with a limtied slip rear. Especialy on sandy corners.

I cant tell you how many times I have broken the rear loose on my GSL turning corners or going up an on ramp under moderate power.

The stopping distance really doesn't improve either from what I can tell. I'd save the money for somethign else.

Wankelguy

The GSL has a limited-slip rearend and rear disc brakes, and the GSL-SE has a FI 13B, limited-slip rearend with larger disc brakes all around, as well as 14" wheels stock. A GSL rearend can be installed in a non-LSD car with a little adaptation of the brake lines.

BrewerBob

I have the base model. Or so I think it is. No GSL badge, 12A motor, rear drums, and 13" wheels.

I want the limited slip. I should improve in the wet and sand, that's what it is made for. Disks are just an added bonus. From what I understand, the car is so light that stock brakes are just fine.

BrewerBob

So, let me make sure I have this right.

Base = 12A, no LSD, drums, and 13" rims.

GSL = 12A, LSD, disks, and 13"rims.

SE = 13B, LSD, disks (bigger), and 14" rims

Now, given that you can get anything you want for the same price, would you convert and to what?

MosesX605

In the test data of the time, the debut of the 1981 RX-7 with disc rears actually had WORSE stopping distances than the original disc-drum setup. Moreover, in a comparo in R&T between the 1979 RX-7, the 1988 GTU and the 10th Anni, the 1979 and the 1988 got nearly identical braking distances, with slightly more fade on the '79. I can't speak to the LSD, as I've never had the opportunity to drive one, but the rear discs aren't all they're cracked up to be.

The main benefit to the GSL-SE besides the beautiful 13B is the larger wheel size and more favorable bolt pattern. The SE wheels are a 4X114.5 pattern, which is very common, whereas the standard GS/GSL 13 inch wheels have the 4X110 pattern, which is essentially exclusive to older Mazdas. The SE has some various suspension tweaks, a better oil cooler and what-not as well.

peejay

The GSL-SE also weighs a bit more than the GSL. Not as much as you would think, though, looking at the numbers. There was a huge lead time between when cars were made in Japan and the time they would get to the dealer lot in the US, so special ordering cars was next to impossible. So the 12A cars were shipped without any options and they were installed at the port of entry or at the delaership. 12A car listed weights are as-shipped, meaning without options.

GSL-SE's came standard with everything except power steering (optional) and leather interior (optional). So GSL-SE as-shipped weights are of cars that are fully optioned up.

The 13B engine doesn't really weigh more than the 12A. Maybe 20lb. Most of the weight increase is due to the larger brakes/wheels. The rear axle itself (minus brakes) also weighs about 50lb more than the '79-83 setup (according to Blake Qualley, and I'd trust him) but keep in mind that *all* '84-85 RX-7s had the heavier rear axle.

So when you compare an '81 GSL to an '85 GSL-SE looking at magazine tests, it's no wonder the GSL-SE weighs 200lb more. The GSL-SE's weight includes air conditioning, a heavier rearend, heavier brakes, and heavier wheels, as well as a bit of weight from the engine itself.

racermike

LSD helps keep the power to the pavement in autocross where you may unload a side. On the street it helps with traction in snow. (yes, I DO drive mine in ALL conditions!) In "normal"(?) driving it probaly doesn't help much.

Rear disks help mostly with brake fade,,,,, IF you drive in a manner to generate fade, and makes changing shoes/pads quicker.

SE gives you more braking ability front and back (if you need it) and a better selection of aftermarket wheels. Some 12As also came with 14 inch wheels.

peejay

I find the LSD makes driving in snow a nightmare. When you lose traction, both tires spin. At least with an open diff, you have the possibility of only one tire spinning (not necessarily the case though) and allowing you to maintain some semblance of directional stability.

Also it's damn near impossible to turn the car around on snow. At low speeds, the car just crabs, it won't turn.

I'll put up with that, and the trickier handling, for the advantage that I won't have to worry about blowing diffs left and right due to one-wheel-peels snapping the spider gear shaft.

I do not like rear discs. All they do is cause problems with rusting the rotors and rusting the slides and the handbrake is so weak it's generally useless since discs have less static (as well as dynamic) holding ability. Sure they don't fade, but when was the last time you faded the rear drums on an RX-7.

racermike

"""I find the LSD makes driving in snow a nightmare. When you lose traction, both tires spin."""

Peejay, take the race tires off and put snow tires on. Then add 150 lbs. of "snow melt" in the rear!

BrewerBob

An open diff. is worthless. You get one wheel spinning and you aren't going anywhere. The Limited Slip is designed to tranfer some (limited) power to the other wheel. If you want both wheels to spin, it's either a limited slip or a live axle (karts).

What about fade on the track? I'd rather not go into a turn at a 100mph to find the brakes aren't there.

racermike

If you are going to do track events, then the brakes are probably a good option (rear disk). The SE upgrades them even more. Of course you can make good gains by just doing the normal things (pad selection, fluid, etc.) without doing the whole SE swap.

ps If you do "sanction events" you may want to check the rules 1st.

BrewerBob

The Santioned Events will be autox. The track will be track days. CSP would be the class for Solo II, don't know about Solo I if I get to that point.

racermike

For autocross the swap is legal under "update/backdate" I believe. On the track the extra capacity won't hurt.

peejay

I was taught to get moving in snow by burning down to the asphalt. Try that with a tight LSD. Ain't gonna happen, because the *** end is going to continually move around.

I never had problems driving an RX-7 in the snow... until I started driving one with an LSD.

(Race tires? My "race tires" are Goodyear economy all-season tires. Cheap *and* they hook hard)

If you're braking hard enough the rear brakes are doing nothing major, anyway. If you're braking lightly enough that the rear brakes are vital, you're not getting much load transfer to the front.

BrewerBob

Um, I'm from FL and I know better than that. You don't burn down to the ashault to get going. Who told you that crap?! Move to ND and see how long just burning down the the pavement takes. My guess would be sometime in Spring. Ease the gas, brakes and steering. You don't want to do anything sudden.

And don't worry about me braking hard enough. I brake plenty hard. I've flat spotted 2 sets of tires on my Sentra (no ABS). I don't know how the RX-7 is balanced but you do use rear brakes in heavy braking, more so than light braking.

racermike

There is another tip that works sometimes for an open diff, if the brakes are adjusted equally. Pull up on the handbrake some when the one tire is slipping. Occasionally the extra drag will tranfer some of the power. I used to carry 3 bags of sodium cloride (I think that was it). It's what they add to the salt trucks when it gets too cold for straight salt. If the extra weight wasn.t enough, that would eat through the ice before you could get back in the car. I had to get up a big hill out of the subdivision one time on glare ice an inch thick. Years later you could still see the tracks,,,,it also eats concrete!
I use a mud and snow tire, but pricey ones. They give up less dry traction and are more predictable.

BrewerBob

I eat sodium cloride on my french fries. NaCl is table salt. KCl (potassium cloride) or some other metal attached to the Cloride may be what is used on the roads.

And with an open differential you are stuck. One wheel spinning is certain doom. If it is spinning slowly, my stand a chance of the other helping but if there is no load (i.e. spinning 60 mph), you ain't going anywhere. I've been stuck too many times out in the woods to believe otherwise. I've been stuck, literally in 2 inches of mud because one wheel just wouldn't grab.

pratch

Actually from what I've seen, Sodium Chloride (yes, NaCl) is the biggest component of road salt. pure "table salt" just has a specific ratio of Sodium to Chlorine whereas most of the road salt varies greatly.

BrewerBob

Wrong. Table salt is only NaCl. One extra electron in the sodium and one missing from the cloride. It's like water. H2O You can only make it with 2 Hydrogens and one Oxygen. You can make Heavy Water (Deuterium) but it is a bit tricky. It requires many distallations.

According to one of my chemistry books, NaCl and CaCl. The NaCl may be dirty and not food grade but are quite edible. I couldn't try the CaCl.

Manntis

About the thrad topic: http://www.rotorhead.ca/ref_1984.php

About getting going in snow: Use 2nd gear instead of first, and ease onto the throttle. Sometimes the snow is so deep burning down to the pavement is impossible.

As to open vs. LSD, sure only one wheel spins with an open diff - the one wheel using all your power and not doing a danged thing. With LSD you have both wheels spinning and have a greater chance that one will actually obtain traction.

Of course, the ideal is a TorSen, which sends power to the wheel with the MOST traction, automatically.

peejay

I've never once got a RWD car stuck using the way I was taught. I was also taught to slide cars around. My stepdad's mentality was: don't bother trying to maintain traction, since it is futile, so you might as well learn how to control a car when it is sliding so you are comfortable *when* traction is lost.

pratch

So I misspoke. I meant to say that Table salt tends to consist of more cubic lattices whereas road salt appears to vary greater.

I do in fact realize that there's only one way to make sodium chloride, however there are ways to have salt consisting of largely NaCl while still having plenty of other fun stuff in there. Not everything in life can be explained with a simple replacement reaction - especially when both sodium and chloride in their natural states enjoy being highly reactive. Of course, you already knew that.

GtoRx7

iTrader: (5)

You guys really know your salt!! I would just like a chance to drive on the Salt Flats for a few hours and see how fast my car will really go On a side note, I seem to enjoy my GS beater in winter due to its awesome drifting around corners in the snow(if done with some good momentum). But in the warm dry or wet weather I'll pull out the Gs(L-SE) widebody, a limited slip and disc bakes helps tremedously in hard driving. And even though the stock lsd is a 2-way limited slip, and takes some good driving to control, once your used to it they are the best. As for the brakes, I've faded too many drums after stopping from 85 more than 3 times, the discs haul down time after time from 100 plus going into a tight exit ramp Also for anyone wondering ; if you have a pre-84 rx7 gsl or gs you cannot upgrade to GSL-SE without some rear link modifications (the Lower link is positioned different)
If I were you, and had it possible, I'd agree with everyone else, go GSL-SE!!! I love my conversion.

racermike

"""I eat sodium cloride on my french fries. NaCl is table salt. KCl (potassium cloride) or some other metal attached to the Cloride may be what is used on the roads."""

I walked out the door right after I wrote that and realized on the road that it wasn't right! I carried CALCIUM chloride!
Now let me read the rest of the posts.