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85 GSL for CSP, keep stock brake/rear setup, or upgrade to GSL-SE?

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85 GSL for CSP, keep stock brake/rear setup, or upgrade to GSL-SE?

Old 01-23-09, 01:20 PM
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OH 85 GSL for CSP, keep stock brake/rear setup, or upgrade to GSL-SE?

I have an 85 GSL that I am going to build in to a CSP car. I also happen to have a complete SE suspension setup laying around. Which is best to run in CSP? I like the idea of the bigger SE brakes and bolt pattern, but is it worth the swap? Not sure what year the rear is, so I am not sure of the gearing (have to count the rotations). I have heard the GSL has a tighter diff than the SE, so I am up in the air. Any opinions? Maybe put the SE brakes on the GSL rear? Not sure.

Thanks,

Jason
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Old 01-23-09, 02:22 PM
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From what I understand, the GSL LSD has an extra clutch plate in it. They had to eliminate one plate from the SE unit in order to fit the larger gear in there.

I'm using one from a GSL and it works great. As far as brakes go, I seem to have plenty for daily driving and weekend racing. So I guess I'd recommend to keep what you've got, and save the other as a spare.



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Old 01-23-09, 03:32 PM
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Thanks. I have to see what gear is in the SE setup, b/c if it's shorter, might be worth it for acceleration. I also like the better bolt pattern and larger brakes for auto-x, but have to see what the weight penalty would be to see if it's worth it.

Looking at your sig, looks like you have a setup very close to what I am leaning towards.

Jason
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Old 01-23-09, 04:56 PM
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I have the GSL-SE rear end, i am at around 50mph at 7K in 2nd gear. You would need to shift to 3rd on National type courses, since they are done at a much higher speed.
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Old 01-23-09, 05:00 PM
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Originally Posted by Kentetsu View Post
From what I understand, the GSL LSD has an extra clutch plate in it. They had to eliminate one plate from the SE unit in order to fit the larger gear in there.
.
True, sort-of. They made the GSL-SE limited slip weaker for driving characteristic purposes.

The diff gear has absolutely no bearing whatsoever on the clutch packs.

I have the -SE rear and I can't tell a meaningful difference between 3.91 and 4.08.
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Old 01-23-09, 05:11 PM
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Good to know. Maybe I'll just swap the SE brakes/rotors/axles in to the GSL housing and keep the GSL pumpkin.
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Old 01-23-09, 05:15 PM
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You get a little bit bigger brakes with the SE rear also.... Not sure if it helps tho
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Old 01-23-09, 11:01 PM
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Originally Posted by peejay View Post
True, sort-of. They made the GSL-SE limited slip weaker for driving characteristic purposes.

The diff gear has absolutely no bearing whatsoever on the clutch packs.

I have the -SE rear and I can't tell a meaningful difference between 3.91 and 4.08.
only the early GSL-SE's have the 4.08 anyways, most of em use the same 3.9 gears as the 12a cars.

part numbers are stamped into the gears, part numbers can be looked up
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Old 01-24-09, 06:55 AM
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Yeah, after finding that out out, that's why I am thinking of keeping the tighter GSL rear, and just swapping on the larger brakes.
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Old 01-24-09, 01:57 PM
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I think autocross pads on stock rotors and hubs would be all you'll need for braking in autox. The few pounds of weight difference probably won't matter either. Suspension, tires and torque. And of course the driver mod.
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Old 01-25-09, 01:43 AM
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Originally Posted by peejay View Post
True, sort-of. They made the GSL-SE limited slip weaker for driving characteristic purposes.

The diff gear has absolutely no bearing whatsoever on the clutch packs.

I have the -SE rear and I can't tell a meaningful difference between 3.91 and 4.08.
What do you mean by they made the LSD weaker? It just doesnt engage as harsh and has less preload?
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Old 01-25-09, 05:58 AM
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It's not as tight (less discs).

I'll probably go to the SE brakes, I like the bolt pattern better (and the added size shouldn't hurt).

Jason
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Old 01-25-09, 05:23 PM
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Originally Posted by wrxracer55 View Post
Thanks. I have to see what gear is in the SE setup, b/c if it's shorter, might be worth it for acceleration. I also like the better bolt pattern and larger brakes for auto-x, but have to see what the weight penalty would be to see if it's worth it.

Looking at your sig, looks like you have a setup very close to what I am leaning towards.

Jason
Thanks man. I'm very happy with my setup since moving from Racing Beat to Respeed products. I don't regret a single part of Billy's that I've added to my car. It's cool to be able to say "I wouldn't change a thing".
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Old 01-25-09, 07:39 PM
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How much heavy braking do you really do in an autox? Any? Do you really need the extra size? The fast guys drill out their rotors to reduce their mass.
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Old 01-26-09, 01:25 AM
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Originally Posted by slowautoxr View Post
How much heavy braking do you really do in an autox? Any? Do you really need the extra size? The fast guys drill out their rotors to reduce their mass.
Heavy braking isn't all that unusual, there just isn't enough of it to require more brake than stock.
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Old 01-26-09, 01:26 AM
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Originally Posted by wrxracer55 View Post
I have an 85 GSL that I am going to build in to a CSP car. I also happen to have a complete SE suspension setup laying around. Which is best to run in CSP?
No help on the GSL from me.

I would just like to see someone in CSP use an RX7 to give the Miata guys some competition.
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Old 01-26-09, 06:09 AM
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I'm goign to have to see what the weight difference would be. There are some bigger sites around here, where I am sure heavy brakes would make a difference, and I'm plannign on running 255s, so I want to make sure I have enough brake for the tire.
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Old 01-26-09, 09:57 AM
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Originally Posted by jkstill View Post
No help on the GSL from me.

I would just like to see someone in CSP use an RX7 to give the Miata guys some competition.

I eat Miatas for breakfast man! Only one of them can stomp me, and he's got a supercharger so its not really a fair fight. lmao.

Yes, there can be some very hard braking in autocross, but its strictly short term (no fade to deal with). I have used stock cheap pads on stock cheap rotors and never had issues. I'm using Hawk pads now, but mostly because they were free (thanks Billy!).

I think there are many other areas that deserve your attention more than braking....
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Old 01-26-09, 10:44 AM
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Kentetsu, If you eat miata for breakfast, I don't think your region is that competitive... There is a guy that has a CSP 1st gen that won the national championships back in the mid 90s, now he can't even get into the top 10 with more upgrades.

In my region, the class winner finished 3rd in the nationals with a miata and I was consistently at least 3-4 secs slower. The car I was driving was under-prepped, it had a 12A with yaw carb and the A3S05 Hoosiers. The double a-arm suspension and independent rear suspension makes the miata a much better handling car. I love the first gen, but even a fully prepped one for CSP will be at least 1-2 secs slower than a miata. The miata turn in is sharper, the response is quicker, and it is way more stable and is easy to drive.

Even though I know the 1st gen has no chance in a competitive level, I am still making more upgrades for it to be better in CSP . it will need a lot stiffer spring rate for R-comps, the car leans way too much and only g-force has a shock that can handle it, but they don't fit without the turn-in spacers (illegal in CSP). I will be looking to get Advance Design shocks with at least 650lbs springs in the front and probably 400 in the back with Tri-link and panhard. My other mods are in my sig

I am driving a FSP Mazda 3 this season (hopefully nationals), so my car won't be ready till the next season
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Old 01-26-09, 01:15 PM
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Yeah, I'm certainly not claiming that I'm running against the fastest Miatas. lol. But I do remember when they used to spank me without mercy. Last year I was only beaten by one Miata in my class, and that was by less than a 10th of a second.

Also, I don't claim to be an expert (that's why I have Billy on speed dial), but those spring rates you have in mind are awful stiff. I know some drivers that run 450 on the front and regret it. Hell, I'm only running 275 on the front and can't see any reason for anything stiffer than that (assuming you have proper swaybars). But if you try it, let me know how it works out because I'd be curious to know...
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Old 01-26-09, 01:19 PM
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Originally Posted by Kentetsu View Post
I eat Miatas for breakfast man! Only one of them can stomp me, and he's got a supercharger so its not really a fair fight. lmao.

Yes, there can be some very hard braking in autocross, but its strictly short term (no fade to deal with). I have used stock cheap pads on stock cheap rotors and never had issues. I'm using Hawk pads now, but mostly because they were free (thanks Billy!).

I think there are many other areas that deserve your attention more than braking....
Thanks for the input. I already have all the SE stuff, so it's not a big deal to do the swap. I'll check the weights, and see the difference.

Thanks,

Jason
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Old 01-26-09, 11:02 PM
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Despite the 4X110mm lug pattern, my vote would be for the GSL brakes because they are lighter and more than up to the task of stopping your car. I club race my car and the GSL brakes are all that I am allowed (Improved Touring A). Despite repeated 100+mph braking I have never had any brake fade.....ever. Invest in good pads (Hawk, PFS, Poterfield, etc) and high temp fluid (Motul, Wilwood, Ford HD Dot3, etc) and you'll be fine.

650/400lb Front/Rear springs is too much considering the weight of an RX7and the relative grippiness of DOT racing tires. My old CP Car (1985 Mustang GT) had wheel rates of 875lb/468lb front/rear and it weighed 800-900lbs more than your car AND ran 12" wheels all-round with real (non-DOT) Goodyear/Hoosier racing slicks. And trust me....my Mustang cornered flat as a pancake.

For comparison's sake, my RX7 (2470lbs w/driver) car runs 400lb/250lb front/rear springs on the track with no rear sway bar. For Solo I run 300lb/250lb front/rear springs (also with no rear bar) and I remove as much rebound dampening from the shocks as possible. My car also has a tri-link rear suspension.

The E Production race cars (2300lb w/driver) that run in this area run 450lb/200-250lb front/rear springs and they run sticky 9.5 slicks. All of them run 4 link rear suspensions with no rear sway bar as well.

As far as whether or not an FB is competitive in CSP.....I think they are. Focus on maximum tire width, light weight components and run a 13B. I have seen several nationally competitive RX7's in CSP. Good luck to both of you
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Old 01-27-09, 12:00 AM
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I got the 650/400 idea from looking at the Jim Susko book, he recommended 600/375 and that is way before the 255 Hoosiers A6 in 13s.
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Old 01-27-09, 06:09 AM
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Alright, sounds like I should just stick with what I have, and sell the SE setup.
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Old 01-27-09, 07:03 AM
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300/275? That's close to a *rallycross* setup...
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