Here our roads are really bad; maybe I should get a 2 point stb for my '89 gta 350 tpi hard top?
I doont intend to race the car...
Thanks

 

how would a 3 point strut tower brace crack your windshield?
if anything I would think it would less prone to crack b/c the strut bar would hold everything together better in turn reducing the flex that could put stress on the windshield

 

It's not unheard of but I'd guess that it was due to faulty installation. There are some people on the board that are running Edelbrock's 3 point STB and I haven't heard of any trouble yet.

 

I believe it's more of a problem for the 4th Gen's than for us. Their windshield is much closer to the lip on the firewall where the 3rd mount point is located. Lon

 

I’m running Edelbrock's 3-point STB for over a year without a problem. And I’ve had some hard corners in that time.

 

I guess I should have added that I'm running a 3-point Edelbrock TBI STB as well, but I modified mine to a 4-point by tying it into the radiator support shroud. Lon

 

I've got the Edelbrock 3-pt STB and I love it. Absolutely no problems and I definately have taken some hard corners.

 

I've had the Edelbrock 3 pt. for years with no problems.

 

I've heard the same thing Lonsol has... and if you guys get a chance to look at a 4th gen, it seems true. Seems like the engine's set back further than the windshield, so it looks like the firewall is deep underneath. The 3 point doesn't tie to their firewall, it ties to the cowl, underneath the windshield.

 

Yes, indeed first I've heard about 4th gen problems... Seems that on our cars it works like it shoud.
Still, I think that the 3 point is mostly a racing sstup. For street use a 2 point should do just fine!
Thanks for all that info!

Can't believe I had an answer from a mazda guy! I never venture their message boards... maybe I should...

 

Actually, all 60's Mustangs had the two diagonal braces back to the firewall as original structure and had the unexpected benefit back then of better crash performance. The lateral bar as OE supplied on those same Mustangs was on export models only. So neither 2-point nor 3-point STB's are necessarily competition oriented nor are they even recent developments.

Re: windshield cracking. That depends on how rigid the structure is in the vicinity of the STB attachment and on how severely the STB gets loaded (suddenly applied loads are typically the worst). If the STB attachment point is flexible and close to the glass, windshield cracking is much more likely.

BTW, a little variety is a good thing, and general automotive knowledge (as opposed to, say, specific part-number info) is where you find it.

Norm

 

Hey Lonsal,

Would it be possible for you to post some pics of your modified STB??????????

 

I already posted a picture of the STB installed back 7 posts ago. Doesn't it show up for you? Lon

 

No it doesn't show up, could you e-mail it to me?

 

I e-mailed it to you. I don't understand why it's not showing up for you. Did you try right clicking, getting the properties and cut and pasting that to the address line. I have to do that for pictures sometimes.

Lon

 

hehe

I think I am about the only import guy on this whole board that has been tolerated so far

but I had a chevy once.. my first car was a 71 camaro ... I miss it yeah but since have bought my rx-7 and well I think I am going to stay..
but I do love domestics still, and I do enjoy to learn and help if I can with your cars

 

I have an Edelbrock 3-pt STB, have had it for almost two years now. It really tied the front end together, and survived two whole autocross seasons. I recently moved to Norfolk, and discovered that the roads here are some of the roughest I've ever seen. I avoid some streets because there are some bumps that will scrape the bottom of the car. One whoop-dee-do took the tail pipes off of the muffler and claimed an exhaust hanger. (justifying my new Hooker setup)
I am not worried about the STB cracking my windshield. it mounts to the cowl, with the firewall between it and the windshield base. on a 4th Gen, the base of the windshield is in front of the firewall, and if you really flex the cowl, you flex the windshield. Result: 3-Point STB is OK for a 3rdGen, iffy for a 4thGen

RX7 is not just tolerated, but even liked by some of us around here because he knows his S____ and can appreciate all types of cars, even though he prefers those Wonky Wankel Rotary Thingies.

 

while we are talking about a 3pnt STB where else can you brace the car. I think i heard someone say that they turned their into a 4pnt? what is it that was done for that?

what other points on the car can you put a brace up?
I know for us (rx7) there is a front, and rear STB and lower control arm bracing. that is about all I am pulling up right now being I just woke up.
how much of a difference will this make on your suspension?
and what about ride quality.
and is there really much difference between a 3pnt and a 2 pnt as far as making the car stiffer?

and SpeedCat86 thanx for the compliment. and who doesn't love the wankel wonder spinamaround things

ooh ooh ooh found a rear STB in carbon fiber I want it now

 

It actually makes more sense from a structural standpoint to tie to the firewall at the sides, near the A-pillars, going straight back from the strut towers and also criss-cross. Porsche did this very thing to stiffen the front ends of their 934/935 racers (see Road & Track, about mid-last year for a picture). That way all the structure is tension/compression including the firewall rather than in bending, which is somewhat less effective (and how the firewall is loaded with a centerpoint STB tie-in, absent a passenger compartment tube to "back up" the STB). Perhaps a 4-point would be a better 4th gen style.

No idea about the relative effectiveness or any ride effects/consequences concerning STB variations without doing structural analyses on them.

Norm

 

RX7, as far as other locations to mount a Strut Tower Brace, it can be mounted on any McPherson Strut suspension, where the strut serves as a suspension member as well as a damper. As opposed to a shock, which just controls the rate of suspension compression.
Making the front or rear struts rigid relative to each other keeps the wheels from moving in different directions during hard cornering, altering camber, caster, and toe-in (this is not a good thing)
A 3rdGen, or most other cars that don't have independent rear suspension, have no use for a rear strut bar, usually because the suspension doesn't use struts, but on a rear drive, solid axle car, both rear wheels are mounted to a single, large, rigid steel casting, and so they cannot move relative to each other. (if they do start moving, all the STBs in the world wouldn't save you)

 

not really talking about a STB to stop the struts from moving but the flex of anything in the car, other susp parts or even the car itself

 

Personally I wold like to have those ties the old stangs had on my GTA (from the fender to the firewall). In fact I've seen something like that under the nose of our cars (from the fender to that structure with the radiator)...
The cage is the answer... It's a guy "RUF" who modifies porsches (i believe one of his cars has a speed record...) who stripes down the interior, installs a cage and then re-installs the triming so that the cage is hidden!!! That would be really nice in our cars (at 100-150 $ not 80K...)

 

Dear Mr RotorHead,
I think that johndinu hit it on the head; a full 10-12 point cage would tie everything in the car together nicely.
But as far as bolt-on stuff goes, Subframe connectors, WonderBar steering braces, Transmission braces and the like will do it for all but the most hardcore of us, and leave the interior unmolested. A 6 or 8 point cage will also work well, but girlfriends tend to object to climbing over the door bars to get in.


I, too would like a Ruf -style hidden roll cage, especialy for $150, But I also want my car to go 200mph, corner at 3 g's and get 40 mpg. I also want an order of fries with that.

 

Plus, if you ever get a chance, check out the upper attachments for a 3rd gen f-body's rear shocks. They're not on either side of a hatchback or trunk well, like most imports are. The rear shocks attach right behind the rear seat's folding seat-back. In that area, right behind the folding seat-back, is an upward slanted piece of metal that almost matches the seat. This metal travels upward, levels out, and travels downward. (As ya know, our gas tanks are there). So, there's already a panel of metal between the two rear shocks that keeps them from flexing inward. We sort of got a "built-in" rear shock brace.

In imports, their rear shocks attach like our front struts do. They attach to the sides of the trunk, and are more prone to flexing, because of the trunk well between 'em. I hope I painted a good picture! Hey, here's some text:

Import:
shock_______shock (where _ is the hatchback well)

3rd-gen-Fbody:
shock-------shock (where - is sheetmetal level with the upper shock nuts)

 

sux the way they did that rear susp on my car
damn mazda

does anyone have a picture of a subframe connector in place
I know what they look like but not how they attach to the car
something us import guys dont use for some reason.

you guys are lots of help though thanx.
and also is it normal for you guys to get crack inthe body near the side window upper rear in that corner


I dont think I would be able to handle a roll cage that well... too much work to get in and out of the car as it is.
you dont get in the car you more of fall and bend to get into the car.

 

rx7 do you mean in the rear of the door glass opening at the roof if so both of my third gens ( i have a 91 5.0 tbi manual trans and a 92 5.0 tbi wuth an auto)have slight wrinckles in that area you realy have to look to see them ...... im here getting info on sub frame connectors and the like to get the flex out so to speak. David

 

those cracks on the roof are done ainly because the front end structure is detaching from the rest of the body...So the car becomes like some sort of mecanism wit the articulation axle alog the intersection between the windshield and hood.
I thought that the cracks are because the car has poor torsional rigidity...
I have (on my hard top) 2 inches cracks... Spohn's sfc attaches the front end and keep him in place (if I did understood crectly how his sfc is....).

to check for these cracks you shoud took the fenders off (the hood first...). now you can see the cracks and weld them or add some brackets...
It's a guy on transamgta.com msg board quickslvergta) who did that. I'm gona do the same ecause tha's my first car and I wann keep it forever!