91 GT Open Track Build

[91GriggsGT]

91 GT Open Track Build **** UPDATED 3/29/11 ****

Figured I would share with everyone my new project. Its a 91 GT that I am building into an Open Track race car. Started a photo journal and will try and keep it updated throughout the build process. Here are a few starter pics, and also a link to the full album. It definately is a work in progress.

Full album link : 91 Griggs GT - Photobucket


The day I bought it:

Let the destruction begin:

Some of the parts going on:

A couple with some of the new parts:

Hope you guys like. I will try and get some more up before I head back to work next week, but cant promise, but I will keep ya'll updated as I go.

 

[G-STANG]

I will be watching this thread. One request please. Could you post pics of your 3-2 port conversion. I will be starting my 4 wheel disc conversion soon and the I want to see what it looks like in the engine bay minus the engine.

Are you going to be using a 93 cobra booster or are you keeping the stock brake booster. I have baer front track kit and they said with their master cyl I don't need to change my brake booster.

 

[Chris06GT]

Nice project!! Definitely keep this thread update fo us

 

[91GriggsGT]

I will be watching this thread. One request please. Could you post pics of your 3-2 port conversion. I will be starting my 4 wheel disc conversion soon and the I want to see what it looks like in the engine bay minus the engine.

Are you going to be using a 93 cobra booster or are you keeping the stock brake booster. I have baer front track kit and they said with their master cyl I don't need to change my brake booster.

Yes, using stock brake booster with a cobra m/c. Thought I was going to have to change the booster, but got lucky.

If you are wondering about the 3-2 port on the m/c, check Maximum Motorsports website, They have an adapter for that. Part #: MMBAK-3

 

[lancec2c30]

Great thread, keep us updated!

 

[G-STANG]

Yes, using stock brake booster with a cobra m/c. Thought I was going to have to change the booster, but got lucky.

If you are wondering about the 3-2 port on the m/c, check Maximum Motorsports website, They have an adapter for that. Part #: MMBAK-3

Thanks for the part number for the adapter. I just wanted to see a pic as when I asked baer they said I didn't need it. At least that is what the guy I spoke to told me. The brake kit came with some not so great instructions. Still trying to figure out where the lines with the kit go to. It said in their instructions to refer to a Ford shop manual :??:

 

[DNA DOA]

Man this is going to be great. Love new builds. Will be watching and also very interested in your brake upgrade. Have fun!

 

[91GriggsGT]

Hmmm. Not sure on that one since I didnt go with Baer. I just went with a stock Cobra M/C, 94-04 Cobra calipers and stock rotors for now which will be changed out to Eradaspeed rotors eventually. I will run down to the shop and see if I can get ya a decent picture of the setup.

 

[G-STANG]

Hmmm. Not sure on that one since I didnt go with Baer. I just went with a stock Cobra M/C, 94-04 Cobra calipers and stock rotors for now which will be changed out to Eradaspeed rotors eventually. I will run down to the shop and see if I can get ya a decent picture of the setup.

Thanks alot :beer:

 

[91GriggsGT]

G-Stang,

Hope this helps and they arent too blury. Kind of hard with the motor in the car.

Here is the actual adapter:

Here it is installed. I dont know what you are running for a M/C, but like I said, this is a stock M/C off a 93 Cobra, and my stock 91 booster and proportioning valve.

And of course, this is what I eventually want the car to be like:

Anything else I can help with, let me know. I will give you as much info and help as I can. My brother and a few guys he races with are my main points of contact on this stuff and I have been following their lead since I know very little about setting a car like this up. Here is what has been done to the brakes so far:


The front brakes consist of SN95 spindles, 94-04 Cobra calipers, stock Cobra 13" rotors, 93 M/C, stainless steel braided hoses from Maximum.

Rears are: Moser 5 lug 31 spline axles, stock cobra rear rotors, 94-04 calipers, hoses from Maximum, as well as a center line adapter from Maximum.

Hope this helps you and anyone else.

 

[91GriggsGT]

Also, If any body repair folks stop by, I could use some advice on how to fix this:

I guess one of the previous owners had the cowl hood fly up and put some nice damage on this piece. :bash:


Any ideas????

 

[tntcobra]

Great start. Just a bit of advice - stay with it! My own car was 2 years from purchase of the car to the first autocross. And the car is really still not done, just safe to compete with.
I swapped the entire rear axle rather than changing shafts & converting. I got a great deal on a '96 Cobra rear with brakes so it made sense ($300 picked up and I sold the 4 lug rear for $150!) I have 255/40 RA1s on the car and have no clearance issues.
RE the brakes, I have 2004 Cobra calipers up front & '96 calipers in the rear. The research I did seemed to imply the factory drum booster was not sufficient for the size increase in the brake calipers. Not sure if that is true or not, but I was at Harry's and pulled a booster with master cylinder from a '95 GT. I think it was $30 or $35 for the assembly. With a little massaging of 2 mounting holes, the entire assembly fit just fine. In hindsite, the '99 up M/C might be a better choice because of the built in bleeding valves.
I had to plum the rear line. I went off of the center soft line and just added hard lines to the Cobra axle. Then I used factory '96 soft lines to the calipers. That seemed to be a better/easier fix than plumming hard lines on the body and routing the soft lines from there. I will say this - the car STOPS.
I also used the Maximum 3-2 conversion along with their proportioning valve elimination kit. (Frustrating because it's just 2 couplers!) I have an SSBC adjustable proportioning at the firewall joint.
I weighed the car after it was painted but before I pulled the climate control, power windows, locks, and with the factory front seats. Then it was 2900 lbs. I figure it's closer to 2800 now. That is a full 800 pounds lighter than my '96 Cobra convertible. With the same size brakes & tires!


Slideshow of my build


Good luck!

 

[91GriggsGT]

Thanks for the advice. I already have the rear end done and ready to go back in now. 8.8 with Torsen T2R 31 spline, Moser 31 spline SN-95 axles. Forgot to take pictures and get them posted. Shouldnt have any problems with the brakes, got couple guys running same setup and works like a champ. For the rear brake lines, I am doin pretty much the same. MM makes a rear brake line kit which is basically a rubber piece of line and a y block that mounts to the diff, then we custom bent some steel lines to the axles, and stock rubber lines to the calipers.

Right now, there isnt a single wire in the car, and waiting on the painless wiring harness to show up.

Inside is stripped and ready for seam welding and paint, plus welding up some metal to seal off all the holes in the firewall.

Forgto to get pics before I went back to work, so will be about 3 weeks before I can get some up.

Still looking for anyone with auto body exp on how to fix the front cowl??

 

[supercarkiller]

badass project ! looking good so far. keep us posted on the build. good luck.

 

[my92gt]

what do you mean by "Right now, there isnt a single wire in the car, and waiting on the painless wiring harness to show up??" Is there a kit for that or something??

 

[91GriggsGT]

Yes, Painless makes a fuel injection harness. Basically it is all the wires from the computer to the engine and power wires. This car wont ever hit the streets so you dont need turn signals, taillights, etc. Will have more info for you when I get home and start installing the wiring harness, but you basically keep your charging wire, and fuel pump wire, and can get rid of the rest.

 

[Rick88LX]

Nice to see some open track stuff here for a change. Thanks for sharing.

A stock booster can be used, but requires a different master cylinder with a different bore diameter. I've done several with and one without the larger booster. If I recall correctly (sorry, it's been 8 years or so), we ran a stock booster (1991) with a 15/16" bore master cylinder and it worked fine. I pulled some stuff from corner-carvers.com and included it here for reference...

Mustang Master Cylinder sizes

Model Bore Primary L-R Rear
79-86 V8 Mustang 21mm (7/8") FF 9/16-18 SAE 1/2-20 SAE
84-86 SVO/Lincoln 28mm (1 1/8") 9/16-18 SAE 7/16-24 SAE
87-93 V8 Mustang 21mm (7/8") FF 12mm-1 ISO 10mm-1 ISO
93 Cobra 25.5mm (1") 12mm-1 ISO 10mm-1 ISO
93 C-R (F3ZZ-2140-A?) 25.4mm (1") 12mm-1 ISO 10mm-1 ISO
94+ GT (& GTS) 27mm (1 1/16") 12mm-1 ISO 10mm-1 ISO (hole in webbing)
94+ Cobra 24.5mm (15/16") 10mm-1 ISO 12mm-1 ISO

Regarding using the larger booster vs your existing one-- the new booster will result in a lower pedal EFFORTS with the same TRAVEL. Keep in mind that the mechanical and hydraulic ratios (pedal ratio, MC size, caliper piston size, rotor diameter, friction material, etc.) will determine the amount of pedal TRAVEL that is necessary to produce a given hydraulic pressure at the master cylinder and thus a given deceleration level. The amount of EFFORT needed to produce that travel/decel comes from a combination of the force at your foot and the assist from the booster. Installing the larger booster means that the the pedal travel vs. decel stays the same, but the pedal force vs. decel becomes better (less effort). I'd go ahead and install the booster; if you find the efforts are too light,switch to a larger master cylinder. This will raise efforts and reduce travel even further.

 

[canibus]

Looks like it'll be tons of fun

 

[91GriggsGT]

A stock booster can be used, but requires a different master cylinder with a different piston diameter. I can't recall the exact specs, but I've done them both ways (several with the Cobra booster and with the stock one....both using Cobra brakes all around). Sorry, but it's been 8 years since the last one. If you do a search over at corner-carvers.com, I'm pretty sure the exact diameters are listed in a thread or two. I'll take a look and see what I can find.

Nice to see some open track stuff here for a change. Thanks for sharing.

Correct. The M/C is from a 93 Cobra, which has a 1" bore. Stock i think is something like 3/4" bore.

 

[Vinyl]

You really didn't start off soft, did you? Just ripped and replaced!

That's the way to do it. Do it once, do it big, and do it right.

Are you going to keep the stock paint code?