After ditching my spec-e30 car, I've decided to build a car I'll actually enjoy working on...
It's a 1993 M6 Z28. 136k on the clock. It had been sitting in a yard in N. GA for the past few years until I rescued her.
$1400 got me an lt1 6 speed car with a powerdyne bd-11a (anyone want it??), had a dead opti, RK sport headers, Borla stainless catback and some other goodies. Put an old opti in it, took the blower off, and it fired right up. The engine makes good oil pressure and sounds pretty good. I think when the opti died, the previous owner just parked it. I Also found out this weekend one of the previous owners had done a T56 upgrade. When I bought it, I just assumed it had the original ZF 6 speed...so this was a pleasant surprise. Also found a Centerforce DF clutch in it! Both quarters are dented, one much worse that the other side...but hell, it's a track car!
Anyway...Just stripped it and started the cage this weekend. I'll update with pics as I build the car if you guys are interested...
I'm planning on running a rear coil over, so upper rear shock mount needs strengthening for the added spring load. I am going to run a clevis type shock mount, with a 9/16 bolt coming up through the mount into the bottom of a 5 inch vertical section of DOM via a 1/2" thick threaded insert in the bottom of the DOM. More work to be done on this section, but this is where I am now...
They put ZFs in f-bodies? I thought they got T-56 93 up.
Cool build! Keep us updated!
__________________ 84 C4 -LS1/T56 in progress(delete:radio-A/C-heater-anything that doesn't make it faster)street legal light weight road racer 1973 Buick Century-delayed by new project, but an L92 waits patiently for it on a stand 2002 Hardtop Z28-MMM M6 Strano-Sway Bars-Springs-Koni S/As-C5 Brakes-Hooker LTs,ORY,CB 2007 2500HD "Classic"-6.0 5-speed ECSB 2wd-trim delete-Bilsteins-Federico Sway Bars-3.42s-Cragar Soft-8s w 285/70/17 BFGs
A few things to consider before you get too far gone ...
You need to read the NASA CCR where it discusses max angle off of the main hoop for rear down bars. going all the way to the rear like that in most cases exceeds the max angle. Also, you have significantly altered an engineered crumple zone of the car. Placing the rear down bars over the rear spring purch is where most every builder puts them.
The area where the shock mounts is plenty strong. The axle tube and tire will hit the body before you run into serious stress problems at the upper shock mount. And the stock upper spring mount is just rearward of the shock mount and all together are triple stamped steel. Also, if you put your rear down bars there, it reinforces the area even more.
I would get all those brackets out of there before you get a spider web of roll cage tubes in place. Makes life (and weight reduction) a LOT easier.
93 is a speed density car, has a one off TPI style ECM, has an unvented opti and the M29 trans has a HUGE leap from 3rd to 4th, your 2 primary gears ... all will hinder your competitiveness and reliability.
The rear diff is also a 3.23 gear, which would be fine for high speed tracks. But in the NASA -SE region, they don;t race at many of those. Road Atlanta is about the fastest. Its an easy fix, I'm just sayin' ...
Why would you even consider an AI build at this point in time with the ruleset in such turmoil and the class dominated by high dollar teams? CMC is the ticket ...
Good luck on your build and do a BUNCH of research.
A few things to consider before you get too far gone ...
You need to read the NASA CCR where it discusses max angle off of the main hoop for rear down bars. going all the way to the rear like that in most cases exceeds the max angle. Also, you have significantly altered an engineered crumple zone of the car. Placing the rear down bars over the rear spring purch is where most every builder puts them.
The area where the shock mounts is plenty strong. The axle tube and tire will hit the body before you run into serious stress problems at the upper shock mount. And the stock upper spring mount is just rearward of the shock mount and all together are triple stamped steel. Also, if you put your rear down bars there, it reinforces the area even more.
I would get all those brackets out of there before you get a spider web of roll cage tubes in place. Makes life (and weight reduction) a LOT easier.
93 is a speed density car, has a one off TPI style ECM, has an unvented opti and the M29 trans has a HUGE leap from 3rd to 4th, your 2 primary gears ... all will hinder your competitiveness and reliability.
The rear diff is also a 3.23 gear, which would be fine for high speed tracks. But in the NASA -SE region, they don;t race at many of those. Road Atlanta is about the fastest. Its an easy fix, I'm just sayin' ...
Why would you even consider an AI build at this point in time with the ruleset in such turmoil and the class dominated by high dollar teams? CMC is the ticket ...
Good luck on your build and do a BUNCH of research.
I appreciate the input, but NASA CCR's state rear downbars must be AT LEAST 30 degrees from the main hoop plane when viewed from the side. No Maximum angle. The only min/max angles in the CCR's are when viewed from above.
I have a 94 pcm and harness for the car, and LT1 Edit. Also, please read the original post, the ZF is gone...the car has a t56 in it. I've got another t56 on the bench too.
15.6.11 Rear Braces
The main hoop must have two (2) braces extending to the rear. The braces shall be
attached as near as possible to the top of the main hoop, and no more than six (6)
inches below the top. The braces must not contain any bends*. There must be at
least 30 degrees between the plane of the main hoop and the plane of the rear braces.
The main hoop rear braces shall be installed to form no more than a one hundred five
(105) degree angle or no less than a seventy-five (75) degree angle with the main hoop
when viewed from the top. The main hoop braces may be mounted at the rear shock
mounts or suspension pickup points (providing that the braces remain in compliance with
all other sections of the CCR). They may go through any rear bulkhead(s) provided the
bulkhead(s) is sealed around the cage braces. *There may be certain exceptions
allowed for cars that cannot possible meet this “no bend” requirement. One exception is
listed [Ref15.6.11.A)]. Other exceptions may be made (not guaranteed) if all of the
required bars meet the specifications for a vehicle in the next heavier weight
classification and the alternative design is submitted to the NASA National Office for
special allowance.
I stand corrected. You are 100% correct on the rear braces. But I still never see the rear braces extend all the way to the back like that.
The 94 still has an unvented opti. Look at a 96/97 conversion with an MSD cap and rotor. Much more reliable.
I did read the original post. ZF was a Vette trans IIRC. So you have an M28 and not an M29? If so, thats a good thing. M29 has no skip-shift and calls for Dexron II fluid.
Again ... good luck on the build and keep eveyone posted.
The '93 6-speeds were Borg-Warner "T56" units, just the differently geared M28/M29 versions, instead of the '94+ T56 that we got used to. The ZF was the late-80's version in the 'Vettes.
My '93 had the 3.23 gears and the M28 or 29 (whichever version had the low 1st-3rd gears, and the big drop to 4th). Well, the tranny acted up (something in the shift rail) so I swapped in a T56 I had from a parted out '97, and the gearing ended up being much better ... a much less significant drop from 3rd to 4th (in particular, I noticed this at Mosport, which is very much a POWER track ... the 3.23's are no detriment there).
Funny enough, the way the cage was built in my '93 is very similar to how you're building yours ... the rear bars go all the way to the back. I've never seen it as an issue, although I can understand how it may not be as "good" as ending the bars over top of the spring or shock mounts, and leaving that "crumple zone" intact. That's something I wouldn't have considered.
Seems like a good platform for a race car though, nonetheless! Have fun building it .
Ha, shows ya what I know about 93's. Guess i need to find out which trans I have...Maybe i'll just run the one out of my '95.
Hey Mitch and Pete. What are your race weights with you in the car?
Due to the 3rd/4th gearing, I WOULD run the '95 transmission . The lower 1st-3rd would be good for a 1/4 mile car, IMO, but I really noticed the severe RPM drop on the back straight at Mosport. The newer T56 really improved that, by keeping the momentum going between 3rd & 4th.
My car's race weight (no driver) was 3038 lbs, with a full (apparently ~20 gallon???) fuel cell. The car is VERY light, and the light weight is VERY noticeable (in a good way). Compared to my '02 Z28 that I raced for a couple years, jumping into the '93 was a "breeze" ... the car is so much more responsive and balanced. If the car had an LS1 instead of the LT1, it could probably be ~100 lbs lighter, between the weight savings of the aluminum block, and running the aftermarket K-member.
Regardless, the fibreglass hood and lexan front/rear windows (and no side glass) REALLY helped to shave the pounds off .
Are either of you running front or rear crash supports/bumpers?
Pete, what brand lexan do you have? I was going to buy the Percy's speedglass 3/16 front and 1/8 rear...any opinions? Also...what wing is that? G-stream?
Are either of you running front or rear crash supports/bumpers?
Pete, what brand lexan do you have? I was going to buy the Percy's speedglass 3/16 front and 1/8 rear...any opinions? Also...what wing is that? G-stream?
I'm not 100% sure about the brand of lexan or the wing ... I bought the car with everything already installed. I do believe the guy said the front lexan was the thicker stuff (3/16"? 1/4"? ... can't remember), and the rear was 1/8".
As far as bumpers, the rear is completely stock still. The front, I believe, has a 2" round tube mounted in behind the bumper cover somehow (not sure to what it is affixed). There are a couple supports mounted off that bar for the air-dam/splitter, as well as a tow hook.
My 1993 Z28 American Iron build thread 
15.6.11.A)]. Other exceptions may be made (not guaranteed) if all of the
.
. The lower 1st-3rd would be good for a 1/4 mile car, IMO, but I really noticed the severe RPM drop on the back straight at Mosport. The newer T56 really improved that, by keeping the momentum going between 3rd & 4th.
.
