Right. The T56 is out of a 2001 Z-28 and I made an adapter to mount it to the c-frame. I hear now you can buy an adaptor. Wasn't available back when I did the conversion. After 50K miles of really fun driving I haven't broken it yet. Just keep tearing up u-joints. It's fun leaving new Camaros in the dust, most stock C5's too. With energy suspension bushings and a centerforce ceramic clutch probably helps stress those joints out too!
Just realized with the all aluminum block the front of the car sits a little higher which probably also adds to the squat on take off. People wonder why I spend all the effort to keep a 25 year old racer on the road every day. Especially in AZ where AC is required as well as passing the sniffer test every year. Way less bucks than most cars not as fast = FUN!! Insurance is a pittance too.

 

Yeah it's prolly a good 150-200 lbs lighter with the ls6 instead of the tpi. If I were you I would go ahead and buy coilovers or adjustable shocks. That's what I will be doing soon along with the new bumpstops. Coil overs for our cars aren't as high as I used to think they were.

 

Lots of good info in this thread! recklessdriver- What did you use for a spool in your D44?

 

Yes there is, in very happy that I got the answers I got and began this thread. Lots of good help. Also to add to this I would like to know which locker he uses in his street car

 

It's a Yukon spool for a regular D44 that I modified to fit the C4 Corvette IRS.

Yukon PN YP FSD44-3-30DN.

To make it physically fit in the IRS case - You have to narrow the width up about .250 and turn down the OD of the carrier bearing surfaces. It's not rocket science. Just take your old Trac Lock and measure it... Then cut the spool the same in a lathe.

After that you have to drill and tap 2 holes in the spool to retain the inner stub axles. I used 3/8" fine thread grade 10 allen cap screws. Of course you have grind a small flat spot on the inner stub axle for the bolt end to engage. This takes a mock assembly of the spool in the case and the inner stub axles to measure where to drill and grind everything.

Then I machined a round piece of alum (or you could use brass or steel) so it will slide in the splines of the spool - also the same width as the spider gear cross pin out of the Trac Lock..... This is to act as a spacer inbetween the stub axles.. like the spider gear cross pin does in the factory Trac Lock. This spacer takes all the stress off the retaining bolts when the suspension compresses as the axles now press against each other (via the spacer) instead of the end of that little bolt.

I cannot stress how important this last "axle spacer piece" is.... many people before me have modified D44 spools to fit in the C4 Corvette IRS and had problems with the stub axles moving around.. which causes camber change in the rear end and the car drives like crap because of it. This axle spacer piece eliminates that. It allows the stub axles to push againt something solid like it was orginallly designed to do.

I use a factory Spicer Trac Lok in my 92 street car. I re-built it with new clutches and careful blue printing.

I documented the one I built for a friend of mine (93 ragtop) so people can see what I do to them and how to make them the best they can be.

http://www.corvetteforum.guru/module...orumpost205410

BTW this Trac Lok posi is in his 93 which I also built the 383 LT4 based engine in (460RWHP) and he has run 11.18@124MPH so far in street trim. He did bust a few U-Joints under full power earlier this year and the posi survived with no damage and still pulls over 100lbs breakaway.

I am glad I was able to help. I know there is not alot of folks drag racing these cars (on any real competitive level) with stock suspension so information is limited.... I found that out myself when I first started and most of the people who were racing these cars and faster than I was (at the time) were less than helpful.... I want other C4 Corvette drag racers to know what works for me and hopefully someday someone will be able to better what I have done.
Will

 

Great that you are willing to share your knowlege to help other C4 members. Gotta get as many C4s down the track as possible.

 

..... I hunted for a spool for mine and discovered that you have to have one modified like Will posted ... I now have the pieces to get it done but in the meantime I decided to give the Eaton True-Trac a shot since my car was seeing some street duty ... So far so good ... the car launches straight and hard and has not yet experienced the one wheel burnout that destroys Trac-Loks ... the only weird part is that it acts like an open diff when you jack up the rear ... when I bought it , I put the Eaton into a Newman Car Creations Dana 44 housing ... super strong in the right places ... ..... I'm currently in the middle of a serious new engine build and hope to see performance levels somewhere near ***** when it gets back to the track (low 10's) ... my bump stops are also set to keep the half shafts level off the line with MT 26 x 10.00 x 15 ET Drag Slicks ... best 60' so far was 1.48 with the 406 ..... C4's have a designed in advantage over most production cars with the factory 4-link rear suspension ... they like to dig in and never wheel-hop like the C5's .......

 

Okay I am back after some time, now I'm almost prepped to go with a 400 trans in my car since I've decided to not give a **** about streetability anymore. Ha! After a while I will build a 4 link kit and likely go with a fab9 rear but until then I need to know how you have your suspension setup in your racecar rckless. If you have coilovers I would like to know how you have them set up and what spring rate you have. Also would need to know if you needed limiters for the front and what your front and rear ride heights are if you can provide it. I have an s480 and an engine so I'll need to get it setup as well as I can until I go SRA

 

I used the factory Z51 rear spring, poly bump stops and DA shocks... thats it. Set the shocks up like I stated in my first post. Limiters maybe... depending on if you can or cannot control the weight transfer with front shock adjustments.

I'll look at my set sheetscand get you the rear ride height.

BTW the race car is apart and being converted to a solid axle 9" with 3 link suspension currently. I have the complete D44 IRS for sale very reasonable.
Will

 

I am confused by what you all a street drag radial vs. True drag 275 or 15 drag radial...

I have a 93 6spd vert supercharged.

I run 315/35r17 bfg drag radial 2 (now discontinued in that size)..

I cut my best 60 ft a 1.8, on a 275/40r17 bfg drag radial 2

I was not impressed this summer when i bogged on one launch (not enough gas while releasing clutch) and then spun irrecoverably/bounced off the rev limiter on the next launch. I even had the air pressures down to 18psi when this happened.

(The same night 2 diesel full size pickup trucks ran 11's that i was shooting for...)

To be honest, i had the same thing happen once on my 275/40r17 drag radials to. But here i thought 315's would be the end all for traction issues at the strip.


Needless to say, it was a bad night.

I like to be able to drive to the track, limp home carefully if it rains, and dead hook 1st gear on the street....all on the same drag radial

 

You need sidewall more than you need width. People run deep in the 6's on a 275 drag radial. Sidewall is what takes the shock out of the initial hit and since you're 6 speed you honestly would need a bias ply more. Radials chatter and hop when you spin, bias ply will take the hit and if you spin they'll recover.

 

The BFG was a decent tire but it's not as good as the Mickey Thompson or the Hoosier radials.

A couple things make the 15"-275 tires better.

1. Roll out of the taller 28" 275/60r15 helps by reducing tire rotational speed and makes for a longer the contact patch on launch.... this is compared to a shorter 25.6 tal tire like the 315/35R17.

2. Also the construction of the MT 275-15's is different than the 17" radials... heck there are even 2 different MT 15" 275's... the old tire and the newer "Pro" which is basically a radial slick with a DOT number.

3. Of course sidewall height means a more flexible sidewall but not nearly as flexible as a bias ply.

The 15"-275's are just more drag race oriented tires... Heck an entire cottage industy of heads up small tire drag racing has grown up around them in the past 15yrs....

That said 15" radials are not a perfect tire for a manual trans car with a street clutch. They need to be dead hooked and thats a hard thing to do with no adjustment on your clutch slippage except for the driver.... your better off than with a 17" radial but not by much. Dead hooked tire with a hard hitting clutch = broken rear end parts.

Guys with race cars going fast on these 275-15 tires use lots of computer/electronic power management stuff just to get down the track.... heck my race car has a Race Pack data aquisition system, Leash progressive nitrous controller, and the Ignition box has programable ramps so we can adjust the timing at every RPM or by time.... all this stuff operating at the same time to manage engine power application as smoothly and as quickley as possible.

You can't show up with a really high powered street car (even with an auto trans) and expect to duplicate what real racers do on those 275 radial tires.... Not that how we run our suspensions and tire pressures won't help you becasue it will... but you can't expect to go out there and go a 1.20 60ft in a real street car.

The 17" based Drag Radial tires are more of a compromise for late model street cars that occasionaly go to the track and need better rubber but can't fit 15's becasue of clearance issues with brakes or body pannels.

For a dual purpose 17" tire IMO, the Mickey Thompson 315/35r17 is the best going but it's not a real racing tire.... I have been some 1.60's in my 92 6spd with them but there has never been any consistincy there.... I have way more 1.80 60ft times than 1.60's.... It takes alot of driver skill to get the car to launch that well with having to slip the clutch and I've not able to nail it even 10% of the time I have had that car to the track....

If your really looking for time slips at the drag strip with a 6spd, then make 15" wheels/tires fit and buy a set of 26" tall bias ply tires. Make sure to launch the car so that it spins the tires a little bit and gets the car up on the tire as soon as possible.... Bias ply tires like a little slippage at the hit.... if you dead hook them you can break stuff just as easily as with a radial.
Will

 

As usual, lots of good info from Will. I might reiterate, it requires a lot of skill and practice launching a stick shift car successfully. There is much more to it than dumping the clutch and flooring the pedal. Unless the car has a clutch specifically for drag racing with the amount of slip adjustable, you have to practice a smooth, quick clutch release (not a dump) and squeezing the gas pedal at the right rate. This takes a lot of practice (and parts replacement). I raced for years with a clutch and still could not launch consistently. I wimped out and went auto.