Whats up guys as im sure some of you already might know this is my first post and look farward to being part of the interactive community.
I have been a heavy equip mechanic for 13 yrs
car audio& fabrication for almost 20yrs
professional rc car racer for 4yrs (dont laugh till u have raced indoor carpet) lol
For those of you that know about autoX racing bare with me , those that dont its basically 200+- road cones in a parking lot and u want to go as fast as possible thru them without running them over ...lol
so needless to say we hardly get over 40mph in maby one area (avg 25ish) 55-75sec layouts...
And I feel if I can get used to the long nose the vett might be pretty competative .
with the tpi being really tq happy without much rev might just be ok.
My plan: I want to remove all unwanted extra weight so I can maximize acceleration/braking effectiveness.
Current issues: when im driving car and make quick L&R turns it feels like the rear is swaying around but looked at the rear suspention and dont seem to have any bad bushings (tho they are old and will be repaced this winter theirs no wabble in the rear hub with car lifted either. Any help here would be great . What I noticed was it dont exactly have a upper control arm to rear hub ....
I also want to remove the smog and ac componets and ut has the serpentine belt so anyone that has a parts list to remove them and relocate the alt would definately save me some time ...
The overdrive on the 4+3 trans automatically engauges any time the car is started (after warm up) so doing auto cross I know its going to try to engauge as I shift into second when im not paying attention... so anyone know the best way to add a interupter switch to that circuit for at the track?
Performance . Yea I know the tpi dont have much head room with the 5.7L... so has anyone installed 1.6rr onnthe heads or bigger duration cam with good gains ?
Car already has custom exhaust tho it is kinda rigged... no mufler and a single cat in the "H" pipe area.... looks to be a 3" . So some suggestions for a cheap exhaust would be nice also. Btw love the sound of this exhaust for sure .
Any other suggestions would be more than helpful.
Already bought some simi race tires. Thy are falcon tires that are 260shore ( lowest I could find above 100, at a decent price )
any tks in advance for any input

 

Welcome aboard.

I believe the rear end "feel" that you talk about is normal. My friend complains about mine everytime he drives my car.

 

Seeing how the rear is designed I can believe it

 

Well been thumbing my way thru this site and found some good info.
Managed to order
a/c compressor delete pulley
bought a 5" pulley to fab up a plate to remove the smog pump.
been drooling over the banski rear suspention!
But is all the links necessary?
thinking of just doing the toe&camber links ... unless theirs a nice cheeper set out there.
this is a track only build so btw.
And do I read this correctly the vet has rear steering built into the geometry? Thats why it feels washy in quick left right areas?
Anyone have any input about cams/rocker combos (flat tap cam :/ ) for future referance?
not sure if I want to deal with the roller conversion any time soon...

 

I would spend the money on camber/strut rods and trailing arms/dog bones and install the toe rods later if funding is an issue. Get a good alignment from someone that is familiar with Vettes in your area and get a good autox or agressive street alignment. Make sure you have good shocks and most importantly good tires.

For performance, I would recommend the 3 piece March under drive pulley set. As far as rockers and cams and engine upgrades, the sky is the limit.

 

Cool tks
I must ask tho what the track rods vs the toe rods?
What adjustment does the track rods give other than farward bite ? Which I think it has plenty of .lol
I have a falcon made tire thats really soft ( great farward bite / will not spin in first from a 5mph punch )
what would be a good shock

 

Double post

 

RC car racer, sweet!

 

Yea its sad I have more money in just one of my 7 rc cars than I do this vette so far ... but if I had 10k to blow
I found a zr1 lt5 and trans that would be dropped in asap! Jjst because I love this motor

 

Welcome to autocrossing!! You will now need to work 2 extra jobs in order to pay for mods

For the 4+3 OD unit, it operates differently depending on the year of the car. Check out this link to see how it works. The key to driving a C4 with the 4+3 for autocross is how much throttle you apply in 1st. I have an '87 4+3 and I never see the OD engage at autocross events.

I have the Banski toe and camber rods and they made a huge difference in how the car handles. Haven't done the dog bones yet, but I may just install some new poly bushings and the Doug Rippie offset brackets. My '87 has the Z52 "Sport" suspension so it has base springs. I use Bilstein Z51-specific shocks and I just finished installing larger front (32mm) and rear (26mm) sway bars and poly bushings. Vette Brakes has some good autocross alignment specs that work for a starting point. See the attachment.

The car also has C5 front brakes and I use 275/40-17 Hoosier A6's for autocross. For track days, I run Nitto NT05's.

For engine mods, the block is bored .030 over (355 cid) GM ZZ3 cam, BoschIII 24lb injectors from FIC, intake ports matched to runners, balanced and blueprinted, Heddman headers with true dual exhaust. There's an X-pipe where the main cat would be located and I use DynoMax race mufflers.

I have removed both the AIR pump and A/C compressor. I bought a TPiS AIR eliminator kit and a Dorman A/C eliminator. Both pieces were a simple bolt-on deal but I had to go to a 2" shorter serp belt.

You didn't say what year of C4, but I would suggest you start with new shocks and a good alignment. Check the front hubs for wear and replace as necessary. Same with the rears. With the car off the ground, grab the front tires at the 12 o'clock and 6 o'clock positions and push/pull in and out. If the wheel moves, the hub is bad. Do the same with the rear wheels.

For lower autocross speeds, stock rotors will work fine. Upgrade to something like Hawk HPS pads to start. Do a full brake fluid flush and use a good DOT4 brake fluid such as ATE TYP200. Motul is also a good fluid. Check the brake hoses at each caliper; can't hurt to get stainless hoses. Both Earl's or Goodridge lines are very good.

 

Tks for all the info!
I have a 86 convertable with 92k on it . It was my dads since 98 and he hasnt driven it 100 miles in past 2 yrs ... so its mine now .
So will look into new shocks this week . Ill be making my own smog delete (cant see spending $150 for 2 plates and a pully..)
Yea the OD seems to always come on on its own in second gear . No matter what acceleration mood im in ... always have to go into second and make sure its off before looking to do a hard pull from a stop

 

There aren't any track rods to the C4 rear suspension, there are toe rods, camber rods, and trailing arms. Sorry I don't know what component you are referring as a track rod.

Sounds like the Falcons you have may have good grip or you are short on some power. Even a fully stock L98 that is running properly should spin the tires (street tires) in first gear at a 5mph roll. Do you still have the original cats on the car? There is a lot of power robbed from clogged cats.

 

Possibly down on power . It does have stock cats which probably will be removed this week if I can get car up in the air .lol but the old tires it would burn them up!
The new falcons are 230shore tires . So between the 2 could be the situation . Is there a o2 sensor beyond the cat.
I was calling the trail rods track rods . Sorry for the confusion

 

Uhhmmm, I don't know. Where did you read that? I'm surprised that the autocrossers haven't said anything about this.

 

Well im the one calling it rear steering .
think its more like the rear toe is dynamic which makes rear swing out in a tight turn situation.
Since their isnt a upper link above the drive shaft.

 

Ahhh, I gotcha..

 

No problem. The trailing arms control the weight transfer from front to rear and vice versa during braking and acceleration. There is no Sensor beyond the Cats, you should just have one on the driver side before the main cat. Get rid of the pre cats too, if you can. The pre cats are located in the front y-pipe one on each side. There are front y-pipes available that don't have them or you can cut them off. If you have the stock exhaust system, that is a good place to start upgrading.

You did ask about shocks. If you want some good shocks, the Bilstein's are very nice. Get the ones for the HD suspension, whether you have a z51 suspension or not. If you want to spend more, step up to Koni Sports.

What do you mean when you say there is no upper link above the drive shaft? You do have toe rods don't you?

 

Well the toe rods r pretty much level with the top of the drive shaft which allows for more dynamic toe/camber angles I believe .
but a normal setup would have a link at the top of the rear hub which would have more support but guessing space was to tight to fit it up there...

 

if you want to get rid of the "side kick" when turning hard, get some torque beam plates fitted, they WILL get rid of the rear suspension movement (if everything in the rear end is good and tight to start with)

http://www.zfdoc.com/c4beamplate.htm

Im just hoping this doesnt start up the old argument that ensued last time someone raised the beam plates issue !

 

I dont think thats what im feeling (tho I do believe it always steps to the right during strait acceleration)
im thinking the toe and camber rods might be the best bang for the buck (s) with the feel I'm having trouble getting used to .
We will find out how it fairs in stock setup this saturday and from there ill spend my money (this first buy will be a grand worth) anyone know where the cheapest place to get the bilstein shocks from zip corvette has them 320 for the full set ... any other options?