Scooter70

Keep us posted. Most of us here are GRM subscribers and follow any type of racing, including ultra-low-budget like you're doing.

Dueller

Will do. 6You guys have been so helpful and welcoming. Couldn't do it without everyone's help and advice. Hope to make y'all proud

mr.beachcomber

According to GRM's #2016 Challenge rules, you have between now and September 30th to prepare your '89 Vette for for three forms of competition: 1) auto-x (4 runs); 2) drag race; and 3) Parc Expose (sort of a show & tell concours d'elegance). Since your first set of four tires are budget-exempt, I would consult with this forum as to which 200 Tread Wear tires to buy for the event. (I'd trust Sam Strano's choice on this one.)

Given your remaining budget of $650 and your maximum recoup through the sale of parts is $1,008, you'll have to choose how to best spend your money as well as time and effort. The following is my take on what I would do in your situation as I have owned both an '89 automatic coupe like yours, and my daily driver is an '89 Z51 (non-FX3) 6-speed. Both cars were/are auto-xed extensively first in the Stock (now Street) class and then in B Street Prepared). These are just my opinions and YMMV according to your own vision for the Vette.

1) First thing I would do is replace the stock braking system with rebuilt calipers, new rubber hoses, and new rotors since their cost won't impact your budget. I don't see the need for the J55 brakes for a parking lot auto-x. Whether you use the stock brakes or the J55 setup, you are still going to use the same size disc brake pad for both setups. The heavy duty brakes have a 13" rotor with cooling vanes versus the stock 12" vented rotor. Sticking with the stock setup has benefit of less weight to rotate (which is where you need to be as you'll see that the L98 only has 240 HP.) You can go to Rock Auto and buy rebuilt calipers if you don't have the time or inclnation to do your own. (I recommend this approach as I spend the better part of a year chasing down braking problems with the Z51 setup due to calipers that needed a rebuild.) Pad choice should be up to your auto-x driver's preference. I've used HPS, HP+, and PFC Z-rated pads on my Vettes with good results. HPS is a good all around performer while the HP+ are best for auto-xing, but dust like crazy. The PFC Z-rated pads are better than the HPS, and have similar stopping power as the HP+ w/o the heavy dusting (which is a bitch to clean off the wheels if you let it set). Price may be the final consideration as both the HP+ and PFC Z-rated pads are a tad expensive.

2) The suspension should be your next target. Ball joints, tie rods, and u-joints's need to checked/replaced as necessary and the car alignment checked. The old Roger (The Famous) Johnson approach to C4 alignment was remove all the alignment shims and just run what you had with some toe-out at the front and toe-in at the rear. As previously posted, you can stack shims and/or grind down the control arm spacers for more camber. If the Vette's frame has seen any damage, the Roger Johnson method probably won't work. Replacing worn out bushings is a good idea, and since Chevy never did offer OEM replacement bushings, your choice of poly replacement bushings should do the trick. Before you start messing with transverse springs, coilovers, and roll bars, get a good set of shocks. The stock Bilsteins are a good choice and available from several Corvette Forum vendors. I'd shy away from single-/double-adjustable shocks right now unless your auto-x driver really can make a good case of why he needs them. Sway bars, front & rear, are a toss up as far as I'm concerned. While the FE1 stock suspension is softly sprung, it's still pretty good overall. The Z51/Z07 suspension was really meant for track use, but works well on smooth surfaces. Still, if your auto-x driver prefers a flat cornering platform, the 1988-1991 Z51/Z07 sway bars can help, but they add weight. (Google "1984-1996 Corvette Suspension Chart" by Hib Halverson to get an idea of what springs, roll bars, etc. were available for each year. Just remember that you need a front sway bar from a 88 and later Vette as the earlier models won't fit your '89.)

3) At some point, you're going to need to make a decision on whether to stick with the TPI system or ditch it for a conventional carburetor setup. My feeling is if the TPI system is working correctly, keep it. Your '89 L98 has a low lift, short duration roller cam that has peak torque around 3200 RPM and peak horse power at 4400 RPM. It's more than adequate for a 700R4 automatic with a 3.07 performance rear end (according to your option codes). Completely stock you'll be turning 4428 RPM at 68 MPH in second gear at the auto-x using the stock size tires (275/40R-17's). That should be plenty fast for a parking lot auto-x. (There are aftermarket intake, runners, and plenums for the L98 TPI system that can add more breathing capability, but since they ceased production on most of the units, they are rare now, and their cost might break your budget.) Adding a big carburetor and a big intake manifold isn't going to do the job if you keep the stock cam. Still, some prefer carburetors over TPI. If you can resell enough parts to add decent heads and cam along with the swap, you will pick up some significant HP.

4) The biggest increase in torque I've experienced short of a cam change (which isn't allowed in the classes I run) was adding small tube (1 5/8") headers. (I had to keep the cat to pass inspection in Virginia. If you don't need it in Mississippi, you can build your own free flowing exhaust system from the headers to whatever you want to use for the rest of the exhaust system. I have muffler eliminators on the Z51 and still pass inspection.) I think that the pay off here is reduced weight and a better scavenging exhaust system.

5) Weight is your enemy if you have an L98. Anything you can legally do to shed the weight will help the engine out. Substituting a racing seat for the 6-way driver's seat is a good example of weight savings. I think you've come up with some good ideas so far. Just keep looking for ways to shed weight as you go along with the build.

6) Finally, you have a blank canvas so to speak when it comes to the parc expose portion of the challenge. I've noticed at the Cars & Coffee events that I have attended that people seem to go nuts over the carbon fiber look achieve with vinyl wraps. If it doesn't break the bank, I think that this look on the replacement back deck would turn some heads. YMMV though.

That's it. Good luck with your Challenge Vette, and remember to have fun!

Dueller

Mr. Beach....wow! Thanks much for your great advice. Following largely down your suggestions. Poly bushing kit on its way thanks to another forum member.

We have the motor mostly sorted and blessedly the TPI seems to being spot on.

This weekend is dedicated to weight reduction. First obvious thing is a.c. and are pump removal. QUESTION FOR THE BRAIN TRUST....What parts do I need and what serpentine belt do I use.

As usual, thanks in advance!

Jim

mr.beachcomber

To retain the stock serpentine belt, you'll need the pulley delete parts for the A/C condenser and the AIR pump. These are available on the aftermarket, but you should be able to make your own. Keep the power steering, alternator, and water pump pulleys in the serpentine loop. If the steel "frisbee" balancer is still on the end of the water pump pulley, remove that too.

Keep in mind that the water pump on the L98's rotates in "reverse" of the normal SBC and the internal vanes compensate for this, so if you can't maintain the stock belt configuration, you may have to swap out the water pump for a normal rotation.

Some one out there has probably done this (keeping just the harmonic balancer, alternator, water pump, and power steering) using a serpentine belt, but I don't have a ready reference. Sorry.

jaa1992

Ahh, forgot you are looking at mostly autox!

So I first autox an 88 automatic with crappy brakes, bad suspension and shot shocks!

PFC - Z pads!!!! (If you can find them) Otherwise the carbotech AX pads
Completely FLUSH the brake system and then replace the calipers with rebuilts.
Stock Bilstien shocks are fine.
Replace the bushings.

Then PRACTICE, PRACTICE, PRACTICE! I could get that 88 auto to dance around an autox course.

Don't expect much from the drag races, high 13 is the best you can probably do with less weight.

Dueller

Thanks for the encouragement, jaa. LOL

I'm just trying to have some chits and giggles...not win SCCA national BSP championship or NHRA Winternationals.

Dueller

First major setback....going thru brake system, the spaghetti like labyrinth of brake lines going to ABS module behind driver seat are rusted and leaking.....thinking about eliminating ABS altogethiner and puting a cockpit adjustable proportioning valve.

What say the braintrust?

mr.beachcomber

Here's a link to an ABS removal in the C4 Tech forum. For most of your questions, that's a good forum to search for technical answers rather just rely upon those of us reading this thread.

Good luck!

jaa1992

For that year, and all you are going to do is autox and drag race?

Get rid of it, I want to get rid of the ASR/ABS on my 92. Its causing more headaches than solving issues on the road course.

Check out the threads over in the C4 tech section

Dueller

Ok....out with ASR/ABS.

GETTING READY TO WEAR OUT MY DEBIT CARD WITH ROCK AUTO.

A quick question first. Since for the purposes of this GRM challenge build brake systems are not included in budget I have some leeway. Obviously not going to go nuts and spend major $$$$ on a $500 c4 that is at best gonna be a local level fun autocrosser so no Baer or Wildwood exotica.

Would you upgrade to J55 ? Or all fresh components in 12" system? Seem the difference in cost is relatively slight. What do I need to convert besides calipers and 13" rotors. Pros and cons? I.e., less unsprung weight vs greater braking power. Ooh yeah car Will be prob 2950 to 3000lbs.

As usual TYIA....

JIM

mr.beachcomber

You don't get "greater braking power" with the J55. (Both it and the stock system use the same size brake pads front and rear.) The J55 is the set up for track racing, not autocrossing. The curved vane J55 directional rotors pump air more efficiently. The larger 13" rotors handle more heat than the stock 12" rotors. Don't get caught up in the "bigger is better" syndrome. Stick with the stock set up.

Forgot to add that the J55 calipers need a different mounting bracket than the stock units.

AND0

Yeah, 13" won't help you at an autocross, lower unsprung rotating mass might.

A 13" rotor will produce ~10% more braking torque then a 12" due to the longer lever it has on the rotor, however at autocross speeds both sizes will be able to overpower whatever tire you use. Just use a good high torque brake pad to maximize what your tires can do.

jaa1992

On the 88, the ONLY thing I did for autocross was fresh parts and fluid and the PFC Z pads (this was many years ago) this worked well until I started going to road courses. The 88 had the JL9 brakes. just get the old nasty fluid out - I still remember replacing the fluid on the 88, the old fluid looked like worms as I flushed it out.

Thats why I said get all the OLD fluid out - then replace the calipers with new/rebuilt.

Dueller

Thx jaa. .I've ordered 4 new calipers , rotors, flex lines, pads, etc. Turning attention to all suspension bushings now. Also ordered all new ball joints. Tie rods seem OK. Rack and power steering pump OK.

Next question....sway bars. Kinda stuck with soft springs at this point due to challengebudget limits. I'm sure the sways are smallest oem stock. Just replace busings with poly or upgrade with at least larger front bar?

As usual I do appreciate every one's help.

Jimo

Dueller

Ok....after all parts spent thusfar, I have all new suspension bushings, brakes(every line. Caliper, rotor ,m/c, etc is new), shocks, Ball joints...all new. Motors has new plugs, wires, filters,lines etc.

Remaining budget is $255,,, not enough for motor upgrades or coil overs...what do I spend it on? Most bang for bug. Many competitors buy cheap/ured nitrous systema for one banzai draga strip pass bit dont wanna blow a healthy L98.

What say the brain trust?

Matt_27

Go test the car for a bit and see what it needs! Testing is free and you will be way ahead of most of the GRM challenge competitors if you have any significant time doing it.

jaa1992

Ya, I'd put it all together and drive it, drive it, drive it.

It will show you the weak points only after you get lots of experience in driving it.

Got a big parking lot you can use? Get someone from the local SCCA to set up an autocross course for you. Set up the cones and paint lines around them so you can set it up over and over and over again. Attend ANY autocross near you, not just SCCA.

BrianCunningham

also drive it to see what breaks!

ie) bearing etc

mr.beachcomber

Time to set aside some of that remaining money for your parc expose session. Most cars that I've seen in GRM's challenge have some type of theme. Don't know if you've that about that or not, but save some money just in case.

At this point in time, I'd concentrate of tuning up the engine after you've finished with the suspension rebuild. Here's what I'd look at:

1) Check the cap & rotor to see if they're good to go or need a replacement. Wouldn't hurt to check out the in-cap coil with an Ohm meter to make sure it's okay.

2) Check the spark plugs if you haven't already replaced them. If they're good, clean 'em up, gap 'em, and re-install them. Check your spark plug wires with an Ohm meter. Replace the set if any wire has excessive resistance (> 2,000 Ohms/ft) to avoid a misfire under acceleration.

3) Check your initial (lead) timing. The SBC distributor's rotor rotates clockwise, and a loose distributor clamp tends to allow the housing to rotate the same direction retarding timing. Don't bump your initial timing more than 8 degrees BTDC (stock is 6 degrees BTDC) as the computer is sensitive to engine knock (virtually any noise in the engine that activates the sensor) and will pull massive amounts of timing out to eliminate the source of the knock.

4) Use Throttle Body and MAF cleaner to clean up those components. The engine will run better for it. I've used the new CRC intake valve cleaner with great results on all my vehicles not just the '89 Corvette. It will remove deposits on the valves from worn guides as well as deposits on the pistons from worn rings. (I inject it directly from the fresh air takeoff on the throttle body while the engine is running. I use a rubber cap for the fitting, drill a hole for the application straw, and follow the directions on the can.)

5) The throttle position sensor can be re-positioned to give you a somewhat better throttle response. The stock setting is 0.54 VDC + or - 0.08 VDC at idle and can be checked just by turning on the ignition. The throttle postion sensor resistance should increase smoothly to ~ 5 VDC as the throttle is opened. Just set the idle voltage to 0.62 VDC to gain a slight advantage in throttle response. (Warning: This is one of those cases where more than 0.62 VDC is NOT better. It will confuse the computer, and you'll likely load up the spark plugs with excess fuel as the computer thinks you're accelerating.)

6) There is no advantage to relocating the manifold air temperature (MAT) sensor as the '89's ECU doesn't use that sensor's input to set timing advance like later models. It'll just add more fuel than necessary to the mixture which will eventually foul the spark plugs.

7) If you haven't already changed out the power steering fluid, I'd do that too because, as mentioned in an earlier thread, the wide 275-40/17R tires really heat up the PS fluid during auto-xing.

8) Don't forget to add a new air filter before the auto-x.

Things to look for while running the Vette before the event:

1) The vacuum booster housing for the brake system is plastic and can develop cracks in the surface over time. These usually occur close to the vacuum port on the booster. Won't disable the Vette, but it makes braking much harder w/o the vacuum boost.

2) The master cylinder internal seals tend to wear out over time and cause a partial loss of braking pressure. You'll see this as either the "brake" light coming on under heavy braking or a slight pause in braking pressure when applying the brakes. (Fresh fluid conditions the seals so that's your best defense.)

3) Vacuum leaks post MAF wreak havoc with the TPI system. With the engine idling, I use a small amount of starter fluid and spray it around the intake runners both at the plenum and intake manifold as well as the mating surfaces for the throttle body. If the idle increases, I know I have a vacuum leak. (BE CAREFUL USING THIS TECHNIQUE! A backfire will cause a fire!)

Hope this helps!