MatthewJP

Hello all,
Long time lurker, first time poster….
I’m looking for wisdom/shop recommendations.

I have an early 1989 base suspension with 6 speed and 3.54 rear end. The only modifications to the L98 so far are Borla exhaust and K&N air filter in an opened up air box. Also have BF Goodrich Eagle F1 tires for what that’s worth. Nothing major planned for the future beyond maybe headers/exhaust. The car has 133k miles, I am the third owner, and it has been mechanically well maintained to the best of my knowledge based on the 32 years worth of records diligently kept by the previous 2 owners. I am not entirely sure what is currently in the transmission. I did not notice any prior clutch replacement, and mine is starting to slip. It is a bit noisy under light acceleration, at idle in neutral, and when the RPMs drop to zero after turning the car off.

It is my daily driver in moderate city traffic and is parallel parked on the street. I don’t drag race the car but I would like to get into autocross, not to win but for the fun. My goal is to modestly “liven” the car up a bit . My current to-do / wish list includes clutch, short throw shifter, shocks, and 1” lowering kit.
I have settled on a short throw shifter from zfDoc since I want a more precise feeling shifter but also want to keep the stock appearance and more importantly want to keep the reverse lockout. I like this because, again, it is parallel parked every day and want to keep the familiar functionality. I already find myself holding it by the lever more so than the ****, so the zfDoc set up sounds like a good compromise between the Hurst and B&M.

I have settled on Bilstein B8 performance plus since these should firm-up the ride well enough over my current old AC Delco shocks.
I would like a 1” lowering kit. If the improvement in handling is negligible, at least the subtly lower ride height will look better. I would go with the kit that includes the bolts for the rear and thinner wedges for the front. My trusted shop is wary about installing this though.

I have not settled on a clutch yet. I love that the current set-up is easy to operate, has long usable travel, and bites predictably. Without giving the car any throttle, I can idle my way up to 15mph in 4th gear. Again, the car is daily driven through moderate city traffic, so I don’t want a leg workout, but would like a slightly grippier clutch and modestly lighter flywheel pair that will feel more spirited but still livable. I don’t mind if it is a bit noisier. I have searched the forums and realize the dual mass flywheel will be near impossible/very expensive to find. I have read up on the RAM conversion but not sure which one would be what I’m looking for. I’m leaning towards 900 series if it will still be livable for commuter duty. Does a grippier clutch mean more pedal force?

What do you guys think? Are my ideas reasonable, or am I opening up a can of worms. Can anyone recommend a shop in the Chicago area that is knowledgeable and capable of this work? Unfortunately I do not have the space or equipment to do the work safely. I checked with one shop in the area that specializes in Corvettes and they seemed to be trying to discourage me from making modifications given the age and mileage.

Your knowledge and experience is greatly appreciated.
Regards,
Matthew

Joe K

You will probably not be able to out drive what the car is capable of as it is. I would take care of any maintenance items that are needed and invest in a High Performance Driving Class. Or just show up at an Autocross event, watch and ask questions. A 32 year old Corvette is still 32 years old no matter how maintained it's been. And as you've found out it's hard to find someone that wants to work on these cars let alone someone that can work on them. I do my best to live by these cliches, though sometimes I fail. "If it ain't broke don't fix it and if it's fixed don't fix it better"
I'd repair only what's needed, find a place to safely drive it like it's a Corvette and daily it as much as I could. JMHO and YMMV.

Welcome to the Forum and the Wonderful World of Corvettes!

Joe K

Joe K

Sorry wasn't trying to be a downer. Was hoping someone would chime in with some positive advice. So I will. I see nothing wrong with any of the things you plan on doing. They have been done to many C4's with great results. I think you should invest in a Factory Service Manual. That would give you information to help you decide who you may want or not want to do any repairs or modifications. You may also look into any "self-serve" type of garages where you could do some things. Those would be ones that rent the space and sometimes the tools to make repairs. I hope this helps. Post up some pictures!

Joe K

ctmccloskey

First, Welcome to the Corvette Forum MatthewJP!

Once you lower this C4 of yours and put stiffer shocks it might be like riding in a buckboard. Just the shocks alone can make such a huge difference. On my C3 I did the bushings as well KYB Gas adjust Shocks and we joke about how you can tell if it is heads or tails when you run over a dime. It is uncomfortably stiff in my humble opinion. On our 1988 C4 I went ahead and replaced all the suspension rubber components but use the noisy Poly-urethane Bushings. It has the KYB shocks on it as well and I am convinced that I won't use them again. I am going to a Stock Bilstein like the ones that came on the C4. If you choose to use Poly-urethane be sure to get the quiet kind or you will have to lube them yearly. I squirt Graphite into my joints and bushings to quiet them down.

My wife and I drove my C4 for about a year and made a long list of things I wanted to fix before any upgrades are made. It probably took a year just to fix the little things but the Car eventually became a comfortable daily driver. The sad part about owning an older Corvette is when I finish one thing I have three more waiting to be done. After I was close to being done my EGR valve went south and that necessitated replacing Injectors, FPR, EGR Vacuum Solenoid and many other parts. I just took my time and tried to restore the Corvette to daily usage.

The first upgrade I did was replace the catalytic converter with a High Flow modern unit from Summit Racing. I then installed a set of Chambered Exhaust pipes and what a great sound it is. This combination allowed my L98 to exceed 30 MPG on a flat interstate with AC blowing. I was really amazed to see a Corvette get 30 mpg.

The Rack and Pinion system on these C4's is a weak link but will last longer if the fluid is kept cooler. Auto crossing and spirited driving can lead to more heat in your Power Steering System. To help the system last longer try and keep it cool. I have larger reservoirs to allow for more power steering fluid. If the fluid still gets HOT then add a tube cooler as it would be very easy.

Find a local Corvette Club and start picking their Brains for quality shops. Even the NCRS folks can help you with this as they would know who to trust and who not to. The experienced C4 owners can point out problem areas to you. Like if you are serious about Auto-Crossing you might have to replace the rear wheel bearings. The factory ones are not quite up to snuff for racing or auto-crossing. You will probably find all the weak points yourself, especially for the drive-line parts. I see mentions about using a stronger rear Differential case. I have a 427 in my 1968 C3 and it came prepared with the right parts for more than normal power production. The day I put Drag Radials I blew a half-shaft U-Joint into a zillion pieces. And that was not doing a hard start either. The C4's were built with 405 HP (on the ZR1) but not the close to 600 hp that some of the C3 race cars. My C4 is more a comfortable Car to drive where the C3 is for scaring the heck out of yourself with its brute power.

Fortunately for you sourcing a good supplier and where to get help is easy with all the knowledgeable folks on this Forum. Most questions get answered quickly and correctly. There are a bunch of very honest suppliers out there that help us keep our C4's on the road where they belong putting a smile on your face! I use ZIP products for most of my Corvette purchases as they are less than a day away by UPS.

NOMOREWORK

I also own a base model 89 but with an auto transmission, I have replaced the stock Bilstein shocks and installed a lowering kit ( bolts and pads ). I also replaced the stock brakes with Power Stop rotors and pads, the car rides like a sportscar not a buckboard.

MatthewJP

Thank you all for the input and recommendations. I genuinely do appreciate the forewarnings. I understand that beefing up one component can move the "weak link" to another area, but I don't plan on adding much more power anytime soon nor driving the car very hard. As I said, the car has been maintained, and I certainly plan on keeping up with that, and I take it to my trusted shop every spring for a driveline inspection before getting it back on the road. Rear hubs were recently replaced, and the transmission fluid was changed last year. I believe all the modifications I am interested in would be reversible (for a price) [but maybe not the front lowering?], and I didn't think they would be that much of a deviation from stock. The car currently drives more like a grand tourer than a sports car. I'm not too concerned about a harsher ride since my commute is not too long and most of it has recently been repaved. I've been a nurse through the whole pandemic, working full time and going to school, and next week is a landmark birthday for me. I would like to reward myself, and accept that I might learn a hard lesson about modifications. Any other "weak spots" I should have looked at before modifying?

Gasnmyveins

Not Zombiefying this thread to be a doofus. I’m just wondering what has been done to the car since the last post, and if you are happy with the mods you made.

Personally, I recently bought a 94 six speed that had been an auto cross racer and a road racer at Sebring. Lots of suspension mods. The roads are really pretty good here, so I harshness has not been an issue with it. On a rough road, it would be terrible.

I hope you are as happy with yours as I am with mine. Or as happy as I will be when I get the clutch changed. I knew it needed that when I bought it. Looking at a better one, so I can mod the engine later.