I'm going to put Bilsteins on my 84 non Z-51 Vette.

I wanted the best handling shocks I can get even if I sacrafice ride quality. Where can I get a great handling Bilstein??

I've seen them in Corvette Central and they were about $75.00 each.

Are there different grades of Bilsteins or is a Bilstein a Bilstein?

Also can I put Z-51 Bilsteins on my non Z-51 car?

Thanks.

 

In my own humble opinion, the "best handling shocks you can get" are not Bilsteins. Oh, they are a GOOD shock, just not the best. If you want the best, be prepared to pay a little more than $75 apiece and move up to a QA-1 or KONI Sport. Since they are both adjustable, they can be fine-tuned to match any suspension.

Larry
code5coupe

 

Not to be harsh, but QA1's are not on the same planet as Bilstein and Konis. The reality of adjustable shocks is that unless people use the car for competition, once they get them dialed in, (which like many with coilovers, they never properly do) they don't re-adjust them. Why would you? Bilsteins are very high quality components, are mono tube shocks and are used in real racing applications off the shelf. Koni makes a wide variety of products, from your basic twin tube shock to F1 dampers.

ffvetteman, keep in mind that like a motor, your suspension is a "system" in which all compoonents need to compliment each other. You would no more stick the biggest cam that would theoretically make a LOT of power in an otherwise stock motor. Would it run? Maybe, but like youknowwhat! Your original C4 as it sits, still out handles the overwhelming majority of the production cars made today, even though it's 20 years old! My recommendation would be to simply replace what you have, after you replace as many of the original bushings as you can, check all your wheel hubs (Being a newbie to C4's you may or may not know that the bearings and hubs are one) all of your suspension ball joints, and tie rod ends, and links. (there are many in that great handling 20 year old hot rod) Also, purge and refill ALL of your fluids. (Five bux say your brake fluid and PS fluid have never been totally flushed.) Anyhow, you get the message. Lastly, THE most important element in a great handling car is the DRIVER. Have a blast and sign up for a drivers school with the BMW or Porsche club at Mid-Ohio. (Marion's around the corner of one of THE finest road race tracks in North America!)

 

I checked all bushing, tie rod ends, ball joints, wheel berings, and anything else in the suspension. For 99,000 mi it looks incredible!!

I bought the car with 50,000 mi so I'm guessing the bushings have never been replaced and are not cracked at all. The baal joints are tight as can be, and the wheel berings are tight and quiet too.

All I'm going to replace is the shocks mainly because they are mismatched now, Bilsteins on front and some unmarked black shocks on the rear.

I'm just not sure if there are different Bilsteins or not. I'm not going with adjustable shocks, because the car is mostly street driven.

The fronts are starting to get a little weak, so now is the time for change.

 

BTW the brake fluid and power steering fluid has all been changed. New brake fluid when I replaced the pads last time and new power steering fluid when I rebuilt the WHOLE steering system, rack included.

BTW You owe me five bucks

 

I've had Koni Sport adjustable shocks on my 88 Z51 and now have Bilstein Z51 shocks. The Konis are a great shock, but unless you do a LOT of autocross I think that they are too rough. On a tarck where the road surface isn't in bad shape they shine, but on real roads the ride is so rough you don't concentrate as well as you should and things vibrate loose.

Remember that the only job of a shock is to keep the tire connected with the road. If the shock is too stiff for the surface you don't stay connected as well as you would with a slightly softer shock. I saw a write-up once showing where the Koni Sports start out at the softest level stiffer than the factory shocks stiffest level by a good margin. My experience has been similar.

The 88 Z51 Bilsteins have made my daily ride MUCH better and I don't feel that I've given up anything in handling. At an autocross course with good pavement I might swap in the Konis, but only while there.


To my knowledge there aren't different grades of Bilsteins for the C4 other than the Z51 and the standard shock versions for that year. Meaning Bilstein builds a quality vehicle specific shock the first time and doesn't have lower grades available directly or in the aftermarket.

A suspension chart that I have from a Hib Halverson article (Corvette expert) shows that the 84 Z51 cars could use either Z51 or standard FE1 shocks. That indicates to me that "physically" the 84 Z51 shock will work on your car.

The chart also shows something interesting concerning the 84 with respect to later C4s.

Front Spring Rate (N/mm)
84 -------- 63.5
85 Z51 ---- 63.5
88-91 ----- 93.1
84 Z51 ---- 102.0
88-91 Z51 - 115.5

Rear Spring Rate (N/mm)
88-91 ----- 39.9
85-91 Z51 - 57.2
84 -------- 72.0
84 Z51 ---- 87.5

The 84 was noted for great cornering and a really rough ride. An unscientific observation based soley on the above tells me that GM realized that the rear of the 84 was initially too stiff and carried the rear sping changes forward for years. I'd look into replacing the rear springs with those from an 85 or later and trying the Z51 shocks from an 85. Bilstein's web page says the standard 84-87 shocks are interchangeable and the 84 Z51 can use STD or Z51 shocks, so the 85 Z51s should fit your 84. The spring rate for the 85 Z51 front is the same as your stock FE1 84, so they should work together nicely. With an 85 rear spring the 85 Z51 shocks should match real well all around.

I second h rocks advice in that attending a good driving school will improve your car's handling far and away more than most any parts.

 

If Van Steel isnt selling the Bilsteins cheap, the best price you're prolly going to find is $250 for 4.

You can use Z51 shocks on a nonZ51, and in 84 it doesnt even matter, a nonZ51 84 is as harsh as a Z51 85

I think they are the best in terms of autox, but theyre not the most gentle shock for street driving.

 

You're one of the few that flush their braking system! You would be surprised how many guys are driving around with brake fluid that looks like molasses. (that stuff probably has in the neighborhood of 5% water in it) Even if the bushings look good, rest assured that they are dry rotted. When you remove the upper shock bushings for instance, they will look OK from the outside, but the ID will be grossly egg shaped. Your bearings may have been replaced prior to your buying the car, as they would be gone by now. The rear toe rods, if worn, will have a hugely (is that a word?) negative impact on handling as you will be getting rear bumpsteer. Check out Imparts for Koni, and RD Enterprises for Bilsteins. The first place is a big BMW parts house, but they move a ton of Koni's and have great prices on every Koni they sell.

 

If the rear tie rods are worn, you should be able to move them, right?

Mine are tight and I cannot move them.

 

As for the bushings, the shock bushings are dry rotted, but I didn't count that because I am replacing the shocks for sure. I checked underneath to see what the rest of it looked like.

Everything back there, and in front for that matter is tight. The bushings show hardly any wear and again is tight.

I'm shocked because I was planning on replacing everything in the rear end.

 

Mike, thanks for the info. It does make you see the changes made to improve ride quality and keep it handling well.

As for what to use, I'm thinking staying with the stock 84 non Z-51 shocks. All the spring rate etc is calculated to form a whole package, and I dont want to mess with that.

I dont want to change the rear spring, due to the cost involved. Too many other things are getting fixed soon and money is always an issue.

Besides, I like the harsh ride of the 84.

 

You can't go by the external appearance of the bushings, nor can you judge the condition of them by wiggling, jiggling or jacking. The dynamic force generated by the 3400# + car in a corner can't be duplicated by those other means. Rest assured that unless the original bushings were replaced, they are gone. My car only had 35k on it when I decided to improve the suspension for DE's a number years ago. Nothing was wrong, and they all looked and felt great. After changing over to poly, there was a very nice difference. Then I upgraded again to the Global West control arm bushings...wow! another step up. They made a huge difference under high speed braking. As "moving" was the change to poly in the third member. (batwing) Wow again...tightened up the whole car. Please don't consider this a flame, I just wanted to give you the benefit of my experience, as I use my car as it was intended...to have FUN!

 

I put Bilsteins (non-z51) on my 84 (non-z51) and I like them a lot. Given my 20 year old Vette had the original factory shocks anything would be an improvement. Just search the Net for the best price you can find and go from there. I found the site - http://www.proamauto.com/page15bch19.htm. They included shipping a couple months back you may want to ask about free shipping. I can't remember if it was a special thing or not.