I think we just went over this but best way to lower an 84. I saw in Ecklers and others a lowering kit, but it looks just like 2 screws. can i do it cheaper
thanks
matt

 

I think that this has been covered a number of times, but I'll give it a shot. The lowering kit that you saw is for the rear of the car only. I would highly recommend using the kit (or similar from other manufacturers), if you plan on lowering it. The bolts are longer than stock, allowing the car to lower itself. Some people have reused the stock bolts by pulling the cotter pin, backing the nut off to the desired height, and redrilling for the cotter pin in the new location. (Or use a self locking nut) The reason that I can not endorse such a strategy, and consequently did not do that to my car, is that the hole in the bolt reduces the strength of the bolt. Since the hole for the cotter pin moves to the portion of the bolt that is under tension, it doesn't seem to be a wise or prudent choice. If you are really going for the stealth look, you can change the location of the shims used to mount the spring to the differential cover. I suspect the added labor isn't worth it for the minor savings in cost of the kit. Front suspension is a whole different, long, story which I can try to explain if you wish. Also note that be lowering the back of the car, you will slightly raise the front (measured at the nose).
I hope this helps, and if I skipped over anything in my tired stupor, just let me know.
Ted
96 CE LT4 Z51
(Set at factory minimum ride height using 100% stock GM parts)

 

You can buy it from your local Hardware store.....take your stock bolts off and match them up at the store. Get the strongest bolts they have....with lock nuts. You can save a little bit. :cheers:


[Modified by Zora, 2:11 PM 12/18/2002]

 

Okay Ted
I understand the back, and that makes sense, I would be paying the extra money for less work.
But then how do i lower the front so it doesnt look funny?
thanks
matt

 

I will explain how the front spring is setup before I explain different lowering techniques. Forgive the crude diagram, but it is the easiest way to explain it. The diagram is a cross-section of the car along the center of the spring.

The BLUE line is the frame cross member.
The RED lines are the spring to cross member spacers, made of rubber.
The BLACK line is the spring.
The GREEN lines are the spring end pads.
The ORANGE lines are the A-Arms.
Most methods of lowering the front are done by changing the cross member to spring spacers from thick rubber to thin poly wedges. The differential in height between the spacers doesn't seem to be too extreme, but it has a significant impact on the ride height. Do not ever attempt to lower the car by removing the spring end pads; the spring will fracture. (I've seen it happen on an SCCA ITE car that had to be REALLY low.) Depending on the factory spring pads they may be modifiable, but I think you will find the wedges are more than acceptable. If you need specific instructions on the installation procedure, I can help you out with that, since I've done it quite a few times. I also recommend keeping a slight rake to the car, because it will increase the high speed stability over being "flat." If you don't exceed the posted speed limits (hopefully in a legal way) than ignore my comment about the rake. You will be amazed at how much of a difference reducing the ride height (CG) will make on the handling of the car. Remember to have the car realigned everytime you change the ride height. I'd also recommend waiting a couple weeks before the realignment because the car will "settle." Once again, if you have any more questions or if I wasn't clear on something, let me know.

Also: I checked the size of the factory rear bolts. They are 14mmx2.0mm 230mm with a 21mm head. They are metric grade 9.8 (Actually .8G). You can use a SAE (fractional) equivalent bolt, but make sure the strength is correct. The minimum tensile strength of a .8G is 113,800 P.S.I and a SAE Grade 6 is 133,000 and Grade 8 150,000 P.S.I. respectively. If this doesn't make sense, just order the pre-packaged kits...
Ted
96 CE LT4 Z51


[Modified by LT4CEZ51, 1:19 PM 12/18/2002]

 

Good way to go ... and what I did. For around $5.00 total.
Be sure to get grade 8 bolts and Nyloc nuts. I also cross drilled the bolts for cotter pins for additional insurance. (take your time drilling ... those bolts are hard & chew up drill bits fast)

 

Ted-

Can you move the shim's out towards the wheels to increase the spring rate? Just a thought.... I seem to remember seeing a kit to do that for the rear.....

jsn

 

JSN,
I am a bit confused by your question. The rear spring spacers can only be moved from the top to the bottom of the spring, and can not be moved sideways. The front spacers (between the spring and the crossmember) should be appropriately seated in a "detent" in the underside of the crossmember. The location of the U-shaped spring retainer also effectively dictates the location of the front spacers. If you are referring to the pads on the end of the front spring, with a stock spring they aren't moveable. However, if you change to the poly wedges, if the spring isn't centered you will end up with different spring rates, different corner weights, and different ride heights. (Yipes!) It is an effective way to set corner weights if you have scales, however... (There is a little more to it that I am glossing over, but isn't brevity a virtue?) If I completely missed what you are getting at, let me know...

Oops, I think I remember what you are referring to. I haven't ever really considered the thing (VBP sell em?) since they aren't legal in my class. It also seems to make a lot more sense to just order a custom spring if that is what you are looking for; I've had excellent experiences from Vette Brakes in regard to springs. They actually read off which rates they had and overnighted it to me when I had a bad one.
Ted
96 CE LT4 Z51


[Modified by LT4CEZ51, 3:49 PM 12/18/2002]

 

Leave it alone, after you lower the front the front tires will be hitting the hood or wheel wells when going over a road dip. That was my experience with this arrangement.

 

Ted-

Thanks, your response makes sense. My thought was to move the poly wedges sideways (towards the wheels) to change the spring rate -- in place of spending the money on a new, stiffer spring. But I hadn't seen the under side of the car yet, so its probably just not possible (i'm still a newbie to the corvette world)

thanks
jsn

 

cool diagram and excellent explaination...
but, what did you mean by rake?? i like to drive VERY fast and so high speed stability is very important to me!!
you mean lower in the front, right? rather than flat?
thanks,
Sonny

 

Good idea, but would take alot to make work. The problem with that idea is the mounts are in a certain place, and the wedges are in that same place. If you were able to move the mounts outward more you could change the spring characteristics. But that would take some serious modifications, not worth it IMO.
http://www.vetteracer.com/pics/vette/Springs.jpg
In that pic you see two front springs, you can see where the mounts are, that upper mount is what gets cut off (http://www.vetteracer.com/pics/vette/Big/Suspension/cut%20side%20with%20wedge.jpg) and replaced. You can also see the bracket, the black thing up front. It goes around the mount...


Matt

 

Is there any known relationship to the amount the front lowers to the replacement of the rubber cross member spacers to poly wedges? Are the wedges available from a supplier in the proper thickness? I assume that this is how the SCCA Corvette racers are lowering their cars since they cannot use coilovers. Is this too drastic a drop for a street driven vette?
Thanks!

 

hmm . My car was lowerd by the pre-owner. He remowed the spacers on the tip of the front springs. I dident know that whas bad?
hmmm...

:eek:

 

how does the eckler kits works?

 

I lowered my car last summer. I took pictures throughout the process. The homepages on here are down so I can't post the pictures. I am going to try find the old link.
Ed

 

Here we go. A link to my post when I lowered the ZR-1. There is about 8 pictures in the post. http://forums.corvetteforum.com/zerothread?id=362047
Here is the spring coming out of the car too.