Here is what QA1 suggested based on at rest stock shock lengths of 13" for the fronts and 14" for the rear:

Based on those numbers I would recommend the DS403 shock for the front and the DS501 for the rears. The DS403 is 11 1/8” compressed and 15” extended. This shock typically takes a 10” spring. The DS501 is 11 5/8” compressed and 17” extended. This shock generally takes a 12” spring.


Any comments?

 

What year is your car?
Reson for going to coil overs?

Looks like a resonable price for the shock alone. Looking at the pictures on the summit racing website I can't see how you would mount them on a Corvette

 

http://www.ndneyes.com/coilovers.html

 

Page not found

 

http://www.ndneyes.com/mo/

 

what year car?

see sig

 

1991. There are other pieces needed to mount them. The Hyperco springs are apparently smaller in diameter than QA1's and thats why Vansteel uses them to avoid some clearance issues. There kits look like they go in without as many modifications as others because of the smaller spring. I'll nail down the other mounting hardware as I get closer. I just can't bring myself to spend the money for the kits out there.

I looked at Moes mods and got some ideas from there. These shocks and spring lengths are different from what some people are using and I was just wanting some input on what QA1 suggested.

 

I guess you're looking for better handling is the reason you want the coil overs? I would stick with the transverse composite spring with higher spring rate and larger diameter anti-roll bars.

 

Better handling and height adjustment. Also it adds a custom touch.

 

Hi guys,

If you have any further questions on the QA1's please let me know. I apologize I have been moving my website around a bit... I received a battery sponsorship

I will leave the /mo site up

Best regards,
Mo

 

Thanks Mo for stepping in. What do you think of the shocks I posted? Also I found out that Vansteel uses a 2.5" diameter spring, which helps with the clearances.

 

I crossed the numbers over...

I'm using the HAL-DR4855 for the front they are 10.130 -14" long versus the DS403 which is 11 1/8" -15" I don't see that as an issue ( the front wheel travels roughly 3 inches to 1 inch of shock travel). However you need to make sure you purchase the "t-bar" mount for the fronts. The DS shocks are the same diameter as I am using 2 " using a 2.5" diameter spring... As was posted earlier you may need to rework your front towers for clearance at the top front mounting point.

On the rears I'm using the HAL-DR5855 which are 11.6" - 17" which looks to be the identical length as the DS501's they are suggesting using the 2.5" coil over and the 12" inch spring as well... My personal opinion is you will still need to shave the bolt heads and reverse them on the knuckles as I have shown on my site as they are REALLY close... Also for added clearance I moved the top mounting hole on the top rear mounting plate forward about .75 inches to move the shock further away from the half shaft ( I redrilled the hole and welded a thick flat washer to keep the shock mount in place). If you go below about 26.5 inches ( as I recall) you will be virtually resting on the rubber snubber. I found the best height to be around 27" with a full tank of fuel, so with the front at about 27" ( center of the fender well to the ground) and the rear at 27 with a full tank, as you burn off fuel you will gain about 3/4" of height in the rear putting it at about 27 3/4" makes for a nice looking rake.

Please let me know if I can be of further help.

To answer your question if you are asking will the van steels work yes they are close enough. Don not worry about the front only going to 10 inches compressed, if you go below 26" in the from the tie rod ends will start to bind so again so 26.5 to 27 inches is what I would call minimum...

FYI with the new HAL numbering system my shock choice came out as a DS 402 front and DS 502 rears which are both eyelet versus bearings ... As you also mentioned the front shock is about an inch longer, the rear is essentially the same with the exception of bearings versus eyelets ( which is really a personal preference).

Regards,

MO

 

Thanks MO, with a 2.5" diameter spring that may eleminate the clearance issue with the front tower. I suspect that is why Vansteel uses them. The instruction for their install does not address doing anything to the front tower. What # springs did you find that worked the best for daily driving?

Thanks

Chuck

 

Yes it pretty much depends on the year. I did take a crescent wrench and slightly opened my tower up near the top to give a little added clearance to the area where the top of the spring is.

I was happy with the #400 the spring rates. On the 1991 it looks like they were much stiffer that the 1996 93.1 N/mm versus 60 N/mm

Here is a reference website with estimated spring rates... 1 N/mm =5.7 lb/in http://zr1netregistry.com/ZR1_suspension.htm

The 93.1N/ mm * 5.7 comes to ~530 lb/in * the .66 (for the angle of the shock) puts the spring rate right at 350 # so if you like that firm ride you could go stiffer, but remember the shocks have 12 valve settings... (The spring would need to be about a 525#)

On my 96 they are 60 N/mm so that equals 342# * .66 = 225#
The spring would need to be a 350# ( this is way too soft) the spring will be wrenched really tight to support the weight of the car... I suggest a 375# as a minimum....

So with the 400# * .66 = 264 as you see is a touch stiffer than the stock 1996...

The front of the car weighs about 1800 and the rear is around 1560 depending on fuel.

With the 400# spring if you tighten it to about 8" high you will be pretty close to 27.5 inches in the front...

I'm running 300# in the rear....

I hope this helps...

MO

 

Mo I appreciate all the input, you've really done your homework. So you would suggest 400# in the front and 300# in the rear and this will allow me to lower the car some and still provide a near stock ride?

Thanks

Chuck

 

Gentlemen,

It might be just a matter of semantics, but SPRING RATE does not change with angle of the coil. It still requires, say, 400 pounds of force to compress a 400 pound spring a single inch. The mounting angle may effect the motion ratio, which, in turn, governs WHEEL RATE.

Ed LoPresti

 

cshuman yes I would say go with the 400 / 300's....

I'm not sure what your ride height is right now but you will be able to go below 27" ( meaning lower than you like) and still have plenty of room to go almost stock ride height.

Hi Ed, yes I agree with you, most coil over sites I have been to they also factor in the angle of the shock, so I was also passing this on as well. I fully agree that no matter what position the spring is in 400 lbs/in is 400 lbs/in.

One example: http://www.proshocks.com/calcs/anglefirst.htm

Best regards,

MO

 

I have 275's in the rear currently and I might be swapping the 275's for 300's or 325's here soon, 275 is a little bouncy or too stiff if I adjust the shock to eliminate the bounce

I am at 26.5" rear and 26" in the front and I plan no moving it back up to 27 rear and 26.5 front,, for some reason my height dropped 1/2 front and rear after my last alignment.

 

In regards t the spring rates, does anyone know what the shocks are rated at per click. if they are 12 settings, what setting truly is set correctly for a an 89 type ZO7 front rear spring?
If you go coil overs, what does the adjustable shock do for you if the spring should be working with the shock to keep tires planted on the road?

 

Quite right, Mo,

In the conversion chart in that link (and probably all the others, as well) they are referring to different angles of attachment to the chassis, which would vary the MOTION RATIO on that corner. The motion ratio (squared), times the spring rate, equals the WHEEL RATE. It appears that they are doing this for simplicity purposes, but their conversion chart (technically) should read "DESIRED WHEEL RATE".

I ran a couple of the calculations, just for fun, and they seem very close, assuming that the attachment point on the chassis is solid, and does not pivot.

Nice topic.
Ed