SB Chevelle spring rates?

[protour_chevelle]

Anyone know what the spring rate is on say a 70-72 Small Block Chevelle? I just need to know so I can kind of figure out if I want 650 or 750 rate springs in the front. Will a 750lb spring be tiresome on a 800km drive? Anymore so then 650 lb springs?

-Matt

[dennis68]

Matt, my 750/175 combo rides great. I am even thinking of stepping up the fronts to 850.

[protour_chevelle]

Thanks Dennis

You think 750/250 would work nice in my Chevelle?

-Matt

[dennis68]

Ohhhh, 250 is going to be too much in the rear.

[zbugger]

Yeah, with the 750 front, that 250 may be a bit much in the rear. Remember though Dennis, his CAR has a little more weight in the back than your.... Ummm..... Thing? What is that anyway?

[dennis68]

Actually bugg, there is only a 100lbs or weight difference. That empty bed thing is very deceiving.......how much more does a velle' have in the space from behind the front seat to the trunk that an Elco doesn't?

Thanks for your input though....... :wedgie:

[USAZR1]

Actually,El Caminos have a little better weight bias than a Chevelle,all things being equal.
I agree that a 250lb rear spring would be very harsh.

[protour_chevelle]

Dennis, Jeeze. :rtfm: :rotfl: You even said to me 250 would be ok. Sooooooooooooo What should I go? 150, 175, or?

Thanks guys!

-Matt

[dennis68]

250...me. Must have been half asleep or something. I'm running 175lbs. I haven't donea frequency analysis yet as the set of scales I was due to have access to several months ago are still "lost" ( in somebody elses garage I'm sure).

I would go with the 175's.

[Conekiller13]

I've been running a 625lbs/250lbs combo for a few years now. Hasn't been rough at all. 625 is too weak though for My use. Going up to 850 in front. I run -3 degrees camber in front and still scrub the outside of the tire on the track. I'm starting with 275lbs springs in the rear for My new coil over set up...........We'll see what happens.

[dennis68]

Daniel...coil-over rates are VERY different than conventional spring rates, that 250lbs coil-over is probably around the same as a 140lbs pigtail spring.

[protour_chevelle]

I've been running a 625lbs/250lbs combo for a few years now. Hasn't been rough at all. 625 is too weak though for My use. Going up to 850 in front. I run -3 degrees camber in front and still scrub the outside of the tire on the track. I'm starting with 275lbs springs in the rear for My new coil over set up...........We'll see what happens.

Daniel,

You and me have the same last name. How do you pronounce yours?

Off topic for a sec.

-Matt

[Norm Peterson]

Anyone know what the spring rate is on say a 70-72 Small Block Chevelle? I just need to know so I can kind of figure out if I want 650 or 750 rate springs in the front. Will a 750lb spring be tiresome on a 800km drive? Anymore so then 650 lb springs?

-MattI've got 639/167 in my '79, along with 32/22 mm (approximately 1.25"/0.88") bars, and I'll drive it almost anywhere (for reference, it's around 3625# with me in it and the rear bar bolts to the LCA's). IOW, it's fine for daily use but still a little too soft for auto-x. Even my wife's complaints about that car are not concerned with the ride quality. YMMV, depending on how firm you individually feel is too firm, though if your car's as-driven weight is slightly higher than mine it will ride marginally better with similar-rate springs. All else equal, as the disclaimer goes . . .

Like Conekiller, I am looking at stiffer springs, and I don't think that even 850-ish/225-ish is going to be a deal-breaker in terms of ride (for me, anyway).

With 750's up front, 175# rears should work fine with a weight distribution that looks like 56% or 57% up front. If you're down around 52% front weight, I'd look at 200's instead.

Conekiller - With rear springs up around 250 lb/in and only 625 fronts, I'm guessing that you're not running any rear bar at all. But what's your front tire/wheel combination?

Edited for clarity

Norm

[USAZR1]

I think the spring rate on my rear coilovers is around 200-225lbs and it's kinda harsh.

[protour_chevelle]

Oh man, Soooo many mixed opinions. 750-850/ 175-250.

Dennis, Does your car 3 wheel going up curbs? What about your El Clint?

-Matt

[dennis68]

Nope, rides very smooth in fact. When I redo the front suspension I will most likely put in 850's.

[protour_chevelle]

hmmm, For comparison....like the title, do you have an idea of what the factor SB spring rate is? Also, factory ride height? I'm thinking a 2 inch drop is all I want.

-Matt

[dennis68]

I beleive the OE spring rate for a small block is like 340lbs in the front and 110lbs in the rear. Factory ride is very difficult to gauge, I have the factory service manual in front of me and I couldn't even begin to explain what is involved in measuring OE height. Maybe somebody from one of the resto site will measure wheelwells for you. I don't think anybody on this site has a complete running A body that has not been altered......if so WHY?

[protour_chevelle]

I beleive the OE spring rate for a small block is like 340lbs in the front and 110lbs in the rear. Factory ride is very difficult to gauge, I have the factory service manual in front of me and I couldn't even begin to explain what is involved in measuring OE height. Maybe somebody from one of the resto site will measure wheelwells for you. I don't think anybody on this site has a complete running A body that has not been altered......if so WHY?

Heres just a quick pic of where my car sits right now. This is where I want it to sit with the new springs. Right now if I take a corner hard my tires rub really bad. Way to soft. I'm guessing my cars at about and 1 1/2 drop from sagged springs? I could just order springs that are 11 inches unsprung with that adjustable spacer which will take to within half inch from a 17inch factory spring.

As for the rear though... 2 inches is where I'm thinkin.

-Matt

[dennis68]

I'd look into some different backspacing....Here (http://www.onrails.net/images/1012.jpg) is mine and it never rubs, quite a bit lower than you it looks. The crossmember height is 4.5".

[Conekiller13]

Matt..........My last name is pronounced Keen.

As far as the coil over rate being way different than a standard spring........I thought the same thing but in talking to the rep at Afco He said 275 should be a good starting point.

Norm Your correct on Your assumption about My sway bars. I'm running 1 1/8" in front and no rear bar. My wheel and tire package is 17x9 wheels with if I remember right 4.75 backspacing with 275/40/17 on all four. Running Kuhmo v700 victoracer tires.

I know ride hieght on My car is LOW. I can't fit a floor jack under the front crossmember. Both lower control arms and steering linkage sit level though. I once parked next a restored '71 at a show and the bottom of stock cars bumper was almost inline with the top of Mine. I never seemed to have any scraping problems on the street though.......only on short and tall speed bumps.

[Norm Peterson]

In the rear a coilover that attaches to the OE shock mounts loses a little bit of effectiveness in that its overall motion ratio for ride (two wheel bump) is slightly lower than that for a conventional sit-on-top-of-the-axle spring. This is mostly a "cosine of shock angle from vertical" thing, so what the chassis sees is that a conventional spring is about 10% stiffer than a C/O for which the spring rate itself is the same. Not drastically different, IOW.

For roll rate, the C/O's sit a little outboard of the conventional spring perches (went out and looked), and that wider base can make them somewhat more effective than conventionals.

FWIW, I think 9" is toward the narrow end of the acceptable rim width range for a 275/40 tire, and that's contributing a bit to your outer shoulder wear. Especially if your username hints at your usage (I've had similar experience with 245/50's on 8.5" wide rims at -1.7* static camber but less so with 225/60's, 8.5", and -2.5*).

Norm

[Conekiller13]

I agree on 9" being on the narrow side......it happend to be the widest one piece wheel in that offset that I liked......We'll be moving to a three piece wheel eventually..........The outer edge wear seems to come more on track days than autocross though.

As far as the C/O goes, They are being mounted a bit to the inside of the stock lower shock mount. My plan is to have no more than 18 degrees of tilt, hopfulley more like 6. I'm also planning on mounting them inverted. I don't know if the effect on unsprung wieght will be enough to make a difference but it makes clearence abit easier.

[protour_chevelle]

Daniel,

Your the first person I have met that has the same last name that is pronounced the same too!

Dennis, I'm not made of money so I'll work with what I have :). With those 5.5 inch spring adjusters in the front I can lower the car a ton so I'm fine there. I'm not going to make my car that low, right now. For the rear 2 inches should be fine.

Also, are you running inner fenders?(or wheelwells, whatever their called)

-Matt

[dennis68]

Nope....I always forget that some folks still use those. They just get in my way.

[zbugger]

Some day Dennis' car is gonna be underground from sitting so low....

[protour_chevelle]

Nope....I always forget that some folks still use those. They just get in my way.

See I use mine. I run into wet weather every now and then. If I didn't have them I wouldn't rub at all!

-Matt

[USAZR1]

My rolling stock consists of 17x9 wheels w/5" backspace and 275/40/17 tires. No rubbing anywhere and the car is really low.(QA1 coilovers)
Oh yeah,I'm still running my inner fenders. Wouldn't be without them.
Different strokes for different folks,YMMV,etc. :poke:

[Conekiller13]

I'm running inner fenders also.......at least so far. They might go away with the addition of the cage..........or I'll fab them to go with the cage.

[protour_chevelle]

Daniel,

Just hit me for some reason....

Could you grab a few measurements? From the ground to the top of your front bumper and the same for the rear.

For the front I'm at 21 1/4 inches
And for the rear 28 1/4 inches

Anyone else with a Chevelle, if you could do the same it would be great! Please list how many inch drop springs you have.(worded weird)

-Matt

[dennis68]

Matt, might I suggest a more universal measuring point like fender opening (top of the tire area) or the frame rail 6" behind the front tire and 6" in fornt of the rear tire.

[protour_chevelle]

Sheesh, fine lol. I'll go get those measurements.

Edit:

Top of Front fender: 25 3/4
Rear: 25

Front frame 6 inches behind wheel: 7
Rear frame 6 inches forward of wheel: 7

-Matt

[dennis68]

Mine measures 6" in the front and 6 1/2" in the rear at the same places. Hoping to get it down to 4 1/2" in the front and 5 1/2" in the rear before it hits the track.

Front fender is 25 1/2" rear fender is 24 3/4"

[USAZR1]

Top of Front fender: 25 3/4
Rear: 25

-Matt

Mine measures 24" in front and 25" in the rear.

[Conekiller13]

My body and frame are in two different places so I can't really measure that right now.................... :pat:

[protour_chevelle]

Mine measures 6" in the front and 6 1/2" in the rear at the same places. Hoping to get it down to 4 1/2" in the front and 5 1/2" in the rear before it hits the track.

Front fender is 25 1/2" rear fender is 24 3/4"

How many inches of drop for your rear springs Dennis?

-Matt

[dennis68]

I am running Black Magic 11" pigtailed circle track springs, not sure how much shorter than stock they are. I haven't had a stock length spring in the garage for over a decade. :icon996:

[wally8]

Matt

I don't have my speedway catalog in front of me right now but I believe the stock springs are 14" thus making Denny's 3" shorter. That's strictly off the top of my head though.


Wally