Rear suspension upgrade\spring rates

tomsti

Veteran Member
Jul 15, 2003
1,214
Redmond, Wa, USA
Thanks, looks like a couple tests are in order. :)

Any idea how to get a baseline of what stock spring height would be? Meaning if I have worn out springs I can confirm if they are bad through the test above. Do OEM springs sag or do they just lose their rigidity and stay OEM height?
 

Lowend

Administrator. .a car, a man, a maraca.
Staff member
Lifetime Gold Member
Mar 25, 1999
16,740
San Jose, CA, USA
OEM springs sag, the spring rate never changes unless the springs are damaged.

Here's the problem with ride height: You could've taken 10 brand-new 1968 Camaro's at the factory optioned the same, and they'd all have different ride heights. QC just wasn't that good. This was true of pretty much every car of the era
 

G72Zed

Veteran Member
Sep 8, 2015
3,757
Canada
I agree with Lowend on the spring sagging, and the OEM stacking tolerances and variances from car to car.

But I'm not 100% on the rate not changing if not broken. If the car sags after the years, and it rear weight is the same, it means the springs can't hold up the car as it did originally, so, it's rate has changed and lowered.

I treat leaf springs almost like valve springs, the need to be measured for "installed" rate and over the nose, they get weak as well, and believe they do loose there rate, perhaps not enough to notice, and it can takes many years.
 

81Z28LS

Member
Dec 16, 2018
66
I think I mentioned that I just installed the Hotchkis ones. Very happy with them, they got rid of the bad wheel hop I had with the stock springs. Stance is bang on what I wanted, and they ride nice. Firm, but not harsh. They have plastic shoes between the leafs. Hardware is very nice too, but takes some work to drill things out for the larger u bolts.
I know DSE makes great stuff, but i would think a 3" drop would require some definitely driveline/pinion angle work to keep u joints happy.

Hey Biker, what is the Hotchkiss part number for those springs? Also, what shocks and what wheel/tire size?

I was planning on buying PTFB Springs but haven't found recent posts with feedback from actual users.
 
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roadrace2

Veteran Member
Jan 13, 2000
1,860
Earth......?
One thing to also consider are the bushings you choose on the leaf spring eye and rear shackle.
I used del-a-lum on all 3 points - this seemed to have given me way too much oversteer.
I went to a rubber spring eye bushing with lower rubber bushing for the rear spring eyelet and a del-a-lum bushing to where it connects to the frame - this is a kit I purchased from a vendor here - this took away some of the understeer - but like others mentioned - rim width, tire and tire pressures also play a major role.

I've seen spherical bearings installed at the front spring eye and rear shackle area - Global West sells them - I have no personal experience with them.

Please correct me if I'm wrong - this is based on personal experience.
 

biker

Veteran Member
Gold Member
Dec 7, 2014
4,704
Canada
Hey Biker, what is the Hotchkiss part number for those springs? Also, what shocks and what wheel/tire size?
Part number for my rear springs is Hotchkis 2408C. Wheels are aluminum 15x8 Ridler 650 with Cooper 235/60-15 tires.
 

G72Zed

Veteran Member
Sep 8, 2015
3,757
Canada
One thing to also consider are the bushings you choose on the leaf spring eye and rear shackle.
I used del-a-lum on all 3 points - this seemed to have given me way too much oversteer.
I went to a rubber spring eye bushing with lower rubber bushing for the rear spring eyelet and a del-a-lum bushing to where it connects to the frame - this is a kit I purchased from a vendor here - this took away some of the understeer - but like others mentioned - rim width, tire and tire pressures also play a major role.

I've seen spherical bearings installed at the front spring eye and rear shackle area - Global West sells them - I have no personal experience with them.

Please correct me if I'm wrong - this is based on personal experience.

Roadrace2 is correct with his post above, the bushing design has a major impact on handling characteristics after the shocks/springs.

Snap oversteer from binding and induced uncontrol rate is not what you want for a nice predictable ride.

I use spherical bushings in the front, Del-A-Lum in both locations in the rear. Never solid in the front, I would use new rubber before in front if not spherical.
 

landpilot

Member
Lifetime Gold Member
Oct 2, 2013
52
Louisville, KY
Roadrace2 is correct with his post above, the bushing design has a major impact on handling characteristics after the shocks/springs.

Snap oversteer from binding and induced uncontrol rate is not what you want for a nice predictable ride.

I use spherical bushings in the front, Del-A-Lum in both locations in the rear. Never solid in the front, I would use new rubber before in front if not spherical.

+1 on this… I use Global West reverse -2 springs with spherical bushings in the front and del-a-lum in the rear, along with Viking double adjustable shocks. It’s a great combo and allows the rear end to track better through the corners. I don’t know if GW is selling any springs right now due to supply issues, but they might have the bushings.
 

biker

Veteran Member
Gold Member
Dec 7, 2014
4,704
Canada
+1 on this… I use Global West reverse -2 springs with spherical bushings in the front and del-a-lum in the rear, along with Viking double adjustable shocks. It’s a great combo and allows the rear end to track better through the corners. I don’t know if GW is selling any springs right now due to supply issues, but they might have the bushings.
I really like the idea of the spherical bushings, and may do that upgrade if I can find them.
 

landpilot

Member
Lifetime Gold Member
Oct 2, 2013
52
Louisville, KY
I really like the idea of the spherical bushings, and may do that upgrade if I can find them.

Here’s a link to the kit ($419) on GW’s website…. https://www.globalwest.net/camaro-f...g-cat5-1967-68-69-70-71-72-73-74-75-76-7.html

1967-81-camaro-firebird-1968-79-nova-cat5-bushing-bearing-shackle-kit-7.jpg


I have the GW CAT 5 springs, they have del-a-alum upper and spherical lower bushings in the rear eye, and spherical bushings in the front eye, just like in this kit.

The kit takes a special tool to insert the spherical bushings.
 




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