70 Supreme spring changes w/measurements and pics for reference
November 5th, 2023, 06:11 PM
#1
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Join Date: Feb 2011
Posts: 646
70 Supreme spring changes w/measurements and pics for reference
Hi All,
In case it helps anyone else with spring measurements and ride height, here are all the details before and after for my 70 Supreme. SBO (374) w/AC #6 heads and Holley SD intake. First the before - running Hotchkis 1" drop springs in the front and 2" drop springs in the rear. The ride height/ground clearance was causing issues including bottoming out in the rear on bumps, occasional scraping exhaust and trans pan (deep pan on my 2004r) on speed bumps and dips in the road or going in and out of steep driveways, entrances, exits. To be clear my before measurements with nothing in the trunk (no spare or anything) was 8 3/4" rear and 8 1/4" front and that's with 275/60/15's rear and 245/60/15s front. Factory was around 9.5 rear and 9.625 front. Low point on exhaust muffler was 3.5" clearance and trans pan was 3.25". Bottom line just not enough ground clearance for street driving in my opinion.
Hotchkis rear 2” drop springs 1914r 12.5” 124-159 rating
Hotchkis front springs 1” drop 1901F 500-512 rating, 14.812”
I love the look with the tires tucked and you can't see the top of the tires but the ride was not good on bumps, potholes, and anything where more ground clearance was needed:
I decided to change to the following Moog springs after researching several previous posts on this site including pics which is why I'm posting my results to help others have a point of reference:
Moog 6321 rear 119 rating 14.29”
Moog 5536 front 488 rating 15.063”
New measurements with this setup and still nothing in the trunk was 10.6" rear and 9.4" front so it basically raised the entire car around 1.5" and with the softer rated springs made a HUGE difference in ride as far as bumps and dips and potholes. No bottoming out in the back and just a softer/smoother ride. Don't like the look as much if I'm being honest but a dramatic difference in the ride quality for street cruising. The low points for the exhaust and trans pan went up to 4.75" and 4.5" respectively.
Sorry the pics are dark around the wheel wells but if you compare to the before pic you can clearly see how much higher the ride height is with the top of both tires clearly visible. I also feel like the rear is sitting slightly higher then the front.
I decided to put the old spare in the trunk to see how much that would change the measurements. I was blown away that it dropped the rear of the car by .6" but had no change on the front measurement or the low points for ground clearance. The new measurements with the spare was an even 10" rear and the same 9.4" front. I think this makes the front and rear ride heights look more balanced now and I also feel like the spare in the trunk helped a little with traction/planting the tires better on launching and the 1-2 shift with my 3.90 gears and the 2004r so added benefit there. Here's that pic:
I also wanted to make sure the golf clubs could still fit in the trunk with the spare. All good there:
Again hoping this might help others with their spring choices.
-Joe
In case it helps anyone else with spring measurements and ride height, here are all the details before and after for my 70 Supreme. SBO (374) w/AC #6 heads and Holley SD intake. First the before - running Hotchkis 1" drop springs in the front and 2" drop springs in the rear. The ride height/ground clearance was causing issues including bottoming out in the rear on bumps, occasional scraping exhaust and trans pan (deep pan on my 2004r) on speed bumps and dips in the road or going in and out of steep driveways, entrances, exits. To be clear my before measurements with nothing in the trunk (no spare or anything) was 8 3/4" rear and 8 1/4" front and that's with 275/60/15's rear and 245/60/15s front. Factory was around 9.5 rear and 9.625 front. Low point on exhaust muffler was 3.5" clearance and trans pan was 3.25". Bottom line just not enough ground clearance for street driving in my opinion.
Hotchkis rear 2” drop springs 1914r 12.5” 124-159 rating
Hotchkis front springs 1” drop 1901F 500-512 rating, 14.812”
I love the look with the tires tucked and you can't see the top of the tires but the ride was not good on bumps, potholes, and anything where more ground clearance was needed:
I decided to change to the following Moog springs after researching several previous posts on this site including pics which is why I'm posting my results to help others have a point of reference:
Moog 6321 rear 119 rating 14.29”
Moog 5536 front 488 rating 15.063”
New measurements with this setup and still nothing in the trunk was 10.6" rear and 9.4" front so it basically raised the entire car around 1.5" and with the softer rated springs made a HUGE difference in ride as far as bumps and dips and potholes. No bottoming out in the back and just a softer/smoother ride. Don't like the look as much if I'm being honest but a dramatic difference in the ride quality for street cruising. The low points for the exhaust and trans pan went up to 4.75" and 4.5" respectively.
Sorry the pics are dark around the wheel wells but if you compare to the before pic you can clearly see how much higher the ride height is with the top of both tires clearly visible. I also feel like the rear is sitting slightly higher then the front.
I decided to put the old spare in the trunk to see how much that would change the measurements. I was blown away that it dropped the rear of the car by .6" but had no change on the front measurement or the low points for ground clearance. The new measurements with the spare was an even 10" rear and the same 9.4" front. I think this makes the front and rear ride heights look more balanced now and I also feel like the spare in the trunk helped a little with traction/planting the tires better on launching and the 1-2 shift with my 3.90 gears and the 2004r so added benefit there. Here's that pic:
I also wanted to make sure the golf clubs could still fit in the trunk with the spare. All good there:
Again hoping this might help others with their spring choices.
-Joe
Last edited by 71 OLDS; November 5th, 2023 at 06:16 PM.
November 14th, 2023, 11:23 AM
#3
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Thread Starter
Join Date: Feb 2011
Posts: 646
I can confirm I have gone over all the speed bumps and dips around town that "got me" before and no more scraping!! Raising the car 1.25" to 1.5" did the trick for me. I would suggest the following for starters - Factory was around 9.5” rear and 9.625” front - that’s 1" rearward of front door opening and 3" forward of rear wheel opening. What are your current measurements there? My before was 8.75"/8.25" and my after was 10.6"/9.4" then with the spare added 10"/9.4".
Next measure the lowest points under the car and especially the spots if you know they are hitting/scraping. As I explained my trans pan was 3.25" off the ground and 2 spots of my exhaust were 3.75" off the ground and those 2 areas were the issue. My rear Hotchkis 2" drop springs were way too low, the 1" drop front were not as bad. My after was 4.5" & 4.75".
Do you know your current spring setup? Also what size tires front & rear? It all makes a difference. The Moog change I detailed worked great to raise mine up and give me the clearance I needed. You would need to know all your "before" measurements and details to know if it may do the same for you. There are taller Moog options too if those are needed for your setup. I'm also happy with the softer rating both front and rear. Really softens the bumps and potholes.
-Joe
Next measure the lowest points under the car and especially the spots if you know they are hitting/scraping. As I explained my trans pan was 3.25" off the ground and 2 spots of my exhaust were 3.75" off the ground and those 2 areas were the issue. My rear Hotchkis 2" drop springs were way too low, the 1" drop front were not as bad. My after was 4.5" & 4.75".
Do you know your current spring setup? Also what size tires front & rear? It all makes a difference. The Moog change I detailed worked great to raise mine up and give me the clearance I needed. You would need to know all your "before" measurements and details to know if it may do the same for you. There are taller Moog options too if those are needed for your setup. I'm also happy with the softer rating both front and rear. Really softens the bumps and potholes.
-Joe
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