Demon rear spring height

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Demonx2

Demonx2

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Still working on some details on my 71 Demon 340. This is a 99% stock/original kind of resto car, not a racer (my 72 Demon is for that!). When I got this car in 1984, it had "helper" springs around the rear shocks ("coil-over" shocks) apparently to assist the sagging rear leafs. It's time to fix that but I have no way to know what the correct stock height would be for this car. I've looked at lots of internet pics and can guesstimate what they should look like. But with the knowledge and cars on here, I thought I'd ask for some help. I'm going to buy new springs/shocks for it and want to get the right ones the 1st time.

Would anyone be able to provide a measurement from the ground to the quarter panel right at the center of the wheel/axle i.e. right at the tallest point of the tire? Mine sits right at 26" with a P245/60R14 tire, clearly too low as the ground clearance under the car is not much (and I don't like the looks of it). I jacked it up and think it looks much better at about 27" but don't know if that's a "stock" height or something taller or ?? I need to know what "stock" height would be to decide if I want stock or +1" replacement springs.

So if anyone can put a simple tape measure by theirs and tell me the tire size and what that number is, I'd be most appreciative!

My 72 Demon is at 29-3/4" with its CalTracs, split mono leafs, and 28.0/10.5-15W slicks. That one sits WAY up in the air so I know that is way too high!! Lol!! Thx for any assist you can provide!
20220618_133008.jpg
 
If you are looking for a leaf spring in the 140 lbs range then the AFCO 20231 would be close to stock.
AFCO Racing 20231 AFCO Racing Race Leaf Springs | Summit Racing

I’m did a deep dive on leaf springs a few hours ago using the search function. /6 were like 90 lbs springs, LA’s were around 100. Circle track springs were 130, Hotchkis are 130, XHD are 140, and SS are 160 lbs/in.
Looking at factory photos of these cars they appear to sit quite low in n the rear. From looking at the photos of cars refitted with -1” springs they seem to look the same as OEM. +1” springs seem to look a little higher but not jacked up looking.
 
No offense, but I love the way the green one is sitting in that pic. I wouldn't change a thing!
(I also think its darn close to stock height.)
 
go-fish said:
If you are looking for a leaf spring in the 140 lbs range then the AFCO 20231 would be close to stock.
AFCO Racing 20231 AFCO Racing Race Leaf Springs | Summit Racing

I’m did a deep dive on leaf springs a few hours ago using the search function. /6 were like 90 lbs springs, LA’s were around 100. Circle track springs were 130, Hotchkis are 130, XHD are 140, and SS are 160 lbs/in.
Looking at factory photos of these cars they appear to sit quite low in n the rear. From looking at the photos of cars refitted with -1” springs they seem to look the same as OEM. +1” springs seem to look a little higher but not jacked up looking.
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Factory XHD springs for A-bodies are 110 lb/in, not 140. SS springs start at 140 lb/in and go up to 160 lb/in.

Factory bumper height is listed here, which will give you the basic factory ride height (loaded). Full size version here The 1970 Hamtramck Registry - Chrysler Passenger Car Bumper Heights 1965 thru 1976 Slideshow
bumper heights 1965 through 1974 cars (18).jpg


Instructions for getting those heights are here The 1970 Hamtramck Registry - Chrysler Passenger Car Bumper Heights 1965 thru 1976 Slideshow
bumper heights 1965 through 1974 cars (3).jpg
 
72bluNblu said:
Factory XHD springs for A-bodies are 110 lb/in, not 140. SS springs start at 140 lb/in and go up to 160 lb/in.

Factory bumper height is listed here, which will give you the basic factory ride height (loaded). Full size version here The 1970 Hamtramck Registry - Chrysler Passenger Car Bumper Heights 1965 thru 1976 Slideshow
View attachment 1715962232

Instructions for getting those heights are here The 1970 Hamtramck Registry - Chrysler Passenger Car Bumper Heights 1965 thru 1976 Slideshow
View attachment 1715962218
Click to expand...
Thx for this! Now let's see...get me and 4 fat friends to pile in the car and measure...not gonna happen! But I can make some estimates from it so it will be helpful. Interesting to see the Demon 340 listed as a lower height than the others. Wonder what that was about. Perhaps the tire profile was a tad lower.

I mentioned the car is a 99% stock resto. The 1% is things like the 340 has the old DC "Hemi grind" cam in it. The rear rallye wheels have about 1-1/2" added to them to make them wider. I always thought these cars need a little more rear tire to fill out the proper look from the rear as well as the rear sitting a tad higher. You know, a little rake to it.
Let's see if any of the other Demon members can get a measurement.
 
72bluNblu said:
Factory XHD springs for A-bodies are 110 lb/in, not 140. SS springs start at 140 lb/in and go up to 160 lb/in.

Factory bumper height is listed here, which will give you the basic factory ride height (loaded). Full size version here The 1970 Hamtramck Registry - Chrysler Passenger Car Bumper Heights 1965 thru 1976 Slideshow
View attachment 1715962232

Instructions for getting those heights are here The 1970 Hamtramck Registry - Chrysler Passenger Car Bumper Heights 1965 thru 1976 Slideshow
View attachment 1715962218
Click to expand...

Using the Duster 340 measurements, this shows my car as being lowered 1.75" (11.2.5") in the front, and the rear being almost 3" (14") higher than stock. I measured at the center of the bumper, which is the bottom of the license plate opening, if I went to the actual bumper, I would show an even higher ride height. I think something is off there. This pic is with a 315/35R17 out back (~26") and a 215/45R17 up front (~25")

253301901_4580435628690971_5755760244174895474_n.jpg
 
72Duster440 said:
Using the Duster 340 measurements, this shows my car as being lowered 1.75" (11.2.5") in the front, and the rear being almost 3" (14") higher than stock. I measured at the center of the bumper, which is the bottom of the license plate opening, if I went to the actual bumper, I would show an even higher ride height. I think something is off there. This pic is with a 315/35R17 out back (~26") and a 215/45R17 up front (~25")

View attachment 1715964169
Click to expand...

So a Duster 340 would have had E70-14's, so, that's a 25.7" tall tire. So right off the bat if your front tires are 25" tall you've lowered it just with the wheels in the front. In the back you've raised it slightly too. The other thing is that the factory measurements are with a "5 passenger load", so, if you measured your car empty it's too high, especially in the back. If you put 3 people in the back seat the rear end is gonna get a lot lower, you have to figure that's at least 500 lbs in the back seat. Because of the location of the passenger compartment relative to the wheels the passenger load will lower the back a lot more than the front.
 
Sublime one said:
I am running factory SS springs and will measure for you when I get home. My Demon is not a race car either. Coil overs on front but “factory” in back. Got my Cuda for racing!
Click to expand...

SS springs are definitely not “factory”. Probably a 2” lift just from those.
 
72bluNblu said:
So a Duster 340 would have had E70-14's, so, that's a 25.7" tall tire. So right off the bat if your front tires are 25" tall you've lowered it just with the wheels in the front. In the back you've raised it slightly too. The other thing is that the factory measurements are with a "5 passenger load", so, if you measured your car empty it's too high, especially in the back. If you put 3 people in the back seat the rear end is gonna get a lot lower, you have to figure that's at least 500 lbs in the back seat. Because of the location of the passenger compartment relative to the wheels the passenger load will lower the back a lot more than the front.
Click to expand...

I missed the load of asses in the back seat. That would drop it a good amount, my rear tire measures out to 25.6", so it is the same size, but yeah, it sags pretty quick with some weight. I agree the front is lowered the amount that it measures to, just seems like it would rub out back or I would be on bumpstops if it was 3" lower. I'm also looking to get new leafs, but trying to keep my same ride height, these 30 year old B body SS springs aren't the best match to my front end setup anymore.
 
Ok as promised here is the tale of the tape with my “factory” reared equipped with SS springs on 72 Demon. Disclaimer number two: I measured the drivers side, passengers side with SS springs is typically one inch or so taller. I want to say this set was blue painted part number manufactured in Mexico. Your mileage may vary. Great discussion, when it comes to suspension and geometry 72blu has forgotten more than most of us know.

6DED3B02-CEE0-48D3-8049-F5159551E04F.jpeg
 
72Duster440 said:
Using the Duster 340 measurements, this shows my car as being lowered 1.75" (11.2.5") in the front, and the rear being almost 3" (14") higher than stock. I measured at the center of the bumper, which is the bottom of the license plate opening, if I went to the actual bumper, I would show an even higher ride height. I think something is off there. This pic is with a 315/35R17 out back (~26") and a 215/45R17 up front (~25")

View attachment 1715964169
Click to expand...
Thx for the info. And wow, what a beauty of a car!!

Interesting that the info 72bluNblu provided shows the 340 Demon rear bumper height (15.2"l much taller than the 340 Duster (11.7"). Must be differences in rear bumper design. Any idea what it measures at the quarter panel in line with the center of the axle? Or are Demon and Duster quarters maybe that different...I dunno.
 
Sublime one said:
Ok as promised here is the tale of the tape with my “factory” reared equipped with SS springs on 72 Demon. Disclaimer number two: I measured the drivers side, passengers side with SS springs is typically one inch or so taller. I want to say this set was blue painted part number manufactured in Mexico. Your mileage may vary. Great discussion, when it comes to suspension and geometry 72blu has forgotten more than most of us know.

View attachment 1715964269
Click to expand...
Thx to you too for that measurement and info. What size tire is that? Your car sits a tad higher than my avatar car (72 Demon). Mine is about 29-3/4" with its CalTracs and split mono springs. So what's interesting is if yours is that tall, how much taller over stock is a SS spring? If it's +2", then a stock spring would be about right for my 71 putting it about 28" less my likely shorter tire. Might get me close to my desired 27" if I know your tire size vs my 245/60-R14's.

Thx to all - I certainly appreciate the info!! I plan to check out as many cars as I can at the Mopar Nats in Columbus in a couple weeks. Planning to have the avatar 72 there (this year w/ mufflers and street tires so I can maybe take my 89+ year old father for a ride when not at the track!!)
 
Demonx2 said:
Thx for the info. And wow, what a beauty of a car!!

Interesting that the info 72bluNblu provided shows the 340 Demon rear bumper height (15.2"l much taller than the 340 Duster (11.7"). Must be differences in rear bumper design. Any idea what it measures at the quarter panel in line with the center of the axle? Or are Demon and Duster quarters maybe that different...I dunno.
Click to expand...

No differences in rear bumper design for the 340 Duster and Demon, they're literally the same bumper. Same for the quarters, a Demon is just a Duster wearing a Dart front end so the quarters are the same Duster or Demon. It's why the marker lights on the '71 Demon don't match front to rear.

Maybe the guy doing the Demon measurements didn't have 5 friends to load in the car first? :rolleyes:

Seriously other than that I'm not sure what the difference would be. The directions are kinda vague, "lowest part of the bumper in the center" leaves some room for interpretation. Like the Dart front bumper in the center is really high because of the license plate cut out, based on their measurement it would have to be from the bottom of the bumper right next to the cut out section. In the back I would assume it's just the bottom of the bumper since it's straight across, just measure right next to the license plate bracket since that hangs down a smidge further.

I never really worried about what stock was anyway, I just set my car where I want it. Measuring to the bottom lip of the quarter in the middle of the wheel opening, through the center of the wheel on my car I get 26". Rear tires are 295/40/18 so they're 27.2" tall. Same measurement at the front fender is 25", front tires are 275/35/18 so 25.6" tall. Rear springs are the discontinued AFCO 20231M's, 120 lb/in.

IMG_2247.jpeg


IMG_2245.jpeg
 
I have modified my bumper to the point taking measurements there is pointless. I have tucked it all in. I will verify tire size tonight when I get home. Heck I don’t even have five friends to put in the back, just a 100 pound dog!
 
I'm sitting right at 25-7/8" with no weight in the car. The car currently has a 285-35-18 tire that is about 50% worn down.

I've got Hotchkis springs. I'd love to get it down another 1/2 or so.
car.jpg
 
72bluNblu said:
Are you running the Hotchkis front hangers? Or stock? Just curious…
Click to expand...


I have a bastard front hanger. It started as the old MP offset hanger, but I modified it to have the mounting holes in the same location as the Hotchkis hanger. The spring is currently in the middle hole. I'll eventually try it in the top hole to see how it sits, but I'm sure that will lead me to shim the housing to get the pinion angle correct.

hanger.jpg
hanger 2.jpg
hanger 3.jpg
 
As promised here is tire size, SS springs. I run Cal trac on my Cuda which is a dedicated drag car and now you boys got me wondering how tall it sits. Certainly no taller than the Demon. PS not to derail the thread but I love my Cal Tracs! Plant and hook!

CBF5FA1B-A350-49FF-A80C-8DE28A167FAC.jpeg


851B0A01-2E37-44D8-8F86-CBE8078ADCEC.jpeg
 
Just measured my 71 340 duster front and rear wheel lips at the center of the hub. Original 80,000 mike car. Original springs.
26” in the front.
25 3/8” in the rear!
 
EBOT said:
Just measured my 71 340 duster front and rear wheel lips at the center of the hub. Original 80,000 mike car. Original springs.
26” in the front.
25 3/8” in the rear!
Click to expand...

Sounds pretty close to me, maybe a little high in the front. If you look at the promotional pictures and stuff from when these cars were new a lot of them looked higher in the front than the back.
 
72bluNblu said:
Factory XHD springs for A-bodies are 110 lb/in, not 140. SS springs start at 140 lb/in and go up to 160 lb/in.

Factory bumper height is listed here, which will give you the basic factory ride height (loaded). Full size version here The 1970 Hamtramck Registry - Chrysler Passenger Car Bumper Heights 1965 thru 1976 Slideshow
View attachment 1715962232

Instructions for getting those heights are here The 1970 Hamtramck Registry - Chrysler Passenger Car Bumper Heights 1965 thru 1976 Slideshow
View attachment 1715962218
Click to expand...
Cool Man! So I can use the front # to get a baseline for 74 Duster I just rebuilt the front end on! Nice! Thanks! I should be right on using ride height measurements.
 
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Thank you folks - appreciate all the info reported!! I have some measuring homework to do out in the garage.

I have to get back on this issue soon. I got derailed when the washing machine malfunctioned and provided me a flood that ran down into the basement. Been hauling wet junk out and running fans to dry the stuff that stays. Oh what fun.... :mad:
 
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