# Rear suspension



## 69 237 (Feb 18, 2018)

I'm trying to correct the rear ride height on my 69 LeMans since it is sitting a bit low. Should I start with the struts or go straight for the rear coil springs?

Also do the rear struts typically have coils on them as well? Mine currently do, but I'm not finding many aftermarket parts with them.


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## PontiacJim (Dec 29, 2012)

69 237 said:


> I'm trying to correct the rear ride height on my 69 LeMans since it is sitting a bit low. Should I start with the struts or go straight for the rear coil springs?
> 
> Also do the rear struts typically have coils on them as well? Mine currently do, but I'm not finding many aftermarket parts with them.



Pontiac's DO NOT have struts. They DO have upper and lower control arms. If you have struts with coils on them, then you most likely have an aftermarket set-up. Need pictures of that set-up for a better answer. :thumbsup:


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## Cafr119 (Dec 9, 2017)

Hi 69 237, I think you might be confused on what your seeing, your car has springs and shocks only. There are shocks that have a spring wrapped around them and I believe that’s what your referring about. You do have options as far as putting a little lift in the rear and there are posts from other members on this issue.


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## 69 237 (Feb 18, 2018)

You're right. I just called them the wrong thing when I posted. I do have rear shocks with helper springs.


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## Cafr119 (Dec 9, 2017)

?, I figured so, no worries, I’ve seen guys on here order spacers that fit under the main springs to help with the rear sag, air shocks which depends on who you talk to isn’t the best idea ( for handling sakes ),replacing the main springs with more firmness , etc just depends on what one can afford, otherwise just play it safe on what ever you decide.


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## 69 237 (Feb 18, 2018)

Is the best route to replace the rear springs theif so, how difficult is that? It looks like it'll be a challenge to even get the springs in and out.


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## BearGFR (Aug 25, 2008)

69 237 said:


> Is the best route to replace the rear springs theif so, how difficult is that? It looks like it'll be a challenge to even get the springs in and out.


Yes, and it's actually an easy job.

Jack up the rear of the car nice and high, support it at the frame with jack stands, then use your jack to lift the rear axle just a bit and support it. Disconnect the shocks at their lower mounts. Lower the rear axle down as far as it will go. You should then be able to pull the springs out without too much trouble, and install new ones. You might consider using station wagon springs to get a little more oomph. You may have to use a long 2x4 or something to pry down on the axle to get a little more room, but it's not hard to do. Lose the helper springs and don't use air shocks -- the shock mounts are not strong enough to support the weight of the car (queue the long line of people who say they've been doing it for years with no problems  - they've been lucky). If after replacing the springs you still don't like the stance and think it's not high enough, then consider either converting to real coilovers on the rear ($$$) or installing AirLift bags into your springs. I've had AirLift bags on my car for years. I didn't put them on to address a ride height problem, I put them on prior to us going on the 2013 Hot Rod Power Tour and wanted to be able to carry a full complement of tools, extra parts, etc. in the trunk.  I mounted the Schrader valves for the air lines in the trunk pan next to the latch mechanism, with a separate valve for each side, to make them individually adjustable and easy to get to.

Bear


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## PontiacJim (Dec 29, 2012)

Cafr119 said:


> Hi 69 237, I think you might be confused on what your seeing, your car has springs and shocks only. There are shocks that have a spring wrapped around them and I believe that’s what your referring about. You do have options as far as putting a little lift in the rear and there are posts from other members on this issue.


They probably still make these, but you could buy a helper coil spring that goes over the shock and gets clamped into place with what looks like an exhaust type clamp. I have used them in my younger years to lift up a sagging rear.

One thing I have to admit to is that the technology and computers have really enhanced what we can learn about with regards to our cars and at a click of the mouse find all kinds of parts & pieces from a host of manufacturers and suppliers. Did not have this in my time - we had junk yards and a JC Whitney catalog. So we did what we knew and worked with what we had - sometimes blindly and sometimes learning lessons of "ut-oh, that ain't goin' work." LOL We also did things that should not have worked, but did. LOL And some things we did almost killed us. :yesnod:


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## 69 237 (Feb 18, 2018)

That's great news. Any advice on specific parts to go with? I was looking at the moog oem replacements

Jim sometimes that's the best way to learn. I am glad we have forums now though.


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## PontiacJim (Dec 29, 2012)

69 237 said:


> That's great news. Any advice on specific parts to go with? I was looking at the moog oem replacements
> 
> Jim sometimes that's the best way to learn. I am glad we have forums now though.



Depends on what you are going for. This has been covered a number of times in past forums and you can do a search just to get some ideas.

You can go stock height, or raise it up a little. So you have choices. Moog typically is a good brand. Get new rubber isolators while you are at it, they go on the top of the springs and then up into the spring pocket - Summit, Ames, OPGI, or.... has them. :thumbsup:


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## 69 237 (Feb 18, 2018)

Is there a benefit to raising the rear height, or is it purely cosmetic? Was the factory height level with the front?


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## PontiacJim (Dec 29, 2012)

69 237 said:


> Is there a benefit to raising the rear height, or is it purely cosmetic? Was the factory height level with the front?


Raising the rear level could be done if you were to load heavy stuff in the trunk or towed something, but generally, it was for the look and to clear the fat wide aftermarket tires that were installed. Ride height from factory was basically level.


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## 69 237 (Feb 18, 2018)

That makes sense. Thank you all again for the help. I'll search for the forum for suggestions on specific coils.


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## tjs72goat (Jul 20, 2017)

I just bought new rear coil springs for my 72 vert. I think they were $89 /pair through Ames. I got the stiffer set to help the rear from sagging when the top goes down. I also bought a set of one inch spring spacers from Mcbay to help the back from a sag look overall.


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## 29585 (Aug 4, 2013)

I replaced the rear coils last year on one of my 69's. 
The MOOG catalog gives a part #5401 for the 69 gto. it has 13.15" free length, and K= 129 lb/in spring rate., installed height listed as 7.5"
However I wanted a bit of an increase in height so I went with the #5413 which is 12.93" free length, but stiffer at 167 lb/in. If you do the math the 5413 should end up sitting about 1" higher about 8.56" due to the higher rate. But the result was hardly noticeable if at all. I did not measure anything but the car still pretty much sits close to level and I'm not satisfied.
So I'm planning on replacing them with the 5415 or 5417 before next summer. Here's a link to a handy chart you can look through for the MOOG coils;

https://www.moog-suspension-parts.com/universal_coil_springs.asp


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## geeteeohguy (Feb 2, 2008)

What Jim said about ride height. Level or even a little low in back from the factory. Look at an old ad. Bear is right on with the Air Lift air bags....plumbed separately, they can be used to tune the suspension for drag racing, can help handling, and you can raise the pressure to keep the car level and the headlights pointing where they should when you have a trunk full of gear. For around $100, impossible to beat. The raised rear end look or 'rake' that is so prevalent with these cars came about in the late '60's-early '70's when people were lifting the rear of the cars to clear large tires on wide aftermarket rims. Unfortunately, the raised rear end causes the driveshaft angle to change, and usually creates or increases wheel hop on a hard launch. YMMV..........


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## PontiacJim (Dec 29, 2012)

clevelandpartsguy said:


> I replaced the rear coils last year on one of my 69's.
> The MOOG catalog gives a part #5401 for the 69 gto. it has 13.15" free length, and K= 129 lb/in spring rate., installed height listed as 7.5"
> However I wanted a bit of an increase in height so I went with the #5413 which is 12.93" free length, but stiffer at 167 lb/in. If you do the math the 5413 should end up sitting about 1" higher about 8.56" due to the higher rate. But the result was hardly noticeable if at all. I did not measure anything but the car still pretty much sits close to level and I'm not satisfied.
> So I'm planning on replacing them with the 5415 or 5417 before next summer. Here's a link to a handy chart you can look through for the MOOG coils;
> ...



I wanted to point out another option to you rather than replace the springs for another set in the hopes that they put the rear ride height where you want it. If you already know how it is going to ride, decide how much higher you want to go.

They make coil spacers which go on top of the axle spring perch and under the coil spring. Real simple. They come in machined aluminum or polyurathane 1" up to 4". Here are examples: https://www.ebay.com/bhp/gm-coil-spring-spacers

I purchased a 3" set for my build. They set on the spring perch of the aftermarket Ford 9" I am using. I don't think 1"-2" will be a problem with the stock shocks. With mine, I also have another 1" or so added through the spring perch due to the design of the set-up. So I should have about a 4" lift. With the 4" lift, I felt I needed to raise the lower mount of the shock up a little so the shock was not over extended closer to its full limit and possibly pulling on the shock kinda hard if going over a hard bump or pot hole.

I used some square tubing I got from work and modified it as you see it. It bolts to the lower hole that held the lower shock mount to the rear. I then drilled a smaller hole through the fab'd mount and lower shock bracket above the larger bolt in the lower mount hole and then used a short bolt and nut to pin it so it would not rotate sideways on me. Using only the bottom hole/bolt lets the fab'd mount to move/rotate left or right. This keeps the fab'd mount in place and straight up to secure the lower shock mount and shock.

The mount may actually be too tall and I may have to drop it down. I should be able to jack up the car like factory and still have the shocks hold compression on the spring at their full extension so the spring does not drop out. I still have to fine tune this and will do that once I have the car near completed with all its weight on the suspension.

You can see the spacer in the photo. I drilled a hole in the center of the 3" lift so I can run the airlift "drag bags" fill tune down the hole and inflate them. I will also use some means to secure the lift to the spring perch - in my case I will drill through the side of the 3" spacer and into the spring perch tube (extra tall on the aftermarket rear) and secure it. If I don't use the drag bags, then I will use the hole I drilled down the center and a cross bar fitted under the spring perch to clamp it like a sandwich. 

So just an option for those who buy new springs and they just don't quite have the lift they were looking for. :thumbsup:


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## tjs72goat (Jul 20, 2017)

Not all spacers go on the bottom. Mine are actually designed to go on top of spring. Has a stock look if viewing underneath.


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## 69 237 (Feb 18, 2018)

Thank you all for the info and suggestions. I know I need to replace my springs for sure. I don't know if they've ever been related and they're very rusty.. It has a very "boaty" smooth ride right now, but I think that's probably impacting performance and handling. I may go with th 5413 springs to try to level out the car.


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## BearGFR (Aug 25, 2008)

69 237 said:


> Thank you all for the info and suggestions. I know I need to replace my springs for sure. I don't know if they've ever been related and they're very rusty.. It has a very "boaty" smooth ride right now, but I think that's probably impacting performance and handling. I may go with th 5413 springs to try to level out the car.


While you're at it, since you seem to be interested in handling, please do consider swapping out the rear upper and lower control arms for some that have spherical joints on at least one end of each arm. Here's why:

With the triangulated upper/lower control arm system, when there is 'body roll' like in a corner that causes the rear axle to have to 'twist' relative to the rest of the car (in other words, one rear spring is being compressed while the spring on the other side is being extended), the only way that the factory setup can allow the axle to move that way is for the rubber bushings at the ends of the arms to get "squished"/twisted in their mounts and/or for the control arms themselves to twist. This puts a lot of stress on those points. Replacing the rubber bushings with stiff poly bushings just makes it worse and can lead to permanently bent/broken parts and/or mounting points if the car is subjected to hard cornering - something has got to give. Using control arms with spherical ends allows free twisting movement and removes all the stress points, so that tuning cornering and handling can be accomplished with shock selection/settings and sway bar options as it should be.

I'm running these on my '69:
https://www.spohn.net/shop/1968-1972-GM-A-Body/Suspension/Rear-Lower-Control-Arms/Rear-Lower-Control-Arms-Tubular-Adjustable-with-Del-Sphere-Pivot-Joints.html
https://www.spohn.net/shop/1968-1972-GM-A-Body/Suspension/Rear-Upper-Control-Arms/Rear-Upper-Control-Arms-Tubular-with-Del-Sphere-Pivot-Joints-Adjustable.html

...with this sway bar:
https://www.spohn.net/shop/1968-1972-GM-A-Body/Suspension/Sway-Bars-Accessories/Pro-Series-Rear-Drag-Sway-Bar-1968-1972-A-Body.html

...these shocks:
https://www.spohn.net/shop/1968-1972-GM-A-Body/Suspension/Shocks-Springs-Coil-Over-Kits/Strange-Double-Adjustable-Rear-Shock.html

...these control arm mount braces:
1968-1972 GM A-Body Control Arm Reinforcements/Frame Braces [4028] - $129.99 : UMI Performance, Inc.

... plus air bags in the rear springs.

My car handles GREAT!

Another advantage of having adjustable upper arms is that they allow you to easily adjust your driveline angles to make sure the drive shaft ujoints are aligned correctly and don't cause any vibration.

Bear


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## 69 237 (Feb 18, 2018)

Thanks for taking the time to share about you build and provide all those links. I'll definitely have to remember these when I upgrade. 

I noticed you mentioned suspension components could impact driveline angles. I've been trying to figure out how to correct my oil pan clearance and I think this may be the culprit. I currently have to add a half inch of spacers between the mount and frame mount bracket on the driver side to get the pan off the frame. I've tried different sets of mounts including one's that have been good before with the stock oil pan. My oil pan is aftermarket but is a known pan from Butler performance that they use fairly frequently


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