68 rear spring
Thread Starter
Racer
Joined: May 2009
Posts: 316
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68 rear spring
While I'm preparing to remove my rear differential for a rebuild I am thinking about the need to replace my original rear spring. Not sure how to tell if it needs it though. The car seems to ride fine. Looking at the spring it is pretty flat with no real bow to it with the car weight on it. Dont want to spend extra $ if its not needed but thought a spring that old might need it. Did the old push down on the rear of the car to see if it bounces but all feels firm. Any thoughts on this?
Team Owner
Joined: Sep 2006
Posts: 31,267
Likes: 4,362
From: Westminster Maryland
Hi gg,
Typically the leaves of the spring should be close to flat when loaded.
The half-shafts should be close to parallel with the road surface.
Replacing the spring sometimes (often?) leads to problems with getting the 'ride-height' back where it's intended to be. Cars tend to sit 'high's some reproduction springs.
If you have wheels and tires on the car that are close to what the original F70-15 tires were in height, the dimension from the ground to the center of the rear wheel arch should be just about 28".
If you're seeing a lot less than that dimension you may have a saggy spring.
Regards,
Alan
Typically the leaves of the spring should be close to flat when loaded.
The half-shafts should be close to parallel with the road surface.
Replacing the spring sometimes (often?) leads to problems with getting the 'ride-height' back where it's intended to be. Cars tend to sit 'high's some reproduction springs.
If you have wheels and tires on the car that are close to what the original F70-15 tires were in height, the dimension from the ground to the center of the rear wheel arch should be just about 28".
If you're seeing a lot less than that dimension you may have a saggy spring.
Regards,
Alan
Last edited by Alan 71; Feb 26, 2016 at 07:57 PM.
Thread Starter
Racer
Joined: May 2009
Posts: 316
Likes: 1
I have original wheels and tires are 60/R15s on the car. Not sure what is meant by measuring from the center of the rear wheel arch.
Hi gg,
Typically the leaves of the spring should be close to flat when loaded.
The half-shafts should be close to parallel with the road surface.
Replacing the spring sometimes (often?) leads to problems with getting the 'ride-height' back where it's intended to be. Cars tend to sit 'high's some reproduction springs.
If you have wheels and tires on the car that are close to what the original F70-15 tires were in height, the dimension from the ground to the center of the rear wheel arch should be just about 28".
If you're seeing a lot less than that dimension you may have a saggy spring.
Regards,
Alan
Typically the leaves of the spring should be close to flat when loaded.
The half-shafts should be close to parallel with the road surface.
Replacing the spring sometimes (often?) leads to problems with getting the 'ride-height' back where it's intended to be. Cars tend to sit 'high's some reproduction springs.
If you have wheels and tires on the car that are close to what the original F70-15 tires were in height, the dimension from the ground to the center of the rear wheel arch should be just about 28".
If you're seeing a lot less than that dimension you may have a saggy spring.
Regards,
Alan
Team Owner
Joined: Sep 2006
Posts: 31,267
Likes: 4,362
From: Westminster Maryland
Hi gg,
tpf is right. A 'sagging' spring affects a car's rear ride height. I was offering a way to to begin to determine if you have a sagging spring.
Also, it's the 3rd part of the tire dimension, (225,235,255,etc), that will tell you how 'tall' the tire is and thus how it MAY be affecting the car's ride height.
There were a group of dimensions listed on a diagram in the front of the AIM called Trim Heights. In the 71 AIM it's on page UPC 0, Sheet A-12.
Dimensions 'P' and 'R' are 2 of the calculations listed and refer to the distance from the ground to the center of the wheel arch for the front and rear of the car.
These 2 are the simplest to do. There are addition dimensions listed using the front and rear suspension members that also will indicate if a car is sitting low or high compared to what the original specifications called for.
'Ride Height' can become a troublesome issue when both the front and rear springs are changed especially if the source and specifications of the springs are unknown.
Regards,
Alan
tpf is right. A 'sagging' spring affects a car's rear ride height. I was offering a way to to begin to determine if you have a sagging spring.
Also, it's the 3rd part of the tire dimension, (225,235,255,etc), that will tell you how 'tall' the tire is and thus how it MAY be affecting the car's ride height.
There were a group of dimensions listed on a diagram in the front of the AIM called Trim Heights. In the 71 AIM it's on page UPC 0, Sheet A-12.
Dimensions 'P' and 'R' are 2 of the calculations listed and refer to the distance from the ground to the center of the wheel arch for the front and rear of the car.
These 2 are the simplest to do. There are addition dimensions listed using the front and rear suspension members that also will indicate if a car is sitting low or high compared to what the original specifications called for.
'Ride Height' can become a troublesome issue when both the front and rear springs are changed especially if the source and specifications of the springs are unknown.
Regards,
Alan
Thread Starter
Racer
Joined: May 2009
Posts: 316
Likes: 1
Thanks for the info. What I have are p245 on the car which are a lower height than the stock tires. Its measuring about 27 1/2" which I would imagine is pretty good with a lower height on the tire.
