Bhebert449

I would like to replace the rear leaf spring on my 69 bb coupe. The driver side sags slightly most likely from uneven wear on the original spring. One option I have seen at duntov is to get the original spring re-arced. Should I go that route or just purchase a new one? Should I also replace the rear shocks? What about going with a composite spring?

63mako

Adjust the spring end bolts to level it out.

Grahamred70

How bad is the sag, mine wasn't bad but was noticeable, I scored a second hand composite spring on E Bay for not a lot and now the car sits dead level, I wouldn't bother to faff with an old spring, it was something the village blacksmith would do back in the old days to get a bit more life out of an old spring. Replacements are readily available and not expensive and it's not a bad job to change it out.
Graham

Big2Bird

If its a show car, re arch it. If its a go car, ditch it and go fiberglass. The ride is much better.

Alan 71

Hi Bh,
Replacing the spring or even having it re-ached can be the start of problem with the rear ride height not being what you'd like it to be.
How much is "sags slightly" ?
What makes you think the spring is causing it"
Could the spring bolt bushings be more deteriorated on that side?
Normally the spring should appear to be nearly flat from side to side or even exhibit a slight negative arch.
The half shafts should appear to be nearly parallel with the ground.
Maybe a couple photos of the rear suspension.
Don't be too quick to replace the spring.
Regards,
Alan

Bhebert449

I'll take some pics and post later today. I've already had the bushings replaced and attempted to level by adjusting the nuts. I'm pretty sure it's the original spring. The car sits about a half to 3/4 inch lower on the driver side rear and it is noticeable

Grahamred70

Mine was a lot less than that but still noticeable and I couldn't ignore it, mine had air shocks fitted when it arrived and they were shot so I fitted new Bilsteins in case they were affecting things but it still had a lean to the drivers side, since fitting the replacement composite spring it's spot on now, just got to get the ride height correct so I can finalise the bolt length, I'm at 6" between the head and nuts will probably go to 6 1/2" and it should be just right.
Graham

Tampa Jerry

Check your front springs. If one is bad, it will transfer the list to the rear. Jerry

71 Green 454

I remember a thread some time ago that turned out to be a weak front spring causing the rear sag problem.

Bhebert449

How do you check the front springs? I was going to start with the leaf spring as it does not look to be too bad of a job and they are pretty inexpensive.

ganshert

You could rule the front springs out pretty easily by supporting the front level on jack stands by the frame not the control arms. Then you could see if the back was now level. You may want to pull the wheels off and lower the front to normal ride height to get a better visual and measure the same place you've been measuring the difference in the rear.

Alwyn678

I went ahead and replaced mine with a steel spring. Rides Great and is level. The other steel one lasted 43 Years, so I will stay with originality, (seems to work).

Bhebert449

Yeah if I do replace, I will most likely go back with a steel spring. There are many sellers out there. Any idea which is the best quality to go with? What is the factory spec for a 1969 bb coupe?

Alan 71

Hi bh,
I believe the same spring was used for sb and sb cars.
The optional spring was the 7 leaf used with rpo F41.
Regards,
Alan

68notray

I'll add that a bent sway bar will cause the car to sit uneven and drive you crazy trying to figure it out.

Bhebert449

These are the best pics I could get of the spring

Alan 71

Hi Bh,
?
I'm surprised to see how much the rubber bushings are compressed already and also by the number of washers being used between the spring bolt's nut and lower bushing.
Were those washers added to try to level the car?
When the bushings were replaced what did the arch of the spring look like with no weight on it?
Has the spring been taken off the car and disassembled to see if it's damaged in some way?
Another spring is one answer, but so often that avenue seems to lead to car's needing longer spring bolts.
What is the dimension from the ground to the center of the wheel arch on each side? (The size of the tires affect this dimension.)
Regards,
Alan

Bhebert449

yes the washers were added to try to level the car. The spring has not been removed. What would cause the bushings to compress?

Alan 71

Hi Bh,
The composition of the rubber determines how much the bushings compress immediately.
It 'appears' just the left side bushings were replaced (the right side look 'aged'). Is that so?
What are the ground to wheel arch dimensions at all 4 corners?
From the photo it 'appears' that wheel/tire has a lot of negative camber. Does it?
Could this be coming into play on the ride height dimension?
Regards,
Alan

Bhebert449

From the center of the wheel arch to the ground:

Driver rear 27 1/8"
Pass rear 28"

so almost 1" difference

The tire is not out of line that is just the angle of the pic.