Coil Springs for an Alpine

[DanR]

Just to let you know the latest on my project to upgrade my V6 Conversion to one of my Alpines, I received a "new" set of springs from Eaton Detroit Spring last week.

Before I install them I decided to "test" them to verify exactly what I had bought!

One of my Racing buddies tested them for me with the following results:

1st spring tested at: 1" = 235
2" = 490
Rated @ 255

2nd spring tested at: 1" = 250
2" = 525
Rated @ 275

He recommended I run the 275 on left side

I also had one of the old springs tested and it came out as:
190
390
rated at 200

I was told the way to rate the spring was to subtract the first reading from the last. SO if that is correct I believe I have a set that will perform as desired for my V6.

 

[phyrman]

Let us know how they perform Dan!!

 

[Charles Johns]

Dan, How did it ride with the OEM springs?

 

[DanR]

Charles, My '67 SV V6 rode OK as far as the ride goes. My problem has been the drifting and squirrely movement even when it was powered by the 1725.

All suspension parts are (were) new during the restoration!

Overall the suspension is a bit stiff, yet a decent ride.

 

[Charles Johns]

Dan, it appears factories made front-to-back bounce a priority while side-to-side movement was no big deal. To my way of thinking, both need to be addressed for a good ride. Radial tires have much more sidewall movement than bias ply tires, causing much of the side-to-side movement. I have bias ply 14" tires on wider rims with a slightly wider track...outboard stance. They are 6" rims and add to the tendency to drift with road surface changes...because radials have a bigger surface contact with the road. I want to avoid as much of that as possible, but still have control of the car. It is a dilemma all suspension engineers must deal with when balancing ride comfort with control. You guys have "Been there" and I am a new-bee in the sporty car area, so any help is appreciated.

 

[Charles Johns]

That should be RADIAL tires on 14" rims.

 

[DanR]

Dan, How did it ride with the OEM springs?

Charlie, I still have the OEM springs installed.... The "new" ones will be installed at first opportunity.

 

[Charles Johns]

Has anyone used a hydraulic press with a scale under the spring to test pressures? I will probably use the OEM but would like to "Rough Test" them to get a matched pair or as close as possible from the 4 I have. There my be some cutting involved to lower the car, and yes, I use an angle grinder with a cutoff wheel...NO HEAT!

 

[DanR]

Charlie, I received a "new" set of springs from Eaton Detroit Spring.

Before I install them I decided to "test" them to verify exactly what I had bought!

One of my Racing buddies tested them for me with the following results:

1st spring tested at: 1" = 235
2" = 490
Rated @ 255

2nd spring tested at: 1" = 250
2" = 525
Rated @ 275

He recommended I run the 275 on left side

I also had one of the old springs tested and it came out as:
190
390
rated at 200

I was told the way to rate the spring was to subtract the first reading from the last. SO if that is correct I believe I have a set that will perform as desired for my V6.

 

[phyrman]

Dan, have you considered a rear sway bar?

 

[PROCRAFT]

Dan I always thought that if the spring had a rate of 250@1 inch the rate would be 500@ 2 ? as to the comment about the press we used a press to rate our springs (once ) with a load cell. we also cut our springs with a cut off wheel reshaped the top coil by heating and ground them flat on a disc sander.

 

[Barry]

Dan I always thought that if the spring had a rate of 250@1 inch the rate would be 500@ 2 ?

Correct in a perfect world, but variations in length measurement / load measurement / phase of the moon / etc. get in the way of perfection.

 

[Barry]

Dan,

Spring rate is important, but so is spring length.

QA1 is a major player in the "performance suspension" market and publishes a lot of suspension and spring information. One of their charts indicates that the appropriate front spring rate for a car with 1,250 lbs. front weight and a 2:1 force ratio (probably pretty close for a V6 Alpine with a driver) is about:

450 to 550 lbs. with a 7" spring
400 to 450 lbs. with a 8" spring
300 to 350 lbs. with a 9" spring
250 to 300 lbs. with a 10" spring
200 to 250 lbs. with a 12" spring​

As you can see, the spring length makes a big difference in the recommended spring rate for the same 1,250 lb. front axle weight.

The QA1 recommendations seem high compared to the rate numbers I have seen for Alpine / Tiger springs, but .....

How long are your new springs?

 

[DanR]

Charlie, I received a "new" set of springs from Eaton Detroit Spring.

Before I install them I decided to "test" them to verify exactly what I had bought!

One of my Racing buddies tested them for me with the following results:

1st spring tested at: 1" = 235
2" = 490
Rated @ 255

2nd spring tested at: 1" = 250
2" = 525
Rated @ 275

He recommended I run the 275 on left side

I also had one of the old springs tested and it came out as:
190
390
rated at 200

I was told the way to rate the spring was to subtract the first reading from the last. SO if that is correct I believe I have a set that will perform as desired for my V6.

Dan,

Spring rate is important, but so is spring length.

QA1 is a major player in the "performance suspension" market and publishes a lot of suspension and spring information. One of their charts indicates that the appropriate front spring rate for a car with 1,250 lbs. front weight and a 2:1 force ratio (probably pretty close for a V6 Alpine with a driver) is about:

450 to 550 lbs. with a 7" spring
400 to 450 lbs. with a 8" spring
300 to 350 lbs. with a 9" spring
250 to 300 lbs. with a 10" spring
200 to 250 lbs. with a 12" spring​

As you can see, the spring length makes a big difference in the recommended spring rate for the same 1,250 lb. front axle weight.

The QA1 recommendations seem high compared to the rate numbers I have seen for Alpine / Tiger springs, but .....

How long are your new springs?

My new springs are 12" and same as one of my stock SV I sent to Eaton for comparison.

 

[Barry]

1st spring tested at: 1" = 235
2" = 490
Rated @ 255

2nd spring tested at: 1" = 250
2" = 525
Rated @ 275

My new springs are 12" and same as one of my stock SV I sent to Eaton for comparison.

Based on the 2" numbers, the "new" spring rates are 245 lbs. and 262.5 lbs. which is close to the QA1 recommendation for 12" springs and 1,250 lbs. front weight. Sounds like you are in the right ballpark.

 

[DanR]

Sure hoping Will find out when I take the old springs out this winter! Keeping it on the road for now,

 

[Charles Johns]

Our Hot Rod guy said to test springs and install the stronger of the 2 on drivers side because the car does not move without a driver...at least one hopes it does not! I have a hydraulic press and the same weight scale I used to weigh engines to test springs. Accuracy is not really important as my purpose is to test differences so I can match used springs. Back in my youth right after "The Flood", we had to use old parts WE rebuilt because what we called re-pops were not available. We got very good at matching old parts, so that is not a problem. One would be amazed at how well an old innertube can be turned into door handle gaskets or tail light seals.