Multi leaf springs

[gro51]

I have a 68 SS RS, 350, 4 speed.  It's a mostly original car.  I need new rear springs.  The ones I have on there now are not original.  From my research it looks like this car should have multi leaf rear springs.  My question is, 4 leaf or 5 leaf?  I have seen both available thru the major Camaro restoration catalogs.   Thanks.

[bertfam]

It could be either, depending on what options you have on your car. In UPC 0 of the AIM, there's a spring chart (Page A9 of the 68 AIM). If you go in there and find out what spring you need (based on the options on your car), post it here and I might be able to look it up for you.

Ed

[gro51]

Thanks Ed.  Fortunately  I have a AIM.    There are a bunch of choices for the L48 on A9 and A10.  Maybe you can help.  My car does NOT have A.C. (C60).   It has 3:73 rear axle ratio.  It has original #s matching tranny but I don't know if it's M20, M21, or M22.  My guess is M20.    One of the options listed in the AIM is  G31, spring, special rear.  Another option listed is  F41 suspension, special performance.  Unfortunately I don't have a build sheet for this car or a protect-o-plate so I don't know if these options were on this Camaro.  Also I see listed H05 and I can't find what that option is.  Are there any other options that would determine the rear springs?

What would be the worst that could happen if I selected the wrong leaf springs?  Ride height?  Handling?

Thanks in advance for your help.     

[bertfam]

Joe,

There are a few things you need to read before making your choice. The first is an ORIGINAL THREAD regarding springs on the old forum. There's a link in one of the replies that will take you to a 1969 Camaro spring calculator. Although it's for a 69, it will get you close enough if you can determine (approximate) what options you car originally had. To be honest, I don't think there are that many versions of the rear springs available, and any set you get would probably be okay. However, your original question was to do with 4 or 5 leaf and if you can give me the spring code you come up with, I should be able to tell you if it was originally a 4 or 5 leaf setup.

Ed

[ogbean]

WOW.. someone need to create a new spring calculator that cover all years! That thing is cool

[nuch_ss396]

Joe,

There are a few things you need to read before making your choice. The first is an ORIGINAL THREAD regarding springs on the old forum. There's a link in one of the replies that will take you to a 1969 Camaro spring calculator. Although it's for a 69, it will get you close enough if you can determine (approximate) what options you car originally had. To be honest, I don't think there are that many versions of the rear springs available, and any set you get would probably be okay. However, your original question was to do with 4 or 5 leaf and if you can give me the spring code you come up with, I should be able to tell you if it was originally a 4 or 5 leaf setup.

Ed

Ed,

What exactly can I do with the information derived from this "spring calculator"?  Will it help me to find the correct springs by passing
this information to the spring manufacturer?  I have read a number of posts over the years from BB Camaro owners who claim that
the new installed springs have the incorrect ride height.  I always wondered why this was the case.  Is it more front than rear spring
related?  I'm going to be ready to install new springs shortly and I would like to get the proper springs the first time.   

Thanks,
Steve

[bertfam]

Steve,

Nowadays I'm not sure how much you'll get out of it. It seems that there are really only a few options when it comes to rear springs on our cars. Places like Ricks, Ground Up, Classic Industries, etc... only sell one or two versions at most. Kind of a "one size fits all" mentality. That's probably why people experience problems when trying to fit these things onto their cars. Some folks complain that the car is too high, others complain of just the opposite! Since GM had hundreds of versions of the same basic spring for each car, we can immediately rule out the "one size fits all" spring.

However, there IS hope! Places like Eaton or Triangle appear to be the answer. (At least according to their ads!!) Therefore, if dealing with one of these type of companies, it's best if you know what you're talking about before contacting a salesman. IF you can give them a rear spring rate and/or a spring code to go by, there's a much better possibility that what you come away with will be much closer to what your car originally came with in the first place.

In some cases, I can look up original codes and/or Part Numbers in the P&A and give you an exact spring count and spring rate. I can't do that with all applications since the P&A doesn't list every spring that came on these cars, but I can probably get you in the ballpark. So in these cases, it would be benificial if you knew the code at the bottom of the calculation program.

If you can get me the code, I'll give it a shot!

Ed

[gro51]

Ed- I ran the Calculator.    As you said it's for 69 and I have a 68, but it should be close.   Here's the boxes I checked:   L48, M20, floor mats, console, dual exhaust, power steering, radio am/fm, rear bumper guards, rs package. 

Here's what the calculator spit out:    Rear spring rate - 73.     RPO Spring code - BY.     F41 code - BM.     G 31 code - BL.

Hope you can help me out based on these codes.  Also, with regard to spring rates, does a higher number mean a stiffer spring?

Thanks again,  Joe

[bertfam]

Joe,

If no one replies before I have a chance to get home and check my books, I'll let you know later on this afternoon.

Ed

[bertfam]

Okay Joe, here's how it breaks down:

The 1968 equivilant of the 1969 standard "BY" code is "OC" (P/N 3930074). The rear spring load on this one is 520. Note that this is the "standard" rear leaf spring for the 68 L48 Coupe with minimal options that would affect the rear end. Also note that this is a 5 leaf rear spring...

The 1968 equivilant of the 1969 optional F41 (Special Purpose) "BM" code is "BI" (P/N 3932719). The rear spring load on this one is 510. Note that this spring load is actually rated less than the "standard" spring above! This is also a 5 leaf rear spring...

The 1968 equivilant of the 1969 optional G31 (Heavy Duty) "BL" code is "OG" (P/N 3932720). The spring load on this one is rated 650. (This one would give you a very harsh ride if you installed it!) This one is a 4 leaf rear spring. The chances your car originally had this spring is slim! (Coincidentally, this is the rear spring that MY CAR came with!)

Now, more than likely your car originally came with the "standard" spring ("OC" or P/N 3932719), which would be the 5 leaf set-up. However, if you want to upgrade a bit, go with the F41 spring. Just remember that your car WILL ride a little higher in the back than "normal".

By the way, if you want to know more about srpings and spring rates, you can download the SPRING TECH 101 book (in PDF format) from Eaton. It has a lot of good info in it.

Hope this helps...

Ed

[gro51]

I really appreciate your help Ed.  And the useful links you provided.   I think I'm going to go with the 5 leaf  "standard" spring ("OC" or P/N 3932719).   Not only is it probably the most "correct",  I really don't want to change the ride height at all from stock, especially not LOWER.   Stock is what I'm looking for.  If anything, slightly higher would be accecptale.  I only use the car for a Sunday drive or occassional cruise in, so I'm not that concerned if the handling is a little too stiff or soft.   - Joe

[bertfam]

Joe,

Before you make up your mind, contact Eaton and see what they recommend. Give them both part numbers and both spring codes and see what they have. You might find yourself going with the F41 spring.

Ed

[nuch_ss396]

Steve,

Nowadays I'm not sure how much you'll get out of it. It seems that there are really only a few options when it comes to rear springs on our cars. Places like Ricks, Ground Up, Classic Industries, etc... only sell one or two versions at most. Kind of a "one size fits all" mentality. That's probably why people experience problems when trying to fit these things onto their cars. Some folks complain that the car is too high, others complain of just the opposite! Since GM had hundreds of versions of the same basic spring for each car, we can immediately rule out the "one size fits all" spring.

However, there IS hope! Places like Eaton or Triangle appear to be the answer. (At least according to their ads!!) Therefore, if dealing with one of these type of companies, it's best if you know what you're talking about before contacting a salesman. IF you can give them a rear spring rate and/or a spring code to go by, there's a much better possibility that what you come away with will be much closer to what your car originally came with in the first place.

In some cases, I can look up original codes and/or Part Numbers in the P&A and give you an exact spring count and spring rate. I can't do that with all applications since the P&A doesn't list every spring that came on these cars, but I can probably get you in the ballpark. So in these cases, it would be benificial if you knew the code at the bottom of the calculation program.

If you can get me the code, I'll give it a shot!

Ed

Hi Ed,

Sorry it took me this long to get back to you on this.  Away too much on business to remember where I left my brain........

Here is the output from the spring calculator.



Thanks for any assistance you can lend.

Steve

[bertfam]

Steve,

The "BK" Standard rear spring is P/N 3955740, the "BM" (F41) rear spring is P/N 3934894 and the "BL" (G31) rear spring is P/N 3955743. Unfortunately, my September, 1968 P&A 34 only shows one spring listing for 1969 rears (P/N 3934894). Luckily, it's your F41 option and is a 5 leaf. The other two aren't shown in my book since it's "new" for 1969. Hopefully someone with a later P&A will be able to give you the other two listings.

Ed

[nuch_ss396]

Steve,

The "BK" Standard rear spring is P/N 3955740, the "BM" (F41) rear spring is P/N 3934894 and the "BL" (G31) rear spring is P/N 3955743. Unfortunately, my September, 1968 P&A 34 only shows one spring listing for 1969 rears (P/N 3934894). Luckily, it's your F41 option and is a 5 leaf. The other two aren't shown in my book since it's "new" for 1969. Hopefully someone with a later P&A will be able to give you the other two listings.

Ed

Hi Ed,

Thanks for the help.  I have to say that I am somewhat confused and need further clarification on the "fields" of the spring calculator.

For the rear springs, what do each of these fields signify:

Rear Spring Wt. = 84
RPO Spring Code = BK ( What does this tell me about my springs )
HD - F41 Spring Code = BM \____ Why two HD spring codes?
HD - G31 Spring Code = BL /

Steve