1969 impala conv front coil springs - Impala Tech
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post #1 of 10 (permalink) Old 12-03-2006, 11:44 AM Thread Starter
 
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1969 impala conv front coil springs

hello everyone, i am new to the forum. here's my problem.

i am in the final stages of a body off custom resto (69 impala convert) and can't seem to get the right front coil springs from moog or trw. supposedly the part #6304 or 6322 is the replacement. 6304s are currently in the car but my alignment guy tells me these springs are not right. the car sits up l (tires are knock kneed) as one would expect when you jack it up or take the motor out. these springs have approximately 10 coils to make up the spring (load hgt 10.25, 2210# rating, 337#/inch springrate and 16.81 free hgt). i was able to get a look at original 69 coils on a parts car and they appear to only have eight coil to the spring.

has anybody ran into this problem. my resto guy has had these springs in and out 3 times. i am of the opinion that moog and trw think the 69 is similar to other model years when in reality the 69 is a unique beast. any suggestion as to where i can get the correct springs would be great, even hubbards impala sent me another different part #6192 that didn't work (it had 10 coils to making up the spring too)
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post #2 of 10 (permalink) Old 12-03-2006, 12:00 PM
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Jeff

I got your email on my site, and I will answer through there. In the meantime I can tell you there were 35 different front springs used in the 1969 full size models, and these were selected via computer based on how the car was equipped, the model, etc.

There is a method for manual calculation as to what the correct springs should be but for that you would need to know exactly how the car was originally equipped. The manual calculation was developed for service folks when they had to determine which replacement springs to use. It will not give you exactly the same results as the computer selected process, since the computer obviously uses more variables. But this will get you very close...close enough that any variances from stock would be too minor to really tell.

I'm assuming you do not have the original springs and if you did, I'd assume also the spring tags are gone (these are two-letter codes used by the assembly line for sping identification) if you have this, then this is all we need. If not, we will have to do the math.

I will send you a chart from GM in 1969 showing all available front springs, and the calculations required to select the right ones for your convert. I will also send you another chart showing the cut-off length, wire diameter, total number of coils, deflection rate, and free and working heights of all the 35 front springs available, as published by the Chevrolet Engineering Center in 1969. You can use this chart to figure out the specifications correct for your car once you can identify which spings it should have.

Matt

www.1969chevy.com

'69 Impala LM1 F40 J52 M38 C60 N33
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post #3 of 10 (permalink) Old 12-03-2006, 12:11 PM Thread Starter
 
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Matt,

That would be great. I was told there were numerous (15 or so) springs available for the 69 based on type of car/options. didn't think there were 35. My car originally is: 69 convertible 327 V8, w/o AC and TH 350, 10 bolt open rear, no power window, drums all way around, bench seat, standard suspension. The restoration made the following changes - hi perf 350 (.030 over) w AC and TH 350 (hi perf 2nd sprague with valve body mods, 2400-2600 stall, 12 bolt posi (3.55 gears), four wheel disk brake conversion.
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post #4 of 10 (permalink) Old 12-03-2006, 07:36 PM
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Manually you weigh the vehicle with four corner scales (used by roundy-round guys if you know any) on a flat level surface, with a quarter tank of gas all fluids full and equipped as desired . That way the spring can be wound to give the correct number of pounds per inch of compression to yield the correct ride height and travel.

Additionally new springs take 48 to 72 hours to settle after they are installed. I wouldn't adjust caster, camber, etc., until I had let them bed in.


Big Dave
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post #5 of 10 (permalink) Old 12-04-2006, 10:36 AM Thread Starter
 
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GM chart for 69 front coils

Matt,

Any progress on the GM chart and calculations. I told my alignment guy about this and he is very interested in the info.

Jeff
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post #6 of 10 (permalink) Old 12-04-2006, 09:28 PM
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Jeff...here you go.

http://www.1969chevy.com/1969_Fullsize_Springchart.pdf

http://www.1969chevy.com/1969_B_BODY_SPRING_SPECS.pdf

Now one thing to note is both documents refer to your car by its series number, not name. So just remember the Impala convert's series name is 16467. If you like a quick reference for other series names, here you go...and I hope this is of use. Just for interest sake reply when you narrow down what your original springs were using the calculations given!

15311 = Biscayne, 6 Cyl, 2-Door Sedan, 6 Passenger
15369 = Biscayne, 6 Cyl, 4-Door Sedan, 6 Passenger
15411 = Biscayne, 8 Cyl, 2-Door Sedan, 6 Passenger
15469 = Biscayne, 8 Cyl, 4-Door Sedan, 6 Passenger
15336 = Brookwood, 6 Cyl, 4-Door Station Wagon, 6 Passenger
15436 = Brookwood, 8 Cyl, 4-Door Station Wagon, 6 Passenger
15511 = Bel Air, 6 Cyl, 2-Door Sedan, 6 Passenger
15569 = Bel Air, 6 Cyl, 4-Door Sedan, 6 Passenger
15611 = Bel Air, 8 Cyl, 2-Door Sedan, 6 Passenger
15669 = Bel Air, 8 Cyl, 4-Door Sedan, 6 Passenger.
15536 = Townsman, 6 Cyl, 4-Door Station Wagon, 6 Passenger
15636 = Townsman, 8 Cyl, 4-Door Station Wagon, 6 Passenger
15546 = Townsman, 6 Cyl, 4-Door Station Wagon, 9 Passenger
15646 = Townsman, 8 Cyl, 4-Door Station Wagon, 9 Passenger
16337 = Impala, 6 Cyl, 2-Door Sport Coupe, 5 Passenger
16437 = Impala, 8 Cyl, 2-Door Sport Coupe, 5 Passenger
16369 = Impala, 6 Cyl, 4-Door Sedan, 6 Passenger
16469 = Impala, 8 Cyl, 4-Door Sedan, 6 Passenger
16339 = Impala, 6 Cyl, 4-Door Sport Sedan, 6 Passenger
16439 = Impala, 8 Cyl, 4-Door Sport Sedan, 6 Passenger
16447 = Impala, 8 Cyl, 2-Door Custom Coupe, 5 Passenger
16467 = Impala, 8 Cyl, 2-Door Convertible, 5 Passenger
16436 = Kingswood, 8 Cyl, 4-Door Station Wagon, 6 Passenger
16446 = Kingswood, 8 Cyl, 4-Door Station Wagon, 9 Passenger
16647 = Caprice, 8 Cyl, 2-Door Custom Coupe, 5 Passenger
16639 = Caprice, 8 Cyl, 4-Door Sport Sedan, 6 Passenger
16636 = Kingswood Estate, 8 Cyl, 4-Door Station Wagon, 6 Passenger
16646 = Kingswood Estate, 8 Cyl, 4-Door Station Wagon, 9 Passenger

www.1969chevy.com

'69 Impala LM1 F40 J52 M38 C60 N33
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post #7 of 10 (permalink) Old 12-04-2006, 09:46 PM
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One more note...things like a 327 (base V-8) open 10 bolt, etc are "standard" equipment, which is why you won't find RPO codes for them in the caculations. The chart takes the base weight by series, in your case a "standard equipped" convert, and for every add-on option over and above standard, you add or take away weight value accordingly. But this is where it is critical to know EVERYTHING it came with on day 1, right down to if it had floor mats or not...

www.1969chevy.com

'69 Impala LM1 F40 J52 M38 C60 N33
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post #8 of 10 (permalink) Old 12-05-2006, 05:02 PM Thread Starter
 
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Matt thanks for the info. How can I tell if my car has the F40 option?

F40 springs are shorter than standards with higher spring rate for a stiffer ride. Looking at the specs it appears my car currently has a QF spring equivalent in it (Moog 6192) but my alignment guy says the car is way to high. Now I am even more confused.

I thinking about getting a F40 equiv spring (QN or QO) or pulling a set from a parts 69 conv i have access to. Any thoughts or suggestions

Jeff
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post #9 of 10 (permalink) Old 12-05-2006, 06:38 PM
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Up front, there wasn't really any difference in the F40, the rear axle had two upper control arms instead of just one. F40 was common, since it was mandatory on all cars with A/C. F40 typically had a 12 bolt rear end also, but it has not been confirmed that this was a hard and fast rule since we have at least one known case of a '67 F40 with a 10 bolt.

So you are saying then that by doing the calculations you come up with a moog equivalent? And you have measured that moog spring to be 100% sure it has the same number of coils, deflection, height, wire diameter, etc?

I guess it would help to know what ride height is considered too high. My '69 sport sedan sits high at the front, but the springs are what it left the factory with. Are you running 14" or 15" wheels? What size tires? All that adds up to ride height, from the factory you would have had 14" wheels with likely 8.25 or possibly G78-14 tires. Compare your current set up with that.

An interesting note...the link I gave you is a guide, since as I said at the factory the springs were selected by computer. My car has the F40 yet the front springs are CG which you will find listed under the standard spring set up. This is because the chart accounts for some variables, the computer accounts for all variables. The chart is a guide, the computer is exact. But this is the only way to get a close estimate if the original springs are not known.

Stock ride height shoud be 6" +/- 3/8". This is determined by the following method:

1) Place the vehicle on a smooth, level floor and bounce and rock the front end several times. Raise the vehicle, then allow it to settle to a normal height.

2) Measure the distance from the floor to the center of the inner pivot of the lower control arm. Take this from the rear end of the pivot.

Measure the distance from the floor to the lower face of the lower steering knuckle boss for the ball joint on the same side of the vehicle. The difference between these two measurements should be 6" +/- 3/8". repeat this for the other side, should be the same +/- no more than 1/2"

This is per the 1969 Chassis manual, section 3-7. This also assumes a full tank of gas, spare and jack in trunk, no passengers.

www.1969chevy.com

'69 Impala LM1 F40 J52 M38 C60 N33
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post #10 of 10 (permalink) Old 12-05-2006, 08:38 PM Thread Starter
 
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Here are the Moog 6192 specs (10 coils):61923.8120.64011.751717.0300.017.53Tangenti al Ends

Here are the QF specs from the info you sent me (10 coils)
3953906??0.63611.761720.0290.017.753TEnds

QF are for a base model from 148-196 extra weight, which would fall in my range.

I can not measure ride height at this point because the car is sitting way to high with these springs in them right now. I believe my car has two upper control arms in the rear, so does that mean its came with the F40 option. Does the F40 have a larger diameter front sway/stab bar?

Is there something I'm missing. If this moog spring is close enough from the specs (I didn't physically measure cause its in the car) what could be keeping the car from being able to have suspension travel. I will try to post a pic of this area of the car.



What is the easiest way to remove these front springs? I will be working with jacks from the ground. I was told to support the lower a-arm with a jack and break the lower ball joint then lower the jack til the spring releases. I then would remove the shock (i figured to leave it in as a safety measure in case the spring decides to get a mind of its own)
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