I have lowered my 32 Ford with a C3 rear axle set-up 3 inches but want another 2 inches lower. I lowered the rear end using longer spring bolts and taking out 3 leaf springs. I would like to have any suggestions to get the addition 2 inches lower.

 

The C3 weighs anywhere from roughly 3,200 to 3,600 lbs depending on year.
The balance is close to 50/50.
How much does your Ford weigh and how much is in the rear?
They also used different spring rates over the years, exactly what spring are you using?

 

Its a 5 window coupe and weight is about 2400 pounds with 50/50 ratio.

 

I'm guessing the weight of the body is sitting on the chassis?

Rookie suggestion:

You can modify the differential crossmember to "raise it on the frame 2" which would raise the differential" but you will also have to modify the front mounting point at the frame the same amount where the trailing arms bolt onto the frame./ upper shock mounts also 2"

 

How long are you bolts going to the springs? Can you go to a spring shop and have them take some of the curve up. As kids we had them recurve them to jack trucks up

 

Composite spring with cut down top spacer and polyurethane insulator, cut down poly spring bolt insulators, and longest spring bolts that will fit inside wheel. Obviously your drop depends on difference of the thicknesses of two spring setups but I think more than 2 inches is doable.

 

I really like looking at that rear end!!!!

 

Sounds like the rear of your truck is 500 lbs lighter than a C3. 1200 vs 1700. So you are going to need some new lighter springs. The steel ones will be the easiest to work with. The OEM 9 leaf has a 196 lb rate and wll feel 40% stiffer on your lighter car. So it will feel like the HD Vette spring a 304 lb F41 spring.
That's what I would use on your truck.

Now it will sit 2.5 inches too high due to less weight. The Most Important thing about a C3 vette rearend is to have the half-shafts almost perfectly level when the car is sitting at rest. You have so many variables going on here I would assemble the truck with the 196lb spring, even sandbags for passengers, measure everything, try some longer bolts if you like, but ultimately you will need to figure out how much you need to lower the spring. 1.0" 1.85" 2.35" etc. Then take the spring out and have it recurved. Tell them you want it X inches lower at a 1200 lb load for a x ride height "arc"

Pulling a few leaves out is stressful on the remaining leaves and they tend to fail/bend at the point where they used to be supported. I would have a spring place re-curve it.

 

Me too! Don't tell my wife.

 

Please see photo's before and after some spring removal and lowering bolts. Just for info I am a long time Corvette owner not just someone surfing. I have a 57 270 car that I have had for over 40 years, a ZR-1 and a C5 with less than 2000 miles. I wanted to build this 1932 coupe with the theme that a kid went to a Corvette salvage yard in 1963 and bought a wrecked 63 Corvette and used it to build his hot rod. I purchased the frame from my cousins estate sale with the vette swing axle already under the frame. The problem is it set too high in relation to the fenders. Too much fender gap ( as you know stance is everything) Using a period 28 tall tire I am still 2 1/2 inches from where I want to be. I appreciate the input so far. I may can get another inch from a little bit longer spring bolt. As you can see with my modifications half shafts are about parallel which is what is wanted. I thought about fabricating a new lower spring bolt box. Any additional comments welcome.

 

After lowering mods

 

I think I suggested this on your other thread, but I'd call Van Steel, tell them what you are doing, tell them the expected corner weights of your car, and ask if their lightest weight, low-arch composite spring will work for your application. Perhaps they can even custom make a spring for you. Or call Eaton and ask them the same question about a steel spring, to preserve the "63 found in a junkyard" aesthetic. If you put on longer bolts, you may end up cutting tires on turns.

So, it looks like you'll need to raise the differential at this point. Or just the spring mounting location. How good are your fab skills? Perhaps you could modify or fabricate a new rear differential cover.

You may also want to take a look at this thread, which has some spring measurements sprinkled through it.
https://www.corvetteforum.com/forums...composite.html

Old thread (with more photos):
https://www.corvetteforum.com/forums...rear-axle.html

 

Looks like you are getting close. However I would recommend caution doing it this way. While it almost works, I see areas of concern. I can see where you removed several leaves. So your spring rate and it's overall durability is a complete unknown. And the longer spring bolts are causing the spring end to get dangerously close to the tires. The tire sidewall can flex up to 2 inches sideways in a turn and may hit the spring end.

I still strongly suggest the safest way to do it is to call Eaton spring and have them or another spring shop re-arch or re-engineer your spring. Cost me $100 years ago at a truck spring place.

Ideally you would want a spring rate at around 140 lbs to ride like a stock vette (that has a 196 but is a heavier car). Maybe you can measure what you have now and see if you're close. I can see that you started out with a stock 6+3 196 spring.

 

Thanks again for the replies. I want to stay with a steel spring for the period look. How could you tell by looking that the spring set was a 196 lb spring? Were there other spring rates available? I am thinking I will try a spring shop to get the required arch. I am trying to preserve this swing axle set-up if possible. Actually the set-up was done good but a little on the heavy duty side. I suspect when the chassis was setup the intention was using a big rear tire/wheel. One thing I noticed was the mustache bar rubber insulators do not set completely down in the fabricated crossmember pucks. The insulators are about 3/4 away from setting flush. Should the insulators set flush? That would give me another 3/4 inch lower maybe. I am just looking to go 2 1/2 inches lower than now so every little bit would help.

 

Yeah the key is to get the half-shafts almost exactly dead level, however you go about it. 1/2" higher in the center is also acceptable. Wheel travel, u-joint bind, shock travel, all become a concern if not at OEM height. I would be very cautious about running it lower than horizontal, you run out of bump compliance very quickly.

That spring is a 9 leaf, and is the 6+3 version. 3 straight leafs at the top and 6 curved ones below.
By the way the spring tips curve it may very well be an original spring, or a very good reproduction. Eaton springs are very good.
That was the standard spring for many years and is a 196lb rate. That is an overall rate, so each side is 98.
The 6+3 configuration even gives it a little bit of a variable rate, and may be slightly softer than that when measured. I have seen some numbers as low as 146 and that may be what is going on there. Sounds like a base car rear end.
There is also an all curved 9 leaf version which is not variable rate.

The optional HD spring only has 7 leaves, and they are much thicker, and the rate goes up to 304, and it rides very stiff. It is suitable for a racetrack.

The real key to a C3 rear is to make sure the inner yokes in the diff are good and have no sideplay in-out. They are under sideload as the car drives and sometimes the wear gets pretty bad. IIRC something like .050" sideplay or less is OK. Ideal is .001" .140" or .250" means a major diff rebuild is in order. Sometimes the housings even get trashed. Just something to check.

One of my concerns with you removing leaves and winding up with an unknown rate is if it is too soft, the rear will drop so much under power that the trailing arm hits the bump stop hard, the outer u-joints bind, and could break. Happens all the time with the BB cars if they have soft springs, and they are abused at the dragstrip a little bit. Most BB cars run stiffer rear springs to keep the trailing arm off the bump stops.