Heres a good 40 spring question for ya!

I have been mocking up my 29 tudor on a 4" z'd A frame. I was going to use a 40 rear spring to help lower the rear end. I just finished removing the front spring from the 40 axle set up I have. Why cant I use the 40 front spring as a rear spring. Its 2" wide with a height of 10" - a full 3 inches lower that the rear. Width is 37" as opposed to 39 for the rear. I'll be mounting it on an 8" rear housing. Whatcha think is it to flat for the rear? Sure would be great to lower the rear another 3"!

 

doesnt sound like it wouldnt work ,,, but is the spring rate going to be to heavy for the rear since there is no engine back there?? you could take out some leaves (probably already planned that)

 

you need to use the front spring, the rear is too wide, (found out the hard way)

 

SO that worked for you TOQWIK? Do I need a panhard bar?

 

BTTT

 

We had a fairly extensive discussion on panhard bar use or not over on the RRT when I was getting started with my 31 on 32 rails roadster.
Consensus was that it was a good idea.
It will make for a more accurate steering car due to lack of input from the spring shackles.
Especially since the car was dry lakes bound at the time, but it's going on the street for a while first.

Using the 40 front spring strikes me as a good idea provided it's about the right size width-wise.
Not the 2" leaf width you mentioned, but side to side width.

This pic shows about how low you can go with a fairly flat transverse spring in the rear.
The car will be raised a bit in the back for street use, but it would work ok as is.
There's about 2 1/2 - 3" clearance between fender and tire as it sits.

If you run fenders be aware the 28-29 rear fenders are 1" wider than the 30-31 fenders - roadsters anyway - and if they're bobbed which gets rid of the running board apron notch either set of fenders will fit either car as far as the wheel well goes, but the bolt patterns are different.
No big deal, fill the holes required to be filled and drill new ones.
The 31 fenders fit my tire/wheel combo very nicely (6" x 15" wheel, 3" backspacing, 2.35/75R-15 tire) and would look right on the street once the car is raised a touch, but the 29 fenders have a little more room for a larger tire and have better clearance between tire and outer fender edge.
All a moot point with a fenderless car, but if you want fenders, perhaps this info is helpful.

 

Here's an oft seen photo, but it's all I have for an example right now.

The rear spring sits on a flat crossmember as you can see and something like that may work for your Z'd A.
The rear axle spring brackets are 44" apart which is what SoCal recommended for their main leaf with 40 spring pack.
The 40 rear spring leafs are 2 1/4" wide.

There is so much adjustability as far as ride, car height and load carrying ability goes that I don't think I'll ever use coilovers again.
The 1/4" flat piece you see between spring and crossmember is simply a "wear" piece. Probably not needed, but I figured it wouldn't hurt with the 1/8" wall thickness of the rear crossmember.
Note too, the use of bolts instead of U-bolts to retain the rear spring.
The advantage here is all that's required for a taller spring pack is a longer bolt.
The 1" tubes are drilled 1/2", the crossmember is milled out to match the 1" tube and then the tubes are welded in place.
Done to gain a bit of clearance between rear axle and frame.
That part isn't too close, but getting a sway bar and long panhard in there was a tough packaging problem.
The panhard can go in front of the rear axle, but I wanted all the room I could get between the 4 link crossmember and the rear axle.
SCTA rules don't allow for belly pans in the street roadster class, but no one said you couldn't run a pair of well fitting fuel tanks with flat bottoms.

Do make a point to run a rear sway bar.
It will help handling a whole bunch.
The sway bar doesn't have to be very big.
I run a Deuce Factory bar in this car and my 32 and it contributes greatly to it's good handling manners on winding mountain roads.
If you search the junkyards carefully, you should be able to find a small diameter sway bar from a small car that should be very adaptable to your A.

 

If memory serves the leaf spring proper is right around 39-40" long.
I'd measure, but the 31 is in storage.

Couple of other thoughts ... be sure and "C" the rear frame if it goes up and over the rear axle. I didn't on my 32 and have been sorry ever since. One of these days though....

If you're running the spring over axle in front and not using a suicide front spring mount, notch the front of the frame rails for additional travel clearance.
Another one I didn't do on the 32, but the 31 has both a notch and a "C".

The notch in the front is easily filled with a piece of 1 x 2" x .120 wall rect tubing with one of the long sides sawn off which makes a very nice rounded corner channel.
AV8 recommended that I cut the frame notch to match the angle of the curved front spring and install the channel to match.
I did and it's a good idea cuz the spring hits flat inside the channel when the car bottoms out and doesn't hit on an edge which could lead to a weak fatigued out place in the spring.

Here's a pic of the SoCal rear spring bracket - 44" apart in my case - and it should be easy to duplicate at home.

Don't think I mentioned it, but your panhard should be as long as possible.
The aftermarket ones are designed for a quick and easy installation and they're not long enough to my mind.
The frame brackets for the panhards - use one front and rear if you're running transverse springs both ends - are attached to the same side of the frame the steering box is on.

 

You'll note in the second photo posted above, the rear shocks - Speedway item, Canadian made - have the typical coilover lower mount.
Done so the car could be changed to coilovers if desired, but I don't think I will.
I do try to plan for the future and build the car so that some changes would be easy.

The big thing I have against coilovers is their limited amount of travel.

This photo posted to show an alternate shock mounting method.
Not to mention the chrome plated spring et al looks a lot better than the busy looking coilovers.
Little more trad as well.

 

C9 has come thru once again!

 

Since I'm on a roll this morning, here's the good looking little roadster the chrome spring belongs to.

Pic shot at the 2003 CHRR.

This roadster caught my eye and said something to me that no other car at the meet did.
I hope mine comes out as good looking.

 

LC,I use 40 front springs in the rear too.got one in my roadster and it works great.I think I ended up with 6 leafs.Gets the cars down really low like your asking.The width works out well too.
C9,your pics are great,As are your words of wisdom.
LC,we wanna see progress pics......Shiny

 

Levi's, Did you have to do anythingto the 40' front spring to get it to fit the high arch of the stock A X member? I think I might go this route.

C9, Do you have any pics of your completed rear suspension without the body on. I'd be interested to see the whole thing. Thanks

 

Had to use two 6" C Clamps to draw it up into the crossmember. The 40 spring does not have the arch the A spring did but is about 6" lower in height!

 

Here's the only converted (to JPG) one I have right now.
I'll dig through some other files and see what I can find and post again.

 

Levi's; Do you think it will harm the spring after time by forcing it up there? Do you have another 40' front spring?


C9; thanks man