Shackle angle question & harsh ride

I have a Model A Sedan (car weighs 2300lbs - see album) with a Ford 2300 4cyl engine. Its roughly 200lbs lighter than a SBC. It takes small bumps pretty rough even at say 25mph. The shackle angle measures 37 degrees with the second shortest leaf already removed. I have a Speedway motors front end kit with a 4" drop axle and super slider spring. I am using Gabriel "Ultra" rear gas shocks for a 76 Honda Civic wagon (mainly due to the 5/8" eyelets, their length and the civic wagon weighed about 1800 pounds).

I picked up some Gabriel "Classis" gas front shocks for a 65 VW beetle (a tip I found here). These rebound a heck of alot faster than the other ones above but have different bushing setup. Are these considered softer?

Tidbit - when i hit the superslab, the front wheels see-saw up and down slightly going 55-60mph. It shakes the car but after 60+ it smooths back out. I had the tires road force balanced. They are radials. I think it may be the shocks?

Questions:
1) Would removing another leaf help out soften the ride? I don't want to take out too many leaves and make it unsafe.
2) IS 37 degrees shackle angle acceptable?
3) Would the VW shocks make any difference (faster rebound rate)? It's a PITA to press all the bushing out so i thought i'd ask before going thru the trouble.

Thanks! Have an awesome day!

Bryan

 

Pull the shocks and go for a ride to see.

 

I'd remove two more leafs and switch to regular hydraulic shocks.
To me gas shocks always felt a little too firm. But that's just me.

 

Take off the gas shocks. Buy HotRod shocks from Pete and Jakes or So Cal. Pull another leaf and put wheel bearing grease between the leafs!!

 

Are the shocks bottoming out? HRP

 

"Questions:
1) Would removing another leaf help out soften the ride? I don't want to take out too many leaves and make it unsafe.
2) IS 37 degrees shackle angle acceptable?
3) Would the VW shocks make any difference (faster rebound rate)? It's a PITA to press all the bushing out so i thought i'd ask before going thru the trouble."

1- Yes, take the second longest leaf out. Playing with the short top leaves has
almost NO affect on the ride.
2- 37 degrees is fine.
3- It is hard to predict what OEM shocks will do on another application than what
they were intended for unless you have a shock dyno to test them.

When I built my car, I made the shock mounts to take 9 inch sprint car shocks. They are short so easily fit in the available space on most hot rods.
The biggest advantage is, they are stamped on the body what the compression and rebound rates are. You make an initial guess as to what will work and then go from there as to what you need for your desired ride.
Another advantage is, they are available "used" a lot cheaper than new OEM shocks.
Many times they have only 3 or 4 laps on them so they are essentially new.

 

Thanks for all the replies. There were originally 7 leaves in the spring. Yesterday, I took out the 2nd one (from the top) because from what i read, those are the stiffest.

Should i take out the 4th one? Or replace the 2nd one and remove the 1st and 3rd instead?

I doubt it is bottoming out. Fully extended the shock are 16.75". Fully compressed they are around 10.5". At ride height the top and bottom shock mounts are 14" apart with all of the leaves and 13.5" with the 2nd leaf removed.

I have a set of F1 upper shock mounts from speedway. I will have to cut them down and reweld them so they sit about 12" above the lower shock mounts to fit the P&J shocks. I also found out Mid America has Hydraulic VW beetle shocks.

Anymore feedback from the night crew?

Thanks,
Bryan

 

My set up has a SBC and weighs about 2500lbs. I removed the top leaf and the 2nd leaf up from the main and improved the ride a lot.

 

I went into your album and pulled out this picture.



Everything looks pretty standard to me except for those shocks. I have always used the chrome Pro Shocks from Speedway and they have given me good performance and last a long time. Yours look a little on the heavy duty side, but that is hard to tell for sure from a picture.

Strange as it might sound, one thing that might be contributing to a stiff ride is the light weight of your motor setup. If you have ever seen how an empty trailer rides versus one with a load on it, that is what I am saying. Your front end was built to support a heavier V8 engine and is reacting too harshly without that extra weight on it. That at least is my theory for part of the problem.

I would remove a leaf or maybe even two and change to street rod specific shocks. And for the handling issues I would definitely add a SoCal steering stabilizer to the front end. You won't believe the improvement in road feel until you add one.

Don

As you can see, my front end setup isn't a lot different from yours.

 

Hey, thanks for posting my pic from my album. I haven't figured how to do that. Your's looks like a sweet ride!

I don't have any steering dampener or panhard bar. The car tracks great. Even when the car shakes, the car tracks straight and i don't feel it in the steering wheel. A softer setup would help I'd think absorb the wheel oscillation. I don't have any bump steer either.

Looking at the chrome Pro Shocks @ Speedway...they would be a direct fit with no bushing changes or fab. Would they act okay even with my little 4cyl over them?

I have driven it this way for 8500 miles. I just thought these old car drove that way.

Thanks,
Bryan

 

Bryan, well, they never ride like a new Caddy, after all, you are working with a suspension system that was designed over a hundred years ago. But, they can be made to ride surprising good with a few modern additions.

One thing I forgot to mention is that I am running a Posies Super Slide front spring. Is the one you got from Speedway one with the buttons in between the leaves ? Those help a lot. I think the lightweight motor you are running isn't letting the suspension "work" like it would with a big old V8 sitting up front, so you need to remove some of the stiffness.

The reason I mentioned the steering stabilizer is because of what you said in your first post about the wheels wobbling. Maybe I interpreted that wrong.

Don

 

Yeah, i have a super slider spring. It is suppose to be nice this weekend so I'll take different combinations of leaves out. I'll try to get the shackle angle closer to 45 degrees.

I went back and looked up the axle shake thread. In Post #68, they call it "Tramp resonance". They also mentions a stiff front setup as a possible cause.

http://www.jalopyjournal.com/forum/showthread.php?t=465428&highlight=tramp+shake&showall=1

Don, I appreciate your time. Thanks for your help! I'll let everyone know how it goes.

Bryan

 

BTW, what air pressure are you running front and back. Have you played with that ?

Don

 

I'll throw in a question. How old are the front tires?
Does the radiator try to wave goodbye when the irritation starts?
I fixed a jackass radiator waving at me problem by buying another pair of front tires. Just because the tread looks good on a tire, doesn't mean the inner construction of a tire is not failing. Pick your size of tire. Do you want the tire on a Peterbilt or a Honda?

 

Just my two cents worth but I designed suspension systems for a living for appox. 20 years. Let me give you this analogy on the springs.
Leaf springs are like a diving board. How much flex do you think you will get jumping up and down on a 2 foot long board? How much on a 4 foot, how much on a 6 foot? Remember you are anchored at the tie bolt where you are clamped to the frame. The longer the leaf the easier it is to flex the leaf assuming they are all the same thickness and width. If you want it to ride softer imagine the spring from tie bolt to the shackle as a tapered board. By removing leaves you are changing the taper of the board.
The spring has to handle the weight and jounce and rebound of the car. Get the board too thin on the end and it will break. Leave it too thick and you get no flex.
Designing a leaf spring is complicated, there are no formulas and to do the math involved you will need to be capable of doing quantum math.
Getting a spring to work depends on leaf friction (Posy's work), thickness, width, length, tapered or blunt cut.
If you do not have a lot of experience you are left with trial and error. Just remember design your board to give you the spring you are looking for.
As for the shaking any slack, any at all will give you problems. Get your spring too light and it can not handle the un-sprung weight of the wheel and drum setup. Also remember the gas pressure of a shock figures into the spring rate.
Shackle angle will make a huge difference ride. Too steep an angle will allow your shaking problem. I never liked to see a shackle running at more than 25 degrees