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  View original topic: Long Travel Suspension Upgrade Kit
tdoman Wed Jul 29, 2020 8:16 am

I'm looking for a suspension upgrade on my sandrail so riding doesn't take such a heavy toll on my body when riding and feeling every bump/vibration. I'm assuming it will help upgrading the rear with some long travel suspension. My sandrail is the first image below. The second image is an example of what I would like to upgrade to (if possible) or something similar. Can someone guide me to parts/kits online for this and instructions/videos how to do it? If there's better options, I would be open to that as well.





tripicana Wed Jul 29, 2020 8:24 am

Long travel swing axle? No
Why not start with getting rid of those crappy poly seats, and replace with some nice suspension seats.

jsturtlebuggy Wed Jul 29, 2020 9:14 am

What kind of budget do you have? How much are you willing to spend? The 2nd picture is showing a couple of thousands dollars worth of shocks alone. Then there is the Bus IRS transaxle along with axles and CV joint that you will need too.
If you modify the rear suspension, you are going to want to do with the same with the front suspension so they work together.
Can you do fabrication work? or are you going to have to pay someone?

It may be easier to buy something used with the suspension you have in mind.

Q-Dog Wed Jul 29, 2020 10:31 am

The cheap spring shocks aren't doing you any favors. I bet it rides worse than an empty truck.

superpro56 Wed Jul 29, 2020 11:38 am

Definitely start with suspension seats. PRP has some relatively affordable options, they are easy to install and wont require as much fabrication as revamping the suspension.

tdoman Wed Jul 29, 2020 12:16 pm

Budget is limited and $2k is more than I want to spend at the moment. Sounds like the suspension seats are the way I will go and see what diff they make.

I've never used suspension seats. Is this a good option or should I look at something else? If I get new seats, I would like to have some that move forward/back to adjust for different drivers.

https://www.prpseats.com/product/roadster-suspension-seat/

cbeck Wed Jul 29, 2020 3:55 pm

Some thing else to think about.
https://www.google.com/search?q=crow+belt+mounting...5dxKo7zfLM

Wulfthang Wed Jul 29, 2020 5:01 pm

I had those same type of spring shocks on the rear of my Trail Rail and the ride was pretty bad. I notched the swing arm, installed some better shocks and heavier torsion arms. It made a lot of difference for the ride. Plus, I used some neat padding for the seats. It's called Ridge Rest and is made for outdoor camping to pad your sleeping bag. I just cut it to shape and it works pretty well. It helps to keep my backside cool too.

L5wolvesf Thu Jul 30, 2020 7:55 am

My first thing would be to figure out what you have there, which torsion arms and shocks to start with, and see if eliminating the coils springs helps.

Suspension seats would be much better than those types of poly seats. I love the Beards seats in my C11.

DHale_510 Thu Jul 30, 2020 8:43 am

Swing axles have a lot of trouble with longer travel modifications. The tires will decamber or tilt so much the tire can come off the wheel. Just when you have landed hard and the need to have a tire is the greatest. Not good. In fact, reducing the down travel with a small 1/4" spacer is a common modification to prevent this, and that will reduce the total travel. Likewise notching a spring plate is more trouble than benefit. If you really want more than the stock travel, changing to trailing arms is the answer, like the car in your dream shot. Not cheap, lots of cutting, welding and new parts, but it works well.

You can improve the swing axle system a lot, and it is cheaper than all of that. First you need to know how much weight you have on each corner and how much travel you actually have. Then a little arithmetic will help you decide on what springs you really want, then you can decide on shock absorbers to deal with the system.
You can weigh the car with bathroom scales. A buggy likely will weigh about 300# on each rear wheel, and 150# on each front wheel. This is about half the original Beetle.
You can measure the suspension travel, remember it's at the wheel not the bump stops that counts. This can be done with a yardstick and a bunch of weights, but if you are stock, then you have about 8" front or rear. Generally it is divided about halfway between up travel and down travel, less up after 75 years of use...
While you are playing with weights and arithmetic you could also figure out what your spring rate is, pounds divided by distance.

Now the arithmetic part. 300# / 5" = 60#/" springs. Maybe you want twice this if you "accidently" land on one wheel when driving hard.

The stock VW spring rates are about 50#/" front and 75#/" rear. Not a bad number for a light buggy, especially when you add the driver and passenger weight into the arithmetic. Heavier rear torsion springs are available, especially useful if you extend the leverage and travel distance with wider suspension parts and wheels like sand paddles.

Now your system seems to have original torsions, but has added coil springs that may well double the spring rate. This used to be a solution to sagging torsions, but reindexing the torsions is pretty easy and likely needed after 75 years anyway. If you have a 300# spring and 300# corner weight, you will only travel 1" instead of 4" under full load, and that will feel about the same as an empty dump truck.

Then there is the issue of how to pick a shock. Shocks are not springs, they are there to slow the spring absorbsion rate and help smooth both the ride and the traction. Stock travel suspension is not very hard as shock loads go, and fairly inexpensive options exist and are common. Lots of folks like the intermediate level KYB stuff. Those $2000 shocks are great for a wild high speed racer, but you are not there yet anyway. Your existing shocks would appear to be just heavy spring holders, a doubly wrong system.

So, your first step is to remove those overload truck shocks [I still have at least one set in storage from back whennn]. Maybe even just drive the thing with no shocks and see if it is an improvement. Then reset your torsion, You will be able to raise the car to improve the up travel since the car is light, but you will still want a couple or inches of down travel [after the weight is back on the ground, you will likely have little or no gap under the spring plate while in the air], no down travel is back to the dump truck analogy. Resetting your torsions may take three of four tries. It gets easier after the first try, and with fresh bushings.
Then fit some nice new shocks, it's more important at the rear. Lots of light buggies work just fine with weak old stockers up front [read cheap].

And all of this may take some time but fits your budget number nicely.

Dennis

DHale_510 Thu Jul 30, 2020 8:47 am

I also found that those sand paddles work best at about 5#, as do the fronts, on my light buggy. Half pound adjustments are very meaningful.
Dennis



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