If I am going to be test driving the Buggy over the coming days and weeks, I have decided to sort out the speedometer before I get carried away with anything else and end up getting caught by the numerous "Trainee Feds" around here. Originally, I used a small pulse generator on the end of the speedo cable as a temporary solution that lasted over fifteen years, but as the hole for this has now been welded up, I have decided to opt for a better and more permanent solution.

Years ago, I used to sell digital dashboards and gauges, and still have a few bits and pieces kicking about that I had put aside to fit on the Buggy but never got around to. One of the VDO sender kits I had used a serrated ring that attached to the rear driveshaft as it emerges from the gearbox.




I've just quickly fitted this to show how it works as it may prove helpful to others. Rather than removing the driveshafts to slide this ring on, the common practice was to chop it in half and install in two sections. This is known as a "Hall Effect" style sender and it generates a small signal pulse each time the metal moves past it. This system is very accurate and used by many of the higher quality gauges whereas the cheaper ones tend to use small magnets instead to rapidly open and close a small switch to give the signal pulse each time the magnet passes by.




As I am using the magnet version, I have fixed some small rectangular neodymium magnets to the ring - evenly spaced, but I only used 8 of the 16 webs. To prevent them flying out when they are rotating at speed, I also fixed them in place with Araldite, and then put heat shrink around them for good measure.




The sender unit needs to be very close for the magnets to work and as I am using 8 magnets, it means that for every rotation of the wheel, I now get 8 pulses.




How fast the wheel rotates will depend on the tyre size, and this will also affect how many times it rotates in a given distance. There is some serious math to do here because if your pulses are too many over a given mile, then whilst the speedo may display some good bragging speeds, if there are too few pulses, then it can be quite expensive with the number of speed cameras around.

If you want to work it out correctly, then this is the formula you need - (and to save looking it up, there are approx 1,609,344 millimeters in a mile) 

Rolling Circumference (in mm)  = 3.14 x ( Wheel Rim Diameter x 25.4 + 2 x Tyre Width x Tyre Aspect Radio / 100)

or . . . .

To make it easier, I have written a quick Calc that you can download here   

www.beachbuggy.info/DNDSpeedoCalc.xlsx



At long last - Something on my Buggy now works perfectly   

This is a really neat fix Dave.  Do you know if the serrated ring is still available to purchase and if so where from.

Quote from: Paul1953 on September 07, 2021, 07:59:56 AM
This is a really neat fix Dave.  Do you know if the serrated ring is still available to purchase and if so where from.

I don't have any left here, but you can still get them stateside 

https://www.mooreparts.com/vw-bug-cv-joint-pulse-generator-ring-for-hall-effect-speedo-sensor-vdo340020

I do have the VDO sensor and gearbox brackets here though    work with some electronic "rotating needle" speedos and not cheaper LCD ones

Before I start stripping this down for the umpteenth time, I am going to take a few measurements, so I at least have a base line to work with.

One of the subjects that has frequently come up in conversation is that of "weight" and recently, corner weights. If this were a high performance Racing Car being set up for the track, then knowing how much weight over each wheel is absolutely critical for setting up the suspension correctly, whereas in our old Buggies, if asked about weight, the answer is usually . . . erm . . . Yes, it has some.

But, if the truth be told, I don't actually know the answer. Many on here have often asked what the weight of a Buggy is, and the figure banded about is about 750Kg but how accurate is that? How many out there have actually weighed one on a weighbridge? But a weighbridge figure would not give me an indication of how much weight was sitting over each axle. I did a bit of investigating into Corner weight measurement and what it would cost, and I am still laughing from the prices that were being thrown back at me. Bloody Hell, that was expensive, but then when I see how much a professional set of corner weight scales are, even the cheap ones start well into four figures, you can see why prices are so high. There must be a cheaper and easier way to do this. I had a trawl on the net and came across a guy using multiple sets of bathroom scales under each wheel, but as the only ones I could now find were glass topped, I didn't fancy that either. I did however, come across a cheap set of 300Kg warehouse platform scales for £15 and bought a couple as I know you have to keep the car as level as poss and weigh both sides at the same time.




Because I wanted to roll the car on and off the scales, I placed a few strategic bricks under each wheel to give me the right height whilst keeping it level.




Sure enough I got a couple of readings, and over the next 10 minutes tried a few different combinations to see what it would do to the weight.




Now whilst these measurements are particular to my own car, they cannot be far off most others either - This is what I found.

Front Axle Weights measured with a full Beetle shaped tank of fuel, how ever many gallons that is.

Car on its own, no additional weight:
Drivers Side = 133.0Kg
Passenger Side = 126.3Kg

Me sat in Drivers seat (and I eat a lot of Pies):
Drivers Side = 156.9Kg
Passenger Side = 150.1Kg

Driver and Passenger (Me and Liz):
Drivers Side = 180Kg
Passenger Side = 176Kg

So the springs Ed sent to me of 175Kg are pretty much on the money - the smoothness of the ride at the front certainly confirmed that and anything stiffer may be a little too much if I was driving it on my own. I think I will try and stick with these springs for now, unless things go wayward.

And yes, I did weigh the rear end too - Done with nobody sat inside, and also bear in mind I have a heavy 2.0 litre T25 engine fitted.
Driver Side = 233.5Kg
Passenger Side = 241.8Kg




My Maths by adding the four corners together, makes that a Grand Total of around 735Kg so we were not far out with our initial approximation of 750Kg.   

Quote from: Dave DND on September 15, 2021, 12:57:02 PMHow many out there have actually weighed one on a weighbridge? But a weighbridge figure would not give me an indication of how much weight was sitting over each axle.

Actually they can calculate Axle weight too on a weighbridge.  I have my T5.1 done it was 2500kg with most of my camping gear onboard an actually a 50:50 weight distribution.

They can give you corner weights too..... May find public weighbridge depots closed to the general public at the moment. Up my way they have not allowed public use to re-commence as yet. (They are often "council" controlled).

There's a public weigh bridge at the Trading Standards site directly opposite my workplace. Always ooen. You just drive up, press a button to activate, and drive slowly across the scales which are imbedded into the road surfsce.
Gives you axle weight and toal on a large display. Doesn't do corner weight.

local weighbridge is similar in that the drive on section is embedded and therefore level with the ground surface. Just needs each wheel  placed on the plate and you get an accurate corner weight. Double checked the resulting 4 weights and they were as accurate as you could expect...

Quote from: Dave DND on September 15, 2021, 12:57:02 PM

I did however, come across a cheap set of 300Kg warehouse platform scales for £15 and bought a couple as I know you have to keep the car as level as poss and weigh both sides at the same time.

do you have a link for these

Quote from: brummie_steve on September 16, 2021, 11:26:54 AM
do you have a link for these

Sorry, I had the last two from a seller down the road - was hoping he had more, as wanted a full set. 

Plenty on Amazon though - just a bit more expensive 

You got an absolute bargain Dave... Cost me over £130 for four.......  I will, sometime later due to family issues, go into detail regarding a very entertaining and instructive session that came about completely by chance and led me through a pro`s insight to what I thought was a simple Vw suspension system. It really isn`t. What I can say is you are going down the right line, at least in my humble opinion. 

You need a clever head for suspension and steering design when you look at all the angles of turn and suspension travel then add in the other complication of one wheel up and one wheel fully down then start working out the geometry in different places.

Right there Keith.... Modern cars have certainly come light years ahead of what we drove around as new drivers....  A modern car starts stops steers etc with next to no effort from the driver.  I was given the chance to drive a TR6 early this summer. My favourite british car ever made. What an exhilerating experience. Push in the back acceleration with the most amazing exhaust sound. Arms and shoulders steering going fast round country lane bends. Hairy braking. Bouncing suspension.....Got in my car to drive home..... so completely characterless in every way...

Characterless is a good description of modern functional cars, they just do the job easily no messing with chokes and hesitation fighting with a heater that will not clear a screen you just key in and go.

Lots of things to sort out and I have to start somewhere. I think the ride height and suspension travel is the one I shall tackle next, because if I cannot get this one right, then any subsequent alterations will require setting this up again, so might as well tackle this one first.

I know that there are probably some technical do's and don't for this and a correct procedure that should be followed, and lets face it, I have got this completely wrong so far, but this time I intend to tackle this in a slightly different way. Learning, laughing or crying - not sure how this will end, but will try and explain my thoughts for doing it this way. In my haste to get it ready for Stoneleigh, I definitely made a bit of a Rookie error here, as I spent a long time messing about with getting the ride height to both sit and visually look right without taking into account a very important factor - weight and load. In my defense, I thought I had by jumping up and down on it, but I completely underestimated how much the suspension would actually settle after driving around the block.

Currently, the shocks are physically as long as I can get in there, and I have gone for a spring that is one inch longer than it is supposed to be. In a straight line, the ride feels quite smooth so I know that the springs are working correctly. There is more than enough thread on the shocks to raise them up a bit, but I want to ensure that I do not compress the springs too much else they will start to stiffen up and become what is known as coil bound.




Rather than keep endlessly adjusting these, I am going to ignore any ride height settings and see if I can determine how much the shocks are moving up and down. If I can work that out, then I plan to adjust the springs to operate at the maximum ride height possible for the shocks, and not necessarily how I initially want them to perform on the car. It gets a bit complicated here but with the car under normal load, ie: People sat in it, the shock and spring will compress to a particular length which can be measured. I can simulate hard braking with a couple of people stood on the bonnet and when the wheel touches the arches, the spring length can be measured. With no load on the car and physically lifting the front up a bit, the spring length can also be measured. Get the idea? Trying to measure the springs also brings its own challenges, as getting in there with a tape measure is nigh on impossible, but a solution was found for just over a fiver on ebay with a huge 10" long "Wing Compass" that I could then use as a set of dividers by holding them against the springs, and then easily measure the distance with a tape afterwards.




The next few hours were spent measuring both the shock and spring length, writing it down, driving around the block, measuring, driving, standing on the bonnet, measuring, etc etc, and a pattern was not only emerging, but it seemed to be fairly consistent too. From what I thought was under load, to actually being under load was around a centimeter in difference. From being very light, to maximum load touching the arches, the shocks seemed to travel up and down by around 5cm and just below the midway point seemed to be where it sat under normal load. All seems good so far.

The spring did not appear to use the full length of the shock, and if the car was jacked up with the wheels off the ground, there was a clear 2.5cm of extra shock travel. So my thoughts are that if I wind the springs up by this amount, this will give me the maximum ride height possible without compromising how the springs are functioning. If I wind them up by any more then this will compress the springs when under load and I risk them being coil bound, and if I wind them any less, then the ride height will be lower with spring performance unaffected. At least that's the theory. This time around, I am going to set them to the maximum limit and then lower it instead of the other way around, because if I cannot get enough ride height doing this, then I am simply wasting my time with them.

The springs are adjusted up and down the threads using a special "C" spanner and you need to have the right sized spanner for the diameter of the shock else you end up with blooded knuckles from where it keeps slipping off. Actually in reality it makes no difference what size spanner you use as they all keep slipping off as you try to tighten them. I came across an adjustable C Spanner with nothing more than a pivot point on it, and I must say that it seems to function very well. If you ever have to adjust shocks, get yourself one of these for the toolbox.




Whilst on the subject of the spanners that slip when you are applying a lot of pressure to them, I must also mention the locking rings at the base of the springs. When that spanner slips, you will lose your knuckles and trying to get two spanners in there together means that you ought to consider having the Blood Transfusion Service on speed dial. As they are now rejecting my calls and I have lost so much skin trying to adjust these, I have decided to ditch the two locking rings in favour of a single ring with an allen key locknut which should make future adjustments easier and requiring only one spanner at a time.

With the shocks removed, the now uncompressed springs are carefully measured before taking them apart to fit the lower rings. I will now reduce this length by 2.5cm by winding the rings upwards so that when they are refitted fitted and load applied, they should compress back to the same length but I should also now have an extra inch of threads sticking out the bottom with a much higher ride height. Christ, This is quite hard work trying to get my head around this.




Its certainly much easier winding these springs up and checking the length with my Compass whilst they are removed from the Buggy.




With the correct height now reached, they can be easily locked in place with an allen key.




With the shocks refitted to the car, its very clear to see the difference in the amount of the exposed threads at the base of the shock. The ride height looks somewhat ridiculous as the front car really is pointing up towards the sky, no matter how many times I jump up and down on the bonnet. Still, the aim of this bit is purely to see if I can clear the wheel arches whilst keeping a smooth ride. I can always lower it a bit if this works. Time to find Lisa and take this for a drive.




Well that was an interesting trip around the block and I am certain that at one point she was trying to hold the steering wheel steady as well. Sure, the geometry is now all wrong and to say it handled like a Pig is a bit of an understatement, but then that was to be expected and thankfully there were no surprises there. The drive however, was really smooth and even with some seriously heavy braking, I could not get the front wheels to hit the arches at all. Brilliant, my measurement system had worked. But the most interesting bit was only discovered when I returned back to the garage, and it backs up what I said right at the beginning about how the suspension settles after a drive. I left the garage with the car pointing skywards, even after jumping up and down on the front, and after our return, the car appears to be sitting almost level. That had dropped by nearly two inches from driving around the block. With Lisa still on board, I measured the angle of the top suspension A-Arm, and was stunned to see it now at virtually horizontal and also measured my Tow Bar height, which was 30cm from the floor - exactly the same height as when I had made it all those years ago.

The car was now at its original height again - Time for a celebratory beer