1964 Beetle.

[knk]

I'm not as clued in as you guys are to the intricacies of suspension setup but is that ^^^ not only true if the upper and lower arms are the same length? Colm's setup above has much shorter arms on the top which will swing in a much tighter arc giving mucho camber gain when compressed...

As I said harder to explain in writing!

When I say shorter I mean the change in length of the horizontal distance from the pivot point to the ball-joint point. Draw two vertical lines, 1) through the pivot point of the A arm & 2) through the centre of the ball joint. Now draw a circle from the centre of the A arm pivot point to the centre of the ball-joint. This is the path the ball-joint travels as the suspension goes up and down.

Now imagine if the top A arm is level. Any movement up or down will shorten/reduce the distance between the two imaginary vertical lines. This setup would be fine if the chassis/body did not roll/twist but as we know it does. By having the upper A arm slightly pointing upwards and the correct camber setup, when the body rolls the distance between the vertical lines moves back towards it's max distance and in effect helps reduce the change in camber from that original set.

Don't forget as the body rolls the top and bottom pivot points of the A arms move in opposite directions which drastically changes the camber.

Best setup is Unequal Length & Unparalleled A arms.

 

[trev]

Don't forget as the body rolls the top and bottom pivot points of the A arms move in opposite directions which drastically changes the camber.

that's the essence of it there I suppose.

F1 cars appear to have pretty horizontal A-arms I suppose because the body rolls so little...

 

[whatucolm]

thanks for all the advise there knk-haven't got me head around all of that yet.
i know it doesn't really look like it in the photos there,but those wishbones are not parallel-theres more of an angle there than you might think.
i will try and get some pics from straight on,when it in the car next week.
appriciate the advise..

 

[whatucolm]

ha,ha! it was auctually done over 3/4 years.i'm big into armchairs too!
i'd be happy to try and help you if i can,but i,m no expert.i cant remember exactly where i got most of the info-but theres endless amounts sites there with info for free.

 

[whatucolm]

You are dead right, ignore the Roll Centre to some extent as it will not be your main concern for the Beetle set-up. To be honest my suggestion was more geared towards maintaining the correct camber more so than bump steer. If you are getting 0.2m difference throughout the full travel of the shock then you are fine. I use those Pro-tec shocks on everything for the last few years and they are great shocks. I would imagine the travel will be no more than 30mm in either direction when in use.

The reason behind having the top 'A' Arm pointing slightly upwards rather than level is that you want the length of the 'A' arm to be slightly shorter when not under load as this helps maintain the correct negative camber throughout the travel arc of the Arm. Changing the shocks to longer or shorter ones will have no effect on the path which the 'A' Arms travel through. Have you accounted for Body Roll? I mean lift the Jig up on one side by 3 or 4 inches and then measure camber/bump steer change throughout the travel of the suspension?

It's a hard thing to explain in writing...much easy to show in person!

i got some better pics yesterday.i think you can see here the top A arm is pointing slightly upwards,while the bottom one is pretty much horizontal..

in this picture the shock top mount is in the middle position of three settings,height-wise,each 25mm apart.the coil-over is adjusted up to the last height-wise.i think with a full tank of petrol,or over bumps,the bottom wishbone will be angled up more than i want,and the car too low.if i fit a longer shock and spring it will push the bottom wishbone down,raising the car to a more suitable heigth,i think.i made a mistake in ordering 11"shocks,instead of 12/13",and the springs way too short,i think.i would prefer to use the top setting for the shock top mount,and a longer shock,as this should give me more available suspension travel,if i'm not mistaken.

 

[whatucolm]

i think i see what you mean about the body roll now,after reading that again(and again).is it anything i need to worry about tho? as the dimensions i used are almost exactly what most of the Locosts use,and i dont think they have any problems in that regard?wont the in-built camber gain take care of that as the body rolls?the only changes i have made are that the wishbones are slightly further apart,and i moved the heigth between the pivots by the same percentage.i have the exact dimensions written down somewhere,but it was only a slight difference.the only other difference is that the VW hubs are moved slightly inwards on the spindles.also i thought the bump steer was pretty much set by the lenght of the tie-rods,and the height of the rack/rod-ends?-i cant see how this would change with body-roll?i planning on having the car set-up fairly stiff,esp at the rear,so i'm hoping there wont be much body roll.

 

[whatucolm]

this is how it sits with the shock mounted in the top position and full negative camber.it can still go a lot lower by adjusting the coil-over.

and this is how it looks in the middle position-i preferr it around this height;

 

[whatucolm]

this is where the subframe bolts to the floor,at the back;

 

[whatucolm]

this is the jig i was using.some bits of it are dumped at this stage.the two big bolts at the front bolt through the origional VW beam holes.it drew out the dimensions on the white surface,and it was relatively easy to keep an eye on things.the dimensions are pretty much rubbed out now.

 

[whatucolm]

Seanie was working on the loom on New Years Eve! flippin ledgend! cheers Seanie!

 

[whatucolm]

the origional tank still fits,with only a very minor mod to the bottom of it.i cut out part of the support under the tank,as it was a bit of a pain,taking in and out the subframe with it there.i will replace that soon hopefully.

 

[whatucolm]

Bowen Engineering in Athlone made up these front brake caliper brackets for me,to join the CSP kit calipers,to the Cortina spindles.the brakes all round could do with upgrading really,but these will have to do for now.

they also made the square section here,with the hole bored in it,to clamp the steering rack.the steering rack needed slight modification to work with these clamps.

 

[Guest]

this is where the subframe bolts to the floor,at the back;

does the brake master cylinder still fit or are you using custom pedals ?

 

[whatucolm]

ya,it still fits Barry.i'll get a picture of it next i'm out there.i am thinking of changing to a pedal-box inside the car at some stage tho-would love to have the bias adjustable between the back and front-tho should problly get disks on the back first!

 

[whatucolm]

i got this camber compensator bar for the back too.i dont want to fit it yet tho.-i want to try it without first,so i can tell what difference it makes.it bolts up under the gearbox,and pushes up on the axels.

 

[whatucolm]

the master cylinder just about fits in there.its not bolted in,in the picture.

 

[whatucolm]

i got some of the steering column done today.i had the top half of the Beetle column,bottom half of a mk2 escort,a couple of knuckles from Capris,the origional steering shaft cover thing? from the Beetle,and a new bearing,pressed into a collar made by Bowen engineering.

the escort shaft was turned down to fit inside the Beetle one,and welded up.

the bearing and collar press into the cover thingy,and i put a couple of spot welds on too.

and they fit together like this;

 

[whatucolm]

and then back in the car..

still have a good bit to do to mount the whole column solidly in the car..

 

[knk]

Colm this looks good, although I would still probably move to the lower mounting hole on the upper 'A' arm and extend the upper tie-rod out to reset the camber. Couple of reasons. The locost only weights about 450kg and will have less body roll than the heavier beetle. Having the arm more upwards will ensure that you will never get any positive camber when cornering hard. The good thing is that you can drive it like this then try it the other way to gauge the difference. As I said before the shock plays no real part in how camber changes when the 'A' arms move up and down. What I would do is put a jack under the front of the car, take off the two shocks and then jack the car to the ride height you prefer. Then measure the distance between the two mounting holes and order the correct length shock/spring set-up based on this dimension. You will also need to watch what Poundage is on the spring. I would go for something around 180lbs to start with, or even 200lbs. Really it's trial and error, but the more important thing is the shock itself, ie overall length and maximum travel.

The other thing which I can't quite make out from the photos you posted is the actual position of the ends of the Steering Rack? The position and width of the rack is very important to limit Bump steer. You are very limited to the actual positioning of the rack due to the tunnel and frame head of the chassis. One of the most important things is that the ends of the rack (when steering is centred) fall somewhere on a virtual line draw between the pivot points of both 'A' arms. Not sure if you can make out my quick drawing below?

Something else you should consider doing is adding another cross tube to the lower 'A' arm as shown below. The lower 'A' arm takes 99% of the abuse and adding this additional bar will spread the load between the two mounting points better.

Overall...cracking job considering how tight for space it is in that area. Some small fine tuning will have you setting some nice lap times at Mondello next year!

 

[Guest]

.cracking job considering how tight for space it is in that area and some small fine tuning will have setting some nice lap times at Mondello next year!

can we have a calender sent out to john please ?