12-14-2005, 12:36 PM
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Just curious Max, with the new wishbones and changed camber curve and additional castor do you expect to run lighter springs and/or less front bar or are you likely to use the different geometry above and beyond the suspension setting you have worked out thus far?
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12-14-2005, 02:34 PM
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 Quote:
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Originally Posted by Max Banks
Pete... yeh you would not be able to get a rose joint with a thick enough thread area on it with that design.
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It was for these two facts that we did the tubular kits. We also did not feel that it was a safe move to be selling modified standard wishbones... failures etc.... and wanted to do something of high engineering level!
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Again nothing wrong with the engineering of my suggestion if the block is made out of the right stuff (but I'd use an alloy for weight  ) ... but yep I do agree that your tubular kits are very nice.
I only did this sketch as genericwood (I think) was asking the question and it is such a simple solution, Not trying to compete. I used to be a design draughtsman (have a certificate in mechanical engineering and ~10 years in the industry, but now a computer geek) and thus think along these lines all the time. The thing that is nice about the little adapter blocks is NO welds to worry about and it would be dead simple to make ... ofcourse you do not get any caster improvements, etc. Also you would have to make up the taper adapter thingy to ...
I must admit if the rules allowed, I'd bin the standard suspension completely and start again with a clean sheet of paper. Making wishbones is not that hard ... been there and done that AND infact makes getting parts easier as you remove the 'Alfa Romeo' specificness of your car.
In conclusion YOUR wishbone kit has a lot more advantages (caster improvements, unsprung weight, spring kit adaption, probably strength and also no need to hack shell) and thus a good solution for those that like to buy bolt on solutions ... instead of welding machines and steel catalogues  .
Pete
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Last edited by PSk; 12-14-2005 at 02:42 PM.
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12-14-2005, 04:14 PM
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Max, I agree that your system is very nice, and no doubt very expensive to make. You earlier said it would cost about 995 when available. My assumption is that this value is in British Pounds, not US Dollars. If so, that is $1700 for those of us on this side of the pond. I'm sure you can't make and sell them for any less. But many of us look for less expensive (and less elegant) ways to achieve most of the benefit. That is why I have been exploring the various options for lowering the lower spindle ball joint position using the stock a-arms.
To tell you the truth, I'm not sure the vintage groups I run would approve of the ball joint mod, let alone the new a-arms!
Erik |
12-14-2005, 04:59 PM
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Erik,
Do you have to stick with Alfa Romeo uprights? ...
If you could find a more 'correct' upright then you could simply turn the lower ball joint upside down (or replace) and check that the tapers are the same and away you go.
Pete
ps: Many 60's F1 teams used Triumph Herald front uprights ...
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12-14-2005, 06:05 PM
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Raising lower ball joint
Ok, here is another idea. I'm not at home, so the following sketch is by memory, and I cannot check clearances. Instead of making a ball joint replacement using a heim joint, how about a machined spacer that bolts in place of the lower ball joint, and reattaches that same stock ball joint higher (and offset if wanted) ?
Of course, this would be just as racing illegal as knuckle risers or custom a-arms. And yes, it adds a little more weight to the already heavy stock a-arms. But it seems much easier and cheaper to fabricate and does not rely on a spherical bearing being used in the wrong direction.
Now, there might not be clearance inside the bottom of the spindle for some reason i am not visualizing. It also might be raising the ball joint too high . . .
Check out this quick sketch
(showing the ball joint offset for increased castor):
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Last edited by darth dino; 12-14-2005 at 06:09 PM.
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12-14-2005, 07:13 PM
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^^^
Yes, these do work. A friend of mine used to run them. They are rather cheap to machine. You also need a little pad to extend the upper limiting pad like you would when you run a knuckle riser to keep the suspension from dropping too much to avoid binding in the ball joint. The geometry is better than knuckle risers in that you essentially have a lowering spindle and thus you can run longer springs and therefore your roll center won't drop so much. The only thing is that you have to turn the lower wishbones upside down to correct for the changed angle - otherwise you will get some binding in one of the ball joints (upper outer if I remember correctly).
BTW, Robert that is the drawing you were asking for.
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12-15-2005, 01:53 AM
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Quote:
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Originally Posted by darth dino
Ok, here is another idea. I'm not at home, so the following sketch is by memory, and I cannot check clearances. Instead of making a ball joint replacement using a heim joint, how about a machined spacer that bolts in place of the lower ball joint, and reattaches that same stock ball joint higher (and offset if wanted) ?
Of course, this would be just as racing illegal as knuckle risers or custom a-arms. And yes, it adds a little more weight to the already heavy stock a-arms. But it seems much easier and cheaper to fabricate and does not rely on a spherical bearing being used in the wrong direction.
Now, there might not be clearance inside the bottom of the spindle for some reason i am not visualizing. It also might be raising the ball joint too high . . .
Check out this quick sketch
(showing the ball joint offset for increased castor):
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Thats what the alfa guys are running with in Japan but with thread rod ends for further camber adjustment... I'll check to see if I can post a picture.
davbert
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12-15-2005, 06:39 AM
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Yes the current exchange rate does make some of my bigger items a little scary in USD price!... i would dearly love the USD to become similar to £sterling....
Pete, I wasn't sure that you would be able to get a 3/4 UNF thread rose joint in that block of yours... maybe you can? Wouldn't want to use a thinner rose joint than that.
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12-15-2005, 12:56 PM
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hey guys!
Just found a couple of cheap second hand 105 sport springs.
The front ones are useless. By my calculations they have a spring rate inferior to the stock ones. They are 260 lb/in while the stock ones are 330lb/in...  And they call them "sport springs"!
The rear ones were interesting. They have a spring rate of 150lb/in and they have been already cut so the rear would be lower.
The calculations of Spring rate of the original springs are from the dimensions I got from an Alfa Info sheet. It didn't say how many active coils it has, I took a guess...
I'm going to fit the rear ones and see how it handles with the stock front setup. My guess is spectacular turn in with wild oversteer...
Here are the dimensions of the springs:
FRONT
wire diameter: 15.6 mm = 0.61"
Outer diameter: 136 mm = 5.35"
7 active coils
Length: 290 mm
Estimated Spring Rate: 260 lb/in
REAR
wire diameter: 12.5 mm = 0.49"
Outer diameter: 120 mm = 4.7"
7 active coils
Length: 350 mm
Estimated Spring Rate: 150 lb/in
Here are the photos of the springs and my ride height with the original ones. Tomorrow I'll have new photos with the new rear springs fitted...
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1969 Alfa Romeo GT 1300 Junior
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1976 Porsche 924
1991 Mazda Miata MX5
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12-15-2005, 02:27 PM
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Quote:
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Originally Posted by Max Banks
Pete, I wasn't sure that you would be able to get a 3/4 UNF thread rose joint in that block of yours... maybe you can? Wouldn't want to use a thinner rose joint than that.
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darth dino,
How does that alter the position of the ball joint? All that (brilliant sketch ... wish I had a scanner at work so I could do proper sketches too) does is alter the wishbone position in relation to the ball joint. Do they do this to lower the car or something?
Max's idea actually LOWERS the outer balljoint NOT raises it. Thus I think your sketch is what you would do to the UPPER ball joint not the lower one (and again that does not raise the ball joint. Thus I think they do this in conjunction to using a knuckle riser and so that the wishbone angle ends up being in the same position [thus standard bump stops still work] as standard).
Anyway it is great to see all these ideas flowing
Pete
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12-15-2005, 04:10 PM
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Quote:
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Originally Posted by PSk
Agree.
darth dino,
How does that alter the position of the ball joint? All that (brilliant sketch ... wish I had a scanner at work so I could do proper sketches too) does is alter the wishbone position in relation to the ball joint. Do they do this to lower the car or something?
Max's idea actually LOWERS the outer balljoint NOT raises it. Thus I think your sketch is what you would do to the UPPER ball joint not the lower one (and again that does not raise the ball joint. Thus I think they do this in conjunction to using a knuckle riser and so that the wishbone angle ends up being in the same position [thus standard bump stops still work] as standard).
Anyway it is great to see all these ideas flowing
Pete |
Given that I have some experience with the mod depicted in the sketch (I have driven a car with it and actually have a set of those pieces somewhere in my garage) here it goes.
The above modification moves the lower ball joint upward by means of a spacer, thereby moving the spindle upward. Max's solution picks up the spindle from a lower point and thus moves it upward as well. Both Max's and the above modification achieve the same thing in that they raise the axle height and thus lower the car, thereby decreasing the need to shorten springs to lower the car.Further, they both increase the effective spindle height, Max by using a rose joint to pick up the spindle from below, the modification above by adding a spacer between lower wishbone and lower ball joint. The advantage compared to a standard knuckle riser is that in order to lower the car with a knuckle riser you need to reduce spring height more and thus you will lower the roll centre more.
Compared to Jack Beck's solution which uses standard spindle height but with the axle in a different position to lower the car and reduce roll center change, Max's and the above solution change the camber curve so that you have much more negative camber gain when the spring is compressed. This will allow running the same negative camber with more body lean and spring compression, whereas Jack's solution relies on a heavier spring to avoid body lean and ensure appropriate suspension geometry.
Also, you cannot use the above modification with a knuckle riser as the effective spindle height will get too tall and the upper ball joint will run at too much of an angle and will bind. However, because the standard spindle length is increased you have to run an upper bump stop extender, just as you would with a knuckle riser. Where this modification loses out in comparison to Max's wishbone is added rather than decreased weight and the lack of increased caster.
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12-15-2005, 04:28 PM
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Quote:
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Originally Posted by PSk
Max's idea actually LOWERS the outer balljoint NOT raises it.
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First, As most of you probably already know, increasing the castor increases the camber gain as the wheels are steered - good for a race car, but adds to the steering effort, so is bad for a street car without power steering. It seems common practice to dial in more castor using the stock adjusment for racing, but some want more than this adjustment seems to allow. Moving the lower ball joint fore/aft should add/subtract to the stock adjustment capability ?
Second, on Max's a-arm, he is attaching the lower spherical bearing to the bottom of the upright. This raises the spindle along and the entire upright. This does two things. The new spindle height lowers the car by raising the wheel without using shorter springs and the higher upright changes the geometry of the upper control arm without changing the geometry of the lower a-arm (of course, i am sure Max is changing the lower geometry some too). This raises the roll center and increases the camber gain as the suspension compresses while cornering.
My sketch shows an idea to use the stock ball joint and a-arm to accomplish this. The stock ball joint faces down and attaches inside the upright while Max's setup uses a spherical bearing that sticks straight out of the a-arm and attaches to the bottom of the upright - so you can't compare the absolute position of the ball joint vs. the spherical bearing. They mount different. My insert sketch ( well, I guess others thought of it first ) raises the ball joint above the a-arm to therefore raise the relative position of the upright, and can move the ball joint fore/aft - accomplishing, theoretically, similar geometry changes as Max is doing with his a-arms. Of course Max has much experience to justify the exact geometry positions he uses.
I do not have these inserts on my car, so i cannot comment on how well they might work. My mind was just wandering from inspiration of this thread.
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12-15-2005, 06:40 PM
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Darth Dino and Alleggerita,
I will respond by answering or discussing some of the points you guys have made .
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Originally Posted by darth dino
Pete, It seems to me that what Max's trick a-arms are doing is to raise the front spindle AND increase the castor.
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First, As most of you probably already know, increasing the castor increases the camber gain as the wheels are steered - good for a race car, but adds to the steering effort, so is bad for a street car without power steering. It seems common practice to dial in more castor using the stock adjusment for racing, but some want more than this adjustment seems to allow. Moving the lower ball joint fore/aft should add/subtract to the stock adjustment capability ?
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Agree.
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Second, on Max's a-arm, he is attaching the lower spherical bearing to the bottom of the upright. This raises the spindle along and the entire upright. This does two things. The new spindle height lowers the car by raising the wheel without using shorter springs and the higher upright changes the geometry of the upper control arm without changing the geometry of the lower a-arm (of course, i am sure Max is changing the lower geometry some too). This raises the roll center and increases the camber gain as the suspension compresses while cornering.
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Okay IMO you are right but have this backwards . The wheel does not get raised, instead the car shell is lowered because he has increased the angle (slightly it has to be added) of the lower wishbone. But Max has changed springs, and spring location poi | |
