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Discussion Starter #1
I've fitted shorter and stiffer springs to my '74 GTV, and it sits about 2" lower all around.
I have yet to drive it, since I've got the fuel injection apart, converting to EFI.
But I can see already (and others have confirmed) that the front roll center has gone to hell (er... below the ground, anyway) by lowering the front so much.

After some head scratching, and wondering how all racing GTVs can get away with riding so low on the stock suspension pieces, I've figured out a rather simple way to restore the front roll center and bump-steer geometry.

Since it seems so simple, I'm wondering why nobody seems to have done this before. Here's my idea:

The front lower ball joints simply bolt to the lower a-arm. Why not fabricate a bolt-on spacer block that bolts to the original ball-joint holes in the a-arm and lifts the ball joint aprox. 1" up? In one bolt-on operation, the lower a-arm angle is returned to stock, the roll center is restored, and shock-length and bump steer geometry are returned to original. As a bonus, the upper control arm angle would be tilted up more for a given ride height, introducing greater negative camber gain (a good thing). AND, if the spacer were made slightly offset forward, you could introduce a significant amount of positive caster without the current limitations of the upper arm hitting the chassis.

So... has anyone done something like this? Why haven't I seen it on any race cars?

The Alfaholics tubular front a-arms seem to include all the above geometry changes, including the forward offset for greater positive caster, but at a massive price (and rod-ends are a bad idea for street cars, anyway).

Any ideas why this lower ball-joint spacer couldn't be done? Any similar experiences?

George

George
 

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Ah George, if only it was so simple, then everyone would be doing it !

if you look closely, you will notice that the lower ball joint mounts upside down ON TOP of the lower upright recepticle. it is designed that way so the nut is not taking the suspension load, but the ball joint itself is. you cant just turn it over . . . ball joints have a tapered shaft.

these are the common solutions :

1. bolt on a knuckle riser to the top of the spindle.
this helps raise the roll center, but not the lower a-arm geometry
improves camber gain on compression.

2. install drop spindles.
cut up 2 uprights to weld back together as one that is taller.
fixes lower a-arm geometry.
increases camber gain
difficult to fabricate

3. replace lower ball joint with a spherical bearing (closest to your suggestion)
thread said bearing into a block bolted in place of ball joint
mount said bearing UNDER upright
drill out taper in upright, and run a standard bolt through
same results as drop spindle
can alter design of mounting block for increased caster

any of these modifications might require bump-steer adjustments.

do you race, or is this a hot-rod street car ? if its just a street car, i wouldn't worry too much about it.


there has already been a lot of discussion about this. do a search for "roll-center" and "british vs yankee spring rates" or something like that
 

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Discussion Starter #3
Thanks for the reply. Yes, I've found quite a bit of info by snooping around the various BB threads, especially about the upper arm spacers.

My '74 GTV is just a street car, and my goals for it are merely to look cool (therefore lowered like a race car), sound cool (small diameter exhaust gives a nice fruity rasp, not worried about HP), and be entertaining/tossable to drive (easy to pitch and hold sideways).

I've had other lowered cars, though, that exhibited unpredictable and alarming bump steer at the front, and various leaf-sprung and sub-optimal panhard bar rear ends that bump steered as well. I'd like to avoid this if at all possible.

Your option #3 sounds like the geometry solution I want... but I've had bad experiences with spherical bearings/rod ends on street cars (noisy) and race cars (frequent replacement).

First of all, is this lower block available as a "kit" from anyone? Any pictures, or rough dimensions?

I think I can mimic that solution by fabricating a similar block, but one that has "ears" that hold the original ball joint with its two through bolts. The lower ball joint remains in its original location on the upright (inserted from the top), but with the spacer block underneath it, essentially pushes the lower a-arm down (same geometry effect as a taller upright).

I might have to mock this up with some scraps and take a picture.
 

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there are A LOT of people with lowered Spiders and GTVs on the street and few complaints about excessive bump steer. to compensate for the geometry change, an adjustable upper a-arm will allow you to tune the camber how you want.

keep in mind that changing the spindle height will also affect the bump steer. unless you really just want some "cool" project, i would suggest to try what you have before concluding you need to fix it. there used to be sketches and pictures of the lower spherical bearing mod on the "british vs. yankees" thread. i wouldn't worry too much about this mod being too harsh : ball joints are just spherical bearings with a tapered stud incorporated ! for a street car, i would use a rubber boot over the spherical bearing for protection against debris. also, because of the orientation of the bearing, using a safety washer would be prudent.
 

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Don't know how far you want to lower, but my old GTV (pic below) raced with horizontal LCAs for years (and looked pretty racy doin' it too) before we finally got round to fitting a knuckle riser to the top arm and dropped the LCAs a bit more, from which we gained some grip at the expense of a little bit of bump steer - no big problem on the race track, but a bit spooky on a bumpy road at speed.

For a road car, I'd stick with a bit more height (given the proximity of the sump to the ground) and also have good steering.

I actually think the limit for lowering a road car is the rear suspension. You want the rear to be 10mm or so lower than the front. Unless you are into lots of oversteer, you can't fit much more than about 200 pound springs (well, in my exp anyway).

With that rate on a bumpy road you need some travel or you will beat the hell out of the bump stops and we all know how robust the rear end of a 105 isn't...
 

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Gattia86, the options listed by Darth are very good. What you describe in your message WILL NOT affect the roll center. It isn't the angle of the lower a-arm that matters. It is the angle of a line drawn from the center of the inner a-arm bushing to the center of the lower ball joint. In other words, you need to change the position of the ball joint at the upright to impact the roll center. As Darth said, you can do that in several ways. Jack Beck sells a cut and rewelded upright that lowers the position of the ball joint by about 1" without changing the overall length of the upright. They aren't cheap, but then again, this is not a part you want to fail at speed! A lot of the seriously lowered race cars use Jack's uprights. But even with them, the roll center is often still below ground. The roll center on my race GTV is about an inch below ground.

Hope that helps!

Erik



First of all, is this lower block available as a "kit" from anyone? Any pictures, or rough dimensions?

I think I can mimic that solution by fabricating a similar block, but one that has "ears" that hold the original ball joint with its two through bolts. The lower ball joint remains in its original location on the upright (inserted from the top), but with the spacer block underneath it, essentially pushes the lower a-arm down (same geometry effect as a taller upright).

I might have to mock this up with some scraps and take a picture.
 

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Discussion Starter #7
Thanks, Erik, for the clarification.

My simple solution also would've changed the front spring preload, which would require adjustable seats or shims.

I suspected there was something simple I was overlooking, and you named it; changing the lower a-arm angle won't change the pivot point of the ball joint if I don't move it relative to the upright. D'oh.

Darth's #3 suggestion sounds more appealing now (replacing lower ball joint with a rod-end mounted on the other side). But will this give me enough angular travel? Will the suspension travel be limited?

Well, this is my first Alfa, and I haven't driven it with the lowered suspension yet (still a month or two away from running). I really should try it first, and see if it's acceptable.

It just bugs me seeing the angle of the lower arms now, and knowing how my other lowered cars had spooky, un-predictable handling under certain conditions (dramatic bump steer if upset during fast, steady-state cornering, eg: freeway on-ramps).

Thanks for the input so far.
 

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Gattia, just drive it first. I'm guessing you will be satisfied. If not, remember that moving the roll center and fixing bump steer are two different things. A lot of people will fix bump steer issues but are perfectly happy to have the roll center well below ground.

Erik
 

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Erik,

I have a set of those contraptions that Gattia describes and I got it from an old racer a few decades ago. I have had this argument with a friend of mine who is an engineer and I may be off.I think you are partly right with regard to your explanation, eg. it is the angle of the lower A-arm that matters using centers of ball jount and inner bushing.

However, by adding the block at the bottom, you still lengthen the height of the spindle which will affect the angle of the upper arm that will change the camber control curve and I believe that will also affect rollcenter height, eg. increase it.

The advantage of these blocks is that they supposedly do not affect bumpsteer the same way knuckle risers do. I did mount them on one of my cars but took them off again, as I didn't feel good about the upper outer ball joint being brought to its limit of movement and I didn't feel like dicking around with limiting suspension travel at the time.

Curious about your thoughts on this.

Gattia86, the options listed by Darth are very good. What you describe in your message WILL NOT affect the roll center. It isn't the angle of the lower a-arm that matters. It is the angle of a line drawn from the center of the inner a-arm bushing to the center of the lower ball joint. In other words, you need to change the position of the ball joint at the upright to impact the roll center. As Darth said, you can do that in several ways. Jack Beck sells a cut and rewelded upright that lowers the position of the ball joint by about 1" without changing the overall length of the upright. They aren't cheap, but then again, this is not a part you want to fail at speed! A lot of the seriously lowered race cars use Jack's uprights. But even with them, the roll center is often still below ground. The roll center on my race GTV is about an inch below ground.

Hope that helps!

Erik
 

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Discussion Starter #10
The idea of lower ball-joint roll-center correction spacers being possible on my GTV occurred to me after seeing a similar installation being done on an AE86 Corolla in a recent magazine. I've seen similar bolt-on spacer solutions for Ford Mustangs, too.

It's a good idea if it's as simple as a spacer block to re-orient the stock components, and it works on the Corolla and similar cars because the ball joint (and pivot point for plotting roll centers) stays on the a-arm, and the spacer gets bolted between the ball joint and the strut. Bump steer is not affected.

As confirmed by others and finally realized by myself, such a simple idea won't work on the GTV, since the ball joint (and pivot point) stay with the upright and aren't lowered. Dang.

I'm reluctant to get rid of the ball joints (excellent, sturdy design with lots of travel) and replace them with rod-ends (limited travel, limited strength when mounted in "single shear" like a ball joint would be). Plus, I've had to replace countless rod-ends on various race cars, sometimes after a single curb hit.

However, since my car (and most race GTVs) are lowered about 2" anyway, they're already using 2" less suspension travel... so, with taller front droop limiters (or shorter shocks, or dropped lower shock mounts), you could remove 2" of travel from the suspension, and possibly put all the pivot points within their angular limits.

As far as top "knuckle risers" maxing out the available angle of the top ball joint... if you shorten the upper control arm or "kick out" the lower ball joint (assuming you've got the rod-end ajustable lowers), to tip the upright inboard a bit more, you may bring the upper ball joint back into its middle range of movement. Again, this would only work with limited droop travel, and yes, I know that lots of droop travel is desirable to keep the inside wheel on the ground, but...

As long as my car's up on jack stands, waiting for the injection system, I may pull the springs out and fiddle with the suspension movement and geometry, to see what the limiting factors are. This, of course, is the danger of having the car off the road for too long and lots of tools in the garage: too many ideas pop into my head.

George
 

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Discussion Starter #11
Angular limits of ball joints & rod ends

The idea of lower ball-joint roll-center correction spacers being possible on my GTV occurred to me after seeing a similar installation being done on an AE86 Corolla in a recent magazine. I've seen similar bolt-on spacer solutions for Ford Mustangs, too.

It's a good idea if it's as simple as a spacer block to re-orient the stock components, and it works on the Corolla and similar cars because the ball joint (and pivot point for plotting roll centers) stays on the a-arm, and the spacer gets bolted between the ball joint and the strut. Bump steer is not affected.

As confirmed by others and finally realized by myself, such a simple idea won't work on the GTV, since the ball joint (and pivot point) stay with the upright and aren't lowered. Dang.

I'm reluctant to get rid of the ball joints (excellent, sturdy design with lots of travel) and replace them with rod-ends (limited travel, limited strength when mounted in "single shear" like a ball joint would be). Plus, I've had to replace countless rod-ends on various race cars, sometimes after a single curb hit.

However, since my car (and most race GTVs) are lowered about 2" anyway, they're already using 2" less suspension travel... so, with taller front droop limiters (or shorter shocks, or dropped lower shock mounts), you could remove 2" of travel from the suspension, and possibly put all the pivot points within their angular limits.

As far as top "knuckle risers" maxing out the available angle of the top ball joint... if you shorten the upper control arm or "kick out" the lower ball joint (assuming you've got the rod-end ajustable lowers), to tip the upright inboard a bit more, you may bring the upper ball joint back into its middle range of movement. Again, this would only work with limited droop travel, and yes, I know that lots of droop travel is desirable to keep the inside wheel on the ground, but...

As long as my car's up on jack stands, waiting for the injection system, I may pull the springs out and fiddle with the suspension movement and geometry, to see what the limiting factors are. This, of course, is the danger of having the car off the road for too long and lots of tools in the garage: too many ideas pop into my head.

George
 
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front roll center

I am in the process of installing spherical bearings in place of ball joints. Fabricating the mount for the spherical wasn't that difficult.Figuring how to join caster/camber arms proved a challenge but solved. The biggest issue is ride height. Lower control arm has to be perfectly horizontal for proper geometry.Camber arm is nearly parralel but hard to measure.Also by raising roll center, spring/sway bar rates need to be less due to shorter moment arm.[roll & c.g. closer] Also bump steer will need to be addressed.Then front/rear balance.Many,many variables.I hope to test &tune at Sept. vintage race. If all goes well I may build a kit.
 

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Remember that the upright modifications by Beck (and others) will give you a fool proof way to lower the car 1" without changing the geometry. For most street cars, you could use them to lower a car as much as you dare without going subterranean with the roll center. For a race car, I have looked at lots of options for relocating the lower and upper ball joint positions. For the lower, I would think that the best option is the rod end placed under the stock upright. I think I measured that this would lower the lower ball joint relative to the ground about 2 1/4 inches. That would lower the car 2 1/4 inches from stock without affecting the angle of the lower a-arm. Without subsequent changes to the upper arm, this will also lengthen the upright by 2 1/4 inches, dramatically increasing camber gain in bump and actually increasing the height of the roll center. If you consider these mods, do not, I repeat DO NOT do it without putting everything into some good suspension software to make good calcuations. You can easily get significant left/right movement of the roll center which will make handling unpredictable at best. For the upper a-arm, I have played around with the idea of replacing the upper ball joint with a spherical bearing. You can knock the ball joint out of the upper arm and machine the remaining bore to take a spherical bearing receiver (available from some of the off-road race shops) and a high-misalignment bearing. Then you can put the upper pivot anywhere you want it (above the upright).

Ultimately, I didn't pursue any of the above solutions simply because the car performs very well with the roll center an inch below the ground. I run the Beck drop spindles, but otherwise stock geometry, with stock car springs (1200 pounds) that give the ride height I want. Bump steer is corrected by using rod ends in place of the outer tie rods. I suppose I could use lighter springs if I put the roll center back above ground. But for smooth surfaces like most race tracks, the stiff springs are just fine. Maybe more worthwhile for a street car?

Hope my experiences help, Gattia. But if I'm not being clear, PM me to discuss.

Erik
 

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I've done the spherical bearing thing in place of the lower ball joint as well as extensions and replacement tie rods with spherical bearings to dial out bump steer. (With the extra weight of the Montreal up front I was reluctant to have the upright cut and re-welded) I must say that this change made a big improvement to the car with better turn-in and grip through the corners. But then again the Montreal is heavier up front than a 105 so perhaps the improvements to handling from raising the roll centre becomes even apparent.

Dialing out the bump steer is probably more of a comfort thing, but I feel it does make it easier so you can get on the throttle on corner exit if you have a habit of hitting the ripple strips on the the apex. (The bump steer kit I user was the Alfaholics one and I can recommend it as a hassle free bolt on kit.)

I'll post some pictures later tonight (when I get home) of the modification I did to replace the lower ball joint.

Phil.
 

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Discussion Starter #15
Erik,

Thanks for your continued input.
I think I have a pretty good understanding of the modifications and geometry changes you describe. I'm looking forward to the pictures from Phil, but I have a pretty good idea of what it'll look like.

Looking inside my stock 14" wheels, there doesn't seem to be much room for a rod end, washer and bolt head before things touch the inside of the rim.

Your advice to "just drive it" first is probably what I'll end up doing... but I do like fiddling with things, especially when the car is up on jack stands anyway.

George
 

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Erik,Looking inside my stock 14" wheels, there doesn't seem to be much room for a rod end, washer and bolt head before things touch the inside of the rim.
George
George, when I was looking into it, I had a 14" wheel (Melber Major) with a 1/2" spacer mounted to an upright to check clearances. It was tight, but doable with the spacer. I have to run the spacers anyway, since the Beck uprights I've mentioned before put the ball joint stud right into the wheel rim. I've had to file down the stud and run the spacer to get clearance.

Sorry if I'm wasting bandwidth by continuing to add to the thread. But this is an area of car development in which I'm really interested!

Erik
 

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Here are a few pictures... sorry about the poor quality. (Perhaps I shouldn't have been so lazy and removed the wheeel)

And yes there is very little clearance and I'm running 15" wheels. I had some sleaves made up take up the tapper of the ball joint just in case I wan't to reverse the setup.

Let me know if you would like any other pictures, and this time I'll remove the wheel and take the pictures durning the day.

Phil.
 

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Discussion Starter #18
Phil,
Thanks for the pictures. They are exactly the detail I wanted to see. The photo with the wheel on is informative too, regarding the limited distance to the rim.

I can build something like this without too much trouble.

A couple of questions, though:

How much total wheel travel do you have? Are there any range-of-motion problems with the rod-end?
What size rod-end is it? I suppose if I drill out the hole in the upright, I could use a 5/8" or 3/4" rod end.
How is the top of your coil-over damper mounted? A hole through the top of the original spring pocket, or a clevis bolted/welded to the original spring pocket?

I'm also curious about your brake rotors. I see the bracket for the caliper. Are you using larger rotors, or just different calipers? I'd love to find a larger, vented production rotor that'll fit the spindle.

Thanks,
George
 

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Discussion Starter #19
Coilover mounting

Oh... I see from the pics that the lower mount is the original shock mount location.
And the stock spring perches are cut off?

How is the top mount made? Welded on bracket? There's not enough space between the inner fender and the stock top shock mount for a 2 1/4" spring/damper, is there?

And what happened to the droop limiting rubber? Does the shock serve this purpose now?

George
 

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I'd love to find a larger, vented production rotor that'll fit the spindle.
sounds like someone is falling down the slippery slope ;)

FWIW, the stock brakes work VERY well, and can be made to be excellent with just properly working calipers and state-of-the-art pads from Carbotec or Porterfield. remember, these cars are light by todays standards, and have generous sized 4-wheel discs standard.

if you've convinced yourself that you need vented discs, there are upgrade kits available from suppliers like Performatek. Many on this forum have installed various big brake "upgrades". maybe someone will speak up here, or you can always do a BB search.
 
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