ALFAGTV6.COM

[Echo Leader]

Hey everyone,

First post here on alfagtv6.com, but half of you have probably seen me learning about Alfa's over on the BB.

Well, I've been reading quite a bit about suspension setups and trying to figure out what approach I want to take when I begin modifying my car. It seems that the GTV6 has quite a lot of potential but the subject of this tread is the main thing I'm having trouble resolving.

It seems fairly obvious that the front of the GTV6 has some roll center issues as it goes quite subterranean when the nose is lowered, and in response it seems there are two main ways of attempt to maximize GTV6 suspension performance:

1.) Stiffen the front spring rates and anti-roll bars until the car has virtually no roll anyway, thus eliminating the issue via brute force.

2.) Using a crafty trick ('drop spindle', knuckle raiser', 'inverted ball joints') to lessen the inherent limitations of the geometry.

I somehow feel like option 2 is a bit more....'holistic' an approach, if that makes any sense. But I don't really know if such an approach is needed on a car that is basically not going to be a full fledged racing car, but will be used as a fun autox toy. I feel like if I'm going to keep the front of the car as low as it is (4.5 inches of ground clearance), that it's the right thing to do but, should I bother? And if I should, what method is best employed to correct the geometry?

I get the general impression that by 'fixing' the RC, by raising it after the car is lowered, that the same performance can be generated while utilizing lower spring rates and thinner anti-roll bars, but I've yet to see hard numbers concerning this thought.

So what are the thoughts? Are these modifications a good 'first step' in getting a lowered GTV6 to handle? Are products available and documented? Who can provide insight from personal experience?

Thanks!

[Maurizio]

Ok I give a start.

First don't lower the car too much. Lower A arms with driver in the car horizontal/outside pointing a bit down.
Next for a transaxle the biggest bang for the buck is a huge front anti roll (AR) bar. But the nose of a gtv is not as good constructed as a 75/milano.
If you use the thickest AR bars around ~30mm (my own design is even 32mm) without strengthening, you could rip out the mounting points with a car that is driven a lot in anger.

Add a nice set of shocks (bilstein!)
Some more aggressive alignment and poly bushing in the suspension and you start running on rails

Then it starts to become expensive, stiffer springs (front & rear) with adequate shocks or better a coil over set, geometry changes (RC) on the front/back. Sticker tires and lot more horsepower to match the ride. Loose all unneeded weight/add bucket seat and roll cage/shift from poly to uniball and before you realize it you are building a track dedicated car

Saluti,

M

[Echo Leader]

Ok I give a start.

First don't lower the car too much. Lower A arms with driver in the car horizontal/outside pointing a bit down.
Next for a transaxle the biggest bang for the buck is a huge front anti roll (AR) bar. But the nose of a gtv is not as good constructed as a 75/milano.
If you use the thickest AR bars around ~30mm (my own design is even 32mm) without strengthening, you could rip out the mounting points with a car that is driven a lot in anger.

Add a nice set of shocks (bilstein!)
Some more aggressive alignment and poly bushing in the suspension and you start running on rails

Then it starts to become expensive, stiffer springs (front & rear) with adequate shocks or better a coil over set, geometry changes (RC) on the front/back. Sticker tires and lot more horsepower to match the ride. Loose all unneeded weight/add bucket seat and roll cage/shift from poly to uniball and before you realize it you are building a track dedicated car

Saluti,

M

Good start! and thanks for the reply

Judging from your description of the lower control arms, I think I'm a bit too low as she sits today. Part of my thinking was that the lowering 'too much' is only bad when the geometry gets mucked up (RC too low and lower control arms pointed "up"). So if this could be counter-acted while keeping the car low, wouldn't that be optimal?

I would think that fixing the geometry, via a drop spindle or other device, would also make it so the huge front anti roll bar would be less of a necessity? Or is the enormity good no matter what? In any case, yes I'll be sure to reinforce the chassis mount points if I go with a bigger bar. Just for safety, I might do it regardless.

Bilstein all the way! I replaced the dead Spicas that were on the car and whoa better in every way. I'm a believer, just wish I had seen Mats' post with the part numbers for the slightly shorter variants...

I can see how this would quickly escalate into building a track car. With each improvement a new area to focus on becomes apparent.

[Maurizio]

I forgot an important low budget change, the 2nd bang for the buck:
the 105 castor ball joint conversion. Much better turn in and alignment stability.

True drop spindles will slightly lower the need of more stiffness in the front. But still you need much more stiffness in the front. The fast & cheap way an big ar bar. Suspension design is from the early 70's the tires were bad back then and road even worse. You don't need that much comfort anymore

[Echo Leader]

Interesting that you mention the 105 castor bar ball joints, I was thinking that those might be one of my first upgrades. I really don't like the way Alfa designed that mount on the GTV6, it seems sloppy. How much does this upgrade affect the vibration and harshness? I'd still like some comfort.

Well I like both fast and cheap, so maybe the big anti-roll bar up front is the right way to go.

The inverted ball joints seems like an easy and cost effective way to gain help out the geometry and get some camber gain into the equation, any experience with this?

[grant]

Echo Leader,

I'm really trying to get the 2nd solution to work out for me.

I'm from the BB and I have 28mm front, 26mm Rear sway bars (RSR) and 27.3 AR T-bars and 154lb/inch springs.

The car rolls more than it should, and understeers like hell.

This weekend I should be installing drop spindles. I am hoping to get some grip numbers with my G-tech for before and after, but I cannot make a very lucrative test. I only have -1 degree of camber in the front and after the dorp spindles, I'm going to start off with -2.5 degrees. I can tell you however that at the track, I revert to positive camber once the car starts to roll, with the low roll center.

Another thing to think about is that a GTV-6 actualy has worse LCA positioning than Milanos (A gtv-6 at the AMERICAN RIDE HEIGHT! has it's control arms just barely slanted downwards...lower it to europen ride height and you already have roll center problems. I've done this on my 84 GTV-6 Case in point: I lowered my 84 to just barely lower than euro [I eye'd it] and then installed a 24mm Verde front roll bar, where the stock one was 20mm, and I had almost as much roll as fefore! That's with a 4mm larger front bar and newer rubber b ushings! And ofcourse, 4mm does not sound like much, but I think the rate rises exponentially or something to that effect, so 4mm ends up being a lot stiffer.). You probably have more incentive to get a D-spindle than I do in my Milano. You're only saving grace is that your CG is likely to be much lower than my Milano, not to mention I have a 60lb sunroof mechanism at the roof.

If you can hold off for a couple of weeks, I'm planning on doing an update in my D-spindle thread with some before and after thoughts.

RSR is quite nice on the track, but I've recently stated that I did a 3 hour drive in the mountains with a few road ripples here and there that would have surely bumped an RSR car off line a few feet. RSR has a nice ride up front by using the stock torsion bars, but what about the rear??

Larry Jr. from APE in California is the guy tha makes D-spindles out here and he said that his GTV-6 race car with soft 25.4mm torsion bars and sport springs in the rear and koni yellows developed good grip with D-spindles and a stock dedion in the rear..no camber or roll center modification. I may end up modifying the dedion down the road...we'll see how that goes. I have a parts car, so why not?

PS, could you post some links to where you read about RSR coilovers using brute force to overcome the roll center problem? I'd like to do some more reading on it aswell.

[Echo Leader]

Hey Grant, Excellent to hear you're attempting some interesting suspension modifications. I'll be really excited to hear what results you have when installing the drop spindles, especially if you're able to get some numbers to compare before and after.

I really need to start taking some measurements and begin modeling the suspension, possibly even purchase SusPro3D. At the moment all of my thinking is based on theory and has little tying it specifically to the GTV6 chassis.

It's interesting to hear that Larry Jr. didn't play around with the rear roll center at all. I'd heard that relocating the Watts was a pretty well proven... anyone else out there have insight into any of this stuff?? I'm sure there are some guys here with lots of practical experience dealing with this stuff.

The RSR being a brute force method is just really my interpretation of what Ron and JJ were saying at the NY tech session and my general reading of the suspension theory books. He said a number of times while there that basically, you don't need to worry about the roll centers or camber loss on roll if you simply stop the car from rolling. The RSR is probably the easier and perhaps cheaper way to achieve the correct balance, but the trade off seems to be the need to run a big Front ARB and pretty major spring rates. I guess my curiosity is driving my interest in achieving the same balance with geometry, thinner Front ARB and lower rates....probably a fool's errand...but I find it interesting.

[grant]

Yeah, a lot of people have been telling me to just do RSR. And with about 1.2K invested so far, maybe I should have. One definite benefit the RSR has over my method is crisp turn-in that only stiff wheel rates can give you! And by that I mean, an immediacy in response to whatever steering inputs the driver lays on...compared to my car, it seemed like it would take days to start turning in. Probably more important in the esses than steady state cornering, but whatever, it sure feels more race car like.

I think if we had affordable access to larger torsion bars and rear springs, that were say..half of the spring rates as RSR, that would be something I would be the most happy with. I guess your car is going to be more track oriented than dual purpose? If so, RSR might make you very happy with very few draw backs.

I couldn't find much info on the rear roll center correction. What does this do to the roll-couple? Is it a very worthwhile modification? I'm a bit worried about welding on another bolt to put all of the lateral loads onto tha tisn't factory certified

Please keep us updated with all of your theories on the 116 cars. So far I agree with everything you've said.

[Echo Leader]

I've been getting the same comments about the RSR bits. Generally people whole-heartedly recommending them. While this is nice to hear, and is almost undoubtedly the easier way to achieve a 'race-car like' setup, I'd like to experiment a bit more and learn while doing it. This is probably half the reason you're attempting the same?

As for the end goals I have in mind....who knows, really? I don't think I want to take the GTV6 I current have and turn her into a track machine, she's just too nice. But I have the full blown virus, so I'm constantly looking at rougher examples I could turn into track cars. So at the moment I'm trying to figure out how to achieve the chassis balance I want without having to make the front end as hard as a rock. If I can achieve that, I'll do it on my current GTV6.

As for the rear roll center, if the car has lowering springs the rear roll couple will have been shortened, as the RC remains at the original point. Following this, I think lowering the RC would lengthen the couple, but perhaps even out the roll axis a bit (assuming the front is lowered as well). I haven't thought about it too much. Those previous words may be gibberish...

To all alfagtv6.com/bb experts: Is going with a 30mm Front Anti-Roll Bar really the best 'first step' in dialing in the GTV6 handling balance? So far Maurizio votes for 'Yes', I think grant votes for 'Maybe' (?? )....

[grant]

A couple of questions first..

What is the suspension set up you are running now?

Did you know that the ride of an RSR can be softer in the front than a car with 27.3mm torsion bars? The rear is a different story though..

Using a 30mm bar would depend on what other modifications you plan to do in the future.

Last year I was planning on buying a 30mm RSR bar and using Shankle SS rear springs and Koni yellows for my finished package. I got the 30mm bar but it looked scary big...weighted a ton aswell. I was worried about damaging my front mounting structure aswell. Also, the front end of my car was so soft, that even at stock ride-height, I could hit the oil pan on hard bumps if I was driving full bore!

[Mats]

Me and Maurizio had this discussion at the Ring actually and obviously you can come very close with two totally different setups.

I agree with Grant, it depends on what you are planning to do next. If the front AR-bar is the only mod you will probably get away with it but if you are also planning to do a big-spring upgrade in the future I'm not totally convinced and if you plan to correct the front RC you will need to sell the front one and look for a thinner then stock one...

[Maurizio]

Ok, here is how I went along. This is for a 4 cil 75 TS.
First 27mm ar bar front, castor ball joint and bilstein shocks. The balance of the car was OK for street tires and daily driver.
Did the same for my street V6 with a self made 32mm ar bar.
In my opinion the best low budget stiffness and still some available comfort.

TS upgrade to full trackday car:
Switched also to a 32mm front ar bar, more camber and stickier tires. Uniball links ar bars and watt linkage. Which I liked better on the track, a nice balance.
Then added coil-overs and uprated springs stiffness on all 4 corner by the same factor to keep the balance, + added more camber front and back.
And next upgrades..... we will see

I think the difficulty here is that a suspension is very personal. Everybody likes the car in a different setup, it needs to be adapted to our driving style and skills.
Baseline you need to upgrade the stiffness or/and improve the RC. The rc dictates the needed stiffness, so better rc will reduce the need for harsh springs/ar bars

[GTV27]

I suppose I'm in much the same boat as Echo Leader - looking to improve the handling of my GTV6 for the occasional track outing, without turning it into a monster that is not nice to drive on the road.

Regarding roll centres, is a large part of the problem created when the car is lowered 'too much'? Putting it another way, can you solve some of the handling issues by cranking the torsion bars back up so the lower arms are horizontal at rest?

[Mats]

Maurizio: Better RC?

up or down?

[Echo Leader]

Awesome stuff guys!

A couple of questions first..

What is the suspension set up you are running now?

Did you know that the ride of an RSR can be softer in the front than a car with 27.3mm torsion bars? The rear is a different story though..

Using a 30mm bar would depend on what other modifications you plan to do in the future.

Well, my 'setup' is stock. Pretty much everything is OEM except the Bilsteins I just recently installed. But I'm at the point where I've addressed a bunch of little maintainence issues, begun autoxing and want to start modifying the suspension a bit. Yes, I know there's more time to be found by fixing me vs. the alfa, but this suspension stuff is too fun for me to ignore it...

Yeah, I'm aware of the flexability of the RSR kit. My concern though is that with the rates softened, would it really be all that good at controlling the chassis without fixing the front RC? I just dunno.

Me and Maurizio had this discussion at the Ring actually and obviously you can come very close with two totally different setups.

I agree with Grant, it depends on what you are planning to do next. If the front AR-bar is the only mod you will probably get away with it but if you are also planning to do a big-spring upgrade in the future I'm not totally convinced and if you plan to correct the front RC you will need to sell the front one and look for a thinner then stock one...

Man, I wish I was discussing things at the Ring.... totally awesome.

I like that you say, "obviously you can come very close with two totally different setups". This was the conclusion I was reaching after reading all sorts of bits and pieces of insight on this forum and the BB. I just wanted to really start a dialog about the front RC issues to see what setup philosophy works best. Or maybe "feels right" is a better term?

I know what you and Grant are saying concerning the 30mm RSR bar. I honestly think that a spring rate upgrade is in my future, but I don't know to what level exactly, and the more I hear about it, the more I want to correct the front RC. Especially when you indicate it is so impactful that a reduction from OEM front AR-bar thickness might be in order! I'm guessing that this is on a 4cyl though? So perhaps an OEM or even thicker front AR-bar would still be useful on a V6, but I love hearing the front RC fix is such a big deal. You're using a drop spindle? May I ask the cost of such a solution? Supplier? Any bad side effects?

Ok, here is how I went along. This is for a 4 cil 75 TS.
First 27mm ar bar front, castor ball joint and bilstein shocks. The balance of the car was OK for street tires and daily driver.
Did the same for my street V6 with a self made 32mm ar bar.
In my opinion the best low budget stiffness and still some available comfort.

...

Baseline you need to upgrade the stiffness or/and improve the RC. The rc dictates the needed stiffness, so better rc will reduce the need for harsh springs/ar bars

Awesome Maurizio, thanks for the walk-through. It's good to hear the process you took and some results.

I'm curious about the castor bar ball joints, and like that you did this modification early as it has been on my mind lately. Did you notice big improvements in feel? How much additional harshness/vibration did you get?

I'm very tempted by the monster front AR-bar, and for the reasons you mention: good balance, low budget and still some comfort. But I think you're final sentence really sums it all up perfectly. Something has to be done about the front roll, and if a better RC will allow lower spring and AR-bar rates, maybe this is the way I want to go?

I suppose I'm in much the same boat as Echo Leader - looking to improve the handling of my GTV6 for the occasional track outing, without turning it into a monster that is not nice to drive on the road.

Regarding roll centres, is a large part of the problem created when the car is lowered 'too much'? Putting it another way, can you solve some of the handling issues by cranking the torsion bars back up so the lower arms are horizontal at rest?

I think we're close on what we want to achieve. I want something that is still able to be driven on the street and legal to do so, but for me it doesn't have to be "nice" on the street. Maybe just "reasonable". Aka, 'not insane'. So is that Racecar*2/3??

I think you're right about the RC, but the other side of the equation is that you want the CG to be as low as possible. Doing so make the RC badly below ground, so to achieve both, you modify the geometry. I think while you're doing this, you can add in some other nice features to increase negative camber gain in compression and perhaps modify the steering rack to reduce bumpsteer? Experts?