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I'd second checking and adjusting your alignment. I believe the stock factory setting had a little toe out. 225 with lower profiles on 16" wheels, right? They will tramline and have an unstable, darty feel overall on stock alignment settings, which were for much narrower and taller tires. I had the same issue on 225/50-15, very darty, solved at zero toe. Some tire designs are more sensitive than others as well. You can have it checked out and set to zero toe or a little toe in for even more stability. Reducing caster will also lighten the steering a bit (but may get a rub on the front).
 

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BTW: Only just thought of this, but who knows, might be useful.

Years ago I ended up leaving my Alfa Sud at my engine builders, which was untypical. Usually I just picked up and dropped off parts. Anyway when I turned up there to pick up the car, all the mechanics gave me a funny look, and then the boss had a chat to me. He said "Man that car of yours is all over the road. In fact we all tested it and found that we needed both lanes of the motorway at over 100 mph" ... I was a little taken back with the fact that the whole shop had been blasting up and down the motorway in my race car, but they hadn't killed or bent it ... so said that's strange, wonder what is wrong.

Anyway on the way home, yes I experienced what they were talking about; most untypical. Inspecting the car afterwards; there were bolts loose on the rear suspension caused by poly bushes. I had to double nut them to stop them working loose. Another reason why I don't use poly bushes.

Pete
 

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Sport Sedan set to mythical Euro ride height. No bumpers. New Koni Yellows set all the way soft.
All bushings good. Aligned at 1.8 negative camber per side. 4* positive caster using poly bushings. 1/16" toe-out. Not squirrely at triple digit speeds. Car is NOT nose high.
If your caster bushings are worn, it will steer all over the place.
Even new caster bushings are somewhat akin to Oreo cookies with marshmallows on each side.
 

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Yep replace your old upper and lower a arm bushings plus use poly bushing for caster arm. These bushings don’t last forever and are part of old car maintenance.
 
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In the same vein as PSK‘s comment, the front end can do funny things if the Watts link bushes are worn, for example, steering Slightly one way on accel, the other on decel. does your car do that too?
 

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You were racing on the street? And you admit to it?
Geez...
So what? He said he “had” (past tense) a ‘76. Maybe he owned it from new and raced it 40 years-ago. Bottom line we have ALL raced on the street at least once. Most cops own Harleys do you think they putter along at the speed limit in their off hours?
 

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Does it have to do with ride height?
Anyone else has the feeling that at 100+ mph you feel too light?
I mean I'm running 225 supersoft. The car does not sway or anything but the steering scares me a bit. Specially at those speeds in NJ highways.
I can't rember my 75 doing that.
The 75 is the same chassis as the Alfetta exactly almost depending on the year.I ran an Alfetta top speed for several great miles years ago.195+ KMH speedometer showing.The faster she went the more she hunkered down.
 

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1986 Alfa Romeo GTV6
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Discussion Starter #49
SIDE NOTE.
I just realised that when post gets too big( 2nd page and over) i stop getting notifications.
I suspected that when i did the tank sale.
Admins please help.
 

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1986 Alfa Romeo GTV6
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Discussion Starter #50
Guys. i just saw how big this post got. For me the conversation had stopped already.
Thank you for all the experienced comments.
Never thought the wide tire could have such a negative effect on stability.
Going to start with the obvious and easy, tire pressure and re align. then asking Paul @ https://www.facebook.com/EuroTecMotorsInc about lowering to euro specs and the toe in situation.
I'm afraid i went looks and did not consider the width of the new rims. I'm stuck with the 225 for a while @Milanoguy. thinnest i can go is probably 215 without stretching too much.
I always thought most alfas come too high stance from factory. Specially the 75, my first one. When i had it lowered can't remember how much, i regret it deeply. The lowest part on the 75 is the curve of the downpipe.. Ended up breaking it and bending headers.
This pic you can actually see it at a distance. (hope this guy won't mind).
1641361



On the Gtv6 the lowest part is the pan. i could protect it a bit with a pan guard, but my biggest concern is the rims. i'am almost sure i can't lower it to euro specs because of the 16"x7,5" wide rims.
Have another set, but also 7.5"x16"
tHIS IS MINE BY THE WAY



1641362


See how tall it is. Even in a downhill front is too high.
 

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1986 Alfa Romeo GTV6
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Discussion Starter #51
For me I always thought a perfect alignment was 0 toe with very little negative camber in the front and, on this car, 0 camber and 0 toe in back.
 

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You can probably lower it. Yes front down pipes take the hit first. On really low cars the middle muffler is tricky on crowned roads.
 

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Assuming you have 225/45-16 those are slightly smaller diameter than the 195/60-15, of course much wider, you don’t mention offset.
 

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Your car looks very low to me. Maybe the back needs to be raised to get the aero right.

I personally don't understand lowering a road car as much as I don't understand low profile tyres. Both ruining the driving experience ...

Pete
 

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Discussion Starter #58
Your car looks very low to me. Maybe the back needs to be raised to get the aero right.

I personally don't understand lowering a road car as much as I don't understand low profile tyres. Both ruining the driving experience ...

Pete
They don't ruin it. They just change it a bit. heavier steering, faster curves, etc.
 

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They don't ruin it. They just change it a bit. heavier steering, faster curves, etc.
Are we talking low profile tyres?

All other things being equal a 45 series tyre will produce slower lap times than a 60 series tyre. Note I'm only talking about lap times, not steering feel, which does not make a car faster.

In the end lap times are produced by grip, and that requires rubber on the track surface. A low profile tyre during cornering ends up with less rubber on the road than a 60 series, because the 60 series can distort more allowing more rubber to actually stay in contact with the track. The 45 series can't do this as well and lifts its tread surface off the track.

This is why F1 tyres have such massive sidewalls. Have a look at a cornering photo, considerably sidewall distortion that you don't see at racing speed. Unfortunately tyre manufacturers are obsessed with low profile tyres (I wonder if they cost less to make?) and are forcing F1 to go slightly lower in tyre profile. Another sad example of marketing getting in the way of the purpose of F1.

There have been tests, TopGear and other magazines, etc. and all cars are faster with the smaller wheel and higher profile option that a manufacturer sells their cars with. Ferraris, Alfa Romeos down to Holden Commodores.

On top of that low profile tyres make you feel every bump. A case of a hard bouncy car feeling more racy but not actually being better at all

Yes my opinion, but in this rare case backed up by physics, and back to back tests. My 156v6 has the 17" wheel option while the 16" was the standard option; if I had bought the car new I'd have specified the 16" wheel, saved money and had a better car

But I'm a grumpy 52 year old man
Pete
 

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Discussion Starter #60 (Edited)
Are we talking low profile tyres?

All other things being equal a 45 series tyre will produce slower lap times than a 60 series tyre. Note I'm only talking about lap times, not steering feel, which does not make a car faster.

In the end lap times are produced by grip, and that requires rubber on the track surface. A low profile tyre during cornering ends up with less rubber on the road than a 60 series, because the 60 series can distort more allowing more rubber to actually stay in contact with the track. The 45 series can't do this as well and lifts its tread surface off the track.

This is why F1 tyres have such massive sidewalls. Have a look at a cornering photo, considerably sidewall distortion that you don't see at racing speed. Unfortunately tyre manufacturers are obsessed with low profile tyres (I wonder if they cost less to make?) and are forcing F1 to go slightly lower in tyre profile. Another sad example of marketing getting in the way of the purpose of F1.

There have been tests, TopGear and other magazines, etc. and all cars are faster with the smaller wheel and higher profile option that a manufacturer sells their cars with. Ferraris, Alfa Romeos down to Holden Commodores.

On top of that low profile tyres make you feel every bump. A case of a hard bouncy car feeling more racy but not actually being better at all

Yes my opinion, but in this rare case backed up by physics, and back to back tests. My 156v6 has the 17" wheel option while the 16" was the standard option; if I had bought the car new I'd have specified the 16" wheel, saved money and had a better car

But I'm a grumpy 52 year old man
Pete
You are absolutely right. I know those tests. I've read some. In my defense size of tires and rims already came with the car when I got it. I do love a little tale wagging on my curves. I have not been able to do such with these wheel set ups. Or maybe too many years driving fwd that I actually forgot how to power slide. It's been 20 years between my first and second Alfa RWD.
It's simple phisics. More contact, more power needed to move the wheel.
Another good example is a 4x4 vs the same car at 2x4 traction. Then compare mpg.
Now, lowering the car just enough. (not low and slow version) as nothing but benefits. In my point of view.
 
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