Fiat 128 rear anti-roll bar

Chris Taunton

Chris Taunton

True Classic
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I am looking to kill some understeer on Gus by installing a rear anti-roll bar. Does anyone here know a source for one?

I have spoken to Matt at Mid-West Bayless, Andrea at Classic Performance, and Ed at Addco and their cupboards are bare. If there are seven people who want one, Addco will make seven more kits. Are there seven of us who will commit? Would there be more interest in a 3/4" (19mm) bar instead of the 5'8" (16mm)?

Does anyone want in? Maybe some of the Fiat parts suppliers might want one or two for stock?

Chris
 
There is a place in Portland, OR which makes them. For the application I was doing, (read, hard race only) I had them fab up a 1-1/4" bar It looked like a tree trunk under the car, but it did what I wanted it to do. ;) If I remember right, it was less than $200 for them to make it and install it. I will see what I can find.
 
fastx19 said:
There is a place in Portland, OR which makes them. For the application I was doing, (read, hard race only) I had them fab up a 1-1/4" bar It looked like a tree trunk under the car, but it did what I wanted it to do. ;) If I remember right, it was less than $200 for them to make it and install it. I will see what I can find.
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That sounds very interesting. I'm curious about the rest of your setup.

Chris
 
If the rear of the 128 is lowered, the the rear roll centre is lowered too... at the moment you have an inclined roll axis, i.e the rear is higher than the front and the lne drawn between the two "theoretical" points will be angling down to the front... That will tend to understeer. If you lower the rear and make the roll axis more level, you'll find understeer is reduced.

I've never run a rear bar on a 128.
even on loose surfaces the 128 can be very neutral steering
128rallyBsmall.jpg128rallysmall.jpg

SteveC
 
fiatfactory said:
If the rear of the 128 is lowered, the the rear roll centre is lowered too... at the moment you have an inclined roll axis, i.e the rear is higher than the front and the lne drawn between the two "theoretical" points will be angling down to the front... That will tend to understeer. If you lower the rear and make the roll axis more level, you'll find understeer is reduced.

I've never run a rear bar on a 128.
even on loose surfaces the 128 can be very neutral steering
View attachment 39169View attachment 39170

SteveC
Click to expand...
Completely instructive post for me, as my 128 Familiare is lowered in the rear and is slightly nose high in front with SL coupe springs. It doesn't understeer. Good to know why.
 
fiatfactory said:
If the rear of the 128 is lowered, the the rear roll centre is lowered too... at the moment you have an inclined roll axis, i.e the rear is higher than the front and the lne drawn between the two "theoretical" points will be angling down to the front... That will tend to understeer. If you lower the rear and make the roll axis more level, you'll find understeer is reduced.

I've never run a rear bar on a 128.
even on loose surfaces the 128 can be very neutral steering
View attachment 39169View attachment 39170

SteveC
Click to expand...

Gus is lowered 1/2" in the rear. Tire clearance with the CD30 wheels is an issue. Once I which to the 14" Alfetta wheels, I will drop the rear another 1/2" and see if that helps.

With the 225 lb/in front springs and wagon front bar, I have a lot more roll stiffness in front than in the rear. I think I will need more in the rear. We will see.

The Alfa Romeo 105 chassis when lowered has the inclined roll axis you describe, and oversteer like crazy. Race cars run 1500 lb/in front springs, 29 mm front away bar, 150 lb/in rear springs, and remove the rear bar all to get the rear to grip. It is common to see pictures of these cars exiting corners with the rear squatted down and the inside front wheel in the air.

So my understanding is backwards from yours. There are probably other factors contributing to the different outcomes.

Chris
 
So, I have always been in the camp of tighten the front if you want the rear to grip better, tighten the rear if you want the front to grip better. Now, on my 128's we have raced, if we left the cross leaf spring in it, I personally, and absolutely no dig at Steve C, I have found it to help. Now, the other option is to remove the cross leaf spring, put coil overs on it and then you have a lot more options. With coilovers on the 128, we never ran a roll bar as there was just no need. Please note, the car I ran the big ass roll bar on was setup for one task, paved hill climbs. It was an all out race car with no other purpose. So keep that in mind.

Finally, I am actually picking up some parts in Portland next weekend and there is a chance a roll bar may be in the stash. I will let you know.
 
Fastx19,

That sounds awesome. Thank you.

Was your hill climb car a coupe or 3P? The people I have talked to that have raced those cars ran no front bar and a big rear bar. The idea was to set up the car to oversteer so that you can use lots of throttle early. I am not going for that aggressive a set up, but some lift throttle adjustability would be nice.

Also, tire selection is very limited and I was running the Achilles 122 tires in 165/70HR13 size. I think they are just junk. No grip and poor wear. I've been through 2 set in a year. I am trying the Federal 595s in 185/55VR14 on the winter Alfetta wheels soon and will see if they are better. The summer tires are Yokohama A052, which have lots of grip.

What tires do y'all like best for 128s and X1/9s?

Chris
 
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fastx19 said:
So, I have always been in the camp of tighten the front if you want the rear to grip better, tighten the rear if you want the front to grip better. Now, on my 128's we have raced, if we left the cross leaf spring in it, I personally, and absolutely no dig at Steve C, I have found it to help. Now, the other option is to remove the cross leaf spring, put coil overs on it and then you have a lot more options. With coilovers on the 128, we never ran a roll bar as there was just no need. Please note, the car I ran the big ass roll bar on was setup for one task, paved hill climbs. It was an all out race car with no other purpose. So keep that in mind.

Finally, I am actually picking up some parts in Portland next weekend and there is a chance a roll bar may be in the stash. I will let you know.
Click to expand...
Eric - question for clarity: did you run the transverse leaf spring in the rear *and* coilovers with no rear sway bar? And if so what kind of coilovers?
 
fastx19 said:
So, I have always been in the camp of tighten the front if you want the rear to grip better, tighten the rear if you want the front to grip better. Now, on my 128's we have raced, if we left the cross leaf spring in it, I personally, and absolutely no dig at Steve C, I have found it to help. Now, the other option is to remove the cross leaf spring, put coil overs on it and then you have a lot more options. With coilovers on the 128, we never ran a roll bar as there was just no need. Please note, the car I ran the big ass roll bar on was setup for one task, paved hill climbs. It was an all out race car with no other purpose. So keep that in mind.

Finally, I am actually picking up some parts in Portland next weekend and there is a chance a roll bar may be in the stash. I will let you know.
Click to expand...

Do you have a thread here that shows your hillclimb suspension setup?

Thanks,

Chris
 
Agnelli said:
Eric - question for clarity: did you run the transverse leaf spring in the rear *and* coilovers with no rear sway bar? And if so what kind of coilovers?
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Hi. No, I did not run a transverse leaf spring. Just ran stiff springs on the rear, which was better than trying to add another leave to the spring in the back, which I have done before.
 
Chris Taunton said:
Do you have a thread here that shows your hillclimb suspension setup?

Thanks,

Chris
Click to expand...
I don't, but you bring up a good point, we should start posting some of this and what people found works well for them. I will se if I can find any info or pictures, but it was years ago.
 
fastx19 said:
Hi. No, I did not run a transverse leaf spring. Just ran stiff springs on the rear, which was better than trying to add another leave to the spring in the back, which I have done before.
Click to expand...
My car has the three leaf spring from a wagon in the rear. How are the coilovers better? I know nothing, just looking to learn.
 
bark said:
My car has the three leaf spring from a wagon in the rear. How are the coilovers better? I know nothing, just looking to learn.
Click to expand...
The coil overs allow you to control the level of spring rate from very soft to basically rock hard. It all depends on the type of driving you are doing and what you want or expect you car to do. For example, you may want nice 150lb springs for a soft ride on a daily driver. Something similar or maybe even a bit softer than the standard transverse spring. The maybe you want to go racing, and up the rate in the front, which means you want it stiff in the back so you don't push all over the place. Another fun part is you can easily adjust the ride height as well. Now, the wagon came stock with a 3 leaf spring, which was always a cheap upgrade for the sedan as it only came with a 2 leaf spring. In short, it allows you the ability to set your car up to your taste and desires.
 
Chris Taunton said:
Fastx19,

That sounds awesome. Thank you.

Was your hill climb car a coupe or 3P? The people I have talked to that have raced those cars ran no front bar and a big rear bar. The idea was to set up the car to oversteer so that you can us lots of throttle early. I am not going for that aggressive a set up, but some lift throttle adjustability would be nice.

Also, tire selection is very limited and I was running the Achilles 122 tires in 165/70HR13 size. I think they are just junk. No grip and poor wear. I've been through 2 set in a year. I am trying the Federal 595s in 185/55VR14 on the winter Alfetta wheels soon and will see if they are better. The summer tires are Yokohama A052, which have lots of grip.

What tires do y'all like best for 128s and X1/9s?

Chris
Click to expand...
For fast road, I find that nothing can beat a Toyo R888, or R888R... I'm running 185/60-13 right now, but moving to 225/45-13's on 8" Cromadoras as soon as my group2 rally flares are done! Plus another bonus is the Toyo's stay soft all the way down to the cords, they never harden up. I had some Yokohama A048's, but after awhile they got progressively less sticky and more hard... Even worn down past the wear marks, you can still dig your fingernails into the Toyo's....
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On the 128 sedan I used to race, I ran a three leaf wagon rear spring along with a rear sway bar. That helped not only minimize understeer, but also help minimize front wheel lift, which is a real speed killer if you're not running a limited slip or welded diff. Ideally, you would be lifting your inside rear wheel in hard cornering like a old Mini. The problem with the 128 sedan is you have to overcome the large front sway bar, so you have to go real stiff in the back to minimize understeer. On my current race car, a 1st Gen Civic, I'm running no front sway bar. The plus to coil overs is that it's easier to set corner weights. No as critical in street cars used for occasion track use. By the time you've got your coil overs dialed in, you'll be shaking some fillings loose.:oops:
 
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