Alignment specs

[garygnj]

After rebuilding the entire front end, including new crossmember, soon, I’ll need to bring my 76 spider in for an alignment.
Wondering if anyone familiar on this forum could tell me what specs to provide to the alignment tech.?

Also if there might be some techniques so that I might be able to dial it in myself in the garage reasonably close?

[18Fiatsandcounting]

This can be rather tricky, not because there's anything hard about a Fiat, but just that Fiat usually provided the specs with the car laden, that is, with 2 people plus 130 pounds of luggage. Plus, these "two people" are apparently svelte and trim European models of days-gone-by, not the average size that people are today. Problem is, I have seen very few shops take the time to properly load the car before doing the alignment.

That being said, here are the general rules that I go by:
Camber: Essentially 0 degrees will be close enough.
Caster: About 3 1/4 degrees, although this isn't usually off unless the car's been in an accident.
Toe-In: 3 mm on each wheel*

*I have seen an unladen spec that is around 6 to 8 mm.

These should get you started. Note that Dinghyguy on this forum has written up a very good approach to doing this at home, so you could send him a PM and see if he can send you his document.

-Bryan

[Nut124]

When I rebuilt my -78 quite some time ago, I did the alignment myself.

I did this w/o the coil springs, car on blocks. No wheels. I used an angle gauge for camber, caster. I used long aluminum profiles attached to the hubs allowing measurement of toe-in or toe-out at the bars forward of the front bumber.

W/O springs I could alter the suspension height.

Once done, I installed the springs, shocks. Been driving good ever since.

I saw a spider at my local mechanic. A customer had had it aligned at some tire shop. They had stripped the lower arm stud and lower arm was loose on one side. Big problem as the studs are welded in.

The mechanic was trying to re-thread the stud to some fractional size just under 11mm to avoid taking the entire crossmember off the car. Not good.

Some of fork type alignment shims out there are soft iron and can spread open and fall off. If using fork type make sure they are the right size and solid.

[18Fiatsandcounting]

I've set the toe-in on my spiders myself, and it seems as good if not better than the alignment shops would do. Camber and caster always seemed fine. To set the toe-in, I used a modified Dinghyguy procedure.

It is rather tricky to get everything set up as we OCD-people would want it:
1) Same rotational distance on the steering wheel from all the way left as it is all the way right.
2) Steering wheel spokes are exactly flat when the car is going exactly straight ahead.
3) Steering wheel locks (key pulled out) with spokes even and car pointing exactly straight ahead.
4) Car turns as easily to the right as it does to the left. Feels even.
5) Toe-in, camber, caster all set correctly.
6) Clamps on tie-rod end sleeves have the open end over the open part of the sleeve.
7) Clamps on tie-rod sleeves do not hit the engine crossmember or lower A-arm bolt/nut.

Every shop I have gone to has messed one or more of these things up. Easier for me to do it.
-Bryan

[garygnj]

Thanks Bryan!

[SteinOnkel]

Hello,

here's the after alignment specs

if you go to a random run of the mill alignment shop and let them have at it. This is also after me rebuilding the front suspension.

It's not great. The steering is tighter than it was now, but the car runs decently straight. Tire wear...well, they are $40 a piece so I'm not too worried about it.

Note that all these things are adjustable, it's just that they are too lazy to do it. If you go to a proper shop (think racing shop that does corner balances) they will do a proper job. It won't be $90 though.

[Nut124]

Setting toe-in at home using the parallel strings method.

The accessory below from Pegasus Racing makes it more precise.

https://www.pegasusautoracing.com/produ ... gIoEfD_BwE

[Nut124]

So, I ended up checking my toe-in using this parallel wires method. It is slick and very accurate. No expensive tools needed, Leveling string and a metric ruler is all and some jack stands.

My toe-in is about 2.2 deg. I replaced the steering center link last fall, which could have affected toe-in.

I did find that Excel 2010 ATAN formula or the combination of degrees(atan()) was giving false results (??). So I ended up using an on-line ATAN calculator.

See pictures below.

[18Fiatsandcounting]

Good on you, Nut. That's pretty much how I did it, but I used mm of toe-in instead of degrees. Note that the strings have to be located to account for the fact that the front track is 1350mm whereas the rear wheel track is 1320mm.

-Bryan

[Nut124]

Good on you, Nut. That's pretty much how I did it, but I used mm of toe-in instead of degrees. Note that the strings have to be located to account for the fact that the front track is 1350mm whereas the rear wheel track is 1320mm.

-Bryan

Bryan, you are confusing me now, knowing your scientist background. The strings need to be parallel, no matter front or rear track measurements. Right?

We are trying to measure toe-in in relation to neutral, parallel lines, right?

Or, if for some reason, someone wants to do this measurement with non-parallel lines, then the lines toe-in, or toe-out needs to be included in the results.

[18Fiatsandcounting]

Bryan, you are confusing me now, knowing your scientist background. The strings need to be parallel, no matter front or rear track measurements. Right?

We are trying to measure toe-in in relation to neutral, parallel lines, right?

My apologies, Nut, I can see how what I wrote could be confusing...

Yes, the strings need to be parallel. However, if someone assumed that the front and rear tracks were the same and positioned each string so that the distance to the front wheel is the same as the distance to the rear wheel, then the strings wouldn't be parallel. Hence my note about the front and rear tracks being different.

I position the strings on each side so that the distance between them in the front of the car is the same as the distance between them in the rear of the car. On each side, the center hub of the front tire will be 15mm closer to the string on that side than on the rear hub. (1350-1320)/2

Hope this makes sense, and that I'm doing it right....
-Bryan

[Nut124]

Bryan, got it now.

So are you reading the Fiat spec of 3mm to mean 3mm on each side, or 6mm total? The US convention seems to be that toe-in, when expressed in inches, is the difference between the front-to-front and the back-to-back distance measurements.

[18Fiatsandcounting]

So are you reading the Fiat spec of 3mm to mean 3mm on each side, or 6mm total? The US convention seems to be that toe-in, when expressed in inches, is the difference between the front-to-front and the back-to-back distance measurements.

Excellent question, and this has confused me for quite some time. I *think* the toe-in is the difference in the distance between two points on the front surfaces of the tires as compared to those same points on the rear of the tires. So, in rough numbers, if the front track of the Fiat spider is 1350mm, then a 3mm toe-in would mean that the front of the tires are 1344mm apart, and the rear of the tires are 1356mm apart. 3mm toe-in is for each wheel, so the total is 6mm for both wheels.

However, I believe the Fiat spec is from the rims, not the outer surface of the tire. Since you can't easily measure the distance on the rims, that's where the parallel strings work. You get the string parallel, and you adjust the toe in so that the difference between the string distance from the front and rear of the rim is 6mm. As an example, if your string is 30mm from the "center" of the rim, then you adjust the toe-in so that the front of the rim is 33mm from the string and the rear is 27mm from the string.

Of course, the specs are usually with the car laden, which Fiat defines as two people plus 50kg of luggage or so. I do have a spec which indicates an unladen measurement on a '78 spider as 6 mm of toe-in on each wheel. So, I just use the parallel string and adjust each wheel so that the front of the rim from the string is about 12mm more than the rear of the rim is from the string. Seems to work.

Dinghyguy has a good writeup on this, so I will email that to you.

-Bryan

[RRoller123]

I have had some good results with the string method, but one has to be careful because the track width is not the same front and back, so the assumption that stretching the string around the rear tires and running it up front, and having parallel strings is incorrect! I frankly forget if the track is wider up front or in the rear, I think it is wider up front?

[18Fiatsandcounting]

I frankly forget if the track is wider up front or in the rear, I think it is wider up front?

Yes, 1350mm in front and 1320mm in the rear. Wheel center to wheel center.

-Bryan