Rear suspspension changes - early v. later models

[dozy]

So the early models camewith solid rear axle and a panthard road.

What changed later, and when did this change? I tried to research this, and cannot find much detail. Is the difference in handling a big deal?

Thanks

Dozy

[So Cal Mark]

the later models had the same setup. The earliest models used a torque tube

[dozy]

Wow and here I am thinking they actually got IRS in there.

But you mentioned the later rear ends were prone to failure (this was in some thread about a guy's pinion coming apart).

Mark you really are on the ball moderating this board .. thanks

Dozy

[So Cal Mark]

the differential style was changed in 79 but the basic suspension is the same

[kmead]

The 124 series had 3 different suspension setups.

The first couple of years they used a torque tube, two trailing arms and a panhard rod.

The majority of 124 based cars had 4 trailing arms (two longlowers and two short uppers) with a panhard rod. This came in two slightly different flavors. The early trailing arms have a pinched look to them at the ends with conical bushings and the rear axle has a removeable "pumpkin" style final drive. The later cars (76 plus) have heavier trailing arms with some having pressed in bushings and the later 131 rear axle as the 124 sedan was no longer in production. Both rear ends are strong enough for the job but can fail if you really up the power on the engine or otherwise abuse the car.

There were a very small number of Abarth based cars that went to an independent rear suspension that used large lower A arms and a Chapman/McPherson strut suspension with CV jointed axles off a limited slip differential. These cars are very rare, especially in the US as this was basically a rally car for competition. They did make the needed 400 or so homologation production cars, one of which sold last year in the Chicago area as recall.

All standard Spiders have the same handling characteristics, the later ones have more understeer due to being slightly raised to meet bumper standards but that can be tuned out by shortening the springs or adding a rear anti roll bar (sway bar).

[wmausbach]

Carl,
I just read this post and you are correct with one exception. The Abarth front suspension was not a strut but a modified A-Arm set up. In fact it used a standard upper A-Arm with a modified lower arm attached to a drag strut hooked to the chassis. I was interested in building a IRS Abarth copy a few years ago. I wrote Guy Croft and he sold me copies of the ABarth owners manual that had detailed drawings of the items along with attachment points. Although not quite full engineering drawings they were sufficient to deduce the missing dimensions and fabricatethe parts. I even had a differential from a 2002 BMW that I was going to use. Anyway with all that I deemed it to be more work than was not that much better for smooth roads. I surmise the front was designed to have much more stroke than the standard 124.
Ciao
Wayne

[pope]

Wayne, we are talking rear end here, no one brought up front end.


Brady, oppps!

[azygoustoyou]

Popes taking rear ends What's he doing with them

[engineerted]

One correction, the change was made mid 1978, so yes there are 1800 spiders out there with the non removable pumpkin with the 4.3 ratio.

Ted

[wmausbach]

Brady,
You are right. I was thinking of the 037 rear suspension. I looked at my documentation an it is a strut type probably from a X-1/9 which was being introduced.
In any case the early rear ends were both stronger with better metal. The only problem is the later ratio's are better for highway speeds. It seems Fiat was going after the GM approach on the later designs which was cheaper to manufacture.
Next time I'll check rather than relying on a faulty memory.
Ciao
Wayne

[maytag]

So if I have a '76 and an '80 (THAT i JUST PICKED-UP TODAY!), then the '80 will have taller gearing? (lower, numerically?)

does anyone know what the gear ratios are?
And where is the speedo take-off? is it on the trans?

[kmead]

So if I have a '76 and an '80 (THAT i JUST PICKED-UP TODAY!), then the '80 will have taller gearing? (lower, numerically?)

does anyone know what the gear ratios are?
And where is the speedo take-off? is it on the trans?

Yes the speedometer drive is on the transmission.

The '76 likely has a 4.30 ratio and the 1980 has a 3.90:1 ratio and a completely different rear axle along with a different driveshaft (shorter on the 1980).

The gear ratios on the '76 will be:
.88, 1.00,1.36, 2.05, 3.61

The gear ratios on the '80 will be:
.88, 1.00, 1.36, 2.10, 3.67

Those are 5th through 1st.

This all assumes that nothing has been changed, traded or replaced over the intervening years.

[one24spider]

i have the later style diff that is broken, i bought an earlier style with axle housing, still with the four rods, is there anything i should know about swapping it in?

[Sunracer]

The early style cars, up to 78 used the straight panhard rod, the later ones used a kinked panhard rod. the panhard rod hs to match the style diff to bolt it all in. The driveshafts are different lengths. Use the right driveshaft and remember if you rebuild one to retain the alignment of the two shafts as they are balanced as a unit. On the rear diffs up to 78 used a 4.30 rear. Some coupes and depending on the source, some spiders head a 4.10 rear gear in the drop out diff. 78 1/2 cars used the later style spicer diff with a 4.30, then in 79 you get the spicer with the 3.90. Automatic spider 2000's used a 3.58. The plastic cups that support the springs on the diff are different sizes too, the taller one goes on the passenger side. PB : )

[Exit98]

So if I have a '76 and an '80 (THAT i JUST PICKED-UP TODAY!), then the '80 will have taller gearing? (lower, numerically?)

does anyone know what the gear ratios are?
And where is the speedo take-off? is it on the trans?

Maytag,

I just completed this switch in the last 2 months or so and it transformed my Spider.

I know others have a different opinion, but I'll never go back. And it's not just about 70 MPH crusing (not that I do that much). It's about around town and on the back roads. Third gear is the go-to gear now. Fifth is an afterthought.

Some board math wiz will probably correct me but the speedo I'd estimate is about 5% slow. I don't care. On a real trip I'll have the GPS anyway.

Bunch of little details to attend to in the switch. If you want to know more just PM me.