Rear axle drop stop

[Melchior]

I am happy to provide this information, maybe it saves someone's time in future: the zinc plated metal rope for the drop stop of the rear axle is of dimension 5mm 7x19.

[tyang]

I should add the length of these cables are very important, as the description states, they limit the drop of the rear axle when the rear axle becomes unsprung. The rear shackles can go over center if the axle is dropped too far:

Here's a picture of it "over center."

Here it is in the correct position.

The limiting cable has to allow enough travel of the axle, but not too much to allow the leaf spring to pop into the "over center" position. Getting the spring back to correct placement after it happens is pretty involved!

Tom

[330GT]

...
The limiting cable has to allow enough travel of the axle, but not too much to allow the leaf spring to pop into the "over center" position. Getting the spring back to correct placement after it happens is pretty involved!

Tom

I fought this issue several years ago and found a simple solution using a pipe wrench. Simply use the wrench to grab the shackle plate and rotate the shackle back into the proper place. Then add the wires to prevent the differential from dropping too far. You may have to fix the pipe wrench in position or support the differential to prevent the spring from going over center while you do the wires.

[John Vardanian]

Good trick to know, Kerry... about the pipe wrench.

john

[250gtgt]

Good trick to know, Kerry... about the pipe wrench.

john

Very powerful guys among us CHAPEAUX
I never was able to do this so easy...

C.

[tyang]

Kerry had the luxury of working on a SII 330 that has less leafs in the spring because his car has the additional coil springs to support the vehicle. Earlier cars like SI 250GTEs and early 250s have many more leafs for the rear spring putting a lot of tension on the shackle. I don't think it could be done with the earlier cars with a pipe wrench!

Tom

[330GT]

Kerry had the luxury of working on a SII 330 that has less leafs in the spring because his car has the additional coil springs to support the vehicle. Earlier cars like SI 250GTEs and early 250s have many more leafs for the rear spring putting a lot of tension on the shackle. I don't think it could be done with the earlier cars with a pipe wrench!

Tom

The car I did this on was a series 2 PF coupe. It wasn't too hard to flip the shackle back in the right orientation. For all of the ways I tried first, see http://www.parrotbyte.com/kbc/ferrari/P ... ension.htm.
Note, you will probably leave marks on the edge of the shackle from the pipe wrench teeth.

[enio45]

Nice spring tool C......

i made one as well for the ellena!!

[Melchior]

I received the replacement rope with 5mm and it is too thick. Seems that the original zinc plated metal rope for the drop stop of the rear axle is of dimension 4,5 mm 7x19 and not 5mm as described initially.

[Terry Gardiner]

Hi Melchior
On #4681, my car, the two axle restraint cables are different. This must date back to a repair as one is 4mm od with a smoother exterior and the other is 5mm od and less smooth. The 5mm cable is frayed in two places and looks to be poor quality material, so needs replacing.

4.5mm od cable (or wire rope) is not so common, I’ve found.

As you say, 5mm od is too large.

4mm od cable with a minimum breaking load of over 1.5 tons is available, which may be suitable.

Did you find 4.5mm od and what was/is its minimum breaking load?

[Terry Gardiner]

A couple of further thoughts…

On the later cars, with Koni coil-over shock absorbers, just how important are the wire rope axle restraints?

On #4681 the restraints as I found them were almost, but not quite, set at the fully expanded length of the Konis. The difference was about 1 cm. The principle advantage of this seemed to be to hold the axle clear of the rear silencers when the car was jacked off the ground.

I shall be reinstating the restraints more or less as I found them but I’m curious as to their real value. Perhaps as a reassembly aid when refitting the axle.

You might say it’s easy to tell I’m still learning this stuff!

[Terry Gardiner]

A couple of further thoughts…

On the later cars, with Koni coil-over shock absorbers, just how important are the wire rope axle restraints?

On #4681 the restraints as I found them were almost, but not quite, set at the fully expanded length of the Konis. The difference was about 1 cm. The principle advantage of this seemed to be to hold the axle clear of the rear silencers when the car was jacked off the ground.

I shall be reinstating the restraints more or less as I found them but I’m curious as to their real value. Perhaps as a reassembly aid when refitting the axle.

You might say it’s easy to tell I’m still learning this stuff!

[tyang]

Hi Terry,

The cable are important to keep the axle from lowering past the point where the leaf springs will go "over center" and allow the rear shackles to go out of position. The coil over koni shocks may be at the limit before this positon, but you need the limiting cable if the coil overs are removed.

Tom

[Terry Gardiner]

Tom, thank you. My experience over the past few days bears out what you say.
Terry