Hi all - been working on a disc brake conversion on my 1971 500L. I bought a kit that’s admittedly over the top for the car, but seems very good quality. Anyway, I have the new calipers and wheel hubs bolted on and all set. No wheel clearance issues except that the tie rod ends (ball joints) and their rubber boots just lightly contact the brake rotors (discs) on both sides. It’s not enough to impede the rotors from turning, but definitely a problem because the spinning discs will cut the ball joint boots and probably occasionally contact the discs metal to metal. I have to increase the clearance.

Below are a couple of photos. It looks like the ball joint is severely cocked but even when the car is set down off the lift and the tie rod angle relaxes a bit, it’s still too close.

The tie rods are relatively new - they FRAP. They are pretty robust, but clearly fit prior to the new disc brakes and had no issues with clearance from the old brake drums. I recall the original factory tie rods and ball joint heads being much smaller, but unfortunately I binned them after I replaced them. But my recollection of the originals makes me think the brake kit designer had them in mind when he designed the kit. I think they were small enough to provide clearance.

Wondering if anyone has any ideas. Thanks!

Incidentally, I tried flipping the tie rod upside down, but it won’t install that way due to the tapered seat. It only fits as originally installed, bolt side down.

Have you thought about having the discs reduced in diameter by a couple of mm? Have a look where the pads are incontact on the discs. If the discs extend pass the pads, this part of the disc is not required; have it machined off.

That’s a good idea. I was hoping to not have to pull them all apart, but probably is going to be easier than finding “just right” tie rods that I’m not sure exist. I do have to be careful about the pad; I don’t want it off the disc, but I should have a few mm to spare. I’ll give it a closer look.

Uaglio said:

............................ No wheel clearance issues except that the tie rod ends (ball joints) and their rubber boots just lightly contact the brake rotors (discs) on both sides. .....................

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I did a lot of playing about with disks and calipers a while ago...
one set up had a similar problem....
It could be cured by spacing the back bearing, which in effect pushed the whole hub and disk out..
It would need a corresponding spacer(s) for the calipers as well...

the down side was the amount of thread left on the spindle for the retaining nut....
this could possibly be overcome if you could find some slimmer bearings ...
or have someone machine the seat where the bearing sits a little deeper in the hub... that depends how much meat there is left....

another alternative was to use Spherical joints (Rose joints as most people know them) buy they have no protection against dust and dirt and wear quicker...

they look like custom made hubs and disks, can i ask who supplied them?

Thanks for those thoughts. The kit was supplied by FD Ricambi in the Netherlands (good vendor - I have received many excellent quality parts from them). But it also appears to be the same “A quality” kit sold by other vendors, such as Axel Gerstl, but the rotor (disc) I have seen pictured on other vendors’ sites is usually drilled. The calipers are high quality and there were no other fitment issues (clearance for original steel wheels is fine, spindle and retaining nut are all good, wheel bearings and races transferred over and fit fine). The only issue I had was that the original wheel bolts were about 5mm too long and I had to grind them down so they didn’t hit the calipers. I also got a a new dual circuit master with the special right angle brake pedal actuator bracket, and I am redoing all the copper lines to the front brakes.

My inclination at this point is as Hobbler suggested - take off the rotor and have it machined down by half a cm or so, to provide extra clearance. That would enable me to use the existing FRAP tie rods and not mess with the wheel hub/spindle dynamics. I just have to confirm that reducing the disc diameter won’t create issues for the pads being too large and riding over the edge of the reduced size disc.

Uaglio said:

.................... take off the rotor and have it machined down by half a cm or so, to provide extra clearance. .

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I think you will find the leading edge of the pad wll over hand the edge of the disk as the pad wears...
due to the thickness of the disks it s unlikely that this unworn overhang will reach the point that the unworn parts of the pads touch so you end up with zero front brakes....
Depending on your usage... the disk thickness will decrease and if new pads are fitted you may find that could happen...

Thanks again. Understood. I guess another option would be to alter the pad itself - grind off any pad material that overhangs the disc.

Uaglio said:

Thanks again. Understood. I guess another option would be to alter the pad itself - grind off any pad material that overhangs the disc.

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are the calipers mounted on Plates?
Also if the disk was turned down can you move the calliper further inwards before it fouls on the inner part of the hub (may need new plates) so all the pad is over the disk..

I have seen Calipers cut down and disks with the inner edges removed to get disks/calipers inside 10" wheels in Italy...

Yes they are mounted on plates. My kit looks identical to the kit posted by another member here (see attached), except the disc in that phot is drilled. I don’t think I can move the calipers inward to accommodate making the disc diameter a little smaller unless I really reengineered the caliper plate/mounting brackets.

My kit:

That looks like a tidy set up once you get it sorted. When I first got my 500 the brakes, king pins and wheel bearings were all shot. In those days I did not shop outside the UK so bought the £450 Ricambio set up which solved the problems. When I examined the parts a few years later I realised that the main brake parts were modified Fiat parts. The discs are machined down in size, the calliper carriers are cut away in a couple of ways and the disc pads themselves are cut down. I have never seen replacement parts available so if you are in the same situation as me you would need to have these parts specially made.

Toshi 975 said:

When I examined the parts a few years later I realised that the main brake parts were modified Fiat parts. The discs are machined down in size, the calliper carriers are cut away in a couple of ways and the disc pads themselves are cut down. I have never seen replacement parts available so if you are in the same situation as me you would need to have these parts specially made.

Click to expand...

Yes, thanks. I am not expecting to ever need to change the pads due to wear, given how little distance I drive mine, but I guess you never know. I figured if the time comes, I’d have to do a bit of goose chasing to find the pads the kit maker used, which I suspect are from a Fiat relative of some sort!

Hi all - so I found a solution that doesn’t involve modifying the discs, which I cannot do anyway, because the pads are already at the disc edges. I found “uniball” style tie rods and centre link that has a head diameter around 30mm. It fits - no clearance issues! These are made by ISB Industries. Now I just have to figure out how to grease them, and make sure I install them correctly!

There are special spray lubes for uniball joints. CRC makes a "Dry PTFE Lube" or there's Tri-Flow's Uniball and Heim Joint Spray lube. DON'T use grease or WD-40.

Curious how much noise/vibe these transfer in the little cinquino, but they should help tighten up the steering a bit.

Thanks! Makes sense. The lube nipple is ridiculously small - 5mm, and looks like it would only accept a thin oil like PFTE. Now I’m trying to find a lube container/spray tip that mates with that tiny nipple. Looking forward to installing it all. Hopefully doesn’t make steering unpleasant. I never intended to change the standard steering, but this was the easiest way to solve the brake disc clearance issue.