I would think you could swap the bolts to the rail with M12X175 Torx seat belt bolts, that would substantially reduce 'head height' and don't require a washer because of head diameter. Sufficient for larger Heim? I've no idea but I'd think ideal for most. Bolts would be an easy JY find.

Mine not being bolted to car but having arms bolted to them I should be able to measure the clearance in some fashion. I might try to do that but not today. Appointments.

A typical M12X1.75 Torx seat belt bolt

 

I was wondering about something like this, too. I guess the big question if if those seatbelt bolts have any strength limitations, and/or whether one can safely torque them to the proper spec with their Torx head design. FWIW, the "head" of the rod ends that Banski uses (Aurora VCM-10 and VCB-10) are only 1.5" in diamter. I think that is actually a smaller diameter than the stock arm "heads." I can measure those later today.

 

I wouldn't think either issue you seem concerned with is an issue. You actually believe a seat belt bolt could be less than 9.8? I don't see where torque should be an issue either.

An issue seems to be that the rods are actually located at 'depressions' in the bracket and there would certainly be limitations as to where they could be located. See SuperL98's snapshots in post#16

I checked mine this AM quickly, at first glance visually it seems to be an issue. Insurmountable? Likely not. That 'local' fella did!!

**Using 'centers' you'd want to locate which direction how much? That would determine the feasibility and the M12 bolt I suggested would certainly make it more feasible.

 

It may not make any difference at all, but it would depend on the grade of the OE bolts (which I don't know offhand - I'd have to look). Seatbelt bolts are mainly designed to work in shear, and as such may be grade 8.8: a little softer than 10.9 and capable of less tensile and clamping force, but also less brittle and therefore less likely to fracture in shear. They can deform in a crash and still do their job, as long as they don't fracture; so yield strength is not as important. The bolts holding the trailing arm brackets to the frame are mainly going to see tension loads (some shear, but not the majority of the force on them); and they must not deform, so high yield strength is important. I would guess (but just a guess) that they might be 10.9 to give them ideal tensile strength, and that shear strength is less important. The flatter head of the seatbelt bolt alone would make me guess it's less strong in tension. Maybe it wouldn't matter at all - maybe three 12mm bolts per bracket is overkill and so grade doesn't matter

Yeah, that's a good point. One would have to measure.

There is room to make some change - it's just a question of how much change is achievable. Or one could always make brackets with the pivot holes further from the frame, and then use shorter arms (rod ends make this easier, obviously). That obviously changes rear geometry in other ways, but probably not by much. Or maybe the seatbelt bolt idea would work well. There are definitely ways around it.

 

It's very easy to take 'center/center' measurements: just measure the distance from the "east" side of one hole to the "east" side of the other hole.

 

Only works if the 'bores' are empty!! Let's consider 'better' if bores are empty and very accessible.

I was measuring with flange head bolts, flange head nuts with brackets and arms assembled. Using 'east to east' side of exposed threaded ends of bolts gets interesting.

**I get the 'east to east' reference - I've a friend who might explain dimensions like that!

 

The example you gave has to have "empty bores".... I was going by your example.

 

Not sure which spring you're talking about here (front or rear), but I thought I'd point out that only the front provides the anti sway properties. The way the rear is mounted in the C4, each side of the spring behaves like a normal, "independant" spring.

 

Not at the rear. In order to provide additional roll resistance (compared to ride rate), a transverse leaf needs to be clamped in two places with significant space between them. That space is what allows the "wave" bend to take place in the middle of the leaf and cause in-phase force on the opposite end of the leaf. The rear spring is clamped in two places, but they are too close together to allow the leaf to bend in between the two clamps. So the anti-roll effect does not happen in the rear, only the front.

 

WHY?

Only if you lowered your rear rates. The rear spring, whether coil or leaf, both act directly on the knuckle. Wheel rate should remain identical if the spring rate is identical.