With the Wilwood 120-11872-RD calipers, the banjo bolt hits the damper mount on the LCA, at full droop / full lock:
To address this, I started by reducing the head height of the banjo bolts, but that wasn't enough.
The Wilwood caliper I have is actually made for a 1.04" thick rotor, so with the 0.87" thick LeBaron rotor, the caliper is excessively wide.
To gain banjo bolt clearance, I decided to narrow the caliper by removing 2.5 mm of material from the outer half:
For more banjo bolt clearance, I also removed 3.5 mm of material from the banjo bolt boss:
I plunged the cutter in the Z-axis, so any machining marks would be circular around the banjo bolt, to avoid creating any radial leak paths.
Then, I bolted the calipers back together:
Next weekend I'll be able to bring the calipers to the car and see how much the banjo bolt clearance situation has been improved.
Since it looks like I'm going to be replacing my sluppy123 hubs with custom hubs, if I need to gain more banjo bolt clearance, I may also draw my custom hubs with some positive offset to push the wheel/caliper a bit more outboard.
With the following mods, I finally have 4 mm of clearance between the banjo bolt and LCA: 2.5 mm removed from outer half of caliper. 3.5 mm removed from fluid port boss on caliper. Banjo bolt head reduced in height. Material ground off from LCA.
That's all with a stock sluppy123 hub.
I think that 4 mm clearance is OK, but if I end up making custom hubs, I'll add a bit more positive offset.
For my front hubs, I'm going with modified front rotor/hubs.
To set up the stock rotor on the lathe, I used a (modified) steering knuckle as a fixture. The steering knuckle is centre-drilled at both ends from the factory.
I crudely statically balanced the steering knuckle by balancing it on one of its centre holes. For torque transmission, I added a steel bracket, which drives one of the hub's ribs.
The setup worked fine without vibration at 150 RPM.
Originally posted by Will: You located it on the bearing races to minimize runout in the final part? Are you planning to face the wheel mounting surface?
Looks like a lot of extra work vs. chucking on the inboard journal, if all you're doing is parting off the rotor
Or are you turning the rotor down from its original OD?
The LeBaron rotor centrebore is slightly large for the Fiero hub's wheel/brake register, so my plan is to build up the area with a Permatex Steel Weld (a steel-loaded epoxy), and then turn it down to fit the LeBaron rotor. This operation needs to be low-runout, so that's why I prepared the setup with location via the bearings. If the brake rotor is mounted eccentrically, then that will cause a static mass imbalance.
Yes, I will be skimming the wheel/brake mounting surface. Initially, that was not part of the plan, but the yahoos at Dynamic Friction (or at the Chinese factory where the rotors were produced) installed the lug studs with an excessive amount of interference (approx 0.025"). This caused some material to be displaced, proud of the surface, hence needing to take a skim cut to make things flat.
As the lug holes are undersized, I'll be able to ream them to 12.5 mm and install Dorman 610-323 studs.
In my previous post, I simply converted the braking surface into a pile of chips. That operation didn't need much precision, but I wanted to do a "shakedown run" of my knuckle / bearing-locating setup, before using it for the more fussy higher-precision operations.
The LeBaron rotor centrebore is slightly large for the Fiero hub's wheel/brake register, so my plan is to build up the area with a Permatex Steel Weld (a steel-loaded epoxy), and then turn it down to fit the LeBaron rotor. This operation needs to be low-runout, so that's why I prepared the setup with location via the bearings. If the brake rotor is mounted eccentrically, then that will cause a static mass imbalance.
The front LeBaron rotor has a smaller rotor pilot than the rear rotor. It's also slightly smaller outside diameter, but it fits the Fiero rotor pilot without modification, IIRC.
In my previous post, I simply converted the braking surface into a pile of chips. That operation didn't need much precision, but I wanted to do a "shakedown run" of my knuckle / bearing-locating setup, before using it for the more fussy higher-precision operations.
I guess if you only need to make two, that's a fine way to do it... a part-off tool would be MUCH easier.
Originally posted by Will: I guess if you only need to make two, that's a fine way to do it... a part-off tool would be MUCH easier.
Besides having to buy (or grind) a tool to do that, I didn't want to deal with the disc coming loose at the end of the cut and possibly smashing/jamming into something.
I also thought about roughly cutting off the disc with an angle grinder + abrasive cutoff wheels, but that would have required many cutoff wheels, and I would have been left with a polygon shape needing to be turned on the lathe. I don't really like cutting polygons into round shapes; I'm not a fan of interrupted cuts like that.
For three hubs (I wanted a spare!), the method was workable, but tedious.
Ideally, I think it would be best to use an endmill to mill a groove to separate the disc from the hub; either conventional mill with rotary table, or CNC. I didn't have either of these tools at my disposal.
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Originally posted by Will: The front LeBaron rotor has a smaller rotor pilot than the rear rotor. It's also slightly smaller outside diameter, but it fits the Fiero rotor pilot without modification, IIRC.
That's a good suggestion / good info.
I looked at pics on Rockauto, and it seems like that rotor has a rather shallow rotor hat. My caliper-to-wheel clearance is quite tight as things are now; I think that might turn into interference with the front LeBaron rotor! I'll stay on my current path for now.
The Grizzly Rotary table has been a great addition to the Bridgeport at work, not too expensive either, and nice for making cuts that are not 90* to one another in addition to doing circular things. Can be mounted vertically or horizontally.
The other way you could have rough cut the rotor off is with a jig saw and a steel cutting blade, it does a decent job, I have done some circular cuts in 0.25" steel with it. Not the speediest operation but much better than using cutoff wheels.
Nice work though, hope you get to enjoy the car this summer now that you have your hubs sorted, I am very curious to hear about how you like the car with your anti dive mod, I would like to do something similar.
Besides having to buy (or grind) a tool to do that, I didn't want to deal with the disc coming loose at the end of the cut and possibly smashing/jamming into something.
I also thought about roughly cutting off the disc with an angle grinder + abrasive cutoff wheels, but that would have required many cutoff wheels, and I would have been left with a polygon shape needing to be turned on the lathe. I don't really like cutting polygons into round shapes; I'm not a fan of interrupted cuts like that.
Sounds like you're talking about making the cut axially through the rotor. I'm talking about making the cut radially through the hat section.
Originally posted by zkhennings: Nice work though, hope you get to enjoy the car this summer now that you have your hubs sorted, I am very curious to hear about how you like the car with your anti dive mod, I would like to do something similar.
The snow is melting fast, so I'm quite looking forward to the summer and getting the car ready!
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Originally posted by Will: Sounds like you're talking about making the cut axially through the rotor.
Yes, that's what I meant.
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Originally posted by Will: I'm talking about making the cut radially through the hat section.
I see what you mean; in your proposition, the ribs keep the disc attached to the hub. Then, as a second step, the ribs could be cut with a small cutoff wheel to free the disc.
I wanted to keep the hat+rib area intact, as I wasn't sure how much material could be removed from there while keeping the hub strong enough. In comparison though, the rear hubs are a lot more flimsy-looking, yet they seem adequately strong.
[This message has been edited by pmbrunelle (edited 03-08-2024).]
Did not realize it was just for the rotors, I wouldn't expect any issues then. I was speaking more to the ability of the metal reinforced epoxy to chip because it is pretty hard, almost like a ceramic, and I have had it chip/crack on me before. The plastic rings are soft enough they will not chip, but they are a pain as eventually they don't fit as snug, I have had to glue mine into my wheels after a few years where they used to stay installed from friction. But removing/installing rotors is much more gentle than removing/installing wheels.
