The LeBaron rear rotor centrebore lies somewhere between a Fiero rotor centrebore and a Fiero wheel centrebore.
Therefore, it is not compatible with stock Fiero hubs.
Up front, I simply used some $$$ to order some sluppy123 7075 aluminium hubs. Brian makes the hub to fit the centrebore of your chosen rotor.
The hubs were almost perfect, though the fit between the pilot and the centrebore was a bit tight for my tastes, so I pressed out the studs, turned down that diameter a hair, and then re-installed the studs.
I painted the backside of the hubs with yellow zinc chromate primer.
Typically, Brian powder coats most of the exterior surfaces black, but my personal preference is to have no powder coating in a bolted joint (i.e. in the wheel-brake-hub stack). Brian left these hubs bare so I could finish them as I pleased.
I'm quite satisfied with these hubs. They didn't require any deburring, and Brian is good at answering questions.
The Dorman 610-323 studs at all four corners are pretty long, so I'll have to use open-ended lug nuts.
That's OK, if I ever want to take this car to the racetrack (tech inspection), having the studs stick out beyond the lug nuts will allow anyone to quickly determine that my lug nuts have sufficient thread engagement.
If my future plans didn't involve custom spindles, I would be all over the aluminum hub, it would be awesome to have something like that, I bet the difference in weight almost makes the brake upgrade overall weigh about what stock did.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
In your case, it would make sense to try to work with a commonly available off-the-shelf hub, perhaps 5x4.5"? How much do you want to keep your current wheels?
On the subject of weight, I did get some Wilwood aluminium calipers for the front; they seem lighter than the cast iron calipers.
I began with the 2.125" parking-brake rear Seville calipers as a "given", so these Wilwoods were the closest match I could find in terms of piston area. I was looking for the same piston area front and rear, or maybe just a little bit bigger up front. I also wanted to be compatible with stock Fiero brake hoses, and have bleeders that would work.
Apparently Wilwood doesn't deburr their stuff, so I had to go at these brand-new calipers with a file.
Forum member wftb uses these same calipers.
[This message has been edited by pmbrunelle (edited 02-18-2021).]
I personally installed a "bias"valve to adjust the forces on the front and reat calipers. I don't need any of those fancy calipers because of the weight of my car. For a stock weight Fiero those calipers would make a big difference, but mine being 500lbs lighter, it doesn't need that much clamping force on the rotors. I use the stock Sevile rear calipers on the fronts, Le Baron rear rotors coupled with the Hawk DTC 30 pads up front and stock pads at the back. I still managed to send plenty of pressure to the back and make the car stop very fast. Of course, I only had 173WHP with the 2.8 back then. Now with over 300+WHP I have to re-think the braking set up. Patrick, that looks very "purdy"!
In your case, it would make sense to try to work with a commonly available off-the-shelf hub, perhaps 5x4.5"? How much do you want to keep your current wheels?
On the subject of weight, I did get some Wilwood aluminium calipers for the front; they seem lighter than the cast iron calipers.
I began with the 2.125" parking-brake rear Seville calipers as a "given", so these Wilwoods were the closest match I could find in terms of piston area. I was looking for the same piston area front and rear, or maybe just a little bit bigger up front. I also wanted to be compatible with stock Fiero brake hoses, and have bleeders that would work.
Apparently Wilwood doesn't deburr their stuff, so I had to go at these brand-new calipers with a file.
Forum member wftb uses these same calipers.
I'm undecided on the wheel pattern yet, there are several viable options that I can see, without making the design too complex. My biggest concern, is maximizing the use of off the shelf parts, which I'm fairly certain will lead to either 5x4.5 or 5x4.75, and new wheels... I think the end product will probably be 5x4.75 and use Corvette wheel bearings, they're brutally strong, even in heavier cars, and will be available pretty much forever. My current prospect, is to utilize a Wilwood kit for the C6 rear on all four corners so that I can utilize the C5/C6 parking brake, something that my current setup is lacking.
The distinct advantage to using Wilwood parts, is that every shred of info you could need is on their website, and kits can be piecemealed together over a long period of time, and as much as some of the stuff I'm looking at costs, it's definitely worth considering.
All that being said, I don't think updating the brakes is in this car's near future, this is a very long term project, for now, I'll finish the suspension work I have going on, put a bigger MC on it, and drive it a while, we all know it's been way too long since I drove it regularly.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Originally posted by La fiera: Of course, I only had 173WHP with the 2.8 back then. Now with over 300+WHP I have to re-think the braking set up.
Your front/rear brake bias should stay the same, it would just be the heat/fade resistance that would need to change.
quote
Originally posted by La fiera: Patrick, that looks very "purdy"!
I like purdy!
quote
Originally posted by ericjon262: The distinct advantage to using Wilwood parts, is that every shred of info you could need is on their website, and kits can be piecemealed together over a long period of time, and as much as some of the stuff I'm looking at costs, it's definitely worth considering.
Wilwood offers some parts as drop-in replacement for OEM components.
Since these parts are somewhat dimensioned, you can use the Wilwood information to make some educated guesses on the OEM parts they're meant to replace, in case you want to use the OEM/jobber version.
I changed the way the car transfer its weight back to front and side to side. The theory behind it is to have more rear bite by preventing some weight from transfering back to front while braking. I went from 350lbs springs all around to 700lbs fronts and 900lbs rear. I'm trying to eliminate nose dive, and body roll which delays response time, I also like my cars/karts a bit on the loose side so I can "dance" through the corners. Do you still think the brake bias would be the same? Thanks in advance for your input Patrick!
[This message has been edited by La fiera (edited 02-19-2021).]
That's definitely an option as well. My biggest goal with a brake upgrade at the moment, is to gain a functional parking brake. the secondary goal, is to lose some weight off of the existing C5/C6 front calipers and rotors. The additional weight of the parking brake may make that difficult, but I suspect I can lose a decent amount of weight via different calipers, and two piece rotors.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
I changed the way the car transfer its weight back to front and side to side. The theory behind it is to have more rear bite by preventing some weight from transfering back to front while braking. I went from 350lbs springs all around to 700lbs fronts and 900lbs rear. I'm trying to eliminate nose dive, and body roll which delays response time, I also like my cars/karts a bit on the loose side so I can "dance" through the corners. Do you still think the brake bias would be the same? Thanks in advance for your input Patrick!
I just installed anti dive spacers on my car, I have yet to drive it with them though, and I also installed drop spindles at the same time, so it will be hard to say how much difference they make. Once I drive it, I'll post a detailed description of what was done, and the difficulties encountered in the process.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
How do those spacers work?? If you add height there is more potential and kinetic energy to be added during braking thus creating more dive! How does your anti-dive plates work?
Rotates the entire front suspension "forward" around the rear pivots of the lower control arms, which are fixed to the body. Yes, it raises the body an inch on the suspension, but he has 2" lowering knuckles.
In stock form, the rear pivots of both upper and lower control arms are below the forward pivots. This is done for ride quality (I guess) so that the wheel moves back when it hits a bump. It also means that braking forces compress the suspension, resulting in pro-dive. Rotating the suspension forward makes those pivots level, eliminating pro-dive. The Fiero finally brakes flat like a supercar.
How do those spacers work?? If you add height there is more potential and kinetic energy to be added during braking thus creating more dive! How does your anti-dive plates work?
I also added drop spindles, the net change actually lowers the car, and the spacers are a negligible amount of mass, so kinetic energy change is also negligible.
They work by changing the angle of the control arms. I haven't driven the car with them yet, so I cannot confirm how well they work. I think further discussion should occur in another thread though.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Originally posted by Will: In stock form, the rear pivots of both upper and lower control arms are below the forward pivots. This is done for ride quality (I guess) so that the wheel moves back when it hits a bump. It also means that braking forces compress the suspension, resulting in pro-dive. Rotating the suspension forward makes those pivots level, eliminating pro-dive. The Fiero finally brakes flat like a supercar.
So you don't actually need anti-dive for a "good result"?
How much elevation difference is there in a stock Fiero between the front and back LCA pivots?
I was thinking that with your spherical bearing kit, I might be able to simply move the pivots a bit without having to move the crossmember.
Also the UCA tube could be welded on with a different angle onto the crossmember.
I changed the way the car transfer its weight back to front and side to side. The theory behind it is to have more rear bite by preventing some weight from transfering back to front while braking. I went from 350lbs springs all around to 700lbs fronts and 900lbs rear. I'm trying to eliminate nose dive, and body roll which delays response time, I also like my cars/karts a bit on the loose side so I can "dance" through the corners. Do you still think the brake bias would be the same? Thanks in advance for your input Patrick!
The ideal brake bias depends on the weight on the front/rear tires, and how much you want the rear loose on braking.
With the stiffer springs / anti-dive, you don't (during sustained braking) change the amount of weight transferred from rear to front, even though the body of the car pitches less. Therefore, your bias requirement shouldn't change.
However, with stiffer springs / anti-dive, you do get the weight transferred more quickly from rear to front. Therefore, you don't have to be as careful with slowly/smoothly applying the brake pedal to avoid locking up the front tires before the weight has been transferred.
[This message has been edited by pmbrunelle (edited 02-20-2021).]
So you don't actually need anti-dive for a "good result"?
How much elevation difference is there in a stock Fiero between the front and back LCA pivots?
I was thinking that with your spherical bearing kit, I might be able to simply move the pivots a bit without having to move the crossmember.
Also the UCA tube could be welded on with a different angle onto the crossmember.
one of the things that will need to be considered, is that with the spacers, the spring moves with the crossmember, by moving just the mount points, your springs will provide less force.
I'll take pictures of the crossmembers later, but I'm also not convinced it would be easier to remove and replace the the pivots. there's alot going on around the UCA tube, and lowering the LCA forward pivot an inch would also result in clearance problems with the edges of the stamping.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Also, changing the *relative* locations of the pivots will alter the bump steer curve from... whatever it looks like now to... something else. That's why I went to lengths to figure out how to make wedges instead of flat spacers.
ETA: Also 2: doing this reduces caster to around zero. I have a design in my head for an adjustable UCA that could fix that, and now that I have my design for the '88 mostly done, I'm working around toward building the design for the '84-'87 cars.
[This message has been edited by Will (edited 02-20-2021).]
Originally posted by ericjon262: one of the things that will need to be considered, is that with the spacers, the spring moves with the crossmember, by moving just the mount points, your springs will provide less force.
The spring rate won't change, but if I move the front LCA pivot down, it will lower the ride height some... which is something I wanted to do. If I lower the car by this method, I'll maintain the same travel as stock, and I won't have to trim the front bumpstops.
quote
Originally posted by ericjon262: I'll take pictures of the crossmembers later, but I'm also not convinced it would be easier to remove and replace the the pivots. there's alot going on around the UCA tube, and lowering the LCA forward pivot an inch would also result in clearance problems with the edges of the stamping.
Yeah, the UCA area might be tricky to work with.
I might just leave it alone, playing only with the LCA pivots may give some beneficial effect, considering that the spindle is closer to the lower ball joint than the upper ball joint.
With the lip on the crossmember, I'm expecting to do a cut+weld+patch job to accommodate a lowered front LCA pivot.
quote
Originally posted by Will: Also, changing the *relative* locations of the pivots will alter the bump steer curve from... whatever it looks like now to... something else.
Right... some study will be in order.
quote
Originally posted by Will: ETA: Also 2: doing this reduces caster to around zero.
By just moving around the LCA pivots, I should still have caster, since the UCA isn't moving forward.
Anyway, I need to think about this, suspension modifications won't be anytime soon. For now I'm in feasibility study / benchracing / dreaming / planning mode.
The ideal brake bias depends on the weight on the front/rear tires, and how much you want the rear loose on braking.
With the stiffer springs / anti-dive, you don't (during sustained braking) change the amount of weight transferred from rear to front, even though the body of the car pitches less. Therefore, your bias requirement shouldn't change.
However, with stiffer springs / anti-dive, you do get the weight transferred more quickly from rear to front. Therefore, you don't have to be as careful with slowly/smoothly applying the brake pedal to avoid locking up the front tires before the weight has been transferred.
Thanks Patrick! That was exactly why I switched to stiffer springs and you just confirmed that! Before with the softer (350lbs) springs all around I had to slowly apply the brakes to prevent reat lock up due to the bias and slow weight transfer. If I didn't get it precise, I had the car dancing from high speed braking (120mph to 40) to low speed while braking on a straight line and trail braking while turning.
[This message has been edited by La fiera (edited 02-21-2021).]
The other thing that worries me with those aluminmu hubs is the growth expation rate. For the street and dragway they will be just fine but at a 30min track session of repetitive braking from 80mph to 40mph happening 20 times per lap would mean an exponential growth of hub size leading to small clearances tightening the bearing and finally locking it! That's why I personally decided to stay with the steel unit; its more forgiving. What do you think Patrick?
The other thing that worries me with those aluminmu hubs is the growth expation rate. For the street and dragway they will be just fine but at a 30min track session of repetitive braking from 80mph to 40mph happening 20 times per lap would mean an exponential growth of hub size leading to small clearances tightening the bearing and finally locking it! That's why I personally decided to stay with the steel unit; its more forgiving. What do you think Patrick?
Before I ordered these hubs from Brian, I had this discussion with him.
My question: Since the hub is aluminium, but the spindle is steel, have you heard of problems from the hub expanding with heat, making the bearings run too tight?
Brian's answer: I haven't nore have any of my customers experienced any problems with dis-similar materials. 3 of my customers use my hubs on all out race cars including one that does 12-24 hour endurance races. No problems to report in the past 5 years.
I was satisfied with his answer (especially the part about the 12-24 hour endurance races), so I decided to try his hubs.
Before I ordered these hubs from Brian, I had this discussion with him.
My question: Since the hub is aluminium, but the spindle is steel, have you heard of problems from the hub expanding with heat, making the bearings run too tight?
Brian's answer: I haven't nore have any of my customers experienced any problems with dis-similar materials. 3 of my customers use my hubs on all out race cars including one that does 12-24 hour endurance races. No problems to report in the past 5 years.
I was satisfied with his answer (especially the part about the 12-24 hour endurance races), so I decided to try his hubs.
Ok. I'm curious because I saw a video on YouTube of a Fiero at an endurance race loosing a front wheel with the hub attatched to it. What's the weight difference between the aluminum vs steel counterpart?
[This message has been edited by La fiera (edited 02-22-2021).]
It would be a good idea to jack up the front of the car after running it hard, and then verify that the wheel bearings still have a small amount of play.
It would be a good idea to jack up the front of the car after running it hard, and then verify that the wheel bearings still have a small amount of play.
Or, to observe indirectly... instrument spindle temperature? Gun drill the spindle and epoxy a TC or other temp sensor into the hole out at the tip...
[This message has been edited by Will (edited 02-27-2021).]
If it is was stock hub, it was neglected. I can't seem to trust those aluminum hubs for racing. (Drag racing yes, road racing; hell no).
how about aluminum wheels?
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
That's a different story. Just the size difference between the hubs and the wheels should answer that question for you. The aluminum wheel due to its size can disipate heat very fast compared to a diminutive aluminum hub.
Since you brought up heat we'll do some math, the coefficient of thermal expansion of 6061 aluminum is about
13.1 μin./in. ·°F.
1μin =0.000001 in
we'll say the hub is 6" long we'll get extreme and say the hub gets 400F hotter than ambient, the drop point of typical bearing grease is about 500F, so this would put the grease close to turning liquid.
The formula for linear expansion is
L=L0⋅(1+α⋅ΔT)
L=length final L0=initial length α=coefficient of expansion ΔT=difference in temperature
L=6"(1+0.0000131*(400)
our final length works out to be 6.03144"
but, we can't discount the expansion of the spindle too, we'll say it's also 6" for simplicity. the expansion coeffcient for steel is about 1/2 that of 6061, at 6.8 μin./in. ·°F
using the same equations as above, we come up with 6.01632" for the final length of the spindle a difference of about 0.0152" A note about the math, coefficients of expansion aren't necessarily linear over large transients, so for the calculations to be 100%, they would need to be calculated at different ranges and added together, not just as one equation as performed here. it's also worth noting that the thermal conductivity of aluminum is much higher than iron or steel, so it will likely dissipate heat better than the steel piece, and remain cooler.
Corvettes and numerous other vehicles use aluminum knuckles, with probably only slightly more mass than a hub like this, and still have to absorb the heat generated in the hub, as the cartridge style bearing is inside the hub.
tl;dr
I don't think heat will be a problem unless you have another problem causing insane temperatures in the hub.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Originally posted by ericjon262: our final length works out to be 6.03144"
but, we can't discount the expansion of the spindle too, we'll say it's also 6" for simplicity. the expansion coeffcient for steel is about 1/2 that of 6061, at 6.8 μin./in. ·°F
using the same equations as above, we come up with 6.01632" for the final length of the spindle a difference of about 0.0152"
The length of the aluminium hub that is sandwiched between the steel bearing cups is about 1-15/16" (I just measured it), so it's about three times less than the 6" figure you used in your example.
So adjusting your 0.0152" figure for the length I measured, that gives 0.0049" of growth (keeping your same assumptions).
It's not insignificant, considering that the bearing endplay is probably around 0.005" at room temp. It's hard to give an exact number; I usually use my feel-o-meter to adjust this type of bearing.
I've never broken out the dial indicator for adjusting wheel bearings. Maybe I should, this time.
The length of the aluminium hub that is sandwiched between the steel bearing cups is about 1-15/16" (I just measured it), so it's about three times less than the 6" figure you used in your example.
So adjusting your 0.0152" figure for the length I measured, that gives 0.0049" of growth (keeping your same assumptions).
It's not insignificant, considering that the bearing endplay is probably around 0.005" at room temp. It's hard to give an exact number; I usually use my feel-o-meter to adjust this type of bearing.
I've never broken out the dial indicator for adjusting wheel bearings. Maybe I should, this time.
I don't think I've ever seen someone use a dial indicator on a wheel bearing.
The other aspect to consider is the ACTUAL temperature of the components, I doubt they're running at 400F+ like my assumption states. Maybe I'll take the Suburban down the interstate for a bit and try and put some heat in the front hubs and see what they look like with my FLIR.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
I don't think I've ever seen someone use a dial indicator on a wheel bearing.
The other aspect to consider is the ACTUAL temperature of the components, I doubt they're running at 400F+ like my assumption states. Maybe I'll take the Suburban down the interstate for a bit and try and put some heat in the front hubs and see what they look like with my FLIR.
Make sure you drive riding the brakes to simulate stop and go traffic and track use. Make that rotor smoke!
Make sure you drive riding the brakes to simulate stop and go traffic and track use. Make that rotor smoke!
My intention would be to determine temperature rise under normal-ish conditions, compared to ambient, I fully understand that an actual test of track conditions would require significantly more maneuvering and abuse than I am going to put an 88 Suburban with no swaybars through. This data would provide a baseline temperature rise, to get an idea of if the nearly 500F figure is insane or not, I suspect the hub will have a temperature rise not greater than 100F under normal driving conditions, maybe tomorrow I can find the time to do it.
It's also worth mentioning that vented brake rotors get a significant amount of cooling via the air gap between the faces. The vanes provide airflow while the vehicle is moving. the vanes operate like a centrifugal fan, cool air enters near the hub, cools the rotor, and is discharged away from the hub near the rim. The rotors on my car take this a step further and curve the vanes to provide more airflow. that's not to say the rotor doesn't get hot, but to say the rotor isn't primarily cooled by the hub via conduction, the primary cooling is forced convection.
It's also important to remember the cooling is taking place, directly where the heat is being generated, between the pads.
I think Will really hit the nail on the head with his instrumentation method, a small probe could be inserted in the back of a gun drilled spindle to provide a very accurate indication of what is going on in the bearings. an IR thermometer could be installed externally to monitor the hub surface.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
Here you go Patrick, this will keep your temps and aluminum hubs from locking up. Turbofans! I'been looking around and found a set for my Supernatural Fiero.
Long lug nuts with a smaller threaded hole on the outside to bolt the fan. At least that's the way I think it could work. I grew up watching IMSA and Group 5 racing from the 80's on. One thing I noticed was the funny looking thing specially on the front wheels. Some had it in all four wheels like the Audi Quattro IMSA and TransAm cars. Besides helping on cooling the brakes and looking cool I want to use them on my Supernatural to give it that retro look.
I honed the bores to remove any corrosion. Then, I sandblasted the exterior.
I applied silicone grease (Kleen-Flo Eze-Slide) to the bores to reduce future corrosion, and to aid in assembly. The pistons were then inserted with a C-clamp. One piston had to be replaced, as I found brake fluid behind the vent hole.
After masking the calipers, and setting them on makeshift "paint stands", I painted them with red spray-can VHT caliper paint.
The shade of the VHT is darker than that of the Wilwood caliper, but it is acceptable (for now).
I will wait perhaps two weeks, then I will bake the calipers 1 hour at 200 °F in the oven, as per VHT instructions.
I got a set of D54 Wilwood Big bore dirt track calipers for the front which I had previosly used but one of them started to stick. Where can get parts to rebuild them?
Thank you guys! I found the kit to rebuild mines. I guess it was lack of use that caused the problem. I had them when I had the 2.8 making 173WHP and the brakes were very touchy and grabby. If I put a bit too much pressure on the pedal the front wheels would lock up. The reason I want to install them back is because since the cam on the 3.7 wont make much vaccuum I'm wondering if by installing these back would give me a bit more bite if I run out of vaccuum assist. I'll give them a try. Forgot to mention I had Hawk DTC 30 pads on them, never had brake fade. The last time I had the car on the track with these calipers I went out on a session and it was a Mustang Bullitt, a NASCAR tube frame chassis car with a wicked high compresssion 2.5L 4 cylinder Pinto engine built for oval track, a ZO6 Vette on slicks and me. The NASCAR and I were matched on power but when it came to braking and exiting cornering speed it was no match for me to outbrake him and drive away off the cornres. The NASCAR weighted about 3000lbs+! With the Mustang and the Vette it was the same story but they could out accelerate my Fiero easily on the straights and then I'd get them braking. It was awesome!
[This message has been edited by La fiera (edited 03-04-2021).]
