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11-1/4" LeBaron brake upgrade guide (Page 1/5) |
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pmbrunelle
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MAY 29, 03:59 AM
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Firstly, some of my general thoughts regarding brake upgrades on Fieros:
Lets not forget the obvious. Get sticky tires.
Leave the factory combination valve unmodified, or gut the factory proportioning valve and install an aftermarket adjustable valve.
A proportioning valve is not a band-aid for poorly sized brake components - it is merely a fine-tuning tool. Brake parts should be sized within the "acceptable range".
Use identical calipers, or calipers with similar piston areas (maybe a touch larger up front) on all four corners.
Use discs of the same diameter all around.
Note that those with Grand AM brakes all around seem very satisfied...
While I'm suggesting that the front and rear brakes should produce roughly equal brake torque per unit line pressure, I also believe that the power dissipation capability should be front-biased, to equally heat up (and thus equally fade) the front and rear brakes on repeated threshold braking. Thicker front discs and thinner rear discs would be a good thing in my book.
Don't go crazy with the rotor diameter. If you have enough mechanical advantage to stop comfortably, then there's no sense in increasing the rotor's moment of inertia. Also, think about the wheels you'll need to clear your choice of brakes.
Proper bias (which depends on the available friction) is key to short stopping distance. Don't confuse gain with stopping distance. If you're capable of locking up the tires, more gain isn't going to shorten stopping distance.
The only way you can hope to improve stopping distance over stock is to optimize the bias better to fully utilize the available friction if it wasn't already optimal. Also, if the "big brakes" are easier to modulate, it will be easier for the driver to make short stops.
A video-game mushy Honda Accord style (over-boosted) pedal makes brake modulation difficult. Lower gain, but firm pedal facilitates modulation and short stops (tires also play a role). Don't over-boost...
Stick with glycol-based, rather than silicone-based brake fluid. I'll leave it at that, as this could be an entire discussion on its own!
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For 88 Fiero owners looking for a brake upgrade, I suggest you go with the C4 Corvette 12" rotor upgrade, which retains stock hydraulics, simply moving the factory calipers outwards using brackets. In my opinion, that is hands-down the best overall compromise of cost/weight/performance for a typical Fiero owner.
For us 84-87 Fiero owners, this is a guide on how to install LeBaron brakes (one of the best options for 84-87 Fieros in my opinion) using the 10 degree rotated brackets, with my opinions on the best compromises of cost/weight/performance. Modify the instructions as you see fit. (if you feel comfortable modifying the instructions, you know who you are.)
Possible ways of doing the swap differently:
Use front LeBaron rotors with different thickness caliper bracket spacers and hubcentric rings Different bore master cylinder Different calipers "Hockey stick" parking brake cable brackets Use of different pad compounds front and rear No parking brake Play around with the spacer thicknesses specified by Walt Zettner - consider that you're bolting stuff onto a rough cast surface, so your mileage may vary...
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Miscellaneous:
You'll probably need to go to 16" wheels or higher to clear LeBaron brakes, but according to this thread: http://www.fiero.nl/forum/A...050818-2-059785.html GT lace wheels may require minor grinding.
Yeah, my instructions say to use identical rotors all around, contrary to my own advice. It's a compromise I'm suggesting for simplicity...
I didn't include instructions for MC removal/installation as that's a standard procedure, not specific to the LeBaron brake swap.
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Typical parts list:
10 degree rotated caliper adapter bracket set Look in the Mall
Master cylinder (see post down the page for details)
Front calipers with pads & hardware (see post down the page for details)
Rear calipers with pads & hardware (see post down the page for details)
4 x M12 x 1.5 x 40 mm bolts, Grade 10.9 or higher suggested (1.5mm thread pitch is the fine thread)
4 x M12 x 1.5 x 25 mm bolts, Grade 10.9 or higher suggested (1.5mm thread pitch is the fine thread)
4 x front caliper bracket spacer, 1" O.D. X 0.5" I.D. X ~ 0.435" thick http://www.mcmaster.com/#shaft-collars/=7ao9m3 should do the trick
4 x rear caliper bracket spacer, ~0.060" thick 1/2" I.D. washer is fine; I just bought a bunch of washers and picked the four that were closest to 0.060"
4 x 90-94 Chrysler LeBaron GTC 11-1/4" diameter ventilated rear discs
10 x DORMAN 610-323 extra-long lug studs Also listed as the stock wheel stud for a 2006 Hummer H3[This message has been edited by pmbrunelle (edited 06-19-2010).]
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pmbrunelle
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MAY 29, 04:07 AM
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Master Cylinder choices
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92-94 Chevrolet Blazer MC with 1-1/8" bore (watch out, Blazers were also available with 1-1/4" master cylinders)
The Blazer MC is essentially a large-bore version of the factory Fiero MC. I used this one. The only caveat is that the Blazer MC's brake fluid reservoir is taller than the Fiero's reservoir, which would interfere with the sunroof glass if stowed away in the front trunk. The solution is to swap the Fiero reservoir onto the Blazer MC. The reservoir is simply pressed into the MC - no hidden fasteners. Prying with a screwdriver may be necessary.
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67-80 Chevrolet Corvette MC with 1-1/8" bore (watch out, Corvettes also came with 3/4" MCs)
Alternatively, the Corvette MC can also be used. It lacks the quick-take-up feature (large bore during low pressure operation) of the Fiero/Blazer MC, which may lead to a slightly lower pedal. I have no experience with this MC. If you don't have a good Fiero donor reservoir to use on a Blazer MC, this might be a good choice. Some people prefer the styling of this MC.
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Factory Fiero MC
I don't recommend this except for cases with calipers with small piston areas, or if you want a really high gain.[This message has been edited by pmbrunelle (edited 05-29-2010).]
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pmbrunelle
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MAY 29, 04:09 AM
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Brake vacuum booster choices
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Factory booster
I happen to like the pedal feel with the factory booster. The pedal is firm, easy to modulate, and not mushy. Maybe if I ever drive an exotic car I'll change my mind about my Fiero's pedal feel...
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Chevrolet S10 booster
aka the $100 brake upgrade: http://www.fiero.nl/forum/Forum2/HTML/072173.html
Dual-diaphragm Vacuum booster with more gain than the factory booster. I've already stated my opinion regarding over-sized brake boosters in the "general thoughts" section of this thread. Keep in mind that it won't reduce stopping distance, but if you prefer the reduced pedal effort, or desire a contemporary Honda Accord-esque feel then go for it.[This message has been edited by pmbrunelle (edited 05-29-2010).]
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pmbrunelle
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MAY 29, 04:10 AM
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Spare Tire choices/alternatives
Problem: the factory Fiero spare tire interferes with the brake calipers.
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I don't know if a wheel spacer in conjunction with the factory spare will provide adequate caliper clearance and retain sufficient lug thread engagement.
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Tire slime is a bad choice, because the garage that has to deal with the mess WILL hate you.
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Tire plugs and a compressor are a good "get-me-home" solution for punctures in the tread of the tire.
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A solution to the spare tire problem, quoted from this thread: http://www.fiero.nl/forum/F...1/HTML/065950-2.html
quote | Originally posted by Fieroseverywhere: I never posted my fix for the spare tire size. I ended up finding a F-body spare in a 16". T135/60-16. It's probably the
max size that can fit under the hood and it still close.
So to summarize...
-96 subaru spare. -Open center bore .1mm. -Mounted F-body tire to suby wheel. (WS6 firebird to be exact) ... -Minor trimming of the lip in the front compartment helped with the increased width of the new tire. It fit before trimming
but fit much easier afterwards.
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[This message has been edited by pmbrunelle (edited 05-29-2010).]
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pmbrunelle
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MAY 29, 04:12 AM
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Rear caliper choices
The challenge is to find rear calipers of a large enough piston area to complement the front calipers that have a parking brake provision. Some options:
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Stainless Steel Brake Corporation Force 10 Sport R1 single-piston aluminium calipers with a 54mm stainless piston rear
Equivalent to a 2-1/8" piston. Aluminium, lightwwight, stylish, $$$.
Credit to Brembo-Fiero from this thread: http://www.fiero.nl/forum/Forum2/HTML/105215.html
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80-85 Cadillac Seville rear calipers
Single 2-1/8" piston. Heavy cast-iron construction. Relatively "cheap"... I used these...
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Use the same calipers as you're using up front on the rear. This will obviously remove parking brake functionality.[This message has been edited by pmbrunelle (edited 05-29-2010).]
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pmbrunelle
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MAY 29, 04:15 AM
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Front caliper choices
For decent bias, these should have equal or similar piston areas as the rear calipers.
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Stainless Steel Brake Corporation Force 10 SportTwin 2-piston aluminium calipers with two 38mm stainless pistons front
Equivalent to a single 2-1/8" piston. Aluminium, lightweight, stylish, $$$.
Credit to Brembo-Fiero from this thread: http://www.fiero.nl/forum/Forum2/HTML/105215.html
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UNDERSIZED METRIC GM CALIPER 2-1/4" bore
I used these on my Fiero, details here: http://www.fiero.nl/forum/Forum2/HTML/103925.html
85 Camaro front caliper hardware (glide pins and rubber bushings) had to be used with these calipers.
http://www.daymotorsports.c...ED-METRIC-GM-CALIPER
These are heavy cast iron, but at least they're relatively cheap. The bleeders point up-side down, in my installation anyway. The 2-1/4" bore size is "acceptable", but probably a touch on the big side.
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80-85 Cadillac Seville front calipers
2-1/2" bore. Too big if installed on a car with 2-1/8" rears. They are ridiculously cheap though.
Due to the lack of similarly sized rear calipers with parking brakes, I would only consider installing these on all four corners, in an installation that is forgoes parking brake functionality. Their large bore also makes for a higher gain than the others (not necessarily a bad thing).[This message has been edited by pmbrunelle (edited 05-29-2010).]
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pmbrunelle
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MAY 29, 04:18 AM
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pmbrunelle
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MAY 29, 04:20 AM
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pmbrunelle
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JUN 19, 05:17 PM
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This is more or less complete for now. If there are any innaccuracies, let me know...
The pictures are a bit funky because I took them while putting back my suspension together while reassembling my car after a suspension rebuild. I actually did the brake modification last fall.[This message has been edited by pmbrunelle (edited 06-19-2010).]
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doublec4
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JUN 19, 08:34 PM
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Looks like a great write up for those looking to do this swap. I wish I could remember what front calipers I went with. I'm pretty sure the camaro ones...
If I recall, I *think* some people claim to have had problems with the stock brake lines bolting up the new calipers. Did you have to grind away any materal on the caliper?------------------
Check out my build! http://www.fiero.nl/forum/Forum3/HTML/000100.html
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