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Custom A-Arms to Clear Large Calipers

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Old 07-05-2017, 12:02 PM
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Custom A-Arms to Clear Large Calipers

Has anyone made/found an a-arm that is built to allow for more space with larger ('vette or otherwise) calipers?

Mine hit the PA a-arm, and the turning radius is already terrible. Setting a stop to prevent it from contacting under a long turn will make the radius even worse.

I don't think there's any way to change the brackets to clock the caliper up higher to gain clearance.

Anyways, just curious if anyone has messed around with this.
Old 07-05-2017, 01:27 PM
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Re: Custom A-Arms to Clear Large Calipers

Reposition the caliper
Old 07-05-2017, 02:19 PM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by Twin_Turbo
Reposition the caliper
from the original question:

I don't think there's any way to change the brackets to clock the caliper up higher to gain clearance.
There isn't really enough room to move the position without hitting the spindle/strut.
Old 07-08-2017, 12:14 PM
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Re: Custom A-Arms to Clear Large Calipers

What setup are you trying to run?
Is it a common setup or is the problem specific to only the PA Arms?
The stock front brakes can lock up the car and our cars not having ABS, you don't need huge rotors.
Old 07-08-2017, 12:36 PM
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Re: Custom A-Arms to Clear Large Calipers

Being able to lock up the brakes says nothing. Its all aboit modulation and feel. Larger rotor mass refuces mean running temp and improves fade resistance. Larger pads have more transfer area... less chance of pad fade. Etc...etc.
Old 07-08-2017, 02:26 PM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by Twin_Turbo
Being able to lock up the brakes says nothing. Its all aboit modulation and feel. Larger rotor mass refuces mean running temp and improves fade resistance. Larger pads have more transfer area... less chance of pad fade. Etc...etc.
Yes, of course all of that is true but the only people who need to think about that are road coarse guys or guys whose Auto cross lets the drivers make multiple runs per heat. Far too many people upgrade simply because big brakes look cool. I'm just trying to make sure he's not one of the guys whose going to spend $200-800 because he thinks he needs it.
Old 07-09-2017, 06:15 PM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by Tibo
Yes, of course all of that is true but the only people who need to think about that are road coarse guys or guys whose Auto cross lets the drivers make multiple runs per heat. Far too many people upgrade simply because big brakes look cool. I'm just trying to make sure he's not one of the guys whose going to spend $200-800 because he thinks he needs it.
Stop the car from 140+ a few times down the drag strip and they get worked pretty hard.

Driving down the twisty canyon highways out here in CA also beats brakes much harder than you'd think, completely different from the relatively mild landscapes in Massachusetts (where I came from).

It's a zo6 caliper (c5) on a 12" rotor. It stops the car 50 feet shorter from 50mph (I tested it). So, is it worth it? Every penny.
Old 07-16-2017, 05:22 PM
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Re: Custom A-Arms to Clear Large Calipers

Is the caliper / carrier mounted to the front or backside of the caliper bracket?
Are the front wheels used the front cross lace 16x8" ?
Old 07-17-2017, 11:27 AM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by jmd
Is the caliper / carrier mounted to the front or backside of the caliper bracket?
Are the front wheels used the front cross lace 16x8" ?
The front side IIRC, and yes, those are the wheels.
Old 07-18-2017, 03:01 PM
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Re: Custom A-Arms to Clear Large Calipers

One way would be to shim the caliper outwards, and shim under the rotor (try and keep hub-centricity.) This would suit small changes. If you wanted to go bigger, a new pair of hubs and brackets (from bbu) might make sense.

How is the caliper clearance with rear wheels on front? If you decided 16mm was a totally ideal amount of change and went that route with hubs, brackets, and wanted to keep wheel placement the same, rear wheels would work, assuming caliper clearance.
Old 07-18-2017, 03:09 PM
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Re: Custom A-Arms to Clear Large Calipers

This is strange.... now i have to go check mine

I have the c5 z06 calipers on c5 rotors on my car. Had them on stock a arms and umi road race a arms. Never came close to hitting

Now have PA racing arms no spring perch and havent completed the install yet. Its mocked up. K member and arms are in but spindle and brake assembly not all way on
Old 07-18-2017, 03:13 PM
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Re: Custom A-Arms to Clear Large Calipers

I think he has 98-02 F rotors, smaller than C5.
Old 07-18-2017, 03:13 PM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by Orr89RocZ
This is strange.... now i have to go check mine

I have the c5 z06 calipers on c5 rotors on my car. Had them on stock a arms and umi road race a arms. Never came close to hitting

Now have PA racing arms no spring perch and havent completed the install yet. Its mocked up. K member and arms are in but spindle and brake assembly not all way on
I have the PA K-member and A-arms. If I could go back in time I'd have not used PA.

That's what I have though, and it def makes the already poor turning radius awful.
Old 07-18-2017, 08:53 PM
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Re: Custom A-Arms to Clear Large Calipers

Why is it so different? What they do differently on arms?
Old 07-18-2017, 08:57 PM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by jmd
I think he has 98-02 F rotors, smaller than C5.
Yeah by .8" or so overall or .4" on each side. Mine dont appear to hit the a arms but car is not at ride height, its on stands, struts out
Old 07-24-2017, 05:31 PM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by Orr89RocZ
Yeah by .8" or so overall or .4" on each side. Mine dont appear to hit the a arms but car is not at ride height, its on stands, struts out
Ya it wouldn't hit on mine with the wheels hanging.

The PA arms aren't the problem by design, it's just where the huge caliper has to fit in there. I think if you used a larger rotor and a much larger wheel (I've got GTA 16"s) it would buy you a LOT more clearance.

The Pa stuff was really shitty powdercoat quality (it's all flaking off now) and I had to cut the K-member apart and weld the rear ears back on because they shimmed the jig wrong and their own a-arms were 3/8" too wide to fit.

It was either that or wait months for a new one from them at the time.
Old 07-24-2017, 05:40 PM
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Re: Custom A-Arms to Clear Large Calipers

Yeah it was a bear to get my a arms installed on their k member as well. Only reason i switched cuz i needed a k member with out engine mounts for my bbc. It was actually no cost to me to sell my umi road race k and arms used, and buy the pa front end kit with no mounts lol hope it holds up. Looks thin
Old 07-25-2017, 06:01 PM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by Orr89RocZ
Yeah it was a bear to get my a arms installed on their k member as well. Only reason i switched cuz i needed a k member with out engine mounts for my bbc. It was actually no cost to me to sell my umi road race k and arms used, and buy the pa front end kit with no mounts lol hope it holds up. Looks thin
Haha ya, it's awfully nice to work on the car from underneath, though. It should be fine seeing the car drags, and cruises and that's about it. It probably never sees anything north of 6/10 on the road.
Old 07-25-2017, 08:21 PM
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Re: Custom A-Arms to Clear Large Calipers

This is a very strange situation - on some cars (2nd gens as an example), using an aftermarket upper control arm gives you more clearance for wider wheels vs. OEM parts.

Now we have several customers on 14" brake kits and monster 6 piston monoblock calipers and not one of them has had any issues with other aftermarket a-arms as you are having.

To answer the too much or too little brake discussion within the thread - a 13" 2pc rotor (they don't warp like oem 1pc styles) with a 4 piston caliper is more than enough for even 200mph capable f-bodies. We are talking sub 100' 60 to 0 braking on 275-40-17 tires and no ABS, which is supercar stopping in 2017.
Old 07-27-2017, 02:26 AM
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Re: Custom A-Arms to Clear Large Calipers

I agree. No need for heavy bling. Keep the unsprung weight down at all costs (meaning it costs you more, but worth it).
I have C6 Wilwood set-up. No problem with a-arms - must be something more going on to incur this problem. Bracket is critical, and shimming is necessary, of course.


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Old 07-29-2017, 10:59 AM
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Re: Custom A-Arms to Clear Large Calipers

Originally Posted by TEDSgrad
I agree. No need for heavy bling. Keep the unsprung weight down at all costs (meaning it costs you more, but worth it).
I have C6 Wilwood set-up.
I use the 4 piston version in the Wilwood FSL series but for all intensive purposes it's the same setup that you and Paul recommend/run. Too many people get swept away in the bigger is better and want whatever the new Corvette or Camaro have.
Old 07-31-2017, 02:43 PM
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Re: Custom A-Arms to Clear Large Calipers

The blame is on the car companies that stuff monstrous brakes on their top priced cars and hype the hell out of them. Tires are holding them all back and many of them have so much brake power that their ABS systems have to be supercomputer powerful to not lock up the wheels on every stop. Of course the aftermarket will gladly sell you 15" 8 piston brake kits when a 13" with a 4 piston will stop equally well in 99.9% of conditions - including road racing.

I must have read a dozen articles in the last two years about how there was an expected braking distance reduction on a car with the $15k ceramic brake rotors vs iron rotors and in most cases, they stop slightly worse. Guess not one journalist has any idea of how brakes work or even bothered to ask someone who does. Then last week i just read an article on how a lot of the top euro cars with the ceramic brakes no one wants to buy used - guess a $12k brake rotor replacement on a $40k used car is a hard to swallow item even for people who asked to get raped by buying used MB, Audi, or BMW.

Regardless, with all the brake tech and systems out today, it is easy to go overboard and get a minimal return - if nothing at all.

Originally Posted by Tibo
I use the 4 piston version in the Wilwood FSL series but for all intensive purposes it's the same setup that you and Paul recommend/run. Too many people get swept away in the bigger is better and want whatever the new Corvette or Camaro have.
Old 07-31-2017, 03:12 PM
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Re: Custom A-Arms to Clear Large Calipers

For accuracy sake, this is not some crazy caliper setup. It's a c5 zo6 caliper, not some massive monoblock setup.

Virtually the same caliper was on the later 4th gen F-body cars minus the nice red powdercoat and corvette logo (along with likely hundreds of other vehicles on the market).




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