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Re: disc conv - a body spindles w/ f body everything else?
[Re: bigslant6fan]
#54949
03/16/08 09:52 AM
03/16/08 09:52 AM
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Joined: Jun 2005
Posts: 4,442
Texas
Daty Rogers
World's Greatest Husband. I love you Robyn
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World's Greatest Husband. I love you Robyn
Joined: Jun 2005
Posts: 4,442
Texas
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Re: disc conv - a body spindles w/ f body everything else?
[Re: dvw]
#54952
03/17/08 12:39 AM
03/17/08 12:39 AM
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Anonymous
Unregistered
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Anonymous
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I’ve heard a lot of enthusiasts say that using the A-Body spindles is not necessary as they use the taller spindles from B/R and FMJ-Bodies. Personally, I’d rather error on the side of the leading professionals who have made their careers in the high performance Mopar area of interest as well as original Chrysler engineers who developed these cars in the first place. Check out the quotes and the provided links below. I know this will probably ruffle a lot of feathers out there, but that’s okay, it’s only my opinion. And if people choose to use taller spindles in their disc brake swaps, that just means more available A-Body spindles for the rest of us, heck! Everybody wins...  “Do not succumb to the temptation to use "lookalike" knuckles from later Mopars, such as 73-up B/R-bodies, F/J/M bodies, etc. These parts, while visually very similar, are taller, altering suspension geometry (camber change, bump steer, etc.), and possibly forcing the ball joints beyond their designed range, a/k/a “over angling”. - Richard Ehrenberg, Mopar Action “Using the correct knuckle avoids any of these potential pitfalls, and results in a "factory engineered" installation. Hey, Chrysler paid those engineers big bucks to get it right, so you might as well take advantage of their know how. Plus, we're getting it for free!” - Richard Ehrenberg, Mopar Action “The later style casting shown on the right came on 1973 or later B body cars as well as the FMJ body cars. Even though it looks the same as the A body part, it will not work since it is too tall to maintain proper suspension geometry.” - Andy Finkbeiner, AR Engineering http://www.moparaction.com/Tech/archive/disc-main.htmlhttp://www.arengineering.com/
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Re: disc conv - a body spindles w/ f body everything else?
#54953
03/17/08 12:40 PM
03/17/08 12:40 PM
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Joined: Mar 2006
Posts: 9,865
MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,865
MI, usa
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Have you ever used them? Have you ever done an alignment? Are you a A.S.E.certified Master tech with over 30 years experience? Have you ever checked bump steer or toe change with these knuckles? Have you ever driven a car with this set-up. My answer is yes to all of the above. If you really want to get picky you should never modify anything on your own. I've seen a lot of good performance upgrades and I've seen a lot of hack jobs, this conversion is not a hack job. If you really believe automotive engineers know it all, you should come work as a dealer tech and witness some really unbelievable engineering masterpieces. You should check out a new Colorado suspension geometrey on the rack, hows 3/4" toe change grab ya?
Doug
Also there was a thread here where both knuckles were compared on a rack ,there was a chart attached also that showed no ill effects.
Last edited by dvw; 03/17/08 12:43 PM.
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Re: disc conv - a body spindles w/ f body everything else?
#54954
03/17/08 01:33 PM
03/17/08 01:33 PM
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Joined: Jan 2003
Posts: 31,060
Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,060
Oregon
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That is an old quote. We now use the taller FMJ knuckles and recommend them for any serious suspension upgrades. The FMJ knuckle is the lightest one available and moving the ball joint up a bit helps with the camber curve.
The taller knuckle does get the ball joint closer to the rim but we would use a 17 inch rim anyway for anything that is actually going to be driven around corners. Use the Firm Feel upper control arm with the revised ball joint angle and it all works out great.
Last edited by AndyF; 03/17/08 01:34 PM.
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Re: disc conv - a body spindles w/ f body everything el
[Re: AndyF]
#54955
03/17/08 02:08 PM
03/17/08 02:08 PM
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Joined: Oct 2005
Posts: 1,392
Thayer, MO
bohmer2
pro stock
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pro stock
Joined: Oct 2005
Posts: 1,392
Thayer, MO
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Quote:
That is an old quote. We now use the taller FMJ knuckles and recommend them for any serious suspension upgrades. The FMJ knuckle is the lightest one available and moving the ball joint up a bit helps with the camber curve.
The taller knuckle does get the ball joint closer to the rim but we would use a 17 inch rim anyway for anything that is actually going to be driven around corners. Use the Firm Feel upper control arm with the revised ball joint angle and it all works out great.
For anyone who doesn't know already, the Andy Finkbeiner, AR Engineering from the above quote is the AndyF who made the post I am quoting.
So it looks like for Andy anyway this argument has finally been resolved and it is OK to use later spindles on A-bodies.
Andy does this mean that the 2" F-body drop spindles could also be used and do you have any research on how these would affect cornering/handling?
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Re: disc conv - a body spindles w/ f body everything el
[Re: AndyF]
#54957
03/17/08 08:03 PM
03/17/08 08:03 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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 Feathers... Ruffled... I was expecting that. But just to clear the air a little, I never used the term “hack job” but merely stated I’d rather stick to the publicized way of doing this disc brake swap and utilize the A-Body spindles. In the end, it looks like it all boils down to how much modification one cares to do with their car. As for myself, I’m making the swap simply because I want to go fast in a straight line and stop fast in a straight line. Any slight deviation from this goal and I’m confident my factory suspension that Ma Mopar produced with be sufficient for what I want to do. I mean, I’m not going road racing, so I won’t need the 17” rims on my musclecar and other serious suspension upgrades. For me, I’m hiding my disc brakes behind reproduction 15” steel rims with dogdish hubcaps for that sleeper look. But my sleeper will stop much quicker and do it with off the shelf Mopar parts, that’s the cool thing about this swap. The other good news is that Magnumforce Race Car Fabrications, Inc, a known fabricator of officially licensed Mopar suspension kits has put the time and money into reproducing A-Body disc brake spindles. I just got an e-mail back from them today, which confirmed that these new spindles are dimensionally exact to the 73 through 76 Mopar A-body disc brake spindles. The bad news, these stronger than original spindles cost $325.00... ouch! So, for now, I’ll just stick with a good used set of A-Body spindles.  www.magnumforce.com
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Re: disc conv - a body spindles w/ f body everything el
[Re: dvw]
#54959
03/24/08 10:22 AM
03/24/08 10:22 AM
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Joined: Sep 2003
Posts: 1,688
Marlboro, NY, USA
Rick_Ehrenberg
top fuel
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top fuel
Joined: Sep 2003
Posts: 1,688
Marlboro, NY, USA
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Quote:
....there was a thread here where both knuckles were compared on a rack ,there was a chart attached also that showed no ill effects.
If you are referring to the same one I saw, the chart showed almost triple the bump steer, which coincided pretty well with the tests I made years back.
I was, and still am, dead set against this swap. I hate bump-steer...I like to drive fast on lousy roads!
There are lots of cars that perform pretty well with less-than-perfect suspension / steering geometry. In fact, virtually every design is a compromise. I just fail to see the rationale behind a deliberate downgrade, esp. when the correct parts are not hard to procure.
Rick
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Re: disc conv - a body spindles w/ f body everything el
[Re: 64Post]
#54960
03/24/08 10:25 AM
03/24/08 10:25 AM
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Joined: Sep 2003
Posts: 1,688
Marlboro, NY, USA
Rick_Ehrenberg
top fuel
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top fuel
Joined: Sep 2003
Posts: 1,688
Marlboro, NY, USA
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Quote:
I was ignorant of the differences when I did my upgrade.I bought a pr. of spindles out of state that happened to be mismatched-1 A body and 1 BFJ.Short version is that the A body spindle allowed the UCA to contact the inner rim/wheel weight.This was on a pr. of custom front steelies.I'm changing the spindle,but everyone should be aware of the issue.I believe the backspace on those fronts was 3 1/2" to 3 3/4".
Hmmm, something's wrong here. The taller (F/J/M/Late-B) knuckles put the UBJ/UCA closer to the wheel's inner lip.
Rick
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Re: disc conv - a body spindles w/ f body everything el
[Re: Rick_Ehrenberg]
#54961
03/24/08 12:38 PM
03/24/08 12:38 PM
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Joined: Jun 2006
Posts: 3,075
Eastern Ohio
mopowergtx
master
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master
Joined: Jun 2006
Posts: 3,075
Eastern Ohio
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Quote:
when the correct parts are not hard to procure.
I assume your meaning the 73-76 A-body spindles? I sure as heck cant find them in any junkyard yards here in OHIO. But you can find Diplomats/5th Avenues around for the F,M,J body spindles no problem.
Quote:
I was, and still am, dead set against this swap. I hate bump-steer...I like to drive fast on lousy roads!
Quote:
Bump steer is the toe-in or toe-out of the front wheels as the suspension goes from normal ride height through full bump (suspension system moves up) to full drop (suspension system moves down). Measurement is usually limited to 3" up and 3" down from ride height. It is specified either by a graph or measurements at 1", 2", and 3".
Bump steer affects handling much as setting toe-in does. All cars have a certain designed-in pattern of bump steer.
At what point does this "extra" Bump-steer caused by the higher spindles come into play?
Is it during a hard turn and with the suspension travel to an exteme? Would it be evan noticed during normal driving conditions. IE a sane commute to work or car show. Down a drag strip?
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