FMJ spindles > POLL

FMJ spindles on A-body

  • Yes I have them on my A-body and have no problems

    Votes: 21 95.5%

  • I have them on my A-body and have had big problems

    Votes: 1 4.5%
  • Total voters
    22
  • Poll closed .
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69MOPE

69MOPE

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Poll
Who here uses Aspen/Volare/Diplomat/Fury spindles without ANY problems on their A-body drum to disc conversion?
Lets settle this question NOW!
 
crackedback said:
What's to settle?

There are many that have FMJ's on their A body cars with no issues. I run only FMJ stuff anymore unless A body stuff falls in my lap.

I'll take real live testing data over what someone wrote, with no supporting data, in the 90's as my reference.

http://www.bigblockdart.com/techpages/spindles.shtml
Click to expand...
I'm with cracked;I see no problem the F's for me are much more plentiful so I guess my vote is-use FMJ
 
In addition: The F, M & J body spindles are also the same as the 73 and up Bbody and Rbody spindles. and I wouldnt hesitate at all to use em in an Abody or 72 and prior Bbody
 
I run them. You couldn't possibly have any issues with them that you wouldn't have had with 73+ A body spindles.

This is the article that anyone questioning this swap needs to read...

http://www.moparmusclemagazine.com/techarticles/suspension/mopp_0503_swapping_a_and_b_disc_brake_spindles/

Actual geometry analysis of actual spindles showing camber gain, toe gain, etc. Short version?

"The Final Outcome
Overall, using the B-spindle will result in geometry changes that are unnoticeable with all but the most aggressive drivers running against a stopwatch. Even at that, there's a good argument that the increased camber gain will have a positive impact on cornering while the increased toe-in through extension will go undetected."

Read more: http://www.moparmusclemagazine.com/...isc_brake_spindles/viewall.html#ixzz2mdrVgwLG

Further argument for those of us running wider tires- the camber gain will be more noticeable with wider tires, while the toe in effect will be decreased. Ultimately, I think this makes the F/M/J spindles a BETTER choice from a geometry standpoint for the Pro-Touring or road race/autocross crowd that run wider and softer compound tires.
 
I seem to sense that a lot of people think the F M J spindles are better than the '73 and up a-body ones. I am not an engineer or a professional racer, so would it be worth it to swap out the a-body ones for the F M J ones? I have a few sets of both, so i wouldn't have to buy anything. Thoughts?
 
YoungGun74 said:
And with that vote i intended to say...i do not have these lol
Click to expand...

Why would you vote for "I've had major problems", when that is simply not true by your own admission?

That is the problem with this whole issue- people who have never done it are saying it causes problems.

On the other hand, people who have done it are saying there are no problems.

That is verifiable and positive proof.


I have M body spindles on my 66 Coronet, but it is not drivable yet.
 
I have FMJ's on my 64 Valiant and I have no problems. I have 14 inch ralley wheels with radials, and i have ran 3 inch skinnies and have had no problems from 80 mph on the freeway to what little cornering my non sway bar car can do, all the way to hard wheels up launches at the track. I vote use them if you get the chance.
 
hell ya i would use them. i have the spindles off an aspen on my dart. i got the whole front end for $50 from a car rotting in a guys front yard. just knocked on the door and asked if he was parting the car. i showed him a $50 and he let me take the complete front suspension. i had my car up to well over 120mph and never had a prob.
 
Don't and won't use them unless and until someone can answer this simple question: if the knuckles interchange with no problem, why would Chrysler invest the not-insignificant coin in tooling up for a new part?
 
Jarlaxle said:
Don't and won't use them unless and until someone can answer this simple question: if the knuckles interchange with no problem, why would Chrysler invest the not-insignificant coin in tooling up for a new part?
Click to expand...

You won't EVER get an answer to that until you speak with the engineer that decided it may be an issue. It could have been as simple as, these aren't the same height, 3/8" difference, they won't work. 10 years later we were putting them on the cars without issue. The binding issue has been debunked and the guy that wrote the original article admitted that. Bumpsteer has been tested and is really not an issue except at the extremes of range, some actually beneficial. Go figure.

Chrysler made the K car... that's more dangerous than the spindles.

Make sure you don't go to any shows or drive next to many A bodies as a lot of them have these dangerous spindles on them.
 
Why would they re-engineer? Well, if the tooling was wore out, then there is no incentive not to make changes when the new tooling is made.

That said, the only issue I've heard with using them is the potential for over-angling ball joints due to the increased height. I won't run them on my car, but have heard of no issues.

Since I won't run them, I don't typically have any around where I could verify the ball-joint issue.
 
3 degrees... that's the change in ball joint inclination throughout the range.

The guy that did alignment work for me laughed at the binding ball joint assertion. If the ball joint was that close to the physical limits, someone messed up badly when they were designed. The upper/ball joint is basically along for the ride in these front ends
 
Maybe it really is time to require any car with altered suspension geometry be fully inspected (up to and including a complete teardown) and certified by an engineer before it is permitted on public roads...any car failing said inspection to be immediately seized and crushed.
 
Jarlaxle said:
Maybe it really is time to require any car with altered suspension geometry be fully inspected (up to and including a complete teardown) and certified by an engineer before it is permitted on public roads...any car failing said inspection to be immediately seized and crushed.
Click to expand...

Wow, okay, talk about throwing out the baby with the bathwater!
 
Jarlaxle said:
Don't and won't use them unless and until someone can answer this simple question: if the knuckles interchange with no problem, why would Chrysler invest the not-insignificant coin in tooling up for a new part?
Click to expand...

jos51700 said:
Why would they re-engineer? Well, if the tooling was wore out, then there is no incentive not to make changes when the new tooling is made.
Click to expand...

The F body was brand new in '76. They came out with basically all new tooling for this model. Tooling wears out, just a simple fact. Why did they change the design? Gosh, maybe because the FMJ spindles are an IMPROVEMENT to the original design. Maybe because bias ply's were no longer the norm, and radial tires have different suspension geometry requirements. Truly, you won't know unless you talk to the engineer that did it. But it probably had more to do with re-tooling everything for the F body than it did with changing the spindles.

Jarlaxle said:
Maybe it really is time to require any car with altered suspension geometry be fully inspected (up to and including a complete teardown) and certified by an engineer before it is permitted on public roads...any car failing said inspection to be immediately seized and crushed.
Click to expand...

They can start with YOUR car!

What would be the inspecting parameters? Originality? Look at the Corvair. That was a factory engineered HORRIBLE suspension design. Much worse designs rolled right off the factory floor. What about putting 73-76 disk spindles on 67-72 cars? Those spindles are in fact different from the originals, and even change the track width as compared to drum spindles. Are cars that came with 9" brakes safer than cars with 10.98" disks? Should you not be allowed to upgrade your car to disk brakes because it the 73-76 A body spindles weren't in fact designed for your 67-72 car?

All these inspections would accomplish is adding a layer of bureaucracy that doesn't need to be there- at best. At WORST, it would price the average car guy completely out of the hobby.

Do us all a favor- actually READ this article

http://www.moparmusclemagazine.com/techarticles/suspension/mopp_0503_swapping_a_and_b_disc_brake_spindles/viewall.html#ixzz2mdrVgwLG

All the information you need to consider when switching to the FMJ spindles is there. They tested bump steer. They tested the "over-angling" assertion that was made up to begin with. They tested the caster and camber changes, roll center, etc.- they analyzed the geometry completely. The DATA is there. How do I know? Because I was an engineer, that's how! And because I run the FMJ spindles on my own cars without any issues whatsoever.

If you want to not run anything other than stock A body spindles on your car, that's your choice, and be my guest. But don't insinuate that the FMJ spindles aren't safe without any information to back up your assertions. They've been tested, and they've been shown to work fine. Why the design was changed isn't relevant in the face of the data showing that the design is safe on our cars.
 
72bluNblu said:
The F body was brand new in '76. They came out with basically all new tooling for this model. Tooling wears out, just a simple fact. Why did they change the design? Gosh, maybe because the FMJ spindles are an IMPROVEMENT to the original design. Maybe because bias ply's were no longer the norm, and radial tires have different suspension geometry requirements. Truly, you won't know unless you talk to the engineer that did it. But it probably had more to do with re-tooling everything for the F body than it did with changing the spindles.



They can start with YOUR car!
Click to expand...

I do not own (and will not own) any vehicle with altered suspension geometry.

What would be the inspecting parameters? Originality? Look at the Corvair. That was a factory engineered HORRIBLE suspension design. Much worse designs rolled right off the factory floor. What about putting 73-76 disk spindles on 67-72 cars? Those spindles are in fact different from the originals, and even change the track width as compared to drum spindles. Are cars that came with 9" brakes safer than cars with 10.98" disks? Should you not be allowed to upgrade your car to disk brakes because it the 73-76 A body spindles weren't in fact designed for your 67-72 car?
Click to expand...

It is a factory-engineered installation, no problem.

All these inspections would accomplish is adding a layer of bureaucracy that doesn't need to be there- at best. At WORST, it would price the average car guy completely out of the hobby.

Do us all a favor- actually READ this article

http://www.moparmusclemagazine.com/techarticles/suspension/mopp_0503_swapping_a_and_b_disc_brake_spindles/viewall.html#ixzz2mdrVgwLG

All the information you need to consider when switching to the FMJ spindles is there. They tested bump steer. They tested the "over-angling" assertion that was made up to begin with. They tested the caster and camber changes, roll center, etc.- they analyzed the geometry completely. The DATA is there. How do I know? Because I was an engineer, that's how! And because I run the FMJ spindles on my own cars without any issues whatsoever.

If you want to not run anything other than stock A body spindles on your car, that's your choice, and be my guest. But don't insinuate that the FMJ spindles aren't safe without any information to back up your assertions. They've been tested, and they've been shown to work fine. Why the design was changed isn't relevant in the face of the data showing that the design is safe on our cars.
Click to expand...

Read the article. Makes no difference. I have insinuated nothing.
 
Bill Reilly did quite a bit of research on this subject. He knows a thing or two about mopar suspension. http://www.bigblockdart.com/techpages/spindles.shtml
I have 5th Ave spindles on my 68. The difference is almost non exsistant compared to a hundred other things that could be a little off or out of whack, like keeping drum brakes on the front.
 
Jarlaxle said:
I do not own (and will not own) any vehicle with altered suspension geometry.

Read the article. Makes no difference. I have insinuated nothing.
Click to expand...

Makes no difference?

The article clearly shows that the FMJ spindles are perfectly safe, and possibly have BETTER geometry than the original spindles did. Especially for cars that use larger, more modern tires and tread compounds.

Suspension design and geometry is always a trade off. In the case of the FMJ spindles, you trade a ridiculously slight increase in toe change for a more significant increase in negative camber gain. Simply put, thats a good trade. If you don't understand that, then you simply don't understand how suspension works.

The factory designed the suspension on these cars for use with rock hard, rail skinny, bias ply tires. It set the alignment specifications for those tires. It sized the torsion bars for those tires and their incredible lack of traction. It based its brakes on those tires' lack of traction. So the only question is, do you run bias ply tires?

If the answer is NO, and you still use the factory geometry, then you have in fact significantly altered the handling characteristics of your car beyond the factory specifications.
 
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