Dr diff spindles
- Thread starter Boduke
- Start date
-
71scamp78
Well-Known Member
I would assume they are good coming from Cass at Dr. Diff. I plan on buying them as well. I have bought a lot of parts off him and never had an issue
ok this post planted a small seed in my mind so in doing addition research i found that some people have had issue with the thickness of the spindle being too thick to allow enough threads of the Upper ball joint to poke through the spindle to get the nut in and the pin in..from what i gather, this may or may not be when using the adapters for 72 small BJ.. is this what you mean by 3/8? I tried to pm you but mailbox full. I only seek truth. I have no issue engineering/modifying a brand new part
To achieve a perfect fit if thats the only issue. Thanks in advance
Inbox full. I already ordered so im just going to assume im good.
The F/M/J spindle is 3/8 of n inch taller overall than the 71-72 B/70-74 E/ 73-75 A body spindle.
This was changed to allow for the additional height of the 73-79 B body only ISO front K frame bushings.
This is not the thickness of the BJ mount.
The discussion concerns what that additional 3/8 does to the geometry.
Some say it hurts (potential bump steer), some say it helps (caster angle).
F/M/J (and 73-79 B which are the same part) are MUCH easier to find than the 71-72 B/ 7-74 E/ 73-75 A part.
This was changed to allow for the additional height of the 73-79 B body only ISO front K frame bushings.
This is not the thickness of the BJ mount.
The discussion concerns what that additional 3/8 does to the geometry.
Some say it hurts (potential bump steer), some say it helps (caster angle).
F/M/J (and 73-79 B which are the same part) are MUCH easier to find than the 71-72 B/ 7-74 E/ 73-75 A part.
Swapping Disc-Brake Spindles - Mopar Muscle Magazine
Im gonna run them and see how good/bad they are. I have my car setup for sunday driving i run < 2 camber and zero toe. I have manual Steering with the 24:1 box. 318 / 904 with 2:73 rear. I cruise. I dont corner,autocross or race. I turn the key and hit the spots. I go to the beach. My car does 85 on the expressway. Im hoping i notice zero difference. Wish me luck
Im gonna run them and see how good/bad they are. I have my car setup for sunday driving i run < 2 camber and zero toe. I have manual Steering with the 24:1 box. 318 / 904 with 2:73 rear. I cruise. I dont corner,autocross or race. I turn the key and hit the spots. I go to the beach. My car does 85 on the expressway. Im hoping i notice zero difference. Wish me luck
I'm sure Cass (DoctorDiff) will chime in after the holidays, but if I remember correctly the reproduction spindles are the same height as the factory 73-76 A-body spindles, not taller like the later FMJ spindles were.
As for the original debate, it was Richard Ehrenberg's fault. In his original "Disc-O-Tech" article he made the claim, without any evidence whatsoever, that using the FMJ spindle for your BBP brake swap would cause all kinds of catastrophe and suspension geometry problems, over-angling of ball joints, terrible bump steer, cats and dog living together.
But here's the deal- he's full of crap. He never posted any geometry numbers to back up this assertions. He never tested bump steer numbers, or looked at camber gain, or even bothered to check if the ball joints were somehow going to have some kind of interference or wear issues. He never bothered, and based on his total lack of evidence I can only assume that everything he said was just speculation on his part.
The article you linked, from Mopar Muscle, actually did all of that. And you see the results. There is a slight change in the bump steer geometry. There is also an improvement in the camber gain. And the ball joint over angling thing is complete BS.
The bottom line is, for most applications most drivers will never notice the difference. It's barely worth a discussion, the changes are so minor. Cruising around town you'd notice nothing at all. I run FMJ spindles on my Challenger and my Duster because of the improved camber gain, because I do run wider tires up front (275's) and the camber gain is more important. But I'm not going to BS you and tell you I noticed the difference when I switched from stock '74 A-body disk spindles to FMJ's, because I didn't.
And yeah, I'm almost positive the reproduction spindles are the factory A-body height, not the FMJ height anyway.
As for the original debate, it was Richard Ehrenberg's fault. In his original "Disc-O-Tech" article he made the claim, without any evidence whatsoever, that using the FMJ spindle for your BBP brake swap would cause all kinds of catastrophe and suspension geometry problems, over-angling of ball joints, terrible bump steer, cats and dog living together.
But here's the deal- he's full of crap. He never posted any geometry numbers to back up this assertions. He never tested bump steer numbers, or looked at camber gain, or even bothered to check if the ball joints were somehow going to have some kind of interference or wear issues. He never bothered, and based on his total lack of evidence I can only assume that everything he said was just speculation on his part.
The article you linked, from Mopar Muscle, actually did all of that. And you see the results. There is a slight change in the bump steer geometry. There is also an improvement in the camber gain. And the ball joint over angling thing is complete BS.
The bottom line is, for most applications most drivers will never notice the difference. It's barely worth a discussion, the changes are so minor. Cruising around town you'd notice nothing at all. I run FMJ spindles on my Challenger and my Duster because of the improved camber gain, because I do run wider tires up front (275's) and the camber gain is more important. But I'm not going to BS you and tell you I noticed the difference when I switched from stock '74 A-body disk spindles to FMJ's, because I didn't.
And yeah, I'm almost positive the reproduction spindles are the factory A-body height, not the FMJ height anyway.
Mopar Momzee
Well-Known Member
Excuses my ignorance FMJ stands for what ?
71scamp78
Well-Known Member
What type of body the car is...like a A B or E body
abodyjoe
Well-Known Member
only douchebag complaining about the tall spindle (with no data to back up his argument) was that clown from a magazine.
the truth and measurements to back it up. Spindle Comparison
.
Agreed. It is the body designation but FMJ have a lot of chassis parts that interchange. That's why they get grouped together FMJ unlike you would ABE
Last edited:
Jim Lusk
Well-Known Member
Bill Reilly (RMS) did the calculations on the taller spindle. He liked everything about them. We did put them on my son's autocross Barracuda, but really I don't think he noticed a difference.
Bigblockdart.com used have a write-up disputing the Ehrenberg claims.
They liked the F/M/J geometry as well, and had proof.
I used to refer people to that but I think that site is either down, or in the process of a rebuild.
They liked the F/M/J geometry as well, and had proof.
I used to refer people to that but I think that site is either down, or in the process of a rebuild.
abodyjoe
Well-Known Member
The information on BigBlockDart is the same as the article that was published in Mopar Muscle, that’s where it came from. And it was written by Bill Reilly of RMS. Same info from the same source, both sources are linked above already.
DoctorDiff
Well-Known Member
My reproduction knuckles are the same height as the stock A/E body version.
I'm not aware of any problems caused by the taller F/M/J body knuckles, however.
I'm not aware of any problems caused by the taller F/M/J body knuckles, however.
-
