FatManFab g-force dropped spindle

[TMat]

Has anyone seen the new spindle from fatman fabrications? It says it eliminates bumpsteer and improves camber gain, costs $299. Could it be true? http://www.fatmanfab.com/06page24.htm

[baz67]

Where to start on that thing. I would not use it. First of all it is a 2" drop. Read that it says for style. If you want to lower your car use springs to do it. It puts the front geometry in a better position. You will run into wheel clearance issues with wider front tires by going with a dropped spindle. To reduce bumpsteer in a first gen the steering arm needs to be lowered. Well at least the outer tie rod the steering arm location. That is fine and I am sure they factored that into the design. However, that lowers the steering arm even more and will create more wheel clearance issues. Depending on what size rims you are using the drop may have scrub line problems.

The taller spindle will improve camber gain, but why spend money doing it. You could do the Guldstrand mod and have it for free.

[sinned]

First of all it is a 2" drop. Read that it says for style. If you want to lower your car use springs to do it. It puts the front geometry in a better position. Actually in the case of the "A" body that is not true. The spindle NEEDS at least a 1.5" drop (more would be better but requires larger wheels to clear the steering arm) to even get close to bringing the geometry back into shape after another 2" of spring drop.



So, like the ATS spindle works well for the “F” body but just so-so for the “A” body the Fatman spindle works vice-versa.


Although the above link is related to the Fatman "F" body spindle there is also an "A" body part. This post was for those seeking advice in that application although I would think the "F" body would also benefit from spindle height adjustment.

[Travis B]

NOt trying to hijak the thread but going to pick dennis' brain for am minute.....So dropped spindles are better on an A-body....I thought the taller B-body spindles was better?????


Actually in the case of the "A" body that is not true. The spindle NEEDS at least a 1.5" drop (more would be better but requires larger wheels to clear the steering arm) to even get close to bringing the geometry back into shape after another 2" of spring drop.



So, like the ATS spindle works well for the “F” body but just so-so for the “A” body the Fatman spindle works vice-versa.


Although the above link is related to the Fatman "F" body spindle there is also an "A" body part. This post was for those seeking advice in that application although I would think the "F" body would also benefit from spindle height adjustment.

[Derek69SS]

The Fatman dropped spindles are tall like the B-body, but use the stock steering arm, so they don't have bumpsteer and turning radius issues like the B-body spindles do.

[DarylH]

The Fatman dropped spindles are tall like the B-body, but use the stock steering arm, so they don't have bumpsteer and turning radius issues like the B-body spindles do.
This leaves me with a couple of questions.

What rotor options are available?

Is the 2" drop in addition to the drop that is given by the tall spindle geometry or because of the geometry change?

[Derek69SS]

You can do any of the same brake conversions that you can do on a stock spindle, from stock 11" discs, to C4 and C5 12 and 13" corvette brakes.

I don't really know much more about it than that. I do believe Dennis has seen the specs on it.

[DarylH]

I don't really know much more about it than that. I do believe Dennis has seen the specs on it.

I was hoping someone from here has actually had the opportunity to see what the geometry is like on these. I have the B body spindles, 1LE rotors and the Pole Position UCA's and am quietly waiting to see what the best update for this conversion is.

[sinned]

Although I haven't seen the spindles in person, ANY spindle that will raise the pin height and the overall spindle length without adversly affecting the steering arm height/length is a good thing.


The "B" spindle swap is about the worst thing ever thought up (yes, I bought into it years ago and still run it today out of nessesity). Very soon (spring) I will have information (not for sale, just free info) on a very good arrangement that will easily outdo anything currently available.

[wickedmotorhead]

Sorry to jump in here but I wanted to be clear up some information on our AFX spindle for the A bodies since it was brought up. For the F-Body platform there is about a 7/8" drop, but for the A Body setup, which will be slightly different, we will be using different ball joints and a proprietary UCA to prevent bind and optimize the geometry due to the added height. The choice of ball joints is not yet concrete but will most likely be 1" taller both top and bottom, hence affectively creating a higher pin height and overall height needed in an A-body. Also if the fatman spindle does indeed "eliminate" the bumpsteer for lets say an F-body that would mean they lowered the steer arm if using the steer arm from the factory. This in return will make the A-body bumpsteer worse since it really needs to be raised from the factory location, that is why we will have a custom steer arm for the A and G body platform as well.

[gchandler]

It seems to me that the ride height of the car and the alignment settings will have an impact on where exactly the steer arm needs to be.

Is this true?

[sinned]

Yes, ride height has a huge impact on bumpsteer as the chassis height determines the inner tie rod pivot location. Alignment plays a minimal role and needs not be considered for design purposes.

[DarylH]

Very soon (spring) I will have information (not for sale, just free info) on a very good arrangement that will easily outdo anything currently available.

I've seen this posted before and am anxiously waiting to see how it will compare to all the current options.

I'm quite interested in the AFX spindle, as it appears to address all of the identified issues...maybe not to everyone's liking, but at least they're trying.

[gchandler]

So given that ride height will dictate where the outer tie-rod needs to be located, it is not possible to have a 100% valid debate about steer arm placement without knowing the final ride height of the car that the spindle will be installed on.

The one thing that I really do like about the ATS setup is that the steer arm is a bolt on piece and could therefore be changed for different applications.

I also think that it bears mention that how much camber gain a certain setup needs depends on what sort of tires a car runs, how it is to be driven, etc.

Basically the reason that there is a continual debate about which setup (tall, stock, taller ball joints, etc) is "best" stems from the fact that numerous factors determin which setup will work best for any given situation.

I just wanted to get it out there that the entire system needs to be looked at when making decisions about spindle height, steer arm placement, ball joint height, control arm length, etc.

Currently we are fortunate enough to have numerous vendors making strong efforts towards giving the aftermarket consumer a fuller compliment of options when making their final purchase decisions.

[DarylH]

Basically the reason that there is a continual debate about which setup (tall, stock, taller ball joints, etc) is "best" stems from the fact that numerous factors determin which setup will work best for any given situation.

Which is why I'm "quietly"waiting to see how all of the various options perform. I've heard a large variety of opinions of each choice and sorting through it all is very challenging to say the least.


I just wanted to get it out there that the entire system needs to be looked at when making decisions about spindle height, steer arm placement, ball joint height, control arm length, etc.

Currently we are fortunate enough to have numerous vendors making strong efforts towards giving the aftermarket consumer a fuller compliment of options when making their final purchase decisions.

I can't say enough about all of the folks that are doing their very best to find a workable solution to this ongoing debate.:cheers:

[gchandler]

Within the next week or so I should be recieving a very exciting set of lower control arms that I will be reviewing for the Hot Rod Homepage, but I will let you guys know more on that when I have a final confirmation.

[Derek69SS]

Very soon (spring) I will have information (not for sale, just free info) on a very good arrangement that will easily outdo anything currently available.

As long as I can run 4" of ground clearance at the crossmember with a 26" tire so I can keep my inner fenders, I may be very interested in a year or so when it's time to upgrade the brakes.

[Marcus SC&C]

I talked to Brent (the FatMan) at the SEMA HotRod and Resto show last year about these (and posted about it here) and examined the rapid prototyped spindle. The steering arm holes are lowered to improve bumpsteer on F bodys. With stock alignment specs it should be just about right on,with more + caster it`ll go a little the other way but still be better than stock. On an A Body (Chevelle etc.) this will roughly double the factory bumpsteer ie. "B Spindle Part II,The Return of Huge Bumpsteer". I talked to him about making a non drop version or perhaps a 1" drop but he wasn`t too interested. After running the numbers,they are much better than stock but due to the 2" drop you can`t lower the car much more if at all with springs so the suspension arms remain in less than ideal locations making the RC height really high (double the height of a C5`s). This applies to both F and A body but the bumpsteer problem would rule it out for A body use in my book. Marcus SC&C

[sinned]

On an A Body (Chevelle etc.) this will roughly double the factory bumpsteer ie. "B Spindle Part II,The Return of Huge Bumpsteer". I talked to him about making a non drop version or perhaps a 1" drop but he wasn`t too interested. After running the numbers,they are much better than stock but due to the 2" drop you can`t lower the car much more if at all with springs so the suspension arms remain in less than ideal locations making the RC height really high
Since I don't have them in my hand I can’t very well put up a good argument but you are going to have explain the part about not being able to spring drop the chassis due to the 2" raised pin height. All of my analysis (hundreds of hour’s worth) has determined that for ideal geometry the typical "A" body needs a 2" pin drop AND another inch or so of spring drop.