Fatman Spindles

[fatiger53]

************ Message from Moderator David Pozzi

This thread was originally part of the A arm discussion (Sticky) thread. I have moved all the off-topic posts here. While the discussion got rather unpleasant, there is some good tech and things to think about. - It just didn't belong in the other thread.





I have been doing some research into UCA designs, and would offer a few points. I agree with Matt at Lateral Dynamics that MIG versus TIG welding is more a matter of style than strength. However, since the TIG process is inherently a hands on process, where automated MIG welding is often used to reduce costs, quality control is often better with TIG. That is assuming that the welder is capable and caring!

Moog introduced offset upper control arm shafts long ago since these cars subframes are often out of whack enough that alignment can be difficult. With an offset shaft design, a 3/16" difference is available thru the offset that lets you change the effective length of the UCA a total of 3/8". That really helps get positive camber numbers when the frame is sagged thru use. The better MFG use these, often in a billet steel CNC machined versions because the original MOOG ones are getting hard to get. Matter of fact, those retaining stock stamped arms would often benefit by using these shafts.

Urethane bushings have become a standard for higher performance thru less compliance, but opinions vary as to their effect on ride harshness. Fresh rubber bushings do pretty good, but normal wear needs repair.

Some MFG also alter the position and angle of the upper ball joint. Since lowering these cars is common, the ball joint angles can suffer getting to their limits, and normal caster is reduced by any rake that results. By setting the upper BJ back, more caster is preset, and good alignment can result without bizarre shim stacks. I run 3 degrees positive caster for a real good in the groove feel at speed.
Some guys claim to improve camber action with their arms, but that seems like marketing, not engineering. The shape of the tube has nothing to do with geometry. It's the position of the pivots that creates the action of the control arms and spindles. That's why the UCA relocation technique and the taller improved camber dropped spindles work.

These are questions that will be worth asking when you are shopping. If they can't answer or seem confused, be wary.

[wendell]

I felt compelled to make a few points. Feel free to concider them opinions..

I have been doing some research into UCA designs, and would offer a few points. I agree with Matt at Lateral Dynamics that MIG versus TIG welding is more a matter of style than strength. However, since the TIG process is inherently a hands on process, where automated MIG welding is often used to reduce costs, quality control is often better with TIG. That is assuming that the welder is capable and caring!

Moog introduced offset upper control arm shafts long ago since these cars subframes are often out of whack enough that alignment can be difficult. With an offset shaft design, a 3/16" difference is available thru the offset that lets you change the effective length of the UCA a total of 3/8". The location of the pick up point will not change the "effective length of the UCA" but will change the static camber.That really helps get positive camber numbers when the frame is sagged thru use. Traditionally, negative camber gain in bounce is the attribute that people covet.The better MFG use these, often in a billet steel CNC machined versions because the original MOOG ones are getting hard to get. Matter of fact, those retaining stock stamped arms would often benefit by using these shafts.

Urethane bushings have become a standard for higher performance thru less compliance, but opinions vary as to their effect on ride harshness. I've yet to find an application that benifits from urethane bushings. They have the life span of a rubber bushing, ofter with increased bind. Aluminumw/ delrin incerts or steel w/ a zerk Fresh rubber bushings do pretty good, but normal wear needs repair.

Some MFG also alter the position and angle of the upper ball joint. Since lowering these cars is common, the ball joint angles can suffer getting to their limits, and normal caster is reduced by any rake that results. By setting the upper BJ back, more caster is preset, and good alignment can result without bizarre shim stacks. I run 3 degrees positive caster for a real good in the groove feel at speed.
Some guys claim to improve camber action with their arms, but that seems like marketing, not engineering. Shorter arms will increase camber gain at the expence of RC migration. The shape of the tube has nothing to do with geometry. It's the position of the pivots that creates the action of the control arms and spindles. That's why the UCA relocation technique and the taller improved camber dropped spindles work.

These are questions that will be worth asking when you are shopping. If they can't answer or seem confused, be wary.

[fatiger53]

Here a couple real world (although fuzzy due to enlargement) photos of Chevelles at the Airride track day at Putnam Park IN. Note that the red car has all stock suspension, and the camber of the front wheels is leaning out of the turn-not handling too good! Body roll is extreme, making the camber control worse and shifting the CG outboard.

The blue car has the Fatman tall spindles, with Airride tubular arms and sway bars. Check out how much flatter the body is, and how the camber change has the tire leaning into the curve. Which one do you want to ride in? Here's proof that the tall spindle works! The same deal works with First Gen Camaros, that photo shows one with a stock suspension.

[TitoJones]

One thing to note on the Fatman tall spindles when applied to an A body car:

These will DOUBLE the amount of bumpsteer that the car already has with a factory spindle. Fatman relocated the steering arm attachment points so they could reduce the bumpsteer on the REAR steer F body cars, but because the A body is FRONT steer, they made it worse than factory by almost double.

The 2 inch drop will also limit the backspacing due to the steering arm/tie rod end hitting the wheel due to the excessive drop.

Tyler

[fatiger53]

I think Tito is possibly forgetting that the front steer Chevelle uses an entirely different steering arms than the rear steer Camaro. The Chevelle steering arms goes almost straight and level forward, while the rear steer Camaro has a distinct drop in it as it goes to the rear. This error is often made when a guy swap disc brake spindles from a 68-72 Chevelle and 67-69 Camaro to get disc brakes on a car that came with drums. Even though the spindle is a direct interchange, you must use the proper steering arm for the suspension type. I have helped a bunch of guys fix their cars after having made this error. Much bumpsteer does result from using the wrong steering arms.

I called Fatman's to ask what they did in their testing. They set up the tall spindle on both a 68 Camaro and a 70 Chevelle. When they did the bumpsteer check, they found that dropping the steering arm .53" got rid of bumpsteer on both chassis.

I have modified the stock centerlink on these chassis, raising the inner tie rod pivot to get rid of the factory designed bumpsteer. Since my own experience shows that this works, it follows that lowering the outer tie rod end as they do would have a similar effect. The taller than stock dropped spindle will alter control arm angles (improving the camber curve), and would require a slightly different change in the tie rod height than a stock height spindle.

Altering the angle of the tie rod assembly relative to the rest of the suspension is a well proven method of reducing bumpsteer, sometimes by raising the inner, sometimes by lowering the outer, as seen in the anti-bumpsteer outer tie rod end kits you see that use a spherical rod end as the outer tie rod end. This is then mounted to a longer stud that bolts into the steering arm and then allows the racer to raise or lower the new outer tie rod with shims.

[TitoJones]

Your info is incorrect. What fatman did not do is testing. There is NO WAY IN HELL that you can LOWER the attachment points on the A body and reduce bumpsteer. You can't have it both ways. One is a front steer car that needs the steering arm attachment point RAISED (A body) and the other is a rear steer car that requires LOWERING of the steering arm.

I know this to be fact. I did the measuring. I confirmed it with multiple other experts, including Mark Stielow, head of R&D for the suspensions at GM.

I know the steering arms are different between the A, and F body cars. You couldn't get them confused even if you tried.

On an A body car, you must replace the upper control arm when using a taller spindle or it will go into ball joint bind. You also mention bumpsteer correction outer tie rod ends. I am very familiar with them, and while they work great on the rear steer F body car, the do the exact opposite on the front steer A body cars. You cannot refute this. I have the engineering data. It is proven solid fact.

Moral of the story- Don't believe everything you hear or read in the magazines. The info Fatman told you is flat out Bullsh*t.

Tyler

[Nine Ball]

I called Fatman's to ask what they did in their testing. They set up the tall spindle on both a 68 Camaro and a 70 Chevelle. When they did the bumpsteer check, they found that dropping the steering arm .53" got rid of bumpsteer on both chassis.

Hmmm... aren't you a representative of Fatman? Why would you call yourself? Hopefully you aren't thinking we are easily fooled by someone acting as a customer...when they aren't.

[Damn True]

Thanks for the effort there but:

I called Fatman's to ask what they did in their testing. They set up the tall spindle on both a 68 Camaro and a 70 Chevelle. When they did the bumpsteer check, they found that dropping the steering arm .53" got rid of bumpsteer on both chassis.

...and in another thread:

What's the word on the taller dropped spindles by Fatman and Heidts? They are supposed to get a better camber curve as well as the drop.

C'mon dude. You clearly attempted to pass yourself off as "just another dude" and made no attempt at all to present yourself as a principal at Fatman.

[79T/Aman]

another thing to point out is that offset cross shafts do not change the effective length of the control arm it only changes the location of the pivot points

[wendell]

Hey! I covered that point already.

[TonyL]

interesting read so far. I await Fatiger53's response.
My reccomendation? Be truthful here. We're all a sharp bunch and know when someone is pretending to be a customer of his own company. It never ends well.

[baz67]

Anyone taking bets he does not respond?

[mpozzi]

Nope, it's tucked and he's running ...

Cheers,
Mary Pozzi

[fatiger53]

Yea, I am Fatman and I am my own customer. I actually use my stuff, test it on the track and in the shop The 69 Camaro and the 70 Chevelle used for fitting and testing did have bumpsteer checks done on them and are then driven in the real world. Airride has tested all the tall spindle set ups, and says our are the best. That's backed up with real testing by Pro race drivers on the track. And I do have the numbers.

Also, since upper shafts do relocate the inner pivot points further from the ball joint than a stock, not offset shaft, logic says they do change the effective length of the control arm. That's not an opinion.

The tall spindle swap on the A bodies used to require a special length UCA to get it to work. Our spindle takes care of that by relocating the upper ball joint. There is a small effect on scrub radius, but with so many different offset wheels used on a regular basis, I am of the opinion that it's not a problem.

I got on this site in an effort to learn more about what's going on in the Pro Touring world. If you think that's evil, sorry 'bout that. What I find is plenty of guys pumping their own stuff and blasting anybody with a different opinion. Here in NASCAR country, there are plenty of different educated opinions on how best to make a car handle.

[wendell]

Wow. Hustling up business with fake posts has been bad form for a LONG time. You're a class act. If these are the ethics you apply to the rest of yuor business, you're going to be a lot hapier selling chromed A-arms to the trailer crowd.

And for the record; changing the inner pick up point w/ an offset shaft does NOT change the distance between the pick up point and the ball joint. It's important that you understand that.

[68Formula]

I got on this site in an effort to learn more about what's going on in the Pro Touring world. If you think that's evil, sorry 'bout that. What I find is plenty of guys pumping their own stuff and blasting anybody with a different opinion. Here in NASCAR country, there are plenty of different educated opinions on how best to make a car handle.

Nobody has faulted you for joining to learn more about what is going on. It's encouraged that you do.

The problem was the fake posts in an effort to drum up business. If you want to tout the benefits of your system do it on a technical basis and be honest about your position.

The two pet peeves people have here is a vendor who claims to be just a pleased customer, or one who offers no technical depth other than "check out my stuff." It's insulting, and no better than spam or male enhancement ads you find in magazines. Be ethical. No one here is going to purchase anything from someone who is not.

[6'9"Witha69]

What I find is plenty of guys pumping their own stuff and blasting anybody with a different opinion.

Funny, all the vendors here have the SAME opinion and while they have competing packages, get along quite well. Misinformation is bashed and we will all back that.

Here in NASCAR country, there are plenty of different educated opinions on how best to make a car handle.

:bsjerk:

[James OLC]

...logic says they do change the effective length of the control arm. That's not an opinion.

I am sorry; this is not a confidence inspiring quote from any suspension vendor, especially one whose products are intended (?) to be used in a 'hard core' driving environment. Logic is one thing; facts are often another, but a good, proven (and demonstratable) design will always be welcomed.

Here in NASCAR country, there are plenty of different educated opinions on how best to make a car handle.

That is true everywhere. There are several ways to get to the same destination and all of them, in the end, should be quantifiable with good engineering.

When I was researching the suspension options for the ’67 I first went through David’s site and a variety of other internet resources before calling all of the vendors who were offering products or services that appeared to meet the needs of the project. While everyone that I contacted had their own opinions on how to achieve the best possible result for the most part they consistently were able to provide engineering and technical backup to demonstrate their design rational. Those that couldn’t were no longer options in our search. In your own words:

These are questions that will be worth asking when you are shopping. If they can't answer or seem confused, be wary.

That is the one thing that you have said that I have to agree with 100% and, based upon your posts, I am.

And even though it has been said several times already, although there may seem to be “plenty of guys pumping their own stuff and blasting anybody with a different opinion”, Marcus, and Tyler, and Blake, and Kyle, and Mark never pretended to be anything other that what they are – enthusiasts, manufacturers, and supporters of this hobby and this site. I (and I think that I can safely say WE) welcome direct participation from anybody involved in this industry and this hobby/sport in particular, provided they are honest about who they are and their intentions. I would have preferred to read a technical post from “a representative of Fatman” rather than a poorly scripted story. Unfortunately, it reflected poorly on yourself and your company.

Just my 2 bits.

[David Pozzi]

fatiger53,
Honest discussion is what we are here for.
You have the opportunity to defend your product if you feel the need to. But you should have been honest from the start about your identity and intentions. Members here would have been quite pleased to have direct tech discussions with a manufacturer.

David

[TitoJones]

You say you have the numbers for the Chevelle and Camaro eh? Post them up. I've posted our numbers for our AFX spindle, and we are not shy about what it is capable of. I'd like to see a graph with the following info on it:

Vehicle year, make and model
Alignment specs (static caster, static camber, and toe)
Upper control arm manufacturer
Spindle, & steering arm used
Amount of total suspension travel measured, and the bumpsteer measurement at each point in 1/2 increments.

I hate to break it to you, but there are no opinions in math or geometry. It is either correct or it isn't. It is like saying 'I think the best way to get 4 is by adding 2 + 1.' It doesn't work that way.

I have some other questions about your spindle if you will actually answer them with technical data, that can be verified with CAD or pictures, or, well- anything at this point.

What is the overall height of the spindle?
What is the king pin inclination?
Where did you relocate the upper ball joint attachment point in relation to factory?
How far did you relocate the steering arm attachment point from factory?
What is the max backspacing you can have on your spindle before the wheel hits the tie rod end?
What is the spindle made from?
Is it forged, cast or billet?
Is it cast/forged/machined here in the USA?
What is the total amount of camber gain in degrees per inch of suspension travel you can get with your tall spindle?
Are you claiming that a factory A body upper control arm can be used with your spindle without going into ball joint bind? If so, do you have pictures of the above combo?
What are your recommended alignment settings for the F and A body cars when using your tall spindle?
What is the total amount of bumpsteer for the A body car over 4.5" of suspension travel (full droop, to full compression?)
What is the total amount of bumpsteer for the F body car over 4.5" of suspension travel (full droop, to full compression?)

That is all I have for today. I'll even answer every question I asked of you, for our own product so you don't feel I'm attacking you.

Here is the camber gain graph for our tall AFX spindle on a 1st gen F body with Global West upper control arms. Recommended alignment specs are as follows:
Camber- 0.25-0.5 neg
Caster- 4.0-5.5 pos
Toe- 1/16" toe in



Here is the caster graph- same setup as above:



Here is the bumpsteer graph:




What is the overall height of the spindle? The overall height of the tall AFX spindle is 8.5"

What is the king pin inclination? The Tall AFX spindle uses a KPI of 8 degrees

Where did you relocate the upper ball joint attachment point in relation to factory? We raised the height by 1.5"

How far did you relocate the steering arm attachment point from factory? For improvement on the F body, we lowered it about .50" from factory. This translated to roughly double on the A body so we made a new steering arm to correct it.

What is the max backspacing you can have on your spindle before the wheel hits the tie rod end? On the Tall AFX spindle which only uses a 7/8" drop you can run up to 6.0" of backspacing.

What is the spindle made from? The Tall AFX spindle is made from Aircraft 6061-T6 aluminum

Is it forged, cast or billet? The Tall AFX spindle is Forged

Is it cast/forged/machined here in the USA? Damn right it is. TX to be exact.

What is the total amount of camber gain in degrees per inch of suspension travel you can get with your tall spindle? Depending on alignment settings and UCA manufacturer anywhere from .7 to .9 degrees of negative camber gain per inch of travel.

Are you claiming that a factory A body upper control arm can be used with your spindle without going into ball joint bind? If so, do you have pictures of the above combo? No way, and not a chance.

What are your recommended alignment settings for the F and A body cars when using your tall spindle? see above graphs.

What is the total amount of bumpsteer for the A body car over 4.5" of suspension travel (full droop, to full compression?) Can't find the figure, but I WILL edit this post when I locate my figures.

What is the total amount of bumpsteer for the F body car over 4.5" of suspension travel (full droop, to full compression?) Thirty-six thousnadths of an inch over 4.5" of travel.

Tyler