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

[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.

[Steve1968LS2]

Moral of the story- Don't believe everything you hear or read in the magazines.

Hey, why ya gotta drag magazines into this ;)

[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.

[Marcus SC&C]

Tito`s right. The outter tie rod pickups on `64-`72 A bodys needs to go up not down to improve bumpsteer. The misalignment is also not .53" on the A body,it`s more. Brett "the FatMan" told me personally that their spindles drop the steering arm mounting points .514", good on a 1st gen F body and particularly effective with near stock alignment specs. Dropping the stock A body steering arm the same amount will increase the already bad factory bumpsteer by nearly double. Similar to B body spindles but without the steering ratio and ackerman issues. The factory misalignment is obvious enough than anyone with a good understanding of suspension/steering can easily see it just looking at the suspension/steering head on. Dropping the outter tie rod end .53" (or .514") would only make it much more obvious. We`ve actually had clients use modified ATS steering arms to correct the bumpsteer with Fatman spindles with good results. It`s not perfect and it`s not a direct swap but it takes care of the bumpsteer problem. We do consulting and testing with many aftermarket companies on their steering and suspension products,we`re testing a rack and pinion system for A body right now. It really doesn`t matter a lick who makes a part or how they market it geometry is geometry is geometry. It`s not a matter of opinion,it`s easily quantified.
I`ll agree that in general taller spindles (or taller ball joints) can be used to huge advantage on the A body chassis though. Once the geometry has been improved the upper arms usually are no longer the right length,offset and angle to fit the car any longer and that`s where specific aftermarket upper arms come into their own,to complete the system. Mark SC&C

PS. A friendly note to other manufacturers new to posting here. The folks on this forum are a SHARP bunch. They know their tech better than a lot of companies out there and you have to be spot on or they`ll call ya on it every time. That`s a good thing!
Keeps us on our toes.

[TitoJones]

Start reading.

post # 5 proves my point: http://www.chevelles.com/forums/show...ghlight=fatman

http://www.chevelles.com/forums/show...ghlight=fatman

http://www.chevelles.com/forums/show...ghlight=fatman

http://www.chevelles.com/forums/show...ghlight=fatman

My favorite REAL WORLD experience thread:
http://www.chevelles.com/forums/show...ghlight=fatman

and the Fix to the above thread:

http://www.chevelles.com/forums/show...ghlight=fatman

All of this is only from one forum. If I add Lateral-G, P-T and Camaros.net you will be reading about yourself for the next 5 days.

If you do work for Fatman, or you happen to be Bret;

Welcome to our corner of the internet. We don't allow mis-information to be spouted off as fact, so you better break out the bumpsteer gauge again and bring technical data to back it up.

Tyler

[69HuggrrrPT]

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.

I was thinking the same thing "FATiger" HMMMM...

[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.

[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