Smackdown Spindles

[Matt49]

Original smack stuff was 6 degrees.
S7 was 7 degrees
Gen-X is 9 degrees

And...just for you Huck...the "crate" spindles for the Gen-X are also 9 degrees. The difference is just the right side steering arm and the snout location on the left. All other geometry is the same.

But thank you, huck, for your numerous contributions to this board and the way you help out so many people looking for information. I'm sure everyone appreciates how much you've helped them with their stuff.

[hucktyson]

In other words crate guys called complaining about being too tight and they needed a solution that required making a purchase and the " crate spindle " was created ...

[Matt49]

In other words crate guys called complaining about being too tight and they needed a solution that required making a purchase and the " crate spindle " was created ...

I only know of one guy around here running the crate spindles and MasterSbilts are 75% of the cars at our track. In fact, we've got guys running the short lower right bar to help tighten entry. I fought loose entry most of the season but that's because I was trying some way outside the baseline stuff on the RF...didn't work, so I'll spare you the details.
My point being, despite your experience, you get a Gen-X plenty freed up on entry for most tracks.
The crate spindles were actually designed for Ray Cook specifically for tracks like Ocala with big sweeping turns where you are turning and on the gas a lot at the same time. The RF has a shorter steering arm which is basically just making it turn faster so that you can still turn in on the gas.
We just don't have tracks like that around here so nobody sees the benefit.
I have a set of the crate spindles but they've never been on our car.

I know you have a dislike for MasterSbilt but you're about the only person I've seen or heard of complain about them to no end. Most folks find it to be a good car. The only real reason some guys around here are switching is because almost everybody has a MasterSbilt and we're all pretty much on the same setup. Folks just wanting to try something different. Personally, I'm thinking about buying another new one.

[save the racers]

Billet what is your opinion on 6 vs 9 degree spindles.Running a 9 on the l/f and a 6 on the r/f looks like a good option to me.

[billetbirdcage]

Billet what is your opinion on 6 vs 9 degree spindles.Running a 9 on the l/f and a 6 on the r/f looks like a good option to me.

I’ve been too busy to really read much and really don’t have time to get overly in-depth, but it’s just my opinion so take it for what it’s worth.

1. Think about what inclination does for a minute? Are you really changing that much if you change both sides at the same time? What did you really do to the overall jacking effect?
2. Do you really want a shorter LF steering arm then the RF? (Another huge pet peeve of mine that drives me crazy when I see that crap). Most people overlook the left to right placement of the tie rod end (left/right of a 90 degree line thru the lower ball joint). Ever notice the RF is generally closer to the wheel then the LF; there is a reason for this as it affects Ackerman. Shortening the LF steering arm is IMO the worst thing you can do on a spindle as there are many ways to get the Ackerman you want without doing that.
3. What is changing the inclination doing to camber when you turn the wheels?
4. If you change inclination, you have to move the upper control arms inner pivot point or shorten/lengthen the upper arm, thus your changing more then just the inclination (assuming you’re using the same camber). On a modified (IIRC as it’s been several years since I did it), it’s 5/8 to ¾” to go from 7 to 10 degree on a pinto spindle and on a LM with a 10 to 10.25” RF it’s about ½” to go from 7 to 9.5 degree’s. So you’re either changing your camber curve from the control arm length change and/or moving your roll center statically and dynamically from the upper inner pivot change at the same time you changed the inclination.


I know that was a little vague but thinking about those few points should help you make a decision on what direction to go. I have way way too much time in testing all this to give more direct answers and some of it's not all that cut and dry.

[fastford]

hey billet, if you don't mind, how much bump steer are you putting in the right front now days?

[billetbirdcage]

hey billet, if you don't mind, how much bump steer are you putting in the right front now days?

Somewhat depends on how much Ackerman a car has built into it, toe out your running, and if it has different steering arm lengths side to side. As a generic answer for most cars: .062 out per inch on RF and .000 on LF.

I'd rather have too much then not enough, if that helps

[fastford]

thanks billet, that's about where im at basically, had to make a little change when I started having more travel in rt frt.

[save the racers]

I was determined to not let this thread die till I got your input .lol .I couldn't find any magic in going from 6 to 9 degree spindles,wanted to make sure I wasn't missing something.I think I will experiment with different degrees on the left and right.Interesting on the .062 bumpsteer .I spend a huge amount of time getting the bump below .010,then keep adding ack. and toe out.All I race on are wrs2 tires.Have you ever found that softer tires want less dynamic toe out?I always wonder if the toe is building heat in the tires or more slip angle in the l/f.

[billetbirdcage]

I was determined to not let this thread die till I got your input .lol .I couldn't find any magic in going from 6 to 9 degree spindles,wanted to make sure I wasn't missing something.I think I will experiment with different degrees on the left and right.Interesting on the .062 bumpsteer .I spend a huge amount of time getting the bump below .010,then keep adding ack. and toe out.All I race on are wrs2 tires.Have you ever found that softer tires want less dynamic toe out?I always wonder if the toe is building heat in the tires or more slip angle in the l/f.

I'm gonna be out of town for several days so there won't be any replies from me for a couple days....

As a quick generalization here is a rough guide (obviously car make, driver and track can/will change what effect or how much effect you see)

Typically:

If I'm gonna change inclination, I'd likely never do both sides at the same time (again my opinion, your mileage may very, lol)
Increasing the RF inclination will tighten the car on exit if you're back steering some
Increasing the LF inclination will loosen the car on off gas entry and no noticeable change on exit (again will be dependent on how much the LF is loaded, less noticeable on a flat track where the LF is less loaded on entry then say a higher banked track that loads the LF more typically).

On hard tires some guys run a fair amount of toe out to help build heat in the front tires, I never been a huge fan of this as when I got to over .75" the car started getting a little darty but maybe cause of the way I have my front ends (typically more Ackerman then most). Guys sometimes run as much a 1.125" with WRS's, but that never worked for me and what I do. Some cars are more sensitive to tire compound changes then others, most of my experience is with cars that aren't overly sensitive to it. Gen-x cars seem to be sensitive to it from what I've been told, but I lack experience with masters cars so not sure what to tell you there.

People often forget adding/subtracting castor is the fastest way to mess up your bumpsteer (longer the steering arm the more off it will be), so keep that in mind if you make a change in caster.

I run a fair amount of bump out on the RF like I said. Now this typically feels more comfortable to most drivers after they get used to having to use a little more input on initial turn in. Since the RF bumps out a fair amount you need to turn a little more left then before, but this is usually way more secure feeling to most drivers after they try it. However if your having hike down issues, this may compound the darting right effect on hike down so keep that in mind. I just want to make sure that when counter steering the car doesn't overly reduce the toe or change to toe in. That is the fastest way to make a car go from a little free to tightening up too fast on counter steer and then getting a push or over tightening itself from the toe in. Obviously most people have hit something and toed the car in and it pushes like a Mack Truck, the last thing I want is my car to toe in on counter steer and overly tighten the car too fast. This is one of my major issue's with shorter LF steering arms, they toe the cars in on counter steer and IMO is the dumbest things to do on a front end. I'm sure in some times it works, but not something I want to do personally

[fastford]

im not a fan off the short left spindle steering arm either billet, never liked it in traffic, that's why I also spent a lot of time on bump steer, I will say it is a time consuming process, but as far as drivability to me , its one of the best things I figured out....or should I say, still figuring out.

[7uptruckracer]

I've thought about it a lot and am pretty proficient with setups but what's the purpose of moving the racks back in the new cars? Your also moved the steer arm back it seems to on the spindle arm but is the rack moving for clearance because it's more towards the car center and for polar moment? Or moving the front wheel back back? What's the actual science behind it?

I'm gonna be out of town for several days so there won't be any replies from me for a couple days....

As a quick generalization here is a rough guide (obviously car make, driver and track can/will change what effect or how much effect you see)

Typically:

If I'm gonna change inclination, I'd likely never do both sides at the same time (again my opinion, your mileage may very, lol)
Increasing the RF inclination will tighten the car on exit if you're back steering some
Increasing the LF inclination will loosen the car on off gas entry and no noticeable change on exit (again will be dependent on how much the LF is loaded, less noticeable on a flat track where the LF is less loaded on entry then say a higher banked track that loads the LF more typically).

On hard tires some guys run a fair amount of toe out to help build heat in the front tires, I never been a huge fan of this as when I got to over .75" the car started getting a little darty but maybe cause of the way I have my front ends (typically more Ackerman then most). Guys sometimes run as much a 1.125" with WRS's, but that never worked for me and what I do. Some cars are more sensitive to tire compound changes then others, most of my experience is with cars that aren't overly sensitive to it. Gen-x cars seem to be sensitive to it from what I've been told, but I lack experience with masters cars so not sure what to tell you there.

People often forget adding/subtracting castor is the fastest way to mess up your bumpsteer (longer the steering arm the more off it will be), so keep that in mind if you make a change in caster.

I run a fair amount of bump out on the RF like I said. Now this typically feels more comfortable to most drivers after they get used to having to use a little more input on initial turn in. Since the RF bumps out a fair amount you need to turn a little more left then before, but this is usually way more secure feeling to most drivers after they try it. However if your having hike down issues, this may compound the darting right effect on hike down so keep that in mind. I just want to make sure that when counter steering the car doesn't overly reduce the toe or change to toe in. That is the fastest way to make a car go from a little free to tightening up too fast on counter steer and then getting a push or over tightening itself from the toe in. Obviously most people have hit something and toed the car in and it pushes like a Mack Truck, the last thing I want is my car to toe in on counter steer and overly tighten the car too fast. This is one of my major issue's with shorter LF steering arms, they toe the cars in on counter steer and IMO is the dumbest things to do on a front end. I'm sure in some times it works, but not something I want to do personally

[Austin34471]

Sorry if my snapchat made illustration isn't as that great lol. This is looking down from the top. Moving the rack back and having the tie rods angle forward from the rack to the steering arms adds toe out when steering in BOTH directions, unlike shortening or lengthening one of the spindle arms, which only may toe the tires out in one direction, but toe them in against each other when turned the opposite direction.

[billetbirdcage]

I've thought about it a lot and am pretty proficient with setups but what's the purpose of moving the racks back in the new cars? Your also moved the steer arm back it seems to on the spindle arm but is the rack moving for clearance because it's more towards the car center and for polar moment? Or moving the front wheel back back? What's the actual science behind it?

Didn't really follow after the first sentence.

It's about the angle in the tie rods. As the RF turns out board it straightens up the tie rod so it's more parallel with the rack. This effectively makes the tie rod end lengthen (from straightening out the angle and turns the tire more then the rack moves. The more angle in the tie rod when the wheels are straight, the bigger this effect is. It's a way to get Ackerman into the car without changing the steering arm length left to right which toes out one way but toes in the other way.

Watch an Indy car or similar car that spins out (watch an in car cam of the front wheels and you will see it plain as day), you will see the wheels toe out no matter what direction they are turned. Where many LM's because of different steering arm lengths toe out when turning left but toe in turning right.

I quickly did a quick drawing in CAD to give some dirty numbers on how much difference it can make:

5" long steering arm
19" long RF tie rod
Rack back so RF tie rod has 6.0 degrees angle in it (with wheels straight) This is 2" behind of the tie rod end
Turning 45 degree's right

The changing of the angle changes the RF toe out and extra .287" from what the rack moved right

Move the rack back 1" more which causes a static angle of 8.97 degrees and it increases that to .457" over what the rack moved right

That is a difference of .17", just moving the rack back 1". Now remember that extra .170" isn't at the tire, that is like lengthening the tie rod .170" which is a pretty fair amount at the center of the tire.

NOTE: I'm also doing only one side not both sides to get total toe changes, again only the change in RF toe.

[billetbirdcage]

Sorry if my snapchat made illustration isn't as that great lol. This is looking down from the top. Moving the rack back and having the tie rods angle forward from the rack to the steering arms adds toe out when steering in BOTH directions, unlike shortening or lengthening one of the spindle arms, which only may toe the tires out in one direction, but toe them in against each other when turned the opposite direction.

Better then the crappy paint one I did and was going to post, lol.