Mini tub S197

[psfracer]

Couple more questions. You are going to have the wheels you have now widen? The 15x10 7.5 back space? If so are you going to have them widen on the front since you are narrowing the rear? Also did you decide to stick with a 3 link or go to ladder bar?

Yes, they will be widened towards the outside (front of the wheel), as I am narrowing the rearend. I decided to go ladder bar, all though the 3 link could have worked. However, the LCA mounts (both front and rear) would have to be moved in, so I decided to just go ladder bar as I already have coil overs, moved inboard, for the rear suspension. The rear mount for the LCA is pretty self explanatory, just move them in on the axle housing the appropriate amount. The front mount you could do like CPRsm if you want to maintain the 3 link.

Sweet! So what are you doing with the suspension? I'm assuming you will be making new brackets and what not.

3 link would work by moving in both the front and rear mounting points of the LCA, but I decided to go ladder bar.

I have a question, Paul.
You have anti-squat brackets correct?
Doesn't that make sure you don't squat, does that go against you wanting an inch of travel in the rear?
just trying to understand weight transfer vs anti-squat

Travel just for street driving, not on launch I assume?

I want an inch of clearance on both the inside and outside, plenty of room so no matter what the car does in the first 60', I won't have to worry about what happened last time out (tire contacted the fenderwell, cut the tire). I also have to worry about tire growth as the car goes down the track. I have video that shows the tires grow quite a bit actually.

My sig pic is with the anti roll bar set to neutral, so the passenger rear does experience some squat as the driver front lifts higher then the passenger front (see sig pic).

 

[CPRsm]

Whaaaa? Why ladder bar? Kinda kills the adjustabilty of the IC in these cars. I can get some of those brakets re-cut if you want. Or the back also?

 

[NDSP]

I have ask with CPRsm, why ladder bar. I'd advise strongly against it. Only because your resale value will go out the window with a ladder bar. I know three guys, over the last 10 years that went ladder bar in their mustangs. Big horsepower tubbed/mini-tubbed setups. All of them could not sell their car when they where ready to move on to something else. They couldn't sell it turn key, they couldn't sell it rolling. Not without giving it away. They all had to part it out and they all still have a shell of a ladder barred race car in storage somewhere. Go four link or stay stock suspension, and you will have a much better chance of selling when it is all said and done. That is just my 2 cents off of what I've seen happen to friends. There may be a different market for ladder bar cars in your neck of the woods.

 

[psfracer]

Whaaaa? Why ladder bar? Kinda kills the adjustabilty of the IC in these cars. I can get some of those brakets re-cut if you want. Or the back also?

I have ask with CPRsm, why ladder bar. I'd advise strongly against it. Only because your resale value will go out the window with a ladder bar.

Not interested in resell value--I spent 1 1/2 years with this in my garage building my "dream car", so I don't see myself selling it. The car doesn't meet stock suspension rules as it is right now, because I changed the shock location (I have strange coil overs, double adjustables), and its too heavy to be competitive in any form of stock style suspension heads up racing. Car is more of a bracket and index car anyway (8.60 B/Gas and Mustang Madness in PSCA)

Yeah its a hard decision. I could make the 3 link work, but I like the simplicity of the ladder bar. Very easy to adjust and I can change the pinion angle without worrying about the UCA. I was looking at these triple adjustables from Chassis Engineering. Would make pinion angle adjustments a snap, and the front mount can change the height of the IC, but not the location of it, as you mention.

I have seen some big horsepower cars work well with ladder bars, where 4 links are outlawed. I do agree 4 link would be best, but there are so many ways to adjust a 4-link, I would screw it up for sure.

 

[psfracer]

The ladder bar I am looking at by chassis engineering (outlaw bar) has enabled this MMR car to do a 1.14 60' with the same tire I run (29.5X10.5W) and run 4.58 @ 162 mph to the 1/8th, and 6.99 @ 205 in the 1/4.

There are a few more examples but I think this is the best one being the same chassis and running the same tire.

 

[Whiskey11]

Maybe I'm missing something (Probably, like any experience with drag racing or drag suspension setup) but what makes a 4 link better than a 3 link for drag racing? In sideview they act exactly the same for IC location and behavior for acceleration and braking. The only thing I could come up with is axle torque over control and I'm not sure that is as effective as other methods for the 3 link are.

On the other side of the argument you already have the 3 link and with that gobs of adjustment for IC location, arm length (well, sorta that) and so on. If more antisquat is your drug of choice and you are out of locations on your relocation brackets then why not an aftermarket UCA mount with lower chassis mounting points to move it further back?

PS: I'm here to learn more about drag setups even though I have only a passing curiosity about drag racing so hopefully my post doesn't come off as anything but me trying to learn something new.

 

[fdjizm]

Interesting...

 

[NDSP]

So your going to go with stock frames rails ( notched possibly ) or are you considering a complete back half?

I could be wrong, probably am, but I think going with a back half 4-link will allow you to sit the car down over the rear tire as far as you want. Using a ladder bar, back half or not, the lower you sit the car in the rear the harder it is to keep your rear geometry in an optimal range. Because the front mount is between and often a little below the frame rails, so the lower you go the worse off your geometry becomes. That is one of the reasons you seem to always see ladder bar cars sitting up on top of the rear tires and not down over them. It is also why they seem to be a lot more squirrely going down the track. That could also be because they don't know how to set it up correctly, so I'm generalizing.

 

[CPRsm]

Maybe I'm missing something (Probably, like any experience with drag racing or drag suspension setup) but what makes a 4 link better than a 3 link for drag racing? In sideview they act exactly the same for IC location and behavior for acceleration and braking. The only thing I could come up with is axle torque over control and I'm not sure that is as effective as other methods for the 3 link are.

4 link has a few advantages. The longer upper arm of the 4 link will maintain pinion angle better. There's more adjustability over all and a lot have arcs in mounting holes the same radius as the arm length. So changes can be made without pinion angle changes. Distance from axle centerline to joint height can be adjusted. Some like that, some say it makes a difference.
Hell the ladder bar will work though fo sho. No arguing that.

 

[psfracer]

So your going to go with stock frames rails ( notched possibly ) or are you considering a complete back half?

I could be wrong, probably am, but I think going with a back half 4-link will allow you to sit the car down over the rear tire as far as you want. Using a ladder bar, back half or not, the lower you sit the car in the rear the harder it is to keep your rear geometry in an optimal range. Because the front mount is between and often a little below the frame rails, so the lower you go the worse off your geometry becomes. That is one of the reasons you seem to always see ladder bar cars sitting up on top of the rear tires and not down over them. It is also why they seem to be a lot more squirrely going down the track. That could also be because they don't know how to set it up correctly, so I'm generalizing.

I am trying to stay away from a back half---which at this point I should be able to get the clearance I need by notching the frame.

I have seen many ladder bar cars with them sitting over the tire vs on top of it--but yes they are typically not slammed like the back halfed 4 link cars, where the fenderwell even comes over part of the wheel.

I haven't decided yet--but I have seen a lot of cars work with the ladder bar, run 6s, and I personally like the simplicity. For me more possible adjustments isn't necessarily better for me, as it may be just more ways for me to screw it up.

 

[LockNLoad]

a little. I want the rear suspension / tire to be ready for more power in the future......

I can relate to that. Looks like a cool build please keep us updated

 

[Whiskey11]

4 link has a few advantages. The longer upper arm of the 4 link will maintain pinion angle better. There's more adjustability over all and a lot have arcs in mounting holes the same radius as the arm length. So changes can be made without pinion angle changes. Distance from axle centerline to joint height can be adjusted. Some like that, some say it makes a difference.
Hell the ladder bar will work though fo sho. No arguing that.

Why not just lengthen a 3 link? Kinematically it is the same. He is already to cutting up parts of his car so why not lengthen the 3 link setup rather than cut up more to fit a 4 link in? I dont know, when someone says 4 link I instantly think of all of the bind associated with them.

Or you could also torque arm the car and hack up nothing, put the force that causes axle wind up into tire planting goodness and get the IC stability of a ladderbar setup without the bind. Probably cheaper too...

 

[psfracer]

How does a properly set up ladder bar suspension create any kind of bind? You lost me there. I can see that if someone was putting a ladder bar setup with a leaf spring. I am using DA coil overs that have already been moved inboard.

Torq arm suspension looks like alot of weight to me. That also doesn't solve the fact that the LCA mounts need to be located inboard -- regardless if I stick with the 3 link. I figure if the mounts need to be moved inboard, then there is really no difference (work wise) in keeping the 3 link or going ladder bar, due to the front frame mounts being moved to a crossmember, like a ladder bar set up. Remember I am notching the frame for more clearance, in conjunction with the mini tub.

Lastly, the reason why I am considering a Ladder bar setup is this type of suspension has proven itself on the drag strip over and over again. Look at the MMR car above. Hard to argue with a 1.14 60'. I know of many other examples of this type of suspension on the BBF guys I know, many of which run into the 4s at the 1/8th.

 

[CPRsm]

You can lengthen the upper 3rd link, but then turns into a back half to mKe room for length. That's all really. But kinetically the same
I like torque arms, too. Planned that for my '67. But I like a 3 link better. TA are great, but they are a bit limited in IC locations like a ladder bar. But was toi g to be much easier and less fab than a 3 link in a car that was originally a leaf car.

How does a properly set up ladder bar suspension create any kind of bind? You lost me there. I can see that if someone was putting a ladder bar setup with a leaf spring. I am using DA coil overs that have already been moved inboard.

It can't articulate. But that's a street car/road race problem

 

[psfracer]

Ok got yeah, I am in a drag race mind set--didn't think about that.

 

[DTL]

I won't try to argue that a ladder bar setup is superior to 4-link, but ladder bars do have several advantages in this instance.

- You can (usually) keep the stock floorpan with a ladder bar setup. Not (usually) true with 4-link. Stock floorpan rules appear in a lot of different sanctioning bodies.

- Ladder bars can be made to work with the stock frame rails, even in a unibody car. 4-link requires an upper frame to mount the upper arms and usually needs to be tied in to the cage for support.

- Ladder bars are far cheaper to install and simpler to set up for someone who's never done it before.

- Many classes allow ladder bars with only a modest weight penalty, whereas 4-link is specifically outlawed.

- Ladder bars can work with a very small tire (for class rules) where 4-link can struggle without being "hit" hard enough with a larger tire. (in my experience)

- Ladder bar cars are a lot easier to drive sideways if the car does something silly (again, just in my experience)

 

[Sky Render]

What is this "hit" you are talking about?

Sincerely,
A Corner-Carver

 

[CPRsm]

A hit would be like a transbrake release or clutch drop. In his example, it's kinda like the hit comes from the tire because it's larger, taller, heavier, etc. that split second that slows the tire speed causes more torque to be applied to the suspension.
I guess you can round about call a hit, axle rotation?

 

[Sky Render]

So the hit is the initial force acting on the tires to make them achieve grip and "push" the car forwards?

 

[Whiskey11]

It can't articulate. But that's a street car/road race problem

See, I am looking at the lack of articulation from a stress standpoint. Specifically stress at the unibody end of the ladder bar. Any time you turn, say at the end of a run, I would think you are applying a large amount of load on the chassis side points of the ladder bar up until you started dragging the tire through the corner. At least with an articulating suspension that force gets presented as body roll (however small it may be) rather than a force at your suspension mounting points that is trying to damage the unibody. That of course ignores the rotational forces on the axle from engine torque too.

Maybe I am overthinking this (probably am) but it seems like the wrong way to do things with a suspension. Maybe it doesnt matter as much with soft sidewall slicks as much as a street tire but I would think that a ladder bar would react extremely poorly to any uneveness in the track surface.

Again, I wont profess to know anything about drag setups. I am willing to bet Colin Chapman would be pleased by a ladder bar setup: "Any suspension, no matter how poorly designed, can be made to work if you just keep it from moving."