Like the title says I'm interested to see if there is a shop that can drill high steer arms. Draglink is a TRE and would need to be tapered. Tie rod is Heim. I have a double arm for the passenger side and want the tie rod behind the axle. Here's the tricky part. I would like a shop that knows how to determine Ackerman and drill the tie rod holes correctly for it. This is a daily driver so I want it done right. I already have the blanks. This is on a ford KP 60. Price guesstimate would be appreciated as well. Thanks!
Shop that can drill high steer arms
- Thread starter Team1k
- Start date
Tacoma
Et incurventur ante non
- Location
- far enough away
Talk to Summit Machine. I know Jimmy spent a lot of time on their arms working out Ackerman.
Ill have to shoot them an email. Im a little nervous though seeing as their arms are so expensive....Hopefully their drilling isnt quite as much
Do you know if they can calculate ackerman? Probably something ill have to call on. I would just have Matt H. do them, and i still may, but i dont know if he knows how to calculate ackerman and thats the main thing im after.
Tacoma
Et incurventur ante non
- Location
- far enough away
their drilling is nowhere near as pricey as their beautiful, beautiful arms.
Thought this might help others understand the Ackerman principle. Pretty much why you see curved inward steering arms.
http://www.rctek.com/technical/handling/ackerman_steering_principle.html
http://www.youtube.com/watch?v=oYMMdjbmQXc
http://www.rctek.com/technical/handling/ackerman_steering_principle.html
http://www.youtube.com/watch?v=oYMMdjbmQXc
Last edited:
Ok. Well ive attached pictures of what the arms look like. Can you tell from the pictures if they are the "right" arms for this? If so can you PM me an estimate on cost of doing this?
So since I am using stock ford knuckles with a straight tie rod on a narrowed axle is my ackerman all messed up? Seems like drag link wouldn't concern ackerman
Nathan
Right, drag link doesn't count.
Your axle is being used on a shorter wheelbase than what it was intended for--that will mess up the Ackerman angles. (assuming they were correct to begin with, which I'm not at all convinced it was). Narrowing the axle will tend to bring it closer to what you need.
Bottom line, I'm sure it's fine--and the scrub radius of kingpin D60 knuckles screws you up more than incorrect Ackerman ever will.
You do not have the right arms for perfect Ackerman. Those arms look to be perfectly straight, as in, the centerline of the four bolt pattern follows the centerline of the arm.
Ackerman is generally determined by the following process. Draw up a sketch of your two axles, as viewed from above, including the kingpin centerline locations. Now draw a straight line from the very center off the rear axle, though the kingpin pivot center. For perfect Ackerman, your holes for your tie rod need to be located on this line. If the your rod is in front of the axle, then the holes would make for a tie rod that is longer than your kingpin width, which sure doesn't fit between your wheels, tires, or brakes. If it's behind the axle, the your rod must be narrower than your kingpin width, which rarely gets along with suspension, engine, frame, and the pinion of the axle itself.
In short, it's a very difficult thing to nail on a crawler, and it very rarely actually ends up being perfect. Unless you are actually sitting down and looking at slip angles, scrub radius, and a slew of other factors related to your steering, there are more important things to focus your energies on. If you are solely focused on Ackerman, you are overlooking more important factors.
It is possible, but d@mn hard to physically package under a crawler.
Ackerman is generally determined by the following process. Draw up a sketch of your two axles, as viewed from above, including the kingpin centerline locations. Now draw a straight line from the very center off the rear axle, though the kingpin pivot center. For perfect Ackerman, your holes for your tie rod need to be located on this line. If the your rod is in front of the axle, then the holes would make for a tie rod that is longer than your kingpin width, which sure doesn't fit between your wheels, tires, or brakes. If it's behind the axle, the your rod must be narrower than your kingpin width, which rarely gets along with suspension, engine, frame, and the pinion of the axle itself.
In short, it's a very difficult thing to nail on a crawler, and it very rarely actually ends up being perfect. Unless you are actually sitting down and looking at slip angles, scrub radius, and a slew of other factors related to your steering, there are more important things to focus your energies on. If you are solely focused on Ackerman, you are overlooking more important factors.
It is possible, but d@mn hard to physically package under a crawler.
Last edited:
The arms are straight but from what ive seen companies that have what ill call the "shotgun" attempt at ackerman have straight arms as well. Then the tie rod holes are drilled off center to compensate. The issue is in drilling the holes in the correct place. With these arms being like they are that leaves a whole lot of real estate for me to be able to work with.
At the moment i am working with summit machine who will be drilling the arms. They say the arms can be drilled correctly and we are working on setting up a time for me to come in. Im hoping for this week but it will most likely be next. Ill be sure to post up when its finished.
Also i cant comment 100% on not needing ackerman with a behind the axle tie rod, but from what ive seen online and from manufacturers it appears you need correct ackerman regardless of where the tie rod is located. I could be wrong though and would love an explanation on why its different for behind the axle applications. It surely would make my life easier.
As a side note i do know this is possible as my friend has done it. He is an engineer and calculated it. I would have him do mine as well but he is quite busy with his job and im running out of time on this. Ive attached a picture of his jeep for reference. He is using the same axle as me, with a behind the axle tie rod setup. The differece is his wheelbase is longer and my axles are narrowed so i cant just copy his. Anyway as you can see in the picture the inside tire is turned in more than the outside. He has no negative side effects while driving on the street. That is my goal as well.
At the moment i am working with summit machine who will be drilling the arms. They say the arms can be drilled correctly and we are working on setting up a time for me to come in. Im hoping for this week but it will most likely be next. Ill be sure to post up when its finished.
Also i cant comment 100% on not needing ackerman with a behind the axle tie rod, but from what ive seen online and from manufacturers it appears you need correct ackerman regardless of where the tie rod is located. I could be wrong though and would love an explanation on why its different for behind the axle applications. It surely would make my life easier.
As a side note i do know this is possible as my friend has done it. He is an engineer and calculated it. I would have him do mine as well but he is quite busy with his job and im running out of time on this. Ive attached a picture of his jeep for reference. He is using the same axle as me, with a behind the axle tie rod setup. The differece is his wheelbase is longer and my axles are narrowed so i cant just copy his. Anyway as you can see in the picture the inside tire is turned in more than the outside. He has no negative side effects while driving on the street. That is my goal as well.
Btw, the factory steering holes in the knuckle are way, way, way off for perfect Ackerman (in fact, they are offset nearly precisely the correct amount, only in the completely wrong direction on a 60). Chevy, Ford, Dodge, and Dana all decided to place several other design considerations well above Ackerman.
I don't think your worse off for trying to optimize it, but what's good for a road racing car is often very different than what's good for an offroad vehicle. I know some people who advocate for a certain type of imperfect Ackerman for our type of vehicles, and discussions with them regarding slip angles and traction realities have ben fairly convincing. That said, I designed perfect Ackerman into my pile of junk.
I don't think your worse off for trying to optimize it, but what's good for a road racing car is often very different than what's good for an offroad vehicle. I know some people who advocate for a certain type of imperfect Ackerman for our type of vehicles, and discussions with them regarding slip angles and traction realities have ben fairly convincing. That said, I designed perfect Ackerman into my pile of junk.
Last edited:
I may try your method you posted before with drawing the lines and such, just to verify what we are doing is correct. Im by no mean an expert and im willing to learn.
Go back to my post regarding the drawing of your two axles, and the theoretical line from the center of the rear end, though the steering pivots. Your tie rod holes must be on this line. It's shaped like a V, and behind the axle, it's skinnier than out is in front of the axle.
Grab a piece of paper and sketch out up if my explanation leaves you wanting.
Grab a piece of paper and sketch out up if my explanation leaves you wanting.
Ackerman can be nailed both in front of, and behind the axle. In fact, behind the axle is pretty much the only way to package it while maintaining Ackerman with a 60 front.