Hot Rod Forum banner

Hair Pin (Radius Rods) Installation Question

19K views 20 replies 6 participants last post by  hotwheels1 
#1 ·
I have done a pretty good search on this and haven't really been able to find an answer, but what is the correct way to install hair pins on a suicide front end? Should i connect the ends of the rods to the axle, then drill my hole in the frame and adjust the axle from there? Or ?
 
#2 ·
hair pins

how i did mine... i have a 4" drop front axle w/ 15" tires..
u need the bracket welded on the front end to bolt the hair pins to, equal distance top/bottom. measure to the center of axle on the ground with weight on it.(motor installed)
clamp a bracket to frame and a hole drilled to match the ctr of axle. the heim joints should be screwed in a equal distance in/out for adj when done.. when done do a square of rear axle and front axle.. also start with 1/8" toe in. make sure your steering box is adj'd properly for slack.. don't want death wobble at 50mph.. thats the ususal sp'd when u hit a bump and the front end goes out... its NOT fun.. bill
 
#4 ·
I call it dry fitting..clamp the parts in place and check the castor and see just where the mounting point of the radious rods are on the chassis. Once you are satisfied all is well then do any welding that needs to be done,,

Sam
 
#6 ·
I just did a quick look - there is actually a You Tube series on this kind of set up. I didn't watch all of the various videos, but they seem to start out well. Might not all be relevant or well done, but some interesting stuff :http://www.youtube.com/watch?v=eXjGu8gy6DY.

Before you commit to hair pins, make sure you know the difference between them and 4 bars and what each will do for the suspension. Light cars do fine with hairpins, heavier cars, probably best with 4 bars. It has to do mostly with caster change and possibly with axle twist/frame deflection and maybe even weld integrity.

And yes, I know that both are used with good results.

Dave W
 
#11 ·
hotwheels1 said:
So which way is actually a positive camber, the bottom of the kingpin facing forward and the top tipped back a bit?

If that is the case, can i use an angle finder and put like 6* degrees with the hairpins?

I attached a couple images.
Yes, You have the right idea . If you were to take a level and hold it on the center of the spindle nut to make a true vertical to the floor and then make a centerline through the center of the kingpin, it would need to hit the floor ahead of the other center line . I personally like a lot of positve caster 'cause it makes the steering self centering after negotiating a curve . I never had the luxury of an angle finder, but using my method I shoot for about 2-1/2' to 3" difference . What that is in degrees, I can't tell you for sure but the 6 deg sounds good to me .
 
#13 ·
another point..

irelands child made me remember the 4 link setup.. i have wish on the front and 4 bar on rear.. IF u have not gotten then wishbones yet then i highly recommend looking hard at 4 links... the wish are a pain to do front end alinments, because u need to unbolt both heims to make an adj.. where as the 4 link u just turn the rods... little more to make brackets but u can do an alinment in minutes vs an hour.. i love them 4 links.
bill
 
#14 ·
Looking at your pictures, you need to swap the spindles from side to side. Having them reversed as you do will cause the "Ackerman" angle to be off and you will have the steering geometry way off. To best understand this do a search for "Ackerman Angle". Basically what this is can be shown if you draw a line from the center of the tie rod hole in the steering arm, thru the center of the kingpin on both sides towards the rear, the intersecting point should be about the center of the rear end. Handling will be very difficult at any speed the way you have it set up. If you want to keep the spindles as you have them, you must heat and bend the steering arms outward towards the wheel rim to correct the angle. This can seldom be properly corrected this way as the steering arms will tend to hit the rim before achieving the correct angle needed. Best to put the spindles on the correct sides and lower the steering arms to clear your frame.
 
#15 ·
delawarebill said:
where as the 4 link u just turn the rods... little more to make brackets but u can do an alinment in minutes vs an hour.. i love them 4 links.
bill
Not necessarily as most mfrs make them with a fixed loop at the axle end with the frame end adjustable. Generally the tie rod and drag link are made with R & L hand threads on opposite ends





Since I just adjusted my differential/wheelbase dimension these are fresh photos from last week.

Dave W
 
#16 ·
Thanks frisco. I will have to sit and relook at the front end. If i swap the spindles back to the opposite sides, the steering rod hit's the frame. I have already cut the frame to spring shackle to bring the frame up off the ground a couple of inches. thanks for the heads up and i will do some reading on the ackerman angle.

doug
 
#17 ·
hotwheels1 said:
If i swap the spindles back to the opposite sides, the steering rod hit's the frame.
You can modify the existing arms to clear. See the illustration below. Another alternative is to remove the existing steering arms and replace them with aftermarket dropped steering arms. They are available in 1 3/4" drop or 3 3/4" drop. The pictures below are from a Speedway Motors catalog for illustrative purpose. I believe Chassis Engineering manufactures a set of dropped steering arms that mount flatter and clear a dropped axle better than the ones I show below. Left click on the images for a larger view.
 

Attachments

#19 ·
Here are some additional pics. Two show the stock steering arm with a dropped axle and almost '0' clearance. The next two show the same axle with the Chassis Engineering steering arms. Lots of clearance.
 

Attachments

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top