radius rod length with dropped i beam? need helpmy

[kev23t]

My spirit frame uses 27" radius rods with dropped tube front axle. I want to use a dropped I beam instead. Since the perches on them are wider than on the tube axle will I need different length radius rods?

 

[bobscogin]

My spirit frame uses 27" radius rods with dropped tube front axle. I want to use a dropped I beam instead. Since the perches on them are wider than on the tube axle will I need different length radius rods?

Considering the geometry involved, it would seem likely. However, it depends on the design of the radius rod brackets. If the rods fall short of the mounting points on the axle, you may be able to use radius rod brackets that extends further rearward.

Bob

 

[ellis8500]

You might need longer ones but you have to check first. The actual length of the rods with ends attached is 30". you can adjust to about 30-3/4 or perhaps out to 31" long. So, try and see. Also, use some simple trigonometry. A slightly widehe perch spacing will change the overall length of the rods very little. A 2" wider spacing will increase rod length by about 0.03 inches!!!!! I'm guessing they will fit.

 

[ellis8500]

You might need longer ones but you have to check first. The actual length of the rods with ends attached is 30". you can adjust to about 30-3/4 or perhaps out to 31" long. So, try and see. Also, use some simple trigonometry. A slightly widehe perch spacing will change the overall length of the rods very little. A 2" wider spacing will increase rod length by about 0.03 inches!!!!! I'm guessing they will fit.

Figure above should be 0.3 inches. Guess it was too early in the morning for decimal places.

 

[Youngster]

The only way to be sure of the length is to set up your front axle and measure for the hair pins. There are just too many variables here. You might have to get a longer spring too. As i said ... set it up and fill the holes.

Ron

 

[Lee_in_KC]

Be careful with screwing out the rod ends (clevises, heims, whatever you're using) too far. Rule of thumb (from the aircraft industry) is you want no less than 1.5 times the diameter of the shank of the rod end engaged in the tube at maximum extension. This is to ensure that a sufficient number of threads are engaged to carry the load. Most folks wouldn't think the front radius rods carry much of a load... that they simply keep the front axle aligned. But remember, when you apply the brakes, there is a huge twisting load put on the axle, and it is the rod ends that transfer that twisting load to the radius rods (seen as tension by the top rod end and compression my the lower).

 

[kev23t]

Thanks guys