Series I, II, III Lower A Arm

[Fordtootsie]

I am putting in new fulcrum pins on my lower A arms on my series I Alpine. The measurement across the large end of the A arms is different on my arms. Does anyone know the correct distance across the large end of the A arm. I think that series I, II and III use the same A arms.

John in Colorado

 

[Toyanvil]

I have a set I just rebuilt, I can look tomorrow for you. I cut a piece of angle iron to fit between the A arm for pressing, or you will squeeze the A arm.

 

[Fordtootsie]

Toyanvil

Thanks

I am rebuilding mine . But the existing arms have different widths. The last person did not insure that they were the same width when they installed the fulcrum pins. The only mention of a dimension in the service manual is the 1 1/8 inch on the rear position (page 40).

John in Colorado

 

[Toyanvil]

Mine are 8 7/8" wide inside to inside. I used duct tape on the angle iron to protect the powder coat.

 

[Fordtootsie]

Toyanvil

Thanks !!

One of my A arms has good bushings on the fulcrum pin. It measures 8 7/8 - so looks like whoever did the installation knew what he was doing.
The other A arm measures 8 3/8 and does not have a fulcrum pin installed. So I can correct it to the 8 7/8 dimension when I install the new pin.

I will have to make the support tool, but I made one for the upper A arms so that learning curve has been dealt with.

John in Colorado

 

[Fordtootsie]

Toyanvil

I am still having trouble with the dimensions on my lower A arms
I have the 8 7/8 dimension OK
The larger distance from end of pin to bolt slot is to the rear A arm brace. (per manual - if its correct)
The service manual calls for the distance from the inside edge of the rear arm brace to the center of the bolt indention as 1 1/8 inches (page 40 section F figure 33 service manual). However the figure and wright up in the service manual are for a series IV or V as it shows a locking nut on each end of the pin. My series I has two threaded bushings and a zert fitting in the pin end with a dust cap.

If I press the pin so that the dimension of 1 1/8 is held as per the manual, I have the bushing sticking out 2 to 3 eights on the rear arm and recessed 1 to 2 eights on the front arm.

It seems to me that the 1 1/8 demission (page 40 section F figure 33 service manual) used on the series IV and V as listed in the manual may not be correct on a series I.

The 2 to 3 eights and the 1 to 2 eights measurements are different as the bushing may be screwed on tighter on one A arm than the other.

SO what is the correct distance from the rear or front bolt slot to the arm? It seems that both A arms should have the same dimensions so that the geometry is correct.

I thank I need help!!!John in Colorado

 

[Hillman]

The following articles touch briefly on this topic:

http://www.tigerengineering.net/TECHTIPS/Urethane Bushing Pt 1.pdf
http://www.tigerengineering.net/TECHTIPS/Urethane Bushing Pt 2.pdf

 

[Fordtootsie]

Hillman

These are nice articles thanks - BUT - They are not for the series I cars. Our cars have threaded bushings on both ends of the fulcrum pin. Thus both pin and bushings have to pressed into the A arm as one unit.

My problem is I don't have any data to show the correct measurement from the inside surface of the arm to the depression for the attaching bolt.

I thank, and someone will correct me if I am wrong, that the measurements I need will effect the wheel caster. It certainly can change the angle of the swivel pin to the ball joint on the top A arm.

John in Colorado

 

[Toyanvil]

I will PM you my phone #. I screwed my bushings all the way on then backed them off 1/2 turn, then pressed the fulcrum pin centered.

 

[Fordtootsie]

OK

Here is what I have been doing in order to determine what the fulcrum pin edge distance - that is the distance from the inside edge of the lower A arm to the dimple where the bolt goes - is for a Series I car. .

I have installed both the upper and lower A arms - no spring, no spindle . I lowered the front of the car and raised the rear end of the car to get the lower A arm level in both directions. The top of the tail fin is 6 ft 2 1/2 inches from the ground. The front fender top is 42 inches off the ground. My car is just the shell at this point so this is easy to accomplish.

I attached a flat plate to the bottom on the A arm to use as a platform to hold my laser. Then center the laser on the center line of the trunnion and measure the difference if any from the center line of the upper ball joint. If the laser shows an offset distance, the fulcrum needs to be moved so that the center line of the trunnion aligns with the centerline of the ball joint.

This does not sound too bad as I am composing this response - but it took me all day to get it done.

The big question is what is the correct distance from the rear inside edge of the lower A arm to the bolt dimple for a Series I car.

I believe the answer is 1.5 inches .

I measured this on both drivers and passages side lower A arms and got the same answer.

The Sunbeam manual on page 40 section F lists a dimension of 1 and 1/8 inches But I think this is for the series IV and V cars as I have stated .

comments are welcome !!

John in Colorado

 

[jumpinjan]

...It seems to me that the 1 1/8 dimension (page 40 section F figure 33 service manual) used on the series IV and V as listed in the manual may not be correct on a series I...

You are correct, it's not the same distance, but the early, lower fulcrum pin does indicate an larger, off-set distance and that pin end that should be install to the rear of the A-arm.
The early suspension is only covered in pages 16-21, Section F
Jan