Need help with bottom guide pin

A quick learner from 08902 says:
Hi, I have a bi-fold mirror door. There are top and bottom pivot pins attached, as well as a top guide pin. I found a loose/detached pin which appears to be the bottom guide pin. It's 4-1/4 inch long without any threads or cot pin hole. I need help finding the missing parts to put the pin back in place.

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Thumbnail of the uploaded file named Bottom Guide Pin p2.jpg
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Tom from SWISCO responded:

I think we can replace this pin. We have a couple that look very similar, so I already have a few ideas. Before I make any recommendations, though, can you tell me its diameter? That will help us narrow down the list of possible replacements even more. Thank you!

A quick learner from 08902 says:
Hi Tom,

Thank you for your response and time spent researching my issue. I think the diameter is 1/4". There are pin caps in both the top and bottom tracks, they look very much like

I'm not familiar with how this bottom guide pin supposed to work. I can see the bottom pivot pin is fixed. The top pivot pin is spring loaded pushing up towards the track. The top guide pin has a spring and cot pin to keep it retract down toward the door. Does the bottom guide pin set up similarly retracting up towards the door or pushes down towards the track or should it be fixed like the bottom pivot pin?

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Tom from SWISCO responded:

Thank you! This is a huge help. Knowing that the diameter is 1/4", and that it uses our 21-108, then I think you could have either our 21-058, 21-050, or 21-049. I think one of these might be the guide pin you need for your door.

As for how the guide pin functions, I don't think it's meant to move. Many bifold doors have a pin that's completely stationary; that's what you put in first when you install the door, and then all the other pins retract so that you can install each of them. With that in mind, this might be the 21-049.

A quick learner from 08902 says:
Thanks Tom!

Since my current pin doesn't have a cot pin, it most resembles 21-050. Are there any advantage or disadvantage between using a push nut, 21-155, or a spring retainer, 21-157.

I'm still a little confused about how the pins function. The pivot pins seem self explanatory. The bottom pivot pin is stationary to support the door, the top pivot pin is spring loaded pushing upwards into a bracket in the top track to hold the door in place.

The 2 guide pins are not so obvious to me. Currently, the top guide pin is spring loaded to pull down towards the door. But the pin falls off the pin cap, 21-108, after I open/close the door a couple of times. The bottom guide pin was never attached to the door so I have no idea if it should be mounted to push down toward the pin cap on the bottom track or should it pull up toward the door, away from the bottom track. I'd really appreciate if you can clarify this for me so I'd know how to mount the pin to the door.

Thanks again!
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Paul from SWISCO responded:

The company that made your doors used the 21-050 spring loaded pin for the top guide pin. For the bottom guide pin, they didn't feel it was necessary since the pin locks into the 21-208 nylon guide. I feel both pins should use the spring to help keep the pins locked to the nylon guides, but that's just me. 

As for The 21-155 locking push nut and 21-157 retainer, we prefer the retainer so you can remove it and reuse it. The 21-155 push nut locks on and can not be reused.

A quick learner from 08902 says:
Thanks Tom & Paul for your help and your time.

I guess the bottom guide pin was designed to be loose. I'll take your advise and will try to spring load it to see if it'd stay in the nylon guide. Still not sure if it should be pushing against the nylon guide or pulling away from it.

21-049 : Bifold Door Guide Pin, Leigh, Full-VU Doors
Bifold Door Guide Pin, Leigh, Full-VU Doors
21-050 : Bifold Door Guide Pin
Bifold Door Guide Pin
21-108 : Bifold Door Pin Cap
Bifold Door Pin Cap
21-157 : Spring Retainer
Spring Retainer
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