OEM roller Fairlead opening vs 8274 drum width

[Hendrik]

G'day,

I have fitted a Gigglepin +76mm widened AFS drum to my 8274 and have for my own reasons decided to stay with FSWR instead of the newer and lighter UHMWPE rope.



So when looking at roller fairleads, I was not able to find a roller fairlead that had a wide enough opening.

This got me thinking....why?

The original WARN winch and fairlead:-
* fairlead had an opening between the rollers of 7 1/8" = 181mm
* WARN 8274 drum is 8 1/2" wide between the flanges = 216mm
* ∴ fairlead opening is 35mm narrower than the drum.





I understand the need for the fairlead to to be a little narrower than the drum to avoid side loading, but after looking around for a few hours on google I couldn't find any definite reasoning for having it so much narrower than the drum.

Does anyone know why this difference is so great? Is this just a generic compromise to allow for a wide range of winches to fit the same fairlead?

I've heard a few stories of people having troubles to re-load the rope across the full width of the drum with a considerably narrower fairlead opening.

Unless I have missed a fundamental principle of engineering, I would say that the ideal opening need only be about one (1) rope thickness narrower than the drum. This will ensure that there shall be no side loading, and also ensure that the rope can be re-loaded across the full width of the drum, especially when applying the recommended load - 5% of rated rope capacity - when reloading.

So, with the widened Gigglepin I calculated how far I thought the roller fairlead needed to be widened:-
* GIGGLEPIN widened drum is 11 1/2" wide
* The fairlead opening should (I think) be 1/2" smaller than the measured drum width between the flanges
* drum width of 11 1/2" - 1/2" = 11" = 280mm
* 280 - 181 = 99mm
* ∴ fairlead shall be widened by ≈100mm to achieve the 1/2" difference

Since I am lucky enough to work in a fab shop, I am machining up new pins from SAF 2507 and new rollers from INCONEL for improved strength given the longer span of the horizontal rollers.



This is the bar I am fitting it to. These 100 series ARB deluxe bars aren't made to take a high-mount - so due to the lack of space, the winch will be as far forward as possible meaning the fairlead will also be quite close to the winch.

Any comments feedback or advice would be greatly appreciated.

Cheers,
H.

 

[cruiserpilot]

I've been in contact with the Gigglepin tech people before, they know their stuff and use it.
Why not ask them and then let us know what they say? BTW, if I could lay out the money I'd have
one of their twin motor winches in the mail tomorrow!

 

[Hendrik]

Good idea, not sure why the thought hadn't crossed my mind

Here is the Gigglepin FAQ: http://www.gigglepin4x4.net/FAQS.php

And here is their email for questions: shop at gigglepin4x4 dot net

BTW, I bought mine from the Australian agent Smithi Engineering: http://smithiengineering.com.au/

Message sent, let's see what they say.

 

[Hendrik]

Gigglepin replied this evening and it's pasted here:-

Thank you for your mail and apologies for the delay in replying.


The reason fairleads are actually smaller then the drum itself is to protect the winch. When winching, the cable can stack into the side of the drum and then pull down into itself creating huge loads on the drum plates. These plates then flex against the housing and either break the housing or in extreme cases cause the gears to point load and break as they are now out of alignment.

Gigglepin defeat these problems in two ways. Firstly you will notice the drum end plates do not hug your winch casings. This is to allow some flex in the plate if stacking occurs. We also upgrade the drum plates from 4mm to 8mm to again reduce the risk of this happening.

Steel cable is less likely to cause this problem compared to its synthetic counterpart as it is less likely to deform under winching. Unless slack cable is allowed on to the drum, this can then cause exactly the same problem.

The drum you have measures 282mm between the plates. Our Gigglepin fairleads measure 230mm in the throat.

I would strongly recommend not making your fairlead throat any larger than this due the reasons already given.


I hope that helps and if you have any further questions please do not hesitate to ask.

Makes sense to me, so I'll build it as recommended.

 

[cruiserpilot]

Great answer, thanks for doing the research. I learned al long time ago to go directly to the source.
So are you going with the 6 hp motor as well?