Diff Drop Options for Kings

[WldBlue]

Hey everyone,

I've been looking at what coilovers to go with down the road when my HOSS 3.0 Fox 2.5's wear out or I'm just ready for more travel. I'm pretty set on King's due to what seems to be their best overall travel numbers comparing compressed/extended lengths. Multiple sources (mainly Accutune and Shock Surplus) confirm the longer extended length in the front puts the CV into some binding during full droop/turn (pretty rare scenario).

I have really only seen the robinsons front diff drop kit out there for sale. I've heard of the RC brackets but it seems to be incorporated into their spacer kit not sold individually. Also heard of ACFab making a drop kit but I've seen nothing.

Anyone have any experience with the Dobinson's kit or the King 2.5 package? If I wasn't so tied to my truck I'd probably get a Raptor for the travel as prices keep dropping but I'm hoping to build more travel into mine for Silverlake

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[BigMeatsBronco]

a diff drop is fairly easy to build yourself... also there is a member selling his own version of mine as well.

 

[Fordified1]

Hey everyone,

I've been looking at what coilovers to go with down the road when my HOSS 3.0 Fox 2.5's wear out or I'm just ready for more travel. I'm pretty set on King's due to what seems to be their best overall travel numbers comparing compressed/extended lengths. Multiple sources (mainly Accutune and Shock Surplus) confirm the longer extended length in the front puts the CV into some binding during full droop/turn (pretty rare scenario).

I have really only seen the robinsons front diff drop kit out there for sale. I've heard of the RC brackets but it seems to be incorporated into their spacer kit not sold individually. Also heard of ACFab making a drop kit but I've seen nothing.

Anyone have any experience with the Dobinson's kit or the King 2.5 package? If I wasn't so tied to my truck I'd probably get a Raptor for the travel as prices keep dropping but I'm hoping to build more travel into mine for Silverlake

Here.
https://www.bronco6g.com/forum/threads/my-diy-diff-drop.91315/

 

[Fordified1]

@TeocaliMG makes a kit and has it pretty much ironed out. Buy pre-welded or weld yourself. I couldn’t link to his thread for some reason.

This is the route I will take when I lift more for 37’s.

 

[Fordified1]

Figured it out. https://www.bronco6g.com/forum/threads/homemade-diff-drop-for-6g-bronco.89576/

 

[WldBlue]

I had not seen that broken innovations kit before, that looks by far the best engineered of the bunch and moves all three mounts. Most I see don't do the pinion mount and tip the axle down. Probably a bit too much drop for address a mild 1" curb height lift over stock SAS and the extended length on the king's but good protection for full bump/droop. Already knew i'd need to cut the diff slot in my skid plates anyways with a drop

 

[Oldhippie]

I am very happy with the innovations kit…great to work with too!

 

[87-Z28]

Obviously a diff drop can decrease cv maximum angles at full droop, however there is always a trade off. The LCA swings in a predefined arc. So as lift (or ride height) increases then cv angle also increases. Vertically dropping the FDU allows for the cv angle to decrease as wheel rotates downward along LCA arc. An undesirable consequence of the wheel downward rotation is the laterally inward movement of the wheel. This inward wheel movement, along with fdu drop, shortens the distance from wheel to inner cv joint. This then affects cv plunge.

the oem cvs do not likely tolerate large values of cv plunge (in/out movement). So perhaps there is a practical limit to the FDU drop for the oem CVs, ie without inducing cv plunge issues. Improved aftermarket cvs may provide greater tolerance wrt cv plunge. Perhaps only mild fdu diff drops are optimal for oem CVs. So besides the obvious structural concern a viable fdu drop should probably also consider cv plunge tolerances.

 

[Fordified1]

Obviously a diff drop can decrease cv maximum angles at full droop, however there is always a trade off. The LCA swings in a predefined arc. So as lift (or ride height) increases then cv angle also increases. Vertically dropping the FDU allows for the cv angle to decrease as wheel rotates downward along LCA arc. An undesirable consequence of the wheel downward rotation is the laterally inward movement of the wheel. This inward wheel movement, along with fdu drop, shortens the distance from wheel to inner cv joint. This then affects cv plunge.

the oem cvs do not likely tolerate large values of cv plunge (in/out movement). So perhaps there is a practical limit to the FDU drop for the oem CVs, ie without inducing cv plunge issues. Improved aftermarket cvs may provide greater tolerance wrt cv plunge. Perhaps only mild fdu diff drops are optimal for oem CVs. So besides the obvious structural concern a viable fdu drop should probably also consider cv plunge tolerances.

In one of @TeocaliMG ’s threads he talks about and addresses the cv plunge and took that into account. I believe he even shows the geometry figures.

 

[87-Z28]

@Fordified1
Yes I knew that. Just wanted to bring more awareness to his good work without being too direct. Cv plunge is something most folks don’t think of. There are always design trade offs.

 

[Fordified1]

@Fordified1
Yes I knew that. Just wanted to bring more awareness to his good work without being too direct. Cv plunge is something most folks don’t think of. There are always design trade offs.

While on the subject of cv angle and plunge. Do we have aftermarket choices for cv axles that tolerate more angle and/or allow more plunge or are just plane stronger than stock?

Maybe @Snacktime can weigh in on different brands of axles he has abused with his home made diff drop. @BigMeatsBronco also.

 

[WldBlue]

RCV has always been pretty vague about their OBJ/IBJ plunge and angle capacities but I think the strengthened 300M bearing cups give them strength to avoid breakages during over travel. It's just a very overkill solution if you are trying to address a low load high angle scenario like full droop during a jump. Diff drops are a good solution if plunge is kept in check

 

[evilletruck]

+1 Vote for the Broken innovations drop, well thought out and executed, and great to work with.

 

[SierraBronco]

While on the subject of cv angle and plunge. Do we have aftermarket choices for cv axles that tolerate more angle and/or allow more plunge or are just plane stronger than stock?

Maybe @Snacktime can weigh in on different brands of axles he has abused with his home made diff drop. @BigMeatsBronco also.

I still need to do some measuring to see what the droop is with the RK coilover, but just based on the angle of the UCA it seems more droopier than factory coilovers. With the 32 spline Dana FDU and their axles there doesn’t seem to be any bind and they haven’t been yoinked out yet with no limit straps and the swaybar deleted. Perhaps they’re a more droopier and plungier and strongier option for ya.

 

[Fordified1]

I still need to do some measuring to see what the droop is with the RK coilover, but just based on the angle of the UCA it seems more droopier than factory coilovers. With the 32 spline Dana FDU and their axles there doesn’t seem to be any bind and they haven’t been yoinked out yet with no limit straps and the swaybar deleted. Perhaps they’re a more droopier and plungier and strongier option for ya.

“Droopier and plungier” Love it! You’re talking about Dana axles? Are the stock axles not from Dana? Good information.

I’m pretty new to cv axles, with the exception of side by sides and it’s common to carry spare axles just because of what they are required to tolerate, and do eventually fail. I guess it’s just part of the game. They even make roll cage brackets to hold spare axles for UTV’s.
Im already carrying spare inner tie rods in the Bronc.

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