4-6" Cross Member Cut Question

[gmartin1215]

I have been researching lift kits for my 2009 Tahoe LT. Currently, I am leaning toward the BDS 4" lift kit. Why 4" and not 6"? Lower COG, and I still would like for the Tahoe to fit in my garage.

Anyway, looking through the install instructions for the BDS kit, I noticed a step to weld on a plate to the end of the cross member bracket that they cut to make room for the lowered differential.

Instructions for the BDS kit are here.

I was also looking at the Rough Country 5" kit too. The RC kit had similar instructions for lowering the differential. However, RC did not have any step for welding a plate to the cut cross member's end.

Instructions for the RC kit are here.

Given the instructions' differences, I am assuming that the step BDS added to weld the plate on the cross member's end is primarily additional protection or insurance that the differential does not get damaged by this modification.

For anyone who has installed the BDS or RC kits, what is the real risk if the plate's welding on the end of the cross member is omitted? Does damage to the differential frequently occur from the cut cross member that this plate is necessary?

 

[wjburken]

I don't think the plate that BDS says to weld in is to protect the differential. It is there for added structural integrity of that connection point. It helps keep that part of the frame from folding back due to the added moment arm length.

 

[gmartin1215]

I don't think the plate that BDS says to weld in is to protect the differential. It is there for added structural integrity of that connection point. It helps keep that part of the frame from folding back due to the added moment arm length.

Thanks. But if that is true, then why wouldn't the other end of the cross-member connection that was not cut have a welded plate, too? RC doesn't have a step in their instructions for a welded plate, but the other steps are almost the same as BDS.

 

[wjburken]

It probably comes down to what the engineer that designed it thought was best or necessary. Without going into all the load calculations and the like, I would suggest you defer to the directions for whatever system you go with.

 

[gmartin1215]

Anyone who has installed a lift and the rear cross member was cut to make room for the lowered front differential and has NOT had a plate welded on the new end, have you had any issues that made you wish you had the plate?

I still think this plate welded onto the cross member end is a "nice to have" feature that BDS has included, but several very similar kits from other manufacturers omit this step.

I am asking the question because I plan to install this lift kit myself, but I do not have a welder. I can probably find a friend that can weld who can help, but if this plate is only a "nice to have" feature, then I can skip this part of the installation.

I have the same query out to BDS, too, and I am waiting for their reply. However, I am very curious if anyone who has a lift installed and did not have a plate welded on has had any issues caused by not having it on.

 

[DWSmoot]

Might want to post this in the 2009 section. Prob get more response.

 

[Trey Hardy]

I have a 7.5” RC which should be the same as the 5” but stretched. My rear crossmember is cut but no plate welded I’ve never had any issues or complaints my buddy has the same setup with his 4” fabtech and his rear crossmember is cut but never had any issues. Front ends are pretty much the same as the Tahoe minus the lower control arms. Only downside to rough country is like my kit the lower control arm angles suck powder coat sucks if you don’t upgrade to coil overs you’ll have a ugly spacer on top your shocks rough ride etc I’ve replaced everything on my lift other then the crossmember drops which I’m about to do this week.

 

[Trey Hardy]

My angles came out perfect I finally installed the 6” fabtech I got from the 18 Silverado I also threw some icon coil overs off a at4 with some 2” spacers to match the lift height upper uniballs are perfect as well