Don't know if this is more appropriate here, or if this is more general, so move it as necessary.

Anyway, I know what everyone says about ttb, and how much of a problem it is, and I am now getting to experience it first-hand. After installing a 6" ttb lift from Skyjacker, the drivers' side axle bracket, located on the passenger side frame, has caused enough stress on the frame to crack the frame around two of the bolts.

Using my madskillz I made a mock-up in 3d to show where the cracks are and what I plan to do to fix it.

This is the part of the frame, which is the engine crossmember, and the bracket location:

Here is a closeup of where the cracks are. They are on the top of the crossmember, just around the bolts.


Now, I know I need to drill a hole in the ends of the crack to stop it, but what else, if anything, needs to be done?

My solution is to get a 1/4" thick piece of steel to reinforce this area where the bracket bolts onto. Now for a question, do I need to go ahead and weld the crack? This piece will go over the crack and will sandwitch the frame between it and the drop bracket, so will welding it even be necessary?? Or is it a good idea to weld it anyway?? Will that plate be sufficient to support the bracket? Do I need to weld this plate to the frame as well, or will it be sufficient to bolt it only?

What else should be done to strengthen this area?

Is this even the best way to fix this problem, or are there others?? Yeah SAS.....that'll be next year....maybe :D


this is on a '93 F-150 btw.

umm.


if there would have been hardened washers involved, it would have lasted longer.


i have found it to be a good way to prevent crackage the longest..



and i like your fix....it looks like what cured all my bootie fab on the side of the road trans k member fab...you know...pull off the chanel bumper to make a new trannymount cause your old one dropped all your shit in the middle of the road....

to beef up the drilled holes ect i used a lil thinner then what your proposing to use strapping. so far its worked real well.

oh yeah...those are some kick ass renderings!:smokin:

Thanks for the comment...I spent a lot of time on those renderings 5 minutes :D

So do you think 1/8" would work? That was another question I had but forgot to post.

And what about welding the plate? Let's say....bolt it all back together...maybe use some hardened washers too :D....then weld it all together??? Yes??? No?? Maybe???

Thanks.

i have no metalurgical <<<did i spell that right??>>>ability.


there are som unreal welder fabricators around here that will answer this flawlessly, and till recently i never even spoke a word cause i only resarched here.


but first dressing and then welding up the cracks is for sure the route o would take. then i would grind im down a bit and either use those straps or the washers i have always used on the fullsize brackets. i always use new grade 8 finethread(but i guess that dont matter) locktight and the good hardened oversize washers.

i have helped numerous cronies get thier shit welded up by the guy that does my stuff. my ol man. he is a welding fool, unfortunatly he is a very very busy welding fool. anyway this has worked and is the way i have done it since i started putting lifts on for people. that started in 88. but thats just amature turd polishing....

THis is a typical TTB LIFT problem (like most).


I would weld up the crack. Cracks can continue to spread in a high stress area even if "sandwiched" with more plates. The plates certainly will help, though (don't weld the plate to the frame).

What I would look into doing is welding some additional plate on the front of that bracket to extend its footprint down lower on the crossmember to distribute the leverage better (probably should do it to both brackets). The Class2 Skyjacker brackets are made much larger just for this reason.

I would suggect tying the brackets together, and making more reinforcing. Basically, you're giving all the load an extra 6" of leverage, which will proably increase the pulling load on the bolt by something like 2-500% under certain conditions, which is why it's cracking. What needs to happen is you need some more bracing to make any horixontal (perpedicular to the frame from above, parrel from in front - ie - turning, etc) load go sragith into the frame, and not gived it that kind of leverage.
-John

Ok first stop drill the crack (drill a hole at the end), then prep, weld and grind smooth. Then plate with 3/16, weld it to the existing material, use washers when assembling and keep an eye for where else decides to crack. If it's cracking like that in one place fixing it will just usually make it crack elsewhere, you know the weakest chain link thing.
I am not an engineer but from the looks of it the crack is being caused by forward and aft forces not the side load so make sure everything is rite under there.
Just my .o2

Originally posted by EBSTEVE
I am not an engineer but from the looks of it the crack is being caused by forward and aft forces not the side load so make sure everything is rite under there.
Just my .o2


That's exactly what I was thinking too. It looks kinda like if there is any contact with that bracket or that axle and any solid object, such as the ground, it will rip that bracket right out of the frame. I don't see any other areas behind that bracket to weld up any kind of support either.

Unfortunately I am not to knowledgeable about the TTB stuff so I can't be of much help but I do believe that doing what I stated before should fix the current problem and possibly lead to a future problem, but IMO fixing what's up now and worrying about what might happen later is the way to go. It's not like you are thinking about doing something so strong or weak that it's going to cause catastrophic failure elsewhere.
Again just MHO

Your planned fix is a good one. Your renderings piss me off as I have zero artistic talent :flipoff2: My comment, is make sure you have a highly skilled welder finish the job, not your typical hack (yea, yea, that includes me). The reason is welding on your frame should be avoided if at all possible, because the application of heat fatigues the metal and can cause other problems down the road. A good welder will minimize this concern and stress relieve the welds so your fix holds a good long time.

Yeah I try to piss as many people off as I can :p :flipoff2:


Thanks for all the comments so far....

drill out the ends of each crack to about twice the thickness of the crack. "V" notch the entire crack. weld it up and grind it flat. 3/16 or 1/4" plate is what I would plate over it with. use the biggest patch you can (surface area is your friend) and weld it to the frame and use grade 8 washers on the bolts to help minimize more cracking.


:usa:

take tou the ttb, put in a straight axle, and remove that damn crossmember, and fba up some new engine perches if its bolte dto the crossmember

Originally posted by McDerry
take tou the ttb, put in a straight axle, and remove that damn crossmember, and fba up some new engine perches if its bolte dto the crossmember


maybe next year.....maybe....