Soft brakes after lift, and how the dealer accidentally solved it

Apologies in advance, this ended up way longer than I had intended.

I ran into an interesting issue today, and I felt it was worth sharing. A quick timeline:

Sat/Sun - Install new lift on '16 TRD Sport DCSB (5100s, 888, AAL)
Sun - Drive it home, all is well
Monday morning - Alignment
Monday afternoon - Took it back to my shop to do a visual/torque check.
At this point, I set the parking brake while in the shop. I don't know why, as it's shamefully not normally my habit to do so, but I did.
Monday slightly later afternoon - Check was good. Ran it through a quick "slalom" in the parking lot. Rock on. Park. Have a beer. Hop back in truck and go to leave, and BAM!, my brake pedal goes nearly to the floor before engaging. "Huh", I think. Drive around a bit more and it seems to be acting fine, so I take the back roads and head to the house. Brake pedal seems to go to a different position every time I hit them, but they're still working, so I limp home.
Tuesday - After checking the forums, I try all sorts of wacky crap. None of it seems to have a lasting effect, but the brakes "seem" to be getting back to normal. Figured it was a combination of adjusting rear drums and bleeding/etc. Lo and behold, I pull out of the driveway (brakes working fine) and go down the street about 100 feet, where the brakes decide they're going to go to the floor again. Decide to bite the bullet and schedule appointment at dealer for the $60 brake check and adjustment.
Wednesday - Take it to dealer. They say brake pads are worn out, drums need adjusted, and by the way, both front wheel bearings need replaced. And they won't do it under warranty because I installed a lift. "How can both wheel bearings go out. Driveline geometry is good. Please explain" I said. "Well, I drove your truck from the front into the garage, and your suspension is stiff, so that's the problem". "Wait", I say, "you're telling me that my wheel bearings went out because my suspension is stiff?" "Yes" he says, completely serious. "It will be $1800" he says, slightly more completely seriously. "(expletive) you, I'll take my keys back please".

Took it back to my shop and did some digging. Lifted the front end, and sure enough I've got movement at 12 to 6. I dress down the front, and that's when I notice I've got just a smidge of relative motion between the hub and the CV shaft/nut. I put my torque wrench on it, and sure enough it's not torqued. I set it properly, then do the other side (same story), and once again BAM!, all of my problems are solved. I had about 1/32nd of play top to bottom, which was just enough to "decentralize" the brake rotor from the shoes around a hard corner, which caused the inside shoe to have to stroke farther than normal, leading to the excessive pedal stroke. Now everything is centered again, and brakes are working like a champ.

You're probably thinking "what a train wreck, why didn't you torque them properly in the first place?" Well, I did. When I did the "slalom" in the parking lot to force the suspension to settle a bit and find its new home, that's when the issue presented. Even though it was torqued, it simply wasn't seated fully. Bouncing it around allowed the CV to fully seat itself in the hub, which gave about 1/4 thread of free play at the nut. To be completely fair, I would never have found this so quickly (almost immediately) if the dealer hadn't tried to talk me into new wheel bearings.

Maybe I'm the only one to suffer from this, but from this point forward I'll slalom a truck right after the install, and take the time to recheck the hubs then.

 

Your axle nut was loose?

 

Yes it was. A good 40 ft-lbs. Best guess is a bit of extra friction from the new driveline angle allowed me to torque it down without actually seating. Luckily the bearings were in good shape, and I didn't get too many miles on it before discovering the problem.

 

That's why the dealer wanted to do your bearings..

At least you caught it! Good work

 

So, how did your axle nuts become loose? Did you remove your drive axles to install your lift for some odd reason? This isn't making sense.

 

I took the front axle/hub nuts off and broke them loose from the front hubs so when I pulled the spindles and lower control arms down to fit in the new larger struts, I didn't pull the cv out of the front diff.

 

Just FYI, that was a lot of extra work for nothing.

 

Thanks?

 

You're 100% correct, it's definitely something I didn't need to do in hindsight. There's not a wealth of free play on the differential side cv axle spines before you're holding against the circlip. As I was doing UCAs as well, and I knew I'd be pulling the spindles into angles and positions that are well outside of the normal range of motion (more room to work), I bit the bullet and decided to separate it at the hub on purpose instead of separating it at the diff on accident. To be fair though, I had no reason to expect the hubs to be such a bugger to fit back up. Since it's my own truck I'm okay admitting that I do also have a child-like fascination with taking things apart for no other reason than I've never taken that particular piece apart before.

 

I hear ya. I'm all about taking things apart to learn about them as well! I was just informing you it wasn't necessary in case you have to do it again.

 

I’m going to check this tomorrow. Passenger wheel bearing was changed and the cv has to come out for part of that. Wonder if they didn’t torque it right. Thanks for the idea.

 

Just out of curiosity, what’s the torque spec for this nut? Also, nut size?

Edit: 175 ft-lb and 35 mm. Think I’m having the same issue after my lift.

 

I can’t thank you enough for posting this. 3 days after my lift and ECGS install on my 2017 DCLB TRDOR I had this same issue. Brakes didn’t go the the floor but were very inconsistent and soft. Only had the issue on drivers side as that was the only side loosened for the ECGS install. Tighted up the nut and all is well.

 

Wow, I think I may have just found my solution.. I checked EVERYWHERE for a brake leak and I was even about to flush the brakes.. Im going to check this and see if its the cure..

 

was it the cure?