Long Travel BS Thread

Turning full lock is where the problem is, once the end of the rack is leveraged out it’s all bad

 

Shit, I was jumping teeth going straight when they got bad enough. Just took a hit from the right angle to make it happen.

 

Jumping teeth on the rack won't change your alignment, only the steering angle.

 

Without inspecting it, conjecture's conjecture.

@Tacomoto23 can simply measure how much steering angle he has on each side to prove the concept.

I think he was saying his steering wheel's off-center after wheeling.

 

Uhhh it’s not conjecture man. It’s fact. Funny how I used to have issues every time out on 35’s but since the slide rack I haven’t had the issue return on 37’s pushing the truck even harder than before. If that’s not proof, I’m not sure what is….

 

You’re saying you know what’s happening on a vehicle half way across the country for sure without inspecting it. That’s one heck of a diag skill set if not esp, if it’s not conjecture. Pattern failures obviously get people closer to the proper diag without inspecting something, but as discussed there’s several other things that could put a truck out of alignment like failing bushings and frame flex.

 

Well, it’s a known issue. Talked about time and time again. What he described is exactly what everybody else experiences. If it walks like a duck….. well….. it probably is.

 

Here's more information on these racks than anyone wants to know.

The rack itself has 28 teeth. I can turn the steering wheel 3.5 times lock to lock on my 2019. On this old rack from a 2nd gen sitting in a vice I can spin the input around 3.75 full turns.
If I'm doing this math right, if there's 360 degrees in a circle and you make that circle 3.5 times that's 1260 degrees of rotation. Divide that by 28 to get the amount of steering wheel degrees turned per tooth is 45degrees. If I'm right on that, if you're steering wheel isn't off by 45degrees after an impact, it mathematically couldn't have skipped a rack tooth. The number for a skipped pinion tooth is close at 51.4degrees.

I could be wrong on this math, and if I am someone point it out. The only time I've had a steering wheel off by anywhere close to that much was when I partially ripped out the driver side rack mount frame barrel and the rack was sitting cocked at an angle like 3/8" higher on the driver side mount.

And now for all the photos. Up first is the rack with 28 teeth and the pinion with 7 teeth. On the pinion you can see the depth of the tooth contact, its around .135". This is an important measurement, in order for the teeth to disengage and slip by each other, they have to move over an 1/8" away from each other, clear each other, and then relocate without damage. How many gear sets used now-a-days are designed to allow that much slop?


The next photos are to show the ID of the mechanical portion of the rack and the rack itself. As you can see the ID is bigger, but not by much of the rack OD itself. (This particular rack was damaged by a Camburg clevis + 40" tire + screwing around on chocolate thunder, the rack deflected and the clevis contacted the housing extension and cracked part of it off, I shaved it off to get a measurement of the ID of the housing) The diameter of the rack is 1.177 and the ID of the housing is 1.255. Even based on this with the rack would have to move an additional .078 clear the pinion........and that's not even bringing up the adjustable rack guide. Also, both sides of the gear engagement appear to be the same ID, there isn't much room in there for the rack to bend any appreciable amount.


I'm going to be using FSM terms for the next component. The rack guide assembly, while certainly spring loaded, still severely limits the distance the teeth can disengage. The jam nut for the guide spring cap didn't move so I took the measurement of how far it was threaded into the housing at .426. I can force the guide itself into the housing with a C clamp and measure how far it is from the edge of the housing which comes out to .444. With those 2 measurements I can figure there is around .020 of wiggle room for the guide itself with maybe .050 of preload on the spring. Funny enough the spring barely even sits outside of the guide itself....it only sticks out .070... and that's being generous. Not even preloading the spring and only sitting the spring guide cap to hold it in place will only allow a maximum of .070 of movement between the pinion and rack.On this particular rack it looks like it was set up with only .020 of allowable movement. Far, far less than the required .135 for disengagement. The guide also basically backs the rack right at the gear mesh, it doesn't appear physically possible for the rack to "bend" around the pinion since its locked in place with only .020 of wiggle.



Even going with the crazy idea that there's enough room for bending and shifting for the rack and pinion to disengage, I seriously doubt that the amount of force involved in an impact like that won't shear the teeth off as the teeth approach disengagement, there wouldn't be nearly enough strength at the ends of the teeth relative to the force being applied to keep them intact as the teeth roll past each other.

 

that should settle any debate about skipping teeth. I stand by my original comment. I don’t see how it’s possible to skip a tooth without exploding the rack. @tetten you went the full extent to bring some science to this.

 

Well, your scientific experiment ended with skewed results. Real world beats theory 100% of the time.

I see you decided to skip over deflection of the actual housing….

When I finally caught on to what was happening with mine we diaged it on an alignment rack. Alignment was spot on with the wheel at about 1:30. I paint mark all of my stuff including steering shafts. None of which moved any single time.

Keep on believing though.

 

Enough deflection of a cast housing to allow for 0.125" minimum movement between gearsets? That isn't deflection at that point, it's catastrophic failure.

 

Between the housing deflection and the rack deflection you'll get over 1/8". Either way, its obvious nobody will believe the people that have actually experienced and confirmed the issue. So imma go about my day now and you can continue to think we are all dumb.

 

I don't think anyone is dumb, I have a leaky rack and I'm looking for solutions and stumbled onto this.

I do think however that something else is at play here to allow for such play. A cast aluminum cylinder doesn't deflect 0.078" without at least cracking and causing an immediate loss of fluid in a pressurized system, but the forces at play in a gearset that is being transferred through wedges (gears) will most definitely find a weak point and try and move past each other.

 

Biggest thing is everything deflects. Housing, Rack, Pinion. All of it. Combined its clearly and obviously enough. And some have actually broken the housing. The JD slide rack braces all of it and has solved the issue in its entirety for me. The forces the rack sees are pretty wild if you really think about it. Not to mention, the rack its self is actually hollow.

 

Geezus Christ. Way to go balls deep on Tetten’s cock bro….
I’m on team skipping teeth. Only because I’ve heard it on my truck. Driving at speed with my Windows down and bounced off the side of a wash and heard a metallic zipping noise. Then noticed my steering wheel was off. Later that day heard the same noise while hitting something else on the opposite side and the steering wheel went back straight. Go figure. Since putting on the JDFab lower pivot kit and slide rack I’ve hit some shit pretty hard and have not once knocked out my alignment. That covers both my TC LCAs with bushings and the JDFab LCAs with uniballs.

 

That is not accurate i’ve experienced it myself - you can absolutely skip or break teeth. I’ve had it happen twice once when I was playing around on dirt and hit a rut at speed ie: dirt drifting and caught a rut. Tore down the rack but there was no internal damage. Second time was a when a Camry crashed into me basically hit the front edge of my right front tire & bent my inner tie rod a bit and when i replaced the inner and realigned my steering wheel was still off ? drove it a bit and during tight turns my steering wheel would “ skip “ crooked and then go back again later. When we torn the rack down multiple teeth were sheered off at the tips

 

One time I heard a weird metallic popping noise coming from mine, but it wasnt magic gear teeth jumping past each other, it was the steering mount barrel weld failing and partially ripping out.

Have you got your shocks completely tuned yet? Hopefully next weekend I'll be done enough to be able to beat on mine and start tinkering with the tuning.

 

Both arguments seem alright but i'm still not understanding how the rack and pinion splines are jumping teeth before the splines on the lower column. Especially the splines where the rack connects to the column and the middle of the splines is fluted. I get it that finer splines can have greater surface area but i feel like those splines would shear long before the rack could move enough to jump a tooth

 

I don't see anything that's skewed, the gears on the rack I disassembled are only allowed .020" of movement away from each other. No amount of housing distortion is going to allow more since the yoke directly backs the rack where the gear mesh is.

I don't have any way to check force deflection but I definitely thought of it, the press I have in my garage won't be able to simulate distorting the housing. I planned on cutting a hole in the housing and putting a dial indicator in the hole to measure total deflection until something broke. I would need a heavier duty press with 4 posts and put the rack sideways through the press and do it the way I've got pictured in my head. If someone local wants to volunteer their press and press 2 racks until they break, I'm game.