Crawler Box Splines keep stripping.

Correct, I believe there is no vent and vents to the transmissions tail hosing.

Which vent are you referring to? I know there is a vent at the tcase (which has a small plug) and a vent at the bottom of the twinsticks base (tcase) not shown.

 

Im kinda curious, any update / progress @feesquivel ?

 

Yup. I’m interested to hear updates as well.

 

Is the weep hole thru and thru. If that’s supposed to let oil in, I would think that hole should be completely thru that gear. So you should see the hole in between gear teeth.

 

So Marlin asked me to send them back the crawl box. Sent it to them, they are gonna tear into it and let me know what they find. Being the holidays I doubt I’ll hear back till next year.

Yes its thru and thru. Only one and seems kind of small for my liking. I just don’t see it let oil in when spinning.

 

I know if has been a while but with the holidays and everything I decided to stand back and give marlin crawler some breathing room.

Update: Just got off the phone with Wyatt and Marlin believes the coupler mounted to the transmission side is pre-loading the crawler box. They are sending me a new coupler (which I replaced last time) for the transmission side. This could explain the thrust bearing being worn down and having burn marks. But trashing the splines?? I dont know, need to speak with Marlin personally to see the reasoning behind that.

Hope I get call from Marlin since getting past the sales reps is impossible.

Thanks guys, sorry I dont have a solution yet.

 

Any more progress with this?

 

I had this exact problem happen to me on my crawl box install in 2007, it stripped out 1yr later in 2008 due to fretting EXACTLY like the OP pulling away from a stop sign. The issue is metal fretting, like other have said, due to the inherent design flaw on the coupler when it mates to the taco case. That dual row bearing stops most of the wobbling but it still wobbles a bit and the splines wear out, start wobbling more and eventually strip. The other fact is that tiny pocket bearing really doesn't support the end of the coupler very well, that coupler is supposed to be the main shaft running to the rear of the factory mini truck case supported by 2 more big ass bearings. You need to use grey anti seize on there (learned this from wyatt way back when) not grease. Its sticky and stays on there. The other issue is that input shaft on the factory case is too short exacerbating the wobbling in a role it was never intended to be used in. I rebuilt my crawl box with new couplers and a factory rear case and ran it for another year with no issues. I did swap to a lefty with a 23 total spline longer input shaft the old mini truck cases have and the issue has went away now almost 11yrs later. The theory behind that is you have more splinegagement and the coupler stays put better. I now change my fluid once a year to look for brown rust in there, and havent seen anything. Of note I'm running Marlins OLD 4.7 gears without any of the weep holes in the rear case along with factory 2.28 gears in the crawl box, also without any weep holes. This truck gets driven on the highway everywhere, and is now on 37s, was on 33s when I first installed the crawler. I do agree with the crawler holds too little fluid, another reason I went with a lefty because the lefty shares its gear lube with the crawler, so you get 2qts in there circulating around instead of 1. That crawler gets HOT AS FAWK on it's own. Also run a thicker synthetic fluid, I use the highest weight I can find at the store, like a 140 and up.

TLDR: goop your input with a ton of grey antiseize and change your fluid at least annually to look for rust. It's a crap shoot with toyota crawler setups on street driven trucks. Save up for an atlas.

 

Slander thats is good info, thanks for your input. I do believe that is my issue.

So wyatt recommended me to use marine grease and thats what I have been using, you reckon I should switch to anti-seize?? I just finished putting the truck back together lol.

I’m wondering if I can swap to a longer input shaft on my fj tcase. I am assuming you ended up swapping the entire tcase to a lefty. If its the input shaft length, i’m curious why nobody else (besides us) has seen this issue. Something different in my truck?

I’ll be running redline 75-90 gear oil as Marlin recommended, might ask them about 140. I did use half a quart of lucas oil stabilizer to thicken the 75-90 gear oil.

 

Yea that's weird, hes one of the people that told me to use gray anti seize. I have been using that since the first input stripped, so it's your call if you want to pull the rear case off again to do it. It was a common issue back in the TTORA days when people starting swapping crawlers into 1st gen Tacoma's, then if you look further back, it's a common issue with the original crawl boxes in the mini trucks. That's why the marlin total spline input shaft was invented for those gear drive cases. It seems to be hit or miss if people get the fretting issue, you and I happened to be one of the annointed few.

You are correct the rear case is a lefty. I dont think anyone makes an upgraded or longer input for the chain drive cases. I used to always run the 75-90, then started running the thick stuff to quiet it down, I have some very early 2.28 gears in my crawl box that chatter like crazy, and noticed it ran a bit cooler and figured why not. I dont drive the truck in super cold weather anymore, but I did drive it in a few -15* days and it definately was making some odd noises so warm it up first. I see you are in Texas, but added that incase it pops up in a search some day for someone else.

At minimum I would change the fluid every 6months for a while and look for rust in there (fluid will turn red).