Broke down

Hey guys, I was out trail riding yesterday. When I put my 4 runner in reverse l heard a clunk in the front end. When I started driving the clunk issue continued then I lost all gears. The broken sound came from the front end. If I lost my front carrier/dif will it effect the transmission? 2003 4.7 full time 4WD.

 

No it shouldn't effect the transmission. The gears in the front diff or axle shaft could of snapped and has locked up the diff causing the vehicle to not move.

 

It was a broken cv axle. It completely disables the 2003 V8. All good now!

 

Because of full time 4WD?

Were you locked in 4wd at the time?

 

Yes, no getting around the way the full time 4wheel drive works. If the CV axle goes it won't move. It loses all gearing including park.

 

Thanks for following up on your repair, I see too many people ask for help on this forum but never let the community know what fixed it. Glad to hear you're back on the road!

 

I would think locking the center diff would have made it work as 2WD.

 

How common is this failure mode? I was watching a Tinkerer video that included several clips of CV axles breaking in off-road use. Most of them appeared to break primarily from drive train torque, not from getting bashed. It sounded like snapping a wishbone when the drivers were highly articulated and pushing some power.

I also recall reading last month that a member here carries a spare CV axle among his trail repair gear.

 

No, that's not how the locking center diff works. Normal operation has it in 4WD all the time, so AWD in essence. The center differential operates as an open differential, allowing the front and rear axles to turn independently of each other, which makes turning easier. When you lock the center diff, it causes the front and rear axles to turn the same and reduces your turning radius some because of it. Very simplified explanation but hopefully that helps.

Also note that the 4WD V8 4runners did not have a 2WD option on the gear selector. It was 4WD/AWD all the time. This is why the OP had the issue. A trail fix to get himself out would be to remove the CV and dissasemble it and reinstall just the inner part of the CV axle so that the gear oil doesn't all drain out of the front differential. That would/should have unlocked the drive train and allowed the vehicle to be able to move again.

It's not a super common issue, depending on how you use your vehicle. Somewhat common if you are offroading hard and causing a lot of stress on the drivetrain. Also more common with a lack of maintenance. Torn CV boots that aren't fixed in a timely manner can cause the CV to wear out faster and be more prone to breaking.

Carrying a spare CV is a good idea if you regularly go rockcrawling or just overlanding but know you are potentially going to be in remote areas where breaking something as vital as a CV axle could cause you serious issues.

 

I also just noticed you have a 2023. You have a 2WD mode and a broken CV axle would be less of an issue for you. You would still need to do the trail repair I mentioned to take the broken part out as the front CVs, particularly the driver side, still turn in 2WD.

 

I think that's within my capabilities. I'll watch some more videos on CV work. I already watched a couple on needle bearing replacement.

 

I understand how the full time 4wd system works.

What I'm saying is that locking the center differential should have forced the power to the rear wheels, just like you could use it to drive a part time 4wd with the rear driveshaft removed in an emergency.

 

If you remove the front driveshaft, you could do that. But with a broken front CV, the front wheel that was affected would still have an issue turning because of the broken axle still connected to it.

 

Yes, I suppose I should have mentioned that as well. My understanding is that, with the center differential locked, it behaves the same as a part time 4wd with the 4wd engaged.

 

Correct. With one of the driveshafts removed, you would have to have the center diff locked for it to put power to the remaining driveshaft. Otherwise, it operates like an open differential, putting power to the side with the least resistance, which would be the side without the driveshaft.

 

So, I was correct, aside from not specifying that the damaged CV would need to be removed.

 

My 03 v8 with 430K had all gears quit working after a loud pop. I tried 4lo with and without CDL and only grinding noises. I didnt try CDL only. I towed it home and later I installed a used transfer case and swapped the actuator but still the same grinding noises but I guess due to bad timing of the gears in the actuator. (I'll try a new actuator later and/or maybe another transfer case.) Then I tried CDL only and it engaged like normal. So I read on a thread that it was possible to remove one drive axle with CDL engaged. So I removed the front drive axle with CDL on and tried it but I got no engagement which puzzled me. Next day I tried removing the rear axle and leaving the front axle on and low and behold it worked. I still dont know why it works this way only.

 

I solved my own question, I think. I tested the rear axle by lifting the wheels off the ground with the drive shaft removed and turned one wheel at a time. I also turned the flange of the differential or where drive shaft is connected to. You can turn each one independentley but none affect or move the others. They seem to be independent of each other. I think this means it's a broken differential. Am I correct?

 

If you turn the pinion flange with both rear tires off the ground, both tires should spin in the same direction. If you spin one tire, the other tire should spin in the opposite direction. No movement likely means something broke inside the diff.

 

Thank you very much! I am so happy the problem is solved. I really appreciate your input. Thanks again!