HI I need Help with a problem i have with my 4wd not engaging on a 1991 4runner v6. i just replaced my front upper and lower ball joints on both sides and now my 4wd wont engage. My 4wd light comes on but when i try to drive up something only my back wheels spin. i don't know if my cv joints might have anything to do with it or if i could have knocked something out of place while replacing my ball joints. Thank you for your time.

 

This may not be the safest way but if you put your truck on axle stands, front and rear so all your tires are off the ground and put it in 4wd then in gear. If your drive shaft is spining but your front tires arnt then its something in the front end. If you drive shaft isnt spining then its transfer case related. Do u have manual hubs? and are those year trucks electronic 4wd engaged? cv joints probably arnt the culprit if it worked before u did ur ball joints

 

my drive shaft is spinning but just not the tires. im thinking something in the hub becuase i had to take it apart to do the ball joints but im not really sure how the add works on these. i have the automatic disconnecting ones, i dont know if the hubs some how lock in with the shaft of what. Thanks for your help. any ideas?

 

"...i have the automatic disconnecting ones..."

Get some OEM AISIN hubs, and throw the "automatic" ones in the trash!

I'm pretty sure that will fix your problem.

 

how could the add hubs not work? they are constantly locked in. I would have to say that with add, if your wheels are not spinning, it is likely in the front 3rd, the add hubs do nothing, the add means auto disconnecting differential, not auto locking hubs....they are always locked...unless you somehow stripped the splines off the cv shaft.

 

Maybe u can find some tech about it in here.

http://www.4x4wire.com/toyota/tech/add/

Sounds like Team420 knows what hes talking about. Haha have to use the process of elimination, just keep searching, maybe someone else with pipe in. Another thing to check when its off the ground and in gear in 4wd would be to see if the cv's are spining? cuz if they were spinning then it would be stripped splines on the cv shaft like Team420 said, if they arnt spinning then its something between there and the t-case. Wich would be the ADD in your front diff

 

just gonna throw something out there, never pulled apart a front end on one of these.
Did you tighten your cv hub nuts?

 

As another guess, you might have pulled free one of the vacuum lines that go to your ADD actuator on the front diff.

http://www.off-road.com/trucks4x4/ar....jsp?id=399612

 

ADD or Automatic Hubs?

(I had assumed the OP had Automatic Hubs...)

 

check your vac lines they fall off with just a babys fart next to the truck on jack stands


ie..... your vac line poped off no biggie it happens just find it connect it and have fun

 

the cv's are spinning. so if the cv spines are stripped then where would they have stripped at? Would i have to replace the cv's or what. would the the axle/ spindle nuts not being tight enough have anything to do with it at all? i looked for any loose vac lines and didnt find any but if there was one lose would that allow the cv's to spin but not the wheels? sorry for all the noob questions. thanks for every ones help i appreciate it greatly.

 

ok you said that you took the whole front end apart right? (hubs ect..)

so just a though but you should jack it up right away and take it back apart and put it together just like the fsm tells you to cause what i think you did was mess something up and its not "setting" right, and its alowing the cv's to spin and not the tyres so everythings ok and good up to the hubs aye?

driveshaft spins cv's spin tyres dont spin its in the hubs take a look before you blow it all up and cant drive it

 

If your cv axles are spinning, then its something at the end. Wich would be your hub. I dont know anything about the ADD hubs but hopefully someone who does pitches in. Sounds like u have narrowed it down pretty well though.

 

i have taken it apart again and put it back together using the FSM for the second time and still no luck.im going to try again for the third time tomorrow. its got to be something with the hubs and everything is good up to the hubs. i just dont have a clue what it could be or what i could have messed up. Thanks For your time.

 

If you have ADD then you more than likely have drive flanges unless manual hubs were swapped. The only way I could see messing up the installation of the drive flanges is if you forgot to put the outer cone washers and bolts back in. You did put all the bolts back in right?

 

yeah every last one. i made sure every thing was aligned too. any other ideas? thanks for the hint and your time.

 

I'm thinking more along these lines... Or CV, are the CV's turning when the driveshaft turns?

 

yeah the cv's are turning with the drive shaft.

 

Then it's the hubs

 

Did you check the splines at the end of the cv axle? That is really the only thing it could be.... Add hubs, are nothing more than a flange with grooves that fit over the cv axle splines, then the flange has 2 little pins, and 6 holes for the hub bolts, if the cv is spinning, but not the wheels..., it would have to be the splines on the cv, or the bolts and pins broke off of your hub, and i'm pretty sure that would be obvious. I have never seen anyone(and I do alot of stupid stuff) strip the splines on a cv!
Here's another test for ya....Put the truck in 4x4, jack it up...make sure it is running, then try to spin the wheel by hand, and watch the cv...if the cv spins with the wheel (as it ALWAYS should) then your prob is in the diff, if the wheel wont turn at all...no prob, and if just the wheel...no cv movement... then obviously the hubs.