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I've been having a problem with 4 wheel drive and suspect it's a broken shift fork on the right front driveaxle. Can anyone tell me what I should see in the opening when I remove the actuator from the front driveaxle housing. I removed my actuator and couldn't see anything , should there be a short shaft end of the shift fork sticking out or what ?
Thanks,
Joe
 

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2007 chevy trailblazer_ls
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I've been having a problem with 4 wheel drive and suspect it's a broken shift fork on the right front driveaxle. Can anyone tell me what I should see in the opening when I remove the actuator from the front driveaxle housing. I removed my actuator and couldn't see anything , should there be a short shaft end of the shift fork sticking out or what ?
Thanks,
Joe
Is the front drive shaft spinning? Can you lift all four wheels and try to engage? When you do,, do you hear clicking? If so I tell you what you need to do from here. I just got done fixing what 3 GM dealers said they couldnt fix. Its been in my shop for the week, but its finally done. I have a feeling many, many others are having the same problem. Lots of people likely driving around assuming there in 4 wheel, but there not.
 

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I'm pretty sure it's in the shift fork /splined collar assembly . I'd previously jacked up the right front and went through the motions , in 4hi the front driveshaft is engaged but the right front driveaxle turns ( it shouldn't) when it turns I hear a clicking sound coming from the driveaxle housing where the actuator/shift fork /splined collar assembly's are housed. I didn't see anything shiftfork wise for the acuator to push against when I unbolted it from the housing which is why I was wondering what I should see with the actuator removed.
 

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I'm pretty sure it's in the shift fork /splined collar assembly . I'd previously jacked up the right front and went through the motions , in 4hi the front driveshaft is engaged but the right front driveaxle turns ( it shouldn't) when it turns I hear a clicking sound coming from the driveaxle housing where the actuator/shift fork /splined collar assembly's are housed. I didn't see anything shiftfork wise for the acuator to push against when I unbolted it from the housing which is why I was wondering what I should see with the actuator removed.

You wont see much with the actuator removed (back side of the fork). With it removed all four wheels off the ground and someone in the drivers seat. Use a long 3/8 extention or something similar, push this into the actuator hole with the truck in 4 wheel, selector in drive and your foot off the brake. Apply moderate pressure, you should be able to lock up the front axle. If not you may indeed have a busted fork. If it does lock up you have a very common alignment problem (more common than I originally thought) my guess is that there are alot of people driving around thinking there in 4 wheel drive and there actually not.. You can also try this. With the actuator installed and all four wheels off the ground, put the truck in 4 wheel drive. With a pry bar or stick lightly pry up the passenger side inboard CV shaft knuckle. You should hear the clicking sound of the actuator trying to lock the axle. Once this slight pressure is applied the axle will almost imediately engage. If this is the case you have alignment/gear issues. Remove the CV shaft, remove the back side housing bolts that attach the gear box to the oil pan, next (on the bench) remove the gear case bolts, take the gear box apart being careful of the spring keep track as to what goes where, clean out all the grease in the parts washer and get things dried up for analyzing. Look closely at the CV shaft mating gear. Typically this will have a wear ring where it seats in the needle bearing if it does replace it. This is putting slop into the system causing things to cock out of whack. Next look at the shift fork. It will likely be worn at the tips where it rides on the synchronizer, replace it if it does. Most of the time these parts are always worn. Next you have a choice on the syncronizer gear and back side mating gear (thinner of the two) you can either replace or if you have a small pencil die grinder and a small carbide bit put a slight taper on the mating face of the gear and syncro. Your trying to eliminate any restriction in the gear and syncro from meshing without getting carried away. (dont even attempt this with a file, you will ruin your file:nono: these teeth are hard!) I typically do the beveling then I buff the face gear teeth to a mirror finish. Buy new parts or modify, either option works. Just depends on what you have for equipment. With either option I always replace the cv case side needle bearings, gear if worn even slightly, both front and back seals, and almost always the fork. Lastly I DONT use the recomended GM chasis lube. I've been using a molybdenum grease. Pack the gear housing lightly, dont get so much in there that nothing moves. Put a small bead of flange sealer or silicone, reinstall the box and shaft and your good to go. I have noticed that when its cold you may have to wait a few minutes for the grease to warm up with the engine for good engagement. I have often thought about drilling and tapping the case to accept pipe plugs and then use gear oil which would eliminate the cold weather issue. Only problem is that its such a small gear box if a leak were to appear and not get caught in time it would run out of oil quick and you would have some major problems.:eek:
If anyone has any questions let me know. I've done a few of these and its always the same issue weather you have 7k or 80k. Very crappy design...Many customers have had it to the dealer many times before it comes to me, I dont think GM is seeing it as a problem...
:(
 

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If anyone has any questions let me know. ...
First off, WELCOME!! :hail:

Excellent explanation, and I'm an amateur mechanic who bought the factory manual to help with internal issues like this. Never had mine fail yet, although I've fixed an electrical actuator for a friend that had grease build-up on the position feedback PCB.

What your post could really benefit from is pics, of course. Any chance you took some, or could take some when you do this job next? I'm guessing you are an independent driveline mechanic or specialist, or are you one of the few great mechanics GM has left to escalate tough problems to?
 

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some pics for you

I've been having a problem with 4 wheel drive and suspect it's a broken shift fork on the right front driveaxle. Can anyone tell me what I should see in the opening when I remove the actuator from the front driveaxle housing. I removed my actuator and couldn't see anything , should there be a short shaft end of the shift fork sticking out or what ?
Thanks,
Joe

Hey Joe, just today I took my Actuator off for my 05 4wd TB, What I see is in the pics. Im having a problem with my 4wd too and the mechanic thinks that the problem is inside the diff itself not allowing my housing to go far enough in. He told me to put the truck in 4wd take the actuator off and manually push the housing in to see if it will lock into 4wd. IF it does I will know its an issue with the Actuator. If you try this you will need to lift the truck and put it in drive while trying to manually push the housing into 4wd.

I dont know how to post pics on here so I put them on my myspace page the pics are hyperlinked below

http://viewmorepics.myspace.com/ind...dID=13771543&albumID=2312379&imageID=48352237


http://viewmorepics.myspace.com/ind...dID=13771543&albumID=2312379&imageID=48352239
 

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Shawn thanks for the post

Shawn I pushed in on the housing with the actuator out and the front left tried to spin only a lil bit but not all the way around at one time I had to help it keep going and the Right did not do anything I tried lifting up on the Joints on the right and it didnt do anything else.... any Ideas


You wont see much with the actuator removed (back side of the fork). With it removed all four wheels off the ground and someone in the drivers seat. Use a long 3/8 extention or something similar, push this into the actuator hole with the truck in 4 wheel, selector in drive and your foot off the brake. Apply moderate pressure, you should be able to lock up the front axle. If not you may indeed have a busted fork. If it does lock up you have a very common alignment problem (more common than I originally thought) my guess is that there are alot of people driving around thinking there in 4 wheel drive and there actually not.. You can also try this. With the actuator installed and all four wheels off the ground, put the truck in 4 wheel drive. With a pry bar or stick lightly pry up the passenger side inboard CV shaft knuckle. You should hear the clicking sound of the actuator trying to lock the axle. Once this slight pressure is applied the axle will almost imediately engage. If this is the case you have alignment/gear issues. Remove the CV shaft, remove the back side housing bolts that attach the gear box to the oil pan, next (on the bench) remove the gear case bolts, take the gear box apart being careful of the spring keep track as to what goes where, clean out all the grease in the parts washer and get things dried up for analyzing. Look closely at the CV shaft mating gear. Typically this will have a wear ring where it seats in the needle bearing if it does replace it. This is putting slop into the system causing things to cock out of whack. Next look at the shift fork. It will likely be worn at the tips where it rides on the synchronizer, replace it if it does. Most of the time these parts are always worn. Next you have a choice on the syncronizer gear and back side mating gear (thinner of the two) you can either replace or if you have a small pencil die grinder and a small carbide bit put a slight taper on the mating face of the gear and syncro. Your trying to eliminate any restriction in the gear and syncro from meshing without getting carried away. (dont even attempt this with a file, you will ruin your file:nono: these teeth are hard!) I typically do the beveling then I buff the face gear teeth to a mirror finish. Buy new parts or modify, either option works. Just depends on what you have for equipment. With either option I always replace the cv case side needle bearings, gear if worn even slightly, both front and back seals, and almost always the fork. Lastly I DONT use the recomended GM chasis lube. I've been using a molybdenum grease. Pack the gear housing lightly, dont get so much in there that nothing moves. Put a small bead of flange sealer or silicone, reinstall the box and shaft and your good to go. I have noticed that when its cold you may have to wait a few minutes for the grease to warm up with the engine for good engagement. I have often thought about drilling and tapping the case to accept pipe plugs and then use gear oil which would eliminate the cold weather issue. Only problem is that its such a small gear box if a leak were to appear and not get caught in time it would run out of oil quick and you would have some major problems.:eek:
If anyone has any questions let me know. I've done a few of these and its always the same issue weather you have 7k or 80k. Very crappy design...Many customers have had it to the dealer many times before it comes to me, I dont think GM is seeing it as a problem...
:(
 

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2007 chevy trailblazer_ls
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First off, WELCOME!! :hail:

Excellent explanation, and I'm an amateur mechanic who bought the factory manual to help with internal issues like this. Never had mine fail yet, although I've fixed an electrical actuator for a friend that had grease build-up on the position feedback PCB.

What your post could really benefit from is pics, of course. Any chance you took some, or could take some when you do this job next? I'm guessing you are an independent driveline mechanic or specialist, or are you one of the few great mechanics GM has left to escalate tough problems to?
I read your information on the actuator repair. Nicely done. Your fix also applies to windshield wiper motor delay control modules. Some of the early gm trucks had alot of greasy stuff gooped up in the case.
Sorry I dont have any pics from the past repairs. I'll try to take some the next time it comes up. Which might be next week (hopefully it just needs an actuator).
I'm an independent. We work on all kinds of equipment. Never worked for GM. Once I start a project its not leaving the shop until its fixed. No matter how long it takes. I look at it as on the job training. Nice to have a challenge from time to time it breaks up the same old, same old. I spend alot of money each year buying the best equipment to keep us as up to date as possible.

Heres a link to a picture I posted. This will give everyone a look at the internals of the gear box.

http://completemachineservices.weebly.com/
 

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Shawn I pushed in on the housing with the actuator out and the front left tried to spin only a lil bit but not all the way around at one time I had to help it keep going and the Right did not do anything I tried lifting up on the Joints on the right and it didnt do anything else.... any Ideas
Hi Ecir, Did you hear any clicking noise when you were pushing in on it? If not I would recommend removing the gear box. Get it up on the bench and take it apart. See whats going on, I'd be willing to bet the shift fork is broke. If not somethings bidding up.

BTW did you double check to make sure the front driveshaft was in fact moving while you were doing the test??

Heres a link to a parts breakdown. This will give you a little insight as to what your going to find inside.
http://completemachineservices.weebly.com/
 

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Thankyou Thankyou for the reply

I didnt hear any clicking noise, the front driveshaft was turning and the left was trying to turn slightly i had to help it to keep it turning. When i picked up on the left side axle it sorta started to bounce like it was trying to activate... I dont know I think my next step will be to take the whole thing apart and see if any gears are chewed up. Thanks for the links and I will keep coming back for more info :thx:hail::hail::hail:



Hi Ecir, Did you hear any clicking noise when you were pushing in on it? If not I would recommend removing the gear box. Get it up on the bench and take it apart. See whats going on, I'd be willing to bet the shift fork is broke. If not somethings bidding up.

BTW did you double check to make sure the front driveshaft was in fact moving while you were doing the test??

Heres a link to a parts breakdown. This will give you a little insight as to what your going to find inside.
http://completemachineservices.weebly.com/
 

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2003 gmc envoy_slt
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no 4wd

Is there a website for this with pictures? I'm attempting this task soon and in the process of gathering info.. I remember when it happened. I put it in 4wd and waited but I was down in a 1 ft ditch heard two pops when I tried backing out and haven't had 4wd since.. help..
 
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