Home » Public Forums » GMCnet » Before Dropping the Transmission (Just making sure there is not another option)
| Before Dropping the Transmission [message #267480] |
Fri, 12 December 2014 19:29  |
Jeff102410
Messages: 18
Registered: February 2012
Location: Arlington, TX
Karma: 0
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Junior Member |
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Here's the situation:
Over Thanksgiving, we took the motorhome out for the weekend. Arlington, TX to the beach at Galveston, TX. Four hours each way.
On the way home, half way, we stopped at a rest stop (Buc-ee's in Madisonville, TX if it matters to anyone). Parked slightly uphill.
Getting ready to go, started the coach as usual. Since I'm not always sure if I'm in drive or 2, I shifted into reverse, held a second, shifted into neutral, held a second, and shifted into drive.
Immediately on shifting into drive, I heard a pop, more like a bang...whatever...not normal...and not a good noise. Gave it a little gas and was roalling backwards...not good. Hit the brakes, put it back into park and shifted again...same result. Put it into park and jumped off the drivers seat to get ready to pull the hatch, and was rolling backwards again...still in park. Holy crap, Batman...
Grabbed the emergency brake...and...well...you know this was not going to end well. Ultimately, towed back to the house. My call. Expensive, but we are home and I can work the coach without the pressure of being remote...
Anyway...
I've got the coach up on jacks. Pulled the transmission pan, and everything is as expected. No metal in the fluid. The shifter is attached, and when I manually move the shifter, things seem to be moving as expected...at least as far as I can tell.
Pulled the final drive cover, and everything here is as expected. No metal in the fluid. Visual inspection does not see anything unexpected.
Something else to note...and this test is not the same as having the weight of the coach, but with the frame on jacks and no weight on the wheels, the wheels turn as expected. When I spin the drivers side wheel, and with the coach in park, the passenger wheel turns in the opposite direction. In neutral (and reverse and drive), the passenger wheel turns in the same direction. Again, this test was done by rotating the wheels by hand. I don't know if that means anything, but putting it out there just in case it does.
Another tid bit is that regardless of what gear the coach is in, the engine revs up as expected. There is no additional noise, grinding, whatever.
Transmission is a 2010 Manny rebuild with 3800 miles on it. Called Manny, but he has not heard of a transmission doing anaything like this.
Final drive (3.55) was purchased from Jim K. the same time as the transmission.
What I am thinking is that I'm at the point that I have to start taking stuff in order to find the problem...not something I'm wanting to do if there is another alternative...
So...
The ask here is...is there other stuff to check before dropping the transmission??? final drive??? etc.???
Jeff Rogers
Arlington, TX
1978 Former Palm Beach
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| Re: Before Dropping the Transmission [message #267482 is a reply to message #267480] |
Fri, 12 December 2014 19:51  |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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Jeff102410 wrote on Fri, 12 December 2014 18:29Here's the situation:
Over Thanksgiving, we took the motorhome out for the weekend. Arlington, TX to the beach at Galveston, TX. Four hours each way.
On the way home, half way, we stopped at a rest stop (Buc-ee's in Madisonville, TX if it matters to anyone). Parked slightly uphill.
Getting ready to go, started the coach as usual. Since I'm not always sure if I'm in drive or 2, I shifted into reverse, held a second, shifted into neutral, held a second, and shifted into drive.
Immediately on shifting into drive, I heard a pop, more like a bang...whatever...not normal...and not a good noise. Gave it a little gas and was roalling backwards...not good. Hit the brakes, put it back into park and shifted again...same result. Put it into park and jumped off the drivers seat to get ready to pull the hatch, and was rolling backwards again...still in park. Holy crap, Batman...
Grabbed the emergency brake...and...well...you know this was not going to end well. Ultimately, towed back to the house. My call. Expensive, but we are home and I can work the coach without the pressure of being remote...
Anyway...
I've got the coach up on jacks. Pulled the transmission pan, and everything is as expected. No metal in the fluid. The shifter is attached, and when I manually move the shifter, things seem to be moving as expected...at least as far as I can tell.
Pulled the final drive cover, and everything here is as expected. No metal in the fluid. Visual inspection does not see anything unexpected.
Something else to note...and this test is not the same as having the weight of the coach, but with the frame on jacks and no weight on the wheels, the wheels turn as expected. When I spin the drivers side wheel, and with the coach in park, the passenger wheel turns in the opposite direction. In neutral (and reverse and drive), the passenger wheel turns in the same direction. Again, this test was done by rotating the wheels by hand. I don't know if that means anything, but putting it out there just in case it does.
Another tid bit is that regardless of what gear the coach is in, the engine revs up as expected. There is no additional noise, grinding, whatever.
Transmission is a 2010 Manny rebuild with 3800 miles on it. Called Manny, but he has not heard of a transmission doing anaything like this.
Final drive (3.55) was purchased from Jim K. the same time as the transmission.
What I am thinking is that I'm at the point that I have to start taking stuff in order to find the problem...not something I'm wanting to do if there is another alternative...
So...
The ask here is...is there other stuff to check before dropping the transmission??? final drive??? etc.???
Jeff Rogers
Arlington, TX
1978 Former Palm Beach
If it rolls in park, then the problem is downstream from the pawl. If it is an axle shaft you would have seen it. It almost sounds like a snapped output shaft on the transmission. Are you sure the linkage is adjusted correctly? It sounds like you had some issues with the adjustment and it may be the problem--pulling it out of park on a grade can create quite a pop.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: Before Dropping the Transmission [message #267490 is a reply to message #267480] |
Fri, 12 December 2014 21:53 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Senior Member |
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Jeff, having recently come home on a hook myself with tranny problems, I feel your pain. A couple thoughts come to mind...may or not be valid. Keep in mind I'm not a tranny expert, just some troubleshooting approaches and thoughts. OBVIOUSLY do not get under the coach while running. You can use mirrors and such to check things in order to avoid this. MAKE SURE THE COACH IS SECURELY BLOCKED so it can't move at all.
A parking pawl breaking is a cast part of the case I believe. They can just break. It would make a noise.
Rolling in park indicates the parking pawl is gone OR you're not really in park or something broke inside the tranny or differential or CV joint. That's pretty much all the failure points I'd think. Check the linkage and make sure it's actually shifting the transmission. There is a 3/8 bolt that pinches to the shifter shaft. If it slipped, you're not going to be in the gear you think you are. I just yesterday had to tweek mine to get the shifter to 'feel' right. Perhaps you're 'BETWEEN' gears?
BEFORE I pulled the tranny or did anything to remove components, I'd investigate the situation sitting in the driveway. With the coach in park and the front wheels off the ground, neither drive wheels should rotate. That's what I'd check first and make sure the TRANSMISSION is in park, not the shift lever. IRRC that means the lever on the tranny is all the way forward. If the wheels don't rotate, the problem is between the parking pawl and the flexplate. Can't help you there.
On Turbo 350s and 400's (our 425 has the same internals as a Turbo 400), the make what is called a 'case saver' that will replace a broken parking pawl. I have no idea what it looks like but we had one put in my sons 64 Impala once. Don't know if there is one for a 425 or not. Manny would know.
When I first read your post, my first thought was the chain drive but if it rolls in park, than the pawl is broken, tranny is not in park, or something is badly broken upstream of the pawl...like a main shaft or the final drive. I'd be pretty surprised if the final drive failed. They're normally pretty bulletproof. I'd THINK if you broke a tooth in the gear set, you'd hear some noise as other gears failed, not just a single pop and nothing.
If you lost or broke all three flexplate bolts, you wouldn't be able to move but the parking pawl would still hold you in park. I suppose you could have two failures, that is, lost the flexplate/torque converter bolts and THEN broke the pawl but that's a pretty low probability sequence of events I'd think. Still, I'd suggest removing the inspection cover on the bellhousing above the starter and see if the converter is rotating when you turn the engine over (you could pull the hot wire to the distributor so it wouldn't start if you want while looking through the inspection hole through the hatch using a mirror if necessary.
Someone else might know for sure but if you pulled the final drive cover (with the coach up on blocks securely and wheels off), all the stinky fluid will come out, but I'd think you'd be able to see the gears rotate if you started the motor and put it in gear for a second. I wouldn't think a second or two without being submerged in fluid and with no load would hurt the final drive. If they do turn , I'd tend to think the tranny is not the culprit and look at the drive axle. If you don't see anything turning your problem is either the front shaft of the final drive or in the tranny.
Again, not trying to sound like an expert but I made my living troubleshooting systems and I've found that the same principles apply to pretty much everything. That is, try to eliminate major systems as the problem
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: Before Dropping the Transmission [message #267491 is a reply to message #267480] |
Fri, 12 December 2014 22:01 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Senior Member |
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One other thing comes to mind. A few months ago someone (perhaps Ken Burton) mentioned helping someone who was stranded because they had lost all the bolts that hold the axles on the differential hub. If that happened, there is a small male lip on the half shaft that could possibly (but not probably) stay in the final drive hub. If it did, it could allow the hub to spin without turning the shaft.
Low probably problem and even lower probability that you would not have noticed it but just another possibility to eliminate.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: Before Dropping the Transmission [message #267495 is a reply to message #267491] |
Fri, 12 December 2014 23:40 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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kerry pinkerton wrote on Fri, 12 December 2014 22:01One other thing comes to mind. A few months ago someone (perhaps Ken Burton) mentioned helping someone who was stranded because they had lost all the bolts that hold the axles on the differential hub. If that happened, there is a small male lip on the half shaft that could possibly (but not probably) stay in the final drive hub. If it did, it could allow the hub to spin without turning the shaft.
Low probably problem and even lower probability that you would not have noticed it but just another possibility to eliminate.
Yes that was me and I was thinking about posting that. Thanks Kerry.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Before Dropping the Transmission [message #267496 is a reply to message #267495] |
Fri, 12 December 2014 23:56 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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I would be double and triple checking the shifter linkage,especially since you have doubts about the actual position of it during your normal usage.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Before Dropping the Transmission [message #267500 is a reply to message #267496] |
Sat, 13 December 2014 04:37 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Disconnect the shift linkage at the trans and shift it into park right there at the trans to see if it still slips (rolls). You only have to loosen one bolt.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Before Dropping the Transmission [message #267516 is a reply to message #267500] |
Sat, 13 December 2014 13:04 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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I like to start a diagnosis with simple tests. This is usually cheaper, too.
If the Parking Pawl does not hold, then something is amiss down stream of that and there isn't very much.
So, after you do Ken's check to see that the cable is moving the shift lever and it is, then a good next test would be to run the engine with the wheels in the air. If you can get wheels to spin and the speedo goes upscale, then step on the brake and if the speedo stays up scale, then you know the problem is in or past the final drive flange. Don't take the transmission down.
Next cheap and dirty test.... Takes two - maybe three people. You may have blown a CV joint.
Lock down or have someone hold one wheel while you try to spin the other. Have someone else look at the moving parts. Are only things that should be moving?? Are any of the things that should not be moving - moving??
I have had a few front wheel drive cars, several that have gone to high mileage have cracked a ball cage in an outer CV. If this gets real bad, they can spit the balls out into the boot and the boot will tear or slip on the half shaft and the car makes all the going places noises, but it doesn't go anywhere that way.
Good Luck - Hope it is a simple and cheap fix.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Before Dropping the Transmission [message #267531 is a reply to message #267482] |
Sun, 14 December 2014 01:40 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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Bob de Kruyff wrote on Fri, 12 December 2014 17:51Jeff102410 wrote on Fri, 12 December 2014 18:29Here's the situation:
.
The ask here is...is there other stuff to check before dropping the transmission??? final drive??? etc.???
Jeff Rogers
Arlington, TX
1978 Former Palm Beach
If it rolls in park, then the problem is downstream from the pawl. If it is an axle shaft you would have seen it. It almost sounds like a snapped output shaft on the transmission. Are you sure the linkage is adjusted correctly? It sounds like you had some issues with the adjustment and it may be the problem--pulling it out of park on a grade can create quite a pop.
I hate to say it but I think Bob is on it with the output shaft. If the wheels spin opposit as you describe, I believe the shafts are ok. I think it was Emery Stora had a wobbly final drive bearing and it snapped his trans output. Randy Van Winkle checked his (I forget why) and it was floppy and probably would have taken the output shaft as well, very soon.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Before Dropping the Transmission [message #267533 is a reply to message #267516] |
Sun, 14 December 2014 03:43 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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As long as we are throwing wild guesses out here how about the chain or the chain sprocket.
In reality it could be a lot of things between the trans and the wheels. I still suggest that you disconnect the linkage at the trans and manually put the trans in park.
IF that is not it, I think I would put it in gear with the engine running and see if either axle turns. If not then I would look inside the final drive with it running and in gear since the cover is already off. If there is no movement then we need to back up to the trans and chain drive.
I seriously doubt it is the parking pawl since it will not move in gear and the parking pawl has nothing to do with that. Since it starts we can assume that the flex plate is still attached to the crank.
This could be something as simple as a broken cable, or linkage, or cable connection to the trans with the gear selection stuck in neutral.
I could probably dream up a few more possibilities if necessary.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Before Dropping the Transmission [message #267541 is a reply to message #267480] |
Sun, 14 December 2014 13:53 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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Jeff102410 wrote on Fri, 12 December 2014 17:29Here's the situation:
Another tid bit is that regardless of what gear the coach is in, the engine revs up as expected. There is no additional noise, grinding, whatever.
Transmission is a 2010 Manny rebuild with 3800 miles on it. Called Manny, but he has not heard of a transmission doing anaything like this.
Final drive (3.55) was purchased from Jim K. the same time as the transmission.
Jeff Rogers
Arlington, TX
1978 Former Palm Beach
Jeff,
Does the speedometer register when the transmission is in drive and engine revved?
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Before Dropping the Transmission [message #267542 is a reply to message #267541] |
Sun, 14 December 2014 14:15 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Senior Member |
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George Beckman wrote on Sun, 14 December 2014 13:53Does the speedometer register when the transmission is in drive and engine revved?
OOOH Good one George! That is about at the end of the tranny so if it's working the problem is further downstream. If not, well, the tranny probably has a problem.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: Before Dropping the Transmission [message #267551 is a reply to message #267480] |
Sun, 14 December 2014 20:55 |
mild bill
Messages: 98
Registered: November 2014
Location: Edmonton, Alberta, Canada
Karma: 0
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Regarding park not holding, if the linkage is not adjusted properly and detention is not fully in park it might not hold and pop out. Can't explain your noise right now and have not looked at the drivetrain power flow diagrams however I remember 40 years ago rebuilding transmissions some of the guys I worked with would drop the transmission into park traveling at 30 mph when they suspected some crap got in the governor. I tried it once or twice and you could hear the parking pawn rattling and their theory was with transmission oil pressure and the parking pawl rattling the governor Pistons would open and close driving crap out. While I tried it one or twice I didn't like the idea, didn't solve anything I was dealing with however no negative results.
All I am saying if it wasn't in the full detent position allowing the pawl to bottom in the recess and you were still moving even slightly the parking pawl could jump out of the opening for the pawl perhaps making you think you have a condition that doesn't really exist and skew your diagnosis process. Wheels blocked, put in park and determine that the shifter selector on the transmission is actually in park and go from there.
Adding to this should the park situation be simple, drive should have started in first gear. No drive, band, did you try manual first or manual second, reverse? Same thing considering everything is adjusted right for the cable or shifting with cable detached in the detents. Manual second should take the low reverse band out of the equation. I have also seen torque converter hub splines splitting or stripping. No load no problem driving wheels off ground or even light load but give some gas and load heavier, like stall test and you can hear them slipping.
[Updated on: Mon, 15 December 2014 07:48] Report message to a moderator |
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| Re: Before Dropping the Transmission [message #287677 is a reply to message #287534] |
Mon, 21 September 2015 08:42 |
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thesmith
Messages: 589
Registered: February 2015
Location: Cary, NC
Karma: 6
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Senior Member |
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Thanks for adding the final answer.....I hate it when a thread ends and its never revealed what the problem really was......
Pete
Cary, NC
1978 Center Kitchen Royale.
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