I think it happens whenever the truck is moving but more noticable at higher speeds... Especially above 40. Sounds like grinding. Feels like heavy vibration (somewhere after the motor... Maybe clutch asembly or trans). It happens when I let off the gas to apply lite throttle after coasting (to slowly slow down). Also happens when I have the clutch in. Again very noticable at higher speeds. Does not happen during acceration and is very mild when I let off gas completly after coasting and still in gear. I just had the trans rebuilt. The noise happened before and still happens. It's a t 19 wide ratio behind a 345. Any ideas what's going on?
Sounds like trouble
- Thread starter IbRamblin
- Start date
Scoutboy74
Moderator
What vehicle ya drivin'? Have you tried running off just the front axle with the rear shaft completely removed? If the noise continues while coasting with the clutch in and/or trans in n, that kind of points to this being a differential/rear axle issue.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
I agree, isolate the drivelines from the tc output one at a time. Same process as what is discussed in this thread:
http://www.forums.IHPartsAmerica.com/basic-tech-questions/3638-driveline-noise-please-help.html
Front hub/rear axle bearings need to be validated also.
http://www.forums.IHPartsAmerica.com/basic-tech-questions/3638-driveline-noise-please-help.html
Front hub/rear axle bearings need to be validated also.
Scoutboy74
Moderator
It's one way of potentially isolating some culprits. You say the noise was present both before and after the trans rebuild, so assuming the rebuild was done properly, lets look elsewhere for the time being. The t-case is still a valid point of suspicion, as is the rear prop shaft including all universal joints. What's the condition of the transmission mount?
Scoutboy74
Moderator
How much lift do yo have? Are the springs under or over the axle?
While you follow the prescribed diagnostic advice and remove the rear drive shaft; pull some u-joint caps and look at the cross journals, and inspect the splined slip joint as well.
Most u-joints have an 8 degree maximum angle, that is for maximum life, and no more than 12 to 15 degrees without catastrophe. Many times they'll be run at steeper angles and can survive low speed applications like trail runs and farm chores, but will definitely wear out on high speed cruises with steep angles.
Most u-joints have an 8 degree maximum angle, that is for maximum life, and no more than 12 to 15 degrees without catastrophe. Many times they'll be run at steeper angles and can survive low speed applications like trail runs and farm chores, but will definitely wear out on high speed cruises with steep angles.
I took off the rear drive shaft and drove in 4 hi. The noise stopped. So I guess im getting closer to isolating the prob. I called the guy that I bought the truck from and he said that he bought it already lifted. Also that it made that same noise the whole time that he owned it. I looked at the u joints and they looked fine. They were well greased and moving smoothly. If I wanted to focus on the drive shaft, would getting it outfitted with a cv joint solve the angle problem. Im gonna try to get you guys some visuals tomarrow. Is it likely that the differential is the problem? Im looking forward to the feedback. Thanks guys
Ok guys... Here is a link to a video I made of the whole shubang.
youtube - 1972 International Scout rear suspension/driveline.mpg
youtube - 1972 International Scout rear suspension/driveline.mpg
Scoutboy74
Moderator
That driveline angle does look pretty steep. I think it would be especially problematic in articulated situations. I also question the spacer plates between the bottom leaf and the booty-fab spring perches. No scientific reason, it just looks funky. Nice, beefy shaft though...that's what she said!
I have one of those myself, but it's too long...repeat over-used remark from above. It's out of a traveler. I'm going to see about having the requisite 18" whacked off. It sure has a lot more girth than the stock toothpick that's under my Scout now. Did I work in enough double ontondre's or however the frack it's spelled?
I have one of those myself, but it's too long...repeat over-used remark from above. It's out of a traveler. I'm going to see about having the requisite 18" whacked off. It sure has a lot more girth than the stock toothpick that's under my Scout now. Did I work in enough double ontondre's or however the frack it's spelled?I agree with trev. That's a pretty steep angle and the yoke looks like it's been hammered too, prior failure? The slip joint looks too extended for my taste, and I'll bet you'll have a leetle bit'o play in it. It don't take much, they're supposed to be zero slop, to get some noise with a light feather'in of the gas around 35 to 45 mph. I'll post a link here on driveline geometry 101, it's got pictures and a better explanation than I could post up:
Tom wood's custom drive shafts - driveline 101
And a little more:
universal joints, Dana spicer, drive shafts, propeller shafts, gwb - machine service, inc
Thanks for the pictures and crawling around, I know it ain't handy but sure helps the folks on this end.
Tom wood's custom drive shafts - driveline 101
And a little more:
universal joints, Dana spicer, drive shafts, propeller shafts, gwb - machine service, inc
Thanks for the pictures and crawling around, I know it ain't handy but sure helps the folks on this end.
Doubt you could get one mated up with mismatched pieces.
If you did, it should be all little metal pieces by now...
Did you ever change your drive line angle?
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
It's actually very easy to mate up the mis-matched bull gear/d20 intermediate gear! It does make a significant amount of noise when operating however. It could operate for a considerable period of time before failing. There is "only" a 2.5* mis-match in the pitch angle so the gears will mesh to an extent, the problem is not in the tooth count as that is the same for both gears.
There is only one way to determine if a mis-matched gear set is an issue, pull the transfer case off and look at the spicer part number on the intermediate gear and verify that it is a match for the bull gear currently installed.
No I havent changed the angles on it yet. I do plan on putting a cv on both drive shafts and replacing the slip joint on the front one. Im reluctant about the cv's because ive heard that they are nightmares to repair on the trail and that they need a lot more maintenance...
Michael
I will check out those numbers but it will probably be a little while as this project had to take back seat cause my wife and I are gonna have a baby in about 4 weeks. When I et around to it though im gonna need some help...
Which is the intermediate gear and which is the bull gear? Will they both have numbers? If I post them here will you be able to help me determine if they are the correct ones. Ill make another video with the truck making the noise and maybe you could tell me if thats the noise it might make if the parts were in fact mismatched.
Michael
I will check out those numbers but it will probably be a little while as this project had to take back seat cause my wife and I are gonna have a baby in about 4 weeks. When I et around to it though im gonna need some help...
Which is the intermediate gear and which is the bull gear? Will they both have numbers? If I post them here will you be able to help me determine if they are the correct ones. Ill make another video with the truck making the noise and maybe you could tell me if thats the noise it might make if the parts were in fact mismatched.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Congratulations on the upcoming litter drop!
The part number on the bull gear for the 727 is spicer 18-8-56 and is clearly stamped on the gear. That would be a 23 spline count with 26 teeth. There was only one bull gear produced for the ihc/Scout II output shaft spline for the 727.
The intermediate gear part number will be...spicer 18-5-16. That number will be barely visible on the gear set when you look through the mounting hole for the d20 input. You will have to turn the gear to see it and most likely use a mirror and flashlight. That same p/n intermediate gear was used with matching bull gears for other applications, but the only gear gear ever used on the 727 is the 23 spline item. Again, the pitch angle on both of these gears is 17.5*.
This pic shows the intermediate gear on the left. When you look through the opening, that is the face you will see so ya just turn the gear until you can see the part number with a light. On the right is the bull gear, but...it is upside down in that pic so I can show you the part number! The counterbore on the face of that gear is where the retaining nut and washer seats. Those are the "dogs" that engage the d20 output gear which the bull gear plugs into.
See that kinda shiny "ring" around the face of the bull gear where the part number is??? That is an issue. The transmission that this gear was mounted to was assembled to the transfer case with no proper gasket, only freakin' rtv! That is a huge no-no!!! The transmission output shaft always has a given amount of endplay set up in it. We do not want that gear contacting the output gear counterbore at all when the output shaft of the transmission "thrusts". In many cases, I find that the bull gear has actually tried to weld itself to the transfer case output gear due to no internal clearance to allow for thrust and heat expansion. The use of the proper gasket between the trans and the transfer case serves as a "shim" in that regard.
Also...when the transfer case is overhauled, the proper output shaft bearing pre-load must be set through the use of shims. If the unit is not properly set up, then there will also be a collision between the bull gear and the output gear of the transfer case. This is also all too common regarding "just rebuilt" transfer cases...most folks just kinda partially disassemble and clean (half-assed), then put 'em together with no attention paid to replacing bearings and doing proper bearing setup. Rebuilding involves all new bearings, replacing any suspect gears, and usually replacing the intermediate shaft (which is actually a bearing race) with a new one no matter what it's "visual" condition.
When you look into the large "input" hole on the d20 where the tailhousing of the trans and the bull gear mate, the intermediate gear will be to your left and will actually overhang the large mounting opening slightly.
What happens all too often is that folks start boneyardin' d20 units and various transmissions that mount with the "texas" pattern and don't pay attention to the actual match-up of the gear sets. While the difference in the pitch angle is very slight, it is enough to prevent proper engagement though the two components can certainly be forced together.
The part number on the bull gear for the 727 is spicer 18-8-56 and is clearly stamped on the gear. That would be a 23 spline count with 26 teeth. There was only one bull gear produced for the ihc/Scout II output shaft spline for the 727.
The intermediate gear part number will be...spicer 18-5-16. That number will be barely visible on the gear set when you look through the mounting hole for the d20 input. You will have to turn the gear to see it and most likely use a mirror and flashlight. That same p/n intermediate gear was used with matching bull gears for other applications, but the only gear gear ever used on the 727 is the 23 spline item. Again, the pitch angle on both of these gears is 17.5*.
This pic shows the intermediate gear on the left. When you look through the opening, that is the face you will see so ya just turn the gear until you can see the part number with a light. On the right is the bull gear, but...it is upside down in that pic so I can show you the part number! The counterbore on the face of that gear is where the retaining nut and washer seats. Those are the "dogs" that engage the d20 output gear which the bull gear plugs into.
See that kinda shiny "ring" around the face of the bull gear where the part number is??? That is an issue. The transmission that this gear was mounted to was assembled to the transfer case with no proper gasket, only freakin' rtv! That is a huge no-no!!! The transmission output shaft always has a given amount of endplay set up in it. We do not want that gear contacting the output gear counterbore at all when the output shaft of the transmission "thrusts". In many cases, I find that the bull gear has actually tried to weld itself to the transfer case output gear due to no internal clearance to allow for thrust and heat expansion. The use of the proper gasket between the trans and the transfer case serves as a "shim" in that regard.
Also...when the transfer case is overhauled, the proper output shaft bearing pre-load must be set through the use of shims. If the unit is not properly set up, then there will also be a collision between the bull gear and the output gear of the transfer case. This is also all too common regarding "just rebuilt" transfer cases...most folks just kinda partially disassemble and clean (half-assed), then put 'em together with no attention paid to replacing bearings and doing proper bearing setup. Rebuilding involves all new bearings, replacing any suspect gears, and usually replacing the intermediate shaft (which is actually a bearing race) with a new one no matter what it's "visual" condition.
When you look into the large "input" hole on the d20 where the tailhousing of the trans and the bull gear mate, the intermediate gear will be to your left and will actually overhang the large mounting opening slightly.
What happens all too often is that folks start boneyardin' d20 units and various transmissions that mount with the "texas" pattern and don't pay attention to the actual match-up of the gear sets. While the difference in the pitch angle is very slight, it is enough to prevent proper engagement though the two components can certainly be forced together.
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Scoutboy74
Moderator
Holy blast from the past! Since you're asking for numbers to compare, I'm assuming that means you have your t-case out on the bench to where you could possibly look inside and see your gear numbers. Is that correct?
No not yet. I wanna use the numbers to talk to the guys that rebuilt 'em so maybe I can avoid pulling the thing off. If they give me a blank stare when I start talkin then I guess its on. I just dont have a trans jack so im trying to avoid it
I called them this morning and asked if it was possible to get these things mixed up. They were in disagreement with what we've been talkin' 'bout here. Maybe if I have the numbers, a light will turn on in their head. They are very reputable and have come highly recommended by a couple other outfits..
I called them this morning and asked if it was possible to get these things mixed up. They were in disagreement with what we've been talkin' 'bout here. Maybe if I have the numbers, a light will turn on in their head. They are very reputable and have come highly recommended by a couple other outfits..