3 speed RAT trans noisy in 3rd gear?

[Bustedbroc]

You think there's an end?

Touche!

 

[jamesroney]

There is no cardan coupling on the rear drive shaft.

Not sure I understand your problem. Or your diagnosis. You should post your location in your profile. If you are near Northern CA...I can help you. Otherwise...you will have to do some remote diagnosis.

You THINK that you have a drivetrain noise while under coast or light cruise in 3rd gear only? 2WD ONLY, High range ONLY? What exactly does it mean that you have no cardan in the rear shaft? Now I'm lost.

Please answer the following questions:
1. Does it make the same noise when in 2WD as when in 4WD?
2. Does it make the same noise when in lo-range vs high range?
3. Does it make the same noise when testing with the rear driveshaft removed and driving on the front axle only?
4. How much play exists in the transfer case rear output yoke with driveshaft removed?
5. Did someone leave out / count the transfer case roller elements?
6. Did someone verify the intermediate gear thrust washer condition and endplay?
7. Did someone verify the transmission countershaft end play / thrust washer condition when the trans was open?
8 How did you manage to change the shift shaft seals without removing the transfer case? Or did you not service ALL of the seals?

We should be able to knock this out for you.

 

[bronco italiano]

Eh, I hear you but where does it ever end?

It's a Bronco, it never ends.

 

[Yeller]

Since no one said it….. stock is helpful but doesn’t mean that do to the work done that there is not a pinion angle or drive shaft issue. Decribed noise sounds like joint oscillation. It will make a chatter that you swear the transmission or transfer case is about explode or crawl up inside and say hi like it possessed. Does it have a CV joint at the transfer case? I’d the pinion within 1.5 degrees of the driveshaft? And as Paul mentioned, U joints phased correctly? All or any of those things describe your issue, especially with the noise not present in front wheel drive. I know you have a new 3rd member coming, but I’m sure that is not where the source of the noise is originating from.

 

[Bustedbroc]

Not sure I understand your problem. Or your diagnosis. You should post your location in your profile. If you are near Northern CA...I can help you. Otherwise...you will have to do some remote diagnosis.

You THINK that you have a drivetrain noise while under coast or light cruise in 3rd gear only? 2WD ONLY, High range ONLY? What exactly does it mean that you have no cardan in the rear shaft? Now I'm lost.

Please answer the following questions:
1. Does it make the same noise when in 2WD as when in 4WD?
2. Does it make the same noise when in lo-range vs high range?
3. Does it make the same noise when testing with the rear driveshaft removed and driving on the front axle only?
4. How much play exists in the transfer case rear output yoke with driveshaft removed?
5. Did someone leave out / count the transfer case roller elements?
6. Did someone verify the intermediate gear thrust washer condition and endplay?
7. Did someone verify the transmission countershaft end play / thrust washer condition when the trans was open?
8 How did you manage to change the shift shaft seals without removing the transfer case? Or did you not service ALL of the seals?

We should be able to knock this out for you.

Thanks for the offer. I am in NY. A lot of good questions. I have some diagnosing to do........

 

[DirtDonk]

I was wondering about your cardan comment as well.
A cardan is simply an old term for a u-joint. Possibly even the original name.
Most Broncos are equipped with a single cardan at the differentials and double cardan joint setup at the transfer case.
How is your driveshaft set up?

 

[Bustedbroc]

I was wondering about your cardan comment as well.
A cardan is simply an old term for a u-joint. Possibly even the original name.
Most Broncos are equipped with a single cardan at the differentials and double cardan joint setup at the transfer case.
How is your driveshaft set up?

I guess I should have said "There is no DOUBLE cardan coupling on the rear drive shaft by the xfer case. I am assuming some PO replaced the driveshaft and took the cheaper route. On my to do list. No lift on this truck and really just use it for cruising around, not a high priority at this moment.

 

[dmoses42]

I've had a similar noise from a rear axle bearing starting to fail.

 

[Bustedbroc]

Not sure I understand your problem. Or your diagnosis. You should post your location in your profile. If you are near Northern CA...I can help you. Otherwise...you will have to do some remote diagnosis.

You THINK that you have a drivetrain noise while under coast or light cruise in 3rd gear only? 2WD ONLY, High range ONLY? What exactly does it mean that you have no cardan in the rear shaft? Now I'm lost.

Please answer the following questions:
1. Does it make the same noise when in 2WD as when in 4WD?
2. Does it make the same noise when in lo-range vs high range?
3. Does it make the same noise when testing with the rear driveshaft removed and driving on the front axle only?
4. How much play exists in the transfer case rear output yoke with driveshaft removed?
5. Did someone leave out / count the transfer case roller elements?
6. Did someone verify the intermediate gear thrust washer condition and endplay?
7. Did someone verify the transmission countershaft end play / thrust washer condition when the trans was open?
8 How did you manage to change the shift shaft seals without removing the transfer case? Or did you not service ALL of the seals?

We should be able to knock this out for you.

UPDATE: I did some more PD and this is what I have found. (I have not yet removed the rear driveshaft and driven)
I have a 2 stick setup for my Dana 20.
- In rear 2WD Hi truck makes noise when not under a load,(acceleration/deceleration), whether in gear, clutch in or out, or even neutral.
- In rear 2WD Lo it is too hard to tell because you can never get to a point of no load.
- In 4WD Hi it makes noise like 2WD Hi above.
- In front 2WD Hi, (rear drive in neutral), truck makes NO noise.
- If I am in rear 2WD Hi and bump rear xfer case lever into neutral while coasting noise goes away.
- With rear driveshaft removed at xfer case, grabbing yoke I feel no in/out motion and only miniscule up/down. Shaft turns freely with and smoothly by hand.
NOTES: See pic, this xfer case has a Koenig PTO gearbox bolted on for the front winch. I do not think this would come into play with how I described to problem above but I have been wrong before. Xfer case is full of 75-90 gear oil and I replaced both output seals when I had the trans/xfer case out replacing the clutch.
Question, I am assuming if I remove the PTO gearbox I can get a good look inside the xfer case. I just don't know what to look for. I am now thinking it has something to do with the rear output sliding gear, output shaft, and/or bearings. Looking at Dana 20 service manual someone posted on this forum it appears some of the xfer case can be serviced without pulling it from the vehicle.
If anyone is wondering what that green wire is in the pic, I wired the PTO disengaged so there were no accidents!

 

[Bustedbroc]

I've had a similar noise from a rear axle bearing starting to fail

All new, thanks.

 

[dmoses42]

I must have missed that. I even looked through the thread twice. Sorry.

 

[Bustedbroc]

UPDATE: I did some more PD and this is what I have found. (I have not yet removed the rear driveshaft and driven)
I have a 2 stick setup for my Dana 20.
- In rear 2WD Hi truck makes noise when not under a load,(acceleration/deceleration), whether in gear, clutch in or out, or even neutral.
- In rear 2WD Lo it is too hard to tell because you can never get to a point of no load.
- In 4WD Hi it makes noise like 2WD Hi above.
- In front 2WD Hi, (rear drive in neutral), truck makes NO noise.
- If I am in rear 2WD Hi and bump rear xfer case lever into neutral while coasting noise goes away.
- With rear driveshaft removed at xfer case, grabbing yoke I feel no in/out motion and only miniscule up/down. Shaft turns freely with and smoothly by hand.
NOTES: See pic, this xfer case has a Koenig PTO gearbox bolted on for the front winch. I do not think this would come into play with how I described to problem above but I have been wrong before. Xfer case is full of 75-90 gear oil and I replaced both output seals when I had the trans/xfer case out replacing the clutch.
Question, I am assuming if I remove the PTO gearbox I can get a good look inside the xfer case. I just don't know what to look for. I am now thinking it has something to do with the rear output sliding gear, output shaft, and/or bearings. Looking at Dana 20 service manual someone posted on this forum it appears some of the xfer case can be serviced without pulling it from the vehicle.
If anyone is wondering what that green wire is in the pic, I wired the PTO disengaged so there were no accidents!
View attachment 929502

CORRECTION: With rear driveshaft removed at xfer case AND XFER CASE IN NEUTRAL, grabbing yoke I feel .003-5 in/out motion and SAME up/down. Shaft turns freely with and smoothly by hand.

 

[Bustedbroc]

Not sure I understand your problem. Or your diagnosis. You should post your location in your profile. If you are near Northern CA...I can help you. Otherwise...you will have to do some remote diagnosis.

You THINK that you have a drivetrain noise while under coast or light cruise in 3rd gear only? 2WD ONLY, High range ONLY? What exactly does it mean that you have no cardan in the rear shaft? Now I'm lost.

Please answer the following questions:
1. Does it make the same noise when in 2WD as when in 4WD?
2. Does it make the same noise when in lo-range vs high range?
3. Does it make the same noise when testing with the rear driveshaft removed and driving on the front axle only?
4. How much play exists in the transfer case rear output yoke with driveshaft removed?
5. Did someone leave out / count the transfer case roller elements?
6. Did someone verify the intermediate gear thrust washer condition and endplay?
7. Did someone verify the transmission countershaft end play / thrust washer condition when the trans was open?
8 How did you manage to change the shift shaft seals without removing the transfer case? Or did you not service ALL of the seals?

We should be able to knock this out for you.

James/DirtDonk, please see my posts to your questions. In hindsight I guess I coulda, shoulda, woulda, done more when I had the trans being out. That being said, after my latest PD I plan to:
(with xfer case still in truck)
-remove the PTO gearbox for xfer case inspection.
-remove the xfer case rear output shaft/housing for inspection and bearing replacement
-replace the rear driveshaft with the correct double cardan type.
I realize I should pull the xfer case to be thorough and change ALL the seals. Winter is coming in NY and I will have plenty of time to do that.
QUESTIONS:
- should I bother to try and find a good used rear driveshaft to rebuild?
- Is it a good idea to replace the rear output shaft needle bearings and are they available?
Any inspection tips are appreciated. Thanks.

 

[Yeller]

I still say the noise is caused by the drive shaft ujoint angles. you need the correct yoke as well, the one there is not correct for the correct driveshaft. There is a 90% chance the noise will go away. If the tcase is staying in gear and not popping out of 2 high, there is no issue with the rear output. Not saying new bearings aren't s good thing and if it has been vibrating for years/decades it could have created some chop in the races aggravating the noise, but that usually makes the bearing preload very loose. Get a drive shaft and yoke in it and enjoy what is left of the summer.

 

[Bustedbroc]

I still say the noise is caused by the drive shaft ujoint angles. you need the correct yoke as well, the one there is not correct for the correct driveshaft. There is a 90% chance the noise will go away. If the tcase is staying in gear and not popping out of 2 high, there is no issue with the rear output. Not saying new bearings aren't s good thing and if it has been vibrating for years/decades it could have created some chop in the races aggravating the noise, but that usually makes the bearing preload very loose. Get a drive shaft and yoke in it and enjoy what is left of the summer.

Sounds like a plan, thanks. I was thinking whatever took out the driveshaft, (truck shows 69k which I believe is true). probably did some damage to the bearings and it is not much cost to replace. Plus I would not think there should be ANY up/down movement. I can also feel wear/slop in the driveshaft splines. I am curious, how can you tell by the pic that the yoke is incorrect?

 

[jamesroney]

I still say the noise is caused by the drive shaft ujoint angles. you need the correct yoke as well, the one there is not correct for the correct driveshaft. There is a 90% chance the noise will go away. If the tcase is staying in gear and not popping out of 2 high, there is no issue with the rear output. Not saying new bearings aren't s good thing and if it has been vibrating for years/decades it could have created some chop in the races aggravating the noise, but that usually makes the bearing preload very loose. Get a drive shaft and yoke in it and enjoy what is left of the summer.

Yeah, I'm still waiting for the answer to step 3. (the results of driving it in 4WD with the rear driveshaft removed.) If the noise is still present, then that would eliminate your potential root cause. If the noise goes away, then the driveshaft is still in play.

The rear output yoke of a Bronco Dana 20 is a Spicer 1310 CV and it has a different u-joint bolt spacing between the "straps." An experienced eye can see the difference from about 8-10 feet away. You can measure it with a tape measure and see about 3/8 difference. You have the "wrong" yoke.

But I need to get back to work. You are well on your way. I'll leave this thread for @DirtDonk and @Yeller

 

[Bustedbroc]

Yeah, I'm still waiting for the answer to step 3. (the results of driving it in 4WD with the rear driveshaft removed.) If the noise is still present, then that would eliminate your potential root cause. If the noise goes away, then the driveshaft is still in play.

The rear output yoke of a Bronco Dana 20 is a Spicer 1310 CV and it has a different u-joint bolt spacing between the "straps." An experienced eye can see the difference from about 8-10 feet away. You can measure it with a tape measure and see about 3/8 difference. You have the "wrong" yoke.

But I need to get back to work. You are well on your way. I'll leave this thread for @DirtDonk and @Yeller

Thanks, I will measure. Funny, I could swear all the u-joints I purchased were the same except for the grease fitting type.

 

[jamesroney]

Thanks, I will measure. Funny, I could swear all the u-joints I purchased were the same except for the grease fitting type.

You can measure all you want, but I can't seem to post pics anymore. (my subscription expired...)

and yes, all the u-joints are exactly the same. They are all 1310. Both CV and non CV.

The difference is in the spacing between the STRAPS. The standard u-joint is 2-15/16 between strap centers. CV is 2-5/16 between straps. The difference is 5/8 of an inch.

The factory does this to prevent CV driveshafts from being bolted to non-CV yokes. It's an error proofing technique.

I gotta go.

 

[Yeller]

This old thread from Pirate 4x4 explains the difference between a CV and non CV yoke. @jamesroney is right, when you've dealt with them for years you can spot the difference from across the shop LOL.

 

[Bustedbroc]

This old thread from Pirate 4x4 explains the difference between a CV and non CV yoke. @jamesroney is right, when you've dealt with them for years you can spot the difference from across the shop LOL.

AH HA!, the light bulb turned on. Thanks. Just had to look at my front driveshaft.