ACMOC
Login
ACMOC
D6-9U TRANSMISSION ISSUE

D6-9U TRANSMISSION ISSUE

Showing 1 to 10 of 24 results
1
HUNTER
Topic Author
Offline
Member
Send a private message to HUNTER
Posts: 37
Thank you received: 0
Looking for some guidance on a problem that im not sure is fixable or not. I was pulling disc in 3rd gear when there was a loud  pop and the machine stopped moving. The shifter remained in gear but when the clutch was engaged all there was was a  whirling sound near the top of the tranny and no movement. Eventually I found that forward 1-4 would cause this to happen, but 5th woud work fine. Reverse 1-4 would work fine also. I drove home in reverse . I have taken the tranny out and have not been able to go any further yet due to having surgery restrictions . Any idea what I'm looking for when I get to work on it again? Any transmission guys/ places in Northern California that might be able to help with repair/parts?
Please log in or create an account to join the conversation.
Thu, Dec 28, 2023 4:08 AM
Deas Plant.
Offline
Member
Send a private message to Deas Plant.
Location: Currently - DowNunda.
Posts: 6,607
Thank you received: 5
Hi, HUNTER.
In most mechanical transmissions, reverse uses an idler gear to reverse the direction of the output shaft. Seems to me that something has 'come unglued' on the 'forward' side but the 'reverse' side still works 'coz the power is routed slightly differently. I think I'd start by looking at that part of the transmission.

Just my 0.02.

You have a wonderful day. Best wishes. Deas Plant.

Please log in or create an account to join the conversation.
Thu, Dec 28, 2023 6:18 AM
PhilC
Offline
Member
Send a private message to PhilC
Posts: 665
Thank you received: 0
Reply to Deas Plant.:
Hi, HUNTER.
In most mechanical transmissions, reverse uses an idler gear to reverse the direction of the output shaft. Seems to me that something has 'come unglued' on the 'forward' side but the 'reverse' side still works 'coz the power is routed slightly differently. I think I'd start by looking at that part of the transmission.

Just my 0.02.
According to the serviceman's reference book the idler gear Deas is talking about is actually used for the forward gears with the exception of 5th gear which bypasses the secondary gear sets.There are three possible problems,
1) the idler gear's bearing has collapsed causing it to lose mesh with the other gears.
2) Teeth are missing from one or more gears in the forward gear train.
3) The spline is stripped on the main input shaft at the first gear which drives all the forward gears. This is the most likely outcome as I have seen it happen to my D6 which has the same style of transmission.
Please log in or create an account to join the conversation.
Thu, Dec 28, 2023 3:25 PM
Deas Plant.
Offline
Member
Send a private message to Deas Plant.
Location: Currently - DowNunda.
Posts: 6,607
Thank you received: 5
Reply to PhilC:
According to the serviceman's reference book the idler gear Deas is talking about is actually used for the forward gears with the exception of 5th gear which bypasses the secondary gear sets.There are three possible problems,
1) the idler gear's bearing has collapsed causing it to lose mesh with the other gears.
2) Teeth are missing from one or more gears in the forward gear train.
3) The spline is stripped on the main input shaft at the first gear which drives all the forward gears. This is the most likely outcome as I have seen it happen to my D6 which has the same style of transmission.
Hi, PhilC.
Thanks for the correction. I have never seen a serviceman's book for those transmissions and have also never been inside one. I was simply going on how the majority of geared transmissions work.

Just my 0.02.

You have a wonderful day. Best wishes. Deas Plant.

Please log in or create an account to join the conversation.
Thu, Dec 28, 2023 3:39 PM
PhilC
Offline
Member
Send a private message to PhilC
Posts: 665
Thank you received: 0
Reply to Deas Plant.:
Hi, PhilC.
Thanks for the correction. I have never seen a serviceman's book for those transmissions and have also never been inside one. I was simply going on how the majority of geared transmissions work.

Just my 0.02.
Hello Deas
Normally you would be 100 percent correct but Cat decided to use the idler gear as a further reduction for the forward speeds hence why 1st forward is 1.4 but 1st reverse is 1.8 (MPH).
Please log in or create an account to join the conversation.
Thu, Dec 28, 2023 4:25 PM
trainzkid88
Offline
Member
Send a private message to trainzkid88
Location: b.berg qld
Posts: 2,208
Thank you received: 11
Reply to PhilC:
Hello Deas
Normally you would be 100 percent correct but Cat decided to use the idler gear as a further reduction for the forward speeds hence why 1st forward is 1.4 but 1st reverse is 1.8 (MPH).
is that like the british scout cars in ww2 not designed to take on the enemy but make fast advances to the rear if you made contact.

"i reject your reality and substitute my own" - adam savage. i suspect my final words maybe "well shit, that didnt work"

instead of perfection some times we just have to accept practicality

Please log in or create an account to join the conversation.
Thu, Dec 28, 2023 7:40 PM
juiceman
Offline
Member
Chapter Leader
Chapter Fifteen
Send a private message to juiceman
Posts: 3,178
Thank you received: 9
Reply to trainzkid88:
is that like the british scout cars in ww2 not designed to take on the enemy but make fast advances to the rear if you made contact.
From what both Deas and Phil say, I wanted to say reverse idler gear or close by as well, from the description Hunter provided.
Which part of Northern California? I am north of Sacramento and might be able to steer to someone that could repair it for you.
Just as a side note, I think I have a NOS transmission main shaft here if needed; also have guy that has a couple of 9U's that you might be able to buy a take out transmission . JM
Please log in or create an account to join the conversation.
Thu, Dec 28, 2023 9:31 PM
HUNTER
Topic Author
Offline
Member
Send a private message to HUNTER
Posts: 37
Thank you received: 0
Reply to juiceman:
From what both Deas and Phil say, I wanted to say reverse idler gear or close by as well, from the description Hunter provided.
Which part of Northern California? I am north of Sacramento and might be able to steer to someone that could repair it for you.
Just as a side note, I think I have a NOS transmission main shaft here if needed; also have guy that has a couple of 9U's that you might be able to buy a take out transmission . JM
I knew you guys would  have lots of info on this and you came through as ususal. I located about 60miles west of Sacramento. I would like to see/buy the service book for this, as the one I have is an after market version that is scant on details.
Please log in or create an account to join the conversation.
Mon, Jan 1, 2024 9:23 AM
PhilC
Offline
Member
Send a private message to PhilC
Posts: 665
Thank you received: 0
Reply to HUNTER:
I knew you guys would  have lots of info on this and you came through as ususal. I located about 60miles west of Sacramento. I would like to see/buy the service book for this, as the one I have is an after market version that is scant on details.
Hello Hunter
If you join ACMOC then you will have access to the library which has a copy in it.
Please log in or create an account to join the conversation.
Mon, Jan 1, 2024 2:17 PM
HUNTER
Topic Author
Offline
Member
Send a private message to HUNTER
Posts: 37
Thank you received: 0
Reply to PhilC:
Hello Hunter
If you join ACMOC then you will have access to the library which has a copy in it.
I am member, but when I click on the tech library it does nothing. No spinning wheel , no error message. nothing.
Please log in or create an account to join the conversation.
Tue, Jan 2, 2024 5:12 AM
Ray54
Offline
Send a private message to Ray54
Posts: 1,847
Thank you received: 3
Reply to PhilC:
Hello Hunter
If you join ACMOC then you will have access to the library which has a copy in it.
At times Cat books are not as explicit as we want to be mechanics would like to see ether. I have been in one twice but way to long ago. Your problem has to be with the reverse idler gearing.

Without getting into parts numbers now, be careful as the earlier 4and 5 R series transmission is the same shafts and case. Engine RPM was different so gears are different. Also possible differences from dry and wet clutch 8 and 9 U tractors. The top shaft is different to match up to clutch's differently. But I think they are interchangeable otherwise. But I am guessing again.

I am thinking the removing and then reinstall are the hardest part.
Please log in or create an account to join the conversation.
Tue, Jan 2, 2024 5:25 AM
Showing 1 to 10 of 24 results
1
YouTube Video Placeholder

Follow Us on Social Media

Our channel highlights machines from the earliest Holt and Best track-type tractors, equipment from the start of Caterpillar in 1925, up to units built in the mid-1960s.

Upcoming Events

Booleroo 2025

Chapter Thirty

| Booleroo Centre, 54 Arthur St, Booleroo Centre SA 5482, Australia

CAFES 2025 TULARE, CALIFORNIA

Chapter Fifteen

| Tulare, California

Wheatlands Warracknabeal Easter Rally

Chapter Nineteen

| 34 Henty Hwy, Warracknabeal

Veerkamp Open House 2025

Chapter Fifteen

| Placerville, CA
View Calendar
ACMOC

Antique Caterpillar
Machinery Owners Club

1115 Madison St NE # 1117
Salem, OR 97301

[email protected]

Terms & Privacy
Website developed by AdCo

Testimonials

"I also joined a year ago. had been on here a couple of times as a non-member and found the info very helpful so I got a one year subscription (not very expensive at all) to try it out. I really like all the resources on here so I just got a three year. I think its a very small price for what you can get out of this site."
-Jason N

Join Today!