350c is weak in forward strong in reverse

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Warrior0677
40C crawler
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350c is weak in forward strong in reverse

Post by Warrior0677 » Thu May 30, 2019 8:31 am

Ok guys. Loving this site and all the help I've recieved. Need some experienced advice here. I have a 1981 350c. When first starting up it runs well. After about an hour...sometimes longer...the forward gear gets very weak. It'll take a few seconds to finally engage, but eventually it does engage. I haven't checked the pressure yet. I'm also aware that I'm most likely dealing with a seal leak. Cold oil gives plenty of pressure. Warm/thinner oil allows it to bypass a seal. I also have not tried adjusting the screws underneath the control valve. I do have a manual so getting ready to run all of the checks. Sometimes I have to wait for 10 seconds or more before it engages. I'm guessing it's just taking time to build enough pressure to engage the forward clutch packs.

So here's the part I'm trying to understand. I discovered by accident that while the machine is trying to engage, if I "pop" the clutch pedal, it will immediately engage. I've done this several times on a couple of different days just to verify it works (although I haven't and won't make a habit of it). If it was a leaking seal, or an adjustment needed on the screws, why does it immediately engage when I "pop" the clutch pedal? I thought the clutch and reverser handle all controlled the same sytem. Any thoughts? Thanks in advance.
Last edited by Warrior0677 on Thu May 30, 2019 5:08 pm, edited 2 times in total.
1976 John Deere 450C; 1981 John Deere 350C

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Lavoy
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Re: 350c is weak in forward strong in reverse

Post by Lavoy » Thu May 30, 2019 8:39 am

Doubt it is a seal, just hot oil getting thinner so it bypasses the rings in the clutch packs easier. Drain and refill fluid, change filter if you haven't. Then check pressures, guessing hot you will be down a little.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
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Warrior0677
40C crawler
40C crawler
Posts: 21
Joined: Thu Feb 22, 2018 6:04 pm
Location: WV

Re: 350c is weak in forward strong in reverse

Post by Warrior0677 » Thu May 30, 2019 8:51 am

Thanks Lavoy. If that fixes the problem, that would make me a happy person. I rebuilt the reverser a couple of years ago, due to an exploded bearing, and it has run beautifully ever since. So all new seal and bearings. I'm actually stopping by John Deere today to pick up a new filter. But I do have to ask, if it's a filter / oil problem why would it be strong in reverse and weak only in forward?
1976 John Deere 450C; 1981 John Deere 350C

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Lavoy
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Re: 350c is weak in forward strong in reverse

Post by Lavoy » Thu May 30, 2019 1:52 pm

Low pressure not engaging the clutch, forward clutch slightly more worn than the reverse clutch.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com

Warrior0677
40C crawler
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Posts: 21
Joined: Thu Feb 22, 2018 6:04 pm
Location: WV

Re: 350c is weak in forward strong in reverse

Post by Warrior0677 » Thu May 30, 2019 4:52 pm

Ok. Now that makes sense. If I may ask one more question, why would "popping" the clutch pedal result in an immediate engagement forward?
1976 John Deere 450C; 1981 John Deere 350C

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gregjo1948
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Re: 350c is weak in forward strong in reverse

Post by gregjo1948 » Fri May 31, 2019 2:57 am

The reverser lever directs the fluid and the "clutch" pedal stops the flow of fluid. Possibly by depressing the pedal and popping it, the fluid gives the directional clutches more of an instant shot of pressure and engages the clutch.
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford

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Lavoy
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Re: 350c is weak in forward strong in reverse

Post by Lavoy » Fri May 31, 2019 7:50 am

Also make sure that nothing is impeding pedal travel so that when you pop it, it travels further up possibly yielding more pressure. Make sure the pedal return spring is strong too.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
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JWB Contracting
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Re: 350c is weak in forward strong in reverse

Post by JWB Contracting » Fri May 31, 2019 5:56 pm

There is accumulator in or connected to the reverser valve body. It is most likely sticking Best get a book and do some reading. Not easy to work on the valve body but much less time than removing the reverser.
Jason Benesch

John Deere 420, 430, 440 & 350C With 3 Point Hitch
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