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D6B Steering Clutch Question

D6B Steering Clutch Question

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Farmer Z
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Gents,
New to the forum and look forward to your experience with the old cat's. Had the good fortune of acquiring a 61-62 D6B in great condition. The only issue is left side steering clutch is non-operative. Right side clutch and both brakes are working fine. The clutch engagement pull force on the levers is noticibly different from right left, with left being maybe 1/3 force to pull back and engage. Also, the machine was re-painted 3-5 years ago and on the left side clutch rod (under seat) that goes into hydraulic unit there is lubricant residue that can collected dirt/dust where right side is total clean. Seems to me like one of these seals in the hydraulic control mechansim is not holding and leaking back onto the rod. Just obtained the machine and still need to check all normal items like lever free movement, clutch compartment fluid, etc. Hoping someone can help narrow my troubleshooting based on the symptoms. Maybe the rod seal item 7B4375 in attached is good place to start?

[attachment=23848]Hydraulic control unit.JPG[/attachment]
Attachment
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Sat, Jun 14, 2014 1:34 AM
NIK O.
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Start by checking power assist reservoir, under seat, small 1/4 pipe plug for level, faces rear, fill from under sear to level w/ 10 wt non-detergent, may cure it 4 u. Be blessed, grateful, prepared, nik
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Sat, Jun 14, 2014 6:06 AM
Old Magnet
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Reply to NIK O.:
Start by checking power assist reservoir, under seat, small 1/4 pipe plug for level, faces rear, fill from under sear to level w/ 10 wt non-detergent, may cure it 4 u. Be blessed, grateful, prepared, nik
Steering booster calls for 30wt oil, same as engine.

Yes, the 7B4375 seal is leaking. It's a bit of a job to get at the seal, requires drilling out the retaining pins for the seal holder
(aluminum) and making a pulling tool out of all thread and a coupler (7/8-14tpi).

I can post some pictures when you are ready, usually involves pulling the booster and replacing the booster pump seals while your in there.

On the steering clutch, run through the adjustment procedure first.
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Sat, Jun 14, 2014 7:05 AM
catsilver
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Reply to Old Magnet:
Steering booster calls for 30wt oil, same as engine.

Yes, the 7B4375 seal is leaking. It's a bit of a job to get at the seal, requires drilling out the retaining pins for the seal holder
(aluminum) and making a pulling tool out of all thread and a coupler (7/8-14tpi).

I can post some pictures when you are ready, usually involves pulling the booster and replacing the booster pump seals while your in there.

On the steering clutch, run through the adjustment procedure first.
Correct, the first thing to do is loosen the right hand steering adjustment back and try the left again, if one side has become too tight through normal clutch wear, the other side will not disengage.
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Sat, Jun 14, 2014 3:36 PM
Farmer Z
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Reply to catsilver:
Correct, the first thing to do is loosen the right hand steering adjustment back and try the left again, if one side has become too tight through normal clutch wear, the other side will not disengage.
Thanks. I will check adjustment on both sides and let you know how I make out.
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Mon, Jun 16, 2014 8:38 AM
Farmer Z
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Reply to Farmer Z:
Thanks. I will check adjustment on both sides and let you know how I make out.


Update 6/23/14: Spent time working to adjust clutches for free play over the weekend. Boost pump reservoir was really low (prob took 4 qts).

After filling the right side steering lever was much lighter to engage, however left side is still non-op. Free play measurements; left: 2.5 inch, right 4.5 inch, but both tightening and loosening seems to have no effect on lever free play. I did run machine back in forth inbetween adjustments and measurements. Assuming tightening shortens free play and vice versa.
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Mon, Jun 23, 2014 11:09 PM
catsilver
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Reply to Farmer Z:


Update 6/23/14: Spent time working to adjust clutches for free play over the weekend. Boost pump reservoir was really low (prob took 4 qts).

After filling the right side steering lever was much lighter to engage, however left side is still non-op. Free play measurements; left: 2.5 inch, right 4.5 inch, but both tightening and loosening seems to have no effect on lever free play. I did run machine back in forth inbetween adjustments and measurements. Assuming tightening shortens free play and vice versa.
Look inside the back end case while some one else operates the levers to see of the clutch yoke is actually being pulled towards the middle of the machine, it may be that the clutch thrust bearing has failed and the yoke is already over as far as it will go. There is a specification for clearance between the operating arms and the pistons in the booster, worth checking in case someone has been playing around already, and if my memory is correct, you should have somewhere around 4.5" free play on both levers, did you adjust the adjusters under the clutch covers or the clutch linkage from the levers?
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Tue, Jun 24, 2014 3:49 PM
Old Magnet
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Reply to catsilver:
Look inside the back end case while some one else operates the levers to see of the clutch yoke is actually being pulled towards the middle of the machine, it may be that the clutch thrust bearing has failed and the yoke is already over as far as it will go. There is a specification for clearance between the operating arms and the pistons in the booster, worth checking in case someone has been playing around already, and if my memory is correct, you should have somewhere around 4.5" free play on both levers, did you adjust the adjusters under the clutch covers or the clutch linkage from the levers?
Instructions for the 3-3/4" lever free play were provided above.
Problem is that measurement depends on the return rubber bumpers being in good condition as in new when if fact they are usually smashed or sometimes missing.
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Tue, Jun 24, 2014 10:41 PM
Farmer Z
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Reply to Old Magnet:
Instructions for the 3-3/4" lever free play were provided above.
Problem is that measurement depends on the return rubber bumpers being in good condition as in new when if fact they are usually smashed or sometimes missing.
Thanks catsilver and Old Magnet. Rubber bumpers are in place, but began to wonder how much free play in the rod linkages and their bushings I was measuring rather than the measurement as intended. I did adjust the adjusters under the clutch covers per the owner manual and what Old Magnet provided. I will try the clutch yoke check to further the troubleshooting. Do either of you guys recall whether tightening the clutch adjustment is supposed to shorten lever free length or vice versa, manual is not real specific on that point. Thanks again and will advise my progress.
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Wed, Jun 25, 2014 7:34 AM
Old Magnet
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Reply to Farmer Z:
Thanks catsilver and Old Magnet. Rubber bumpers are in place, but began to wonder how much free play in the rod linkages and their bushings I was measuring rather than the measurement as intended. I did adjust the adjusters under the clutch covers per the owner manual and what Old Magnet provided. I will try the clutch yoke check to further the troubleshooting. Do either of you guys recall whether tightening the clutch adjustment is supposed to shorten lever free length or vice versa, manual is not real specific on that point. Thanks again and will advise my progress.
Yes, slop in the linkage/bushings makes it difficult to get a good reading. Just have to give it your best shot but make sure both levers fully return or one lever can affect the operation of the other.

Tightening the adjustment shortens the lever free play.

If you suspect someone has messed with the unit here are the internal A & B adjustments. Ignore the free play adjustment in the picture, that's for a D7 but the A & B specs are the same.
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Wed, Jun 25, 2014 8:27 AM
catsilver
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Reply to Old Magnet:
Yes, slop in the linkage/bushings makes it difficult to get a good reading. Just have to give it your best shot but make sure both levers fully return or one lever can affect the operation of the other.

Tightening the adjustment shortens the lever free play.

If you suspect someone has messed with the unit here are the internal A & B adjustments. Ignore the free play adjustment in the picture, that's for a D7 but the A & B specs are the same.
If you reckon the adjustments are all Ok and there is at least 3.75" free play at the top of both levers, look inside the back end with the engine running and the main clutch engaged while someone else operates the clutch levers and see what happens, the thrust bearing could be broken up, the plates could be rusted together , if the booster is not working you should still be able to get the clutch to release by pulling back on the lever with both hands.
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Wed, Jun 25, 2014 7:41 PM
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