Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Reversing Gear

Reply
 
Thread Tools Display Modes
  #1   IP: 108.14.61.65
Old 08-09-2017, 01:12 PM
pearson1973 pearson1973 is offline
Frequent Contributor
 
Join Date: Aug 2017
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Question No Reverse

My Atomic A4 reverse failed to move the sailboat backwards yesterday for the first time and I am wondering whether I need to adjust the reverse clutch, however I noticed the drive shaft does rotate counter clockwise when the gearbox is in reverse which in my mind says to me the prop must be turning . Is it possible for the prop shaft to turn but slip when throttle is added due to incorrectly adjusted reverse clutch?
Or is it possible for a propeller to drive the boat forward just fine but become loose in reverse?

When I select reverse I can no longer feel the propeller engaging as I did before and the gear lever just moves smoothly to the full reverse position .
Reply With Quote
  #2   IP: 32.211.28.40
Old 08-09-2017, 09:14 PM
Al Schober's Avatar
Al Schober Al Schober is offline
Afourian MVP
 
Join Date: Jul 2009
Location: Uncasville, CT
Posts: 1,220
Thanks: 4
Thanked 107 Times in 96 Posts
Fwd and reverse are separate mechanisms and separate adjustments.
If your reverse 'suddenly doesn't work', I suspect you've had a failure of the reverse actuating mechanism. You're going to have to take the lid off the transmission and have a look (engine OFF).
As you shift into reverse, the mechanism will pull a flat bar away from the engine block. This flat bar fits into a slot in a round bar - this round bar has a nut on one end and a roller (inside the slot) on the other end. The flat bar is tapered, and as you pull it, it tightens the round bar which engages reverse.
I suspect it won't tighten, and you won't find the roller - you may not even find the flat bar! But you know where they are - in the bottom of the transmission.
What happens is that reverse gets adjusted too tight, the pin holding the roller shears, the roller falls out, then you can't get into reverse at all.
This problem in not uncommon, and many A4 owners during an overhaul have had their transmission housings modified to have a 3/4" pipe plug installed (the Kaminsky modification) to facilitate removal and repair of the round bar. If your engine has a 3/4" pipe plug in the transmission housing (carb side) you're in luck.
Let us know what you find. Take off the transmission cover and take some photos (we like photos). We'll walk you through this.
Reply With Quote
  #3   IP: 108.14.61.65
Old 08-10-2017, 09:27 AM
pearson1973 pearson1973 is offline
Frequent Contributor
 
Join Date: Aug 2017
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Thanks

I will take some pictures this weekend, however I removed the top plate yesterday ( before seeing your reply- thank you) and I checked the lever was at full travel with the gear select cable disconnected. I then check the reverse clutch was tightening and was unable to turn the propeller shaft when the gear lever was backwards( in reverse position). I then put the gear lever in neutral and I could clearly see the clutch had released and I was able to turn the propeller shaft again. So I followed the instructions on the site and tightened the reverse get adjuster on notch and put everything back together but the problem still remains. I can see the boat does start to move backwards when reverse is engaged but very slowly and with very weak motion. Even with high RPM it hardly seems to move backwards. When in forward gear I can feel the propeller engaging and I also feel the motion of the boat surging forward so there is a big difference. I used to be able to put the boat in reverse when moving forward and it would stop the forward motion, now it just continues going forward when i have reverse engaged and with fairly high RPM. The propeller shaft is turning so knowing that the propeller shaft is turning in reverse does that still mean I have a broken reverse selector as you suggested ?
Someone suggested the propeller could be fouled but can that stop a boat in reverse and allow it to travel forward just fine?
Reply With Quote
  #4   IP: 72.194.218.136
Old 08-10-2017, 10:27 AM
JOHN COOKSON JOHN COOKSON is online now
Afourian MVP
 
Join Date: Nov 2008
Posts: 2,743
Thanks: 25
Thanked 357 Times in 286 Posts
$.02 worth here.
What kind of oil and additives do you use? Or more to the point have you recently chained the oil\additives?

TRUE GRIT
Reply With Quote
  #5   IP: 71.118.13.238
Old 08-10-2017, 10:41 AM
Dave Neptune Dave Neptune is offline
Afourian MVP
 
Join Date: Jan 2007
Location: Lake Arrowhead Ca.
Posts: 3,660
Thanks: 196
Thanked 198 Times in 139 Posts
Are you "holding" the shift lever in reverse with some pressure? A must in reverse when applying power.

Dave Neptune
Reply With Quote
  #6   IP: 108.14.61.65
Old 08-10-2017, 12:59 PM
pearson1973 pearson1973 is offline
Frequent Contributor
 
Join Date: Aug 2017
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by JOHN COOKSON View Post
$.02 worth here.
What kind of oil and additives do you use? Or more to the point have you recently chained the oil\additives?

TRUE GRIT
I have not changed the oil as I just purchased the boat two months ago, but from your question I will do an oil change and see if it helps. Thank you
Reply With Quote
  #7   IP: 108.14.61.65
Old 08-10-2017, 01:37 PM
pearson1973 pearson1973 is offline
Frequent Contributor
 
Join Date: Aug 2017
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Dave N
Yes I am holding the shift down. Thank you
Reply With Quote
  #8   IP: 108.86.240.22
Old 08-10-2017, 02:25 PM
Jim Booth Jim Booth is offline
Senior Member
 
Join Date: Jan 2005
Posts: 147
Thanks: 1
Thanked 4 Times in 4 Posts
Can you look under the boat and see the prop? Seems pretty strange that the shaft is turning both directions but the prop thrust isn't following along. There are only a couple parts: prop, prop shaft key. I'm voting for something fouling the prop.
Reply With Quote
The Following User Says Thank You to Jim Booth For This Useful Post:
Easy Rider (08-10-2017)
  #9   IP: 72.194.218.136
Old 08-10-2017, 07:42 PM
JOHN COOKSON JOHN COOKSON is online now
Afourian MVP
 
Join Date: Nov 2008
Posts: 2,743
Thanks: 25
Thanked 357 Times in 286 Posts
Quote:
Originally Posted by pearson1973 View Post
I have not changed the oil as I just purchased the boat two months ago, but from your question I will do an oil change and see if it helps. Thank you
Some additives will reduce the friction between the clutch plates and allow them to slip. As I recall slick 50 is one of them. Changing the oil will probably not help the reverse problem in your case since an oil change did not precede the reverse problem.
That said it would be a good idea to change the oil on the new to you engine when it's oil change history is unknown.

TRUE GRIT
Reply With Quote
  #10   IP: 206.125.176.3
Old 08-11-2017, 08:33 AM
sastanley's Avatar
sastanley sastanley is online now
Afourian MVP
 
Join Date: Sep 2008
Location: Solomons, MD
Posts: 6,256
Thanks: 359
Thanked 219 Times in 172 Posts
P73,
First - welcome to the forum!

Where are you? Here in the Chesapeake we've had an unusually heavy year of fouling. A neighbor that had not been to his boat in a while thought reverse was 'broken' on his boat, but realized later (an after a haulout) that the prop was just so fouled he couldn't get any thrust in reverse compared to what he expected.

(The following assumes a direct drive A-4)
Keep in mind that there is also a reduction in prop speed in reverse, like ~1.4:1, so you gotta get the revs up on the motor several hundred more RPM to get the prop to spin in reverse at the same speed it would normally be going in forward for that given engine speed. In forward, there is a distinct engagement..we call it the "detent" around here that actively locks the prop shaft to the engine's output shaft for a 1:1 ratio in forward. A 'brake band' does some magic with the gearset to allow it to spin in reverse, but there is no 'engagement', this is a friction only action, and the shift lever needs to have pressure retained on it to keep the engine in reverse, as Dave Neptune mentioned earlier. Is the shift lever on the cockpit bulkhead or on a steering pedestal?

One more thought to consider is (most) prop blades are more efficient in the forward direction, further exacerbating lack of thrust in reverse.

And a question....Has anything changed from when reverse worked correctly?
__________________
-Shawn
"Twice Around" - '77 Catalina 30, #511 with original A-4 & MMI manifold.
Great fall sailing!!

http://www.moyermarine.com/forums/signaturepics/sigpic3231_6.gif

Last edited by sastanley; 08-11-2017 at 08:41 AM.
Reply With Quote
  #11   IP: 108.14.61.65
Old 08-11-2017, 11:09 AM
pearson1973 pearson1973 is offline
Frequent Contributor
 
Join Date: Aug 2017
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Thanks to everyone for your help. Nothing has changed, the last time I docked I put her into reverse to stop and the thrust was strong and what I had come to expect. I came back two days later to go for a sail and tried to reverse out and she decided otherwise! Just RPM and only the slightest movement backwards. The gear lever is on the port side seat with the engine starter and gauges.
I am in the Hudson river NY and will be taking a dive this weekend to see if the prop is fouled. Not looking forward to jumping in that water but hey I am now out of options

I will update everyone over the weekend and thanks again to all of you as I have a lot to learn.
Reply With Quote
  #12   IP: 24.152.132.65
Old 08-11-2017, 11:52 AM
ndutton's Avatar
ndutton ndutton is offline
Afourian MVP
 
Join Date: May 2009
Location: Torrance, CA
Posts: 7,526
Thanks: 94
Thanked 665 Times in 458 Posts
Let's make absolutely sure the cable jacket is securely mounted at both ends.
__________________
Neil
1977 Catalina 30
San Pedro, California
prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
Reply With Quote
The Following 2 Users Say Thank You to ndutton For This Useful Post:
Administrator (08-12-2017), sastanley (08-11-2017)
  #13   IP: 108.14.61.65
Old 08-12-2017, 08:32 AM
pearson1973 pearson1973 is offline
Frequent Contributor
 
Join Date: Aug 2017
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Thanks will do. I checked the cable was secure down in the engine compartment but did not check the other end that connects to the selector handle.
Reply With Quote
  #14   IP: 23.16.248.137
Old 08-12-2017, 11:04 AM
Marty Levenson Marty Levenson is offline
Senior Member
 
Join Date: Nov 2004
Location: Bowen Island, BC
Posts: 604
Thanks: 47
Thanked 19 Times in 17 Posts
camera

Or borrow an underwater camera?
__________________
Marty
1967 Tartan 27
Bowen Island, BC

Reply With Quote
  #15   IP: 208.93.185.36
Old 08-13-2017, 11:46 AM
zellerj zellerj is online now
 
Join Date: May 2005
Posts: 157
Thanks: 2
Thanked 16 Times in 8 Posts
is prop on a tapered shaft

Forward rotation pushes prop against the taper, and reverse loosens the prop so the shaft spins without the prop spinning.

Just a guess.
__________________
Jim Zeller
1982 Catalina 30
Kelleys Island, Ohio
Reply With Quote
  #16   IP: 134.65.2.119
Old 08-15-2017, 02:51 PM
pearson1973 pearson1973 is offline
Frequent Contributor
 
Join Date: Aug 2017
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Used a camera

I used a camera to see the propeller was not fouled. I have readjusted the clutch a second time and now if I hold the selector down real hard the boat will very slowly starts to move backwards. So I asked the previous owner to reverse her and see if she felt any different and the comments were "seems just like I recall).

I have not really found the problem or problems but the boat does move in reverse again , just not very well at all.
Maybe its time to fit an outboard incase the original engine fails and for when I need a little extra power in reverse.

Thanks for all the great suggestions.
Reply With Quote
  #17   IP: 71.118.13.238
Old 08-15-2017, 03:24 PM
Dave Neptune Dave Neptune is offline
Afourian MVP
 
Join Date: Jan 2007
Location: Lake Arrowhead Ca.
Posts: 3,660
Thanks: 196
Thanked 198 Times in 139 Posts
Remember that in reverse you need many more RPM's than in forward with a direct drive. They have a 1.3 reduction. Also in reverse expect some trans noise when reversing hard. And you have no reverse without holding against the lever, you are the clutch holding mechanism.

Dave Neptune
Reply With Quote
  #18   IP: 206.125.176.3
Old 08-16-2017, 09:18 AM
sastanley's Avatar
sastanley sastanley is online now
Afourian MVP
 
Join Date: Sep 2008
Location: Solomons, MD
Posts: 6,256
Thanks: 359
Thanked 219 Times in 172 Posts
Agree with Dave, it really wails in reverse. Do you have a tachometer?
__________________
-Shawn
"Twice Around" - '77 Catalina 30, #511 with original A-4 & MMI manifold.
Great fall sailing!!

http://www.moyermarine.com/forums/signaturepics/sigpic3231_6.gif
Reply With Quote
  #19   IP: 141.239.218.236
Old 08-16-2017, 01:02 PM
roadnsky's Avatar
roadnsky roadnsky is online now
Afourian MVP
 
Join Date: Dec 2008
Location: Boulder City, NV
Posts: 2,601
Thanks: 10
Thanked 118 Times in 84 Posts
Quote:
Originally Posted by pearson1973 View Post
..Nothing has changed, the last time I docked I put her into reverse to stop and the thrust was strong and what I had come to expect.

...if I hold the selector down real hard the boat will very slowly starts to move backwards.
Something is going on if it had "strong thrust" before and now it doesn't.


Quote:
Originally Posted by ndutton View Post
Let's make absolutely sure the cable jacket is securely mounted at both ends.
Quote:
I checked the cable was secure down in the engine compartment but did not check the other end that connects to the selector handle.
Did you check the other end of the cable yet?
__________________
-Jerry

'Lone Ranger'

1978 RANGER 30
Reply With Quote
  #20   IP: 148.74.164.249
Old 08-18-2017, 06:15 AM
Clucas's Avatar
Clucas Clucas is offline
Senior Member
 
Join Date: Apr 2007
Posts: 82
Thanks: 1
Thanked 7 Times in 6 Posts
Quote:
Originally Posted by pearson1973 View Post
I used a camera to see the propeller was not fouled. I have readjusted the clutch a second time and now if I hold the selector down real hard the boat will very slowly starts to move backwards. So I asked the previous owner to reverse her and see if she felt any different and the comments were "seems just like I recall).

I have not really found the problem or problems but the boat does move in reverse again , just not very well at all.
Maybe its time to fit an outboard incase the original engine fails and for when I need a little extra power in reverse.

Thanks for all the great suggestions.
It doesn't take much growth to cause the prop to cavitate and lose effectiveness. A couple barnacles could do it -- doesn't have to look like The Great Barrier Reef. A little growth or a couple barnacles will cause the prop to lose its 'bite' on the water and significantly reduce your thrust. Still suggest getting in the water (or paying someone else to do it if you're not comfortable) to check it out. What could look clean on a camera may not be so clean when checked out by hand. Wear gloves and bring a scraper. If you're paying someone, have them clean the bottom while they're at it -- you'll get better sailing performance, too.

Tell us about your prop. 2 or 3 blade? Folding prop or fixed?
__________________
s/v Grey Goose
1977 Pearson 30 #995
Glen Head, NY
~~~~~~_/)~~~~~~

Last edited by Clucas; 08-18-2017 at 07:25 AM.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
reverse gear adjustments gilbert landin Reversing Gear 12 10-17-2013 07:31 PM
Forward and Reverse Gear Adjustment Issues CraigRun Reversing Gear 12 05-17-2012 08:15 PM
Reverse gear overheat?? NorfolkRagbagger Reversing Gear 5 10-13-2010 08:20 AM
Where's Reverse?? ElmaBay Introductions 8 06-02-2009 07:52 PM


All times are GMT -5. The time now is 10:30 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2017 Moyer Marine Inc.

All Rights Reserved