Velvet drive good?
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=50635
Printed Date: November-22-2024 at 7:18pm
Topic: Velvet drive good?
Posted By: Doogman4
Subject: Velvet drive good?
Date Posted: May-22-2022 at 4:12pm
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I have done some searching but haven’t found what I am looking for. Last run of the season last year, backing off of the beach, it sounded like the springs letting loose in the pressure plate. So I parked it for the winter. Yesterday I pulled the trans, the bell housing and the pressure plate. I expected to find broken springs fri the pressure plate, but they are enclosed. I did hear a slight bit of movement in the plate but not a rattle that I would expect. So I am looking at the velvet drive and wondering if I may have damage in the reverse clutch pack. Is there any way to test the trans without a test stand or without tearing down? Just trying to find out if it may have failed. I need to add that it did go into and out of forward and reverse but made noise doing it. Drove home from the beach just fine. 1972 Mustang with 302 AS1 71c velvet drive. |
Replies:
Posted By: KENO
Date Posted: May-22-2022 at 8:01pm
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A couple of things that can cause some nasty sounding noises is putting the boat in gear, either forward or reverse with the idle speed too low or having a small misfire on the engine. Both of those will make you think the transmission is getting ready to die till you speed up a little and the noise goes away. But it's too late right now to say "bump up the idle speed a little or make sure your tuneup is good", since the transmission is off of the engine  But since it's off and your damper plate has enclosed springs, you don't really know their condition so you might as well replace the damper plate. Here's a link to a recent thread that has some discussion of damper plates that would fit your application mixed in with some starter talk. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=50285&KW=ALTDA%2D106&title=new-starter-which-to-get" rel="nofollow - link
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Posted By: KENO
Date Posted: May-22-2022 at 8:20pm
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A kinda backyard way of spinning the transmission with normal readily available stuff is to get a length of thick hose to slip over the input shaft, dig out a socket the same size as the shaft and hose clamp the hose to the socket and the input shaft good and tight so nothing slips. Then using a good powerful 1/2 inch drill with an adapter to fit the socket, you can spin the input shaft in neutral, then shift it to forward and back to neutral then reverse and see if you hear any of the same noises you heard last year. Assuming you have a reverse rotation engine, you'll have to run the drill backwards for the pump on the transmission to function correctly and make pressure. The drill depending on how beefy it is will be working pretty hard and may start doing things like getting hot and smoking pretty quickly Remember, I said backyard, but it works and it should tell you if you have any funny noises. Just the fact that you drove it back from the sandbar with no issues, probably tells you that it's OK and you could skip the drill test, but it wouldn't hurt to try it if you really want to.
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Posted By: Doogman4
Date Posted: May-22-2022 at 9:07pm
| Thanks. That’s the advice I was looking for. Plate is getting replaced. Maybe I just cross my fingers on the trans |
Posted By: MourningWood
Date Posted: May-23-2022 at 12:22pm
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IMHO it might be best to do the "off-engine" test (as Keno described) in addition to the plate change. That way, if the trans isn't making the noises you heard, you can be relatively sure that the plate is the culprit. No finger-crossing required. ------------- 1964 Dunphy X-55 "One 'N Dun" 'I measured twice, cut three times, and it's still too short!" |
Posted By: Doogman4
Date Posted: May-23-2022 at 12:38pm
| Yes. i am going to try to get something set up for a bench test. Should be a fun project. Thanks for the advise. |
Posted By: KENO
Date Posted: May-23-2022 at 2:36pm
If you decide to test it, here are a couple of pictures of what you need   The bit is called a hex shank socket driver or adapter, available at Harbor Freight, Home Depot hardware stores etc. The hose is 1 1/4 inch ID and fits over the input shaft tightly. The piece in the picture is 2 1/2 inches long. The socket size depends on the wall thickness of the socket you're using. Put it all together and spin the drill backwards for the right rotation of the transmission for your reverse rotation engine. And.........before you spin things make sure you transmission cooler hoses are hooked to the cooler or at least hooked to each other so you don't pump a bunch of oil out on the floor Also it'll make more of a whirring noise in Reverse than it will in Forward due to the rotation of the planetary gears in Reverse.
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Posted By: Doogman4
Date Posted: May-23-2022 at 6:35pm
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Thanks! 👍 That’s a great help. I just bought a rebuild kit anyhow today. I’m betting I need it. Stay tuned. |
Posted By: Doogman4
Date Posted: June-14-2022 at 8:53pm
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Still in process. Looks like the trans was in working order. No clear signs of any damage. But since I bought the kit, what the hell. Tore it down and found a couple of missing parts. The output shaft thrust bearing was missing. It’s an older trans with the bushings for the output shaft. Then the reverse clutch only had a single fiber plate, no steel or the second fiber. I’m thinking that was my main issue. Replacing the dampener plate also. Re packing the prop shaft and rudder shaft while I have it in the barn. And a new impeller while I’m at it. Stay tuned for the results. |
Posted By: KENO
Date Posted: June-15-2022 at 7:30am
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For an older 71C like yours there were no missing reverse clutch plates, that thick fiber one is all they had. It got pushed by the pressure plate A quick check with it back together would be to hold the output coupling with one hand so it won't move and with the other hand rotate the input shaft. If there's a little drag that's OK. If they feel like they're pretty much locked together you night have a wrong combination of friction and steel reverse plates. Page 64 of the linked manual from the CCF reference section has some reverse plate info and charts http://www.correctcraftfan.com/downloads/Velvet_Drive_70C-71C_Transmission_Service_Manual.pdf" rel="nofollow - link
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Posted By: Doogman4
Date Posted: June-21-2022 at 2:51pm
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Thanks for the heads up on the number of plates. I will check the numbers and trust that the single plate is the requirement. I also found there was no thrust washer on the output shaft so I am putting that back in the assembly. My case has the oil bushings in the output shaft bore. Of course, I am going to check that also with that manual. I appreciate the coaching!!
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