OMC Cobra How much shift chatter is normal?

[kadaro]

I bought a used Chris Craft w OMC Ford Cobra 5.8 sterndrive.

Shifting into gear chatters a bit (both fwd and rev) and I was wondering:

A: Is the chattering / gear meshing sound normal
B: How to adjust this if its not right?
I went through most of the cable adjustment procedure and everything seemed somewhat to spec......
C: Any othe suggestions please?

Thanks

 

[Don S]

Re: OMC Cobra How much shift chatter is normal?

It's a dog style clutch, so if you put it into gear slowly, it will chatter. Just put it solidly into gear so you only get a clunk as it goes into gear.
Also keep your idle rpm in the 700 rpm range. The higher the rpm, the harder it is on the drive

 

[skeat]

Re: OMC Cobra How much shift chatter is normal?

It shouldn't clatter at all, you'll damage the drive. There could be some resistance in the cable or linkage not allowing it to fully engage. There should be only mininal resistance in the shifting motion. As the guru Stuart Hastings says "you should be able to shift with one finger". If you find you really have to push/pull on the lever you have to fix whatever is causing the drag. The shifter arm that the cable hooks up to on the drive could be the problem also. You'll have to pull the drive and make sure that moves freely, if the boat has been sitting awhile that could be pretty stiff. I disassemble that and grease it annually. Good Luck

 

[Lou C]

Re: OMC Cobra How much shift chatter is normal?

There really should be no chattering, just a solid 'thunk' as it goes into gear, as was noted make sure you shift briskly, if you shift it slow it will grind a bit.

 

[scorpion230]

Re: OMC Cobra How much shift chatter is normal?

you check your interupter and make sure that it is working. Also if it is working and the RPMs are to high it wont matter so check you idle.
oh yeah and you should check your intermediate cable if there is to much play it wont trip your interuptor properly

 

[kadaro]

Re: OMC Cobra How much shift chatter is normal?

All good feedback.. thanks

There does not appear to be any cable drag (I did the adjustment checks), but the RPM's are high ...1000-1100. I did some digging and it appears that the carb needs an overhaul. It has a small vaccum leak by the secondary diaphram side (the old carb cleaner squirt trick found it) and I can't get it to idle properly in the 700-750 range. I pulled the carb and am having a carb shop shop rebuild it over the storage season. Easy enough to do myself with a kit...but I'll let the pros give it a good cleaning.

I'll give these points a good look over once I get the carb back and fire her up in the spring. Meanwhile....

I am intrested to know a bit more about how the interupter supposed to work.
I checked the adjustments...but still not clear of the interupters purpose. It only toggles to either high cam point when there is a load/torque on the drive, as when quickly putting it into gear. It causes the engine to drop/pause but not quite stall; is this what it supposed to do?

 

[skeat]

Re: OMC Cobra How much shift chatter is normal?

That is how the ESA is suppose to work. It just stumbles the engine as you move through the shifting motion. If you do it swiftly you hardly even notice it. It helps more in taking the boat out of gear rather than into gear. Your rpms are difinitely too high, as you said, so the interuptor can't really do what it's suppose to. Once you get the carb rebuilt it sounds like you'll be in good shape since everything else works.

 

[whywhyzed]

Re: OMC Cobra How much shift chatter is normal?

There does not appear to be any cable drag

The ESA actually REQUIRES that there be some drag for it to function.

 

[Gary H NC]

Re: OMC Cobra How much shift chatter is normal?

Also the idle should be 700-750 IN gear with the boat in the water.It can't be set while its running on muffs...

 

[crestapre]

Re: OMC Cobra How much shift chatter is normal?

What year is this boat?
Do we really know that it is a dog style drive and not a cone clutch?

 

[bruceb58]

Re: OMC Cobra How much shift chatter is normal?

The ESA won't function until your boat is in the water as it requires the water load on the prop to engage the ESA. The ESA's function is to stumble the engine when you take the drive out of gear. When the boat is on the muffs, there shouldn't be enough load to allow the ESA to work.

 

[kadaro]

Re: OMC Cobra How much shift chatter is normal?

OK all...I'll have to clarify a few things...You guys are doing great digging for detail.
I actually craweled under my winter cover to get more detail so you guys can sort me out.


I don't know the difference between the dog type or cone type....its the 5.8 Cobra stern drive (1992 s/n) Its NOT the SP/SX type. The Seloc manual says the cone type is NOT on the Cobra....

Now its becoming clear...I had 2 issues:

1 High idle, caused by minor vaccum leak on the carb. I think Im good one the rebuild comes back. The question is now.....After warming up and ON the muffs....what would I expect the RPM to be and should I preset it at?


2 Interupter adjustment.
It clearly caused my stalling on the last outing so I need to look this over again.
In moving the shifter, I do have some drag, as I would expect in moving the shifter. The engine is not running (because the carb is at the shop) but I did notice that the interupter is going up on the cam moving into forward, and the switch slightly clicks...but not really going up the cam going into reverse.
I'll have to go through the adjustments once I get started after the winter.
Any suggestions to do/look for for adjusting this and what to look for is most appreciated.

Thanks

 

[Don S]

Re: OMC Cobra How much shift chatter is normal?

The best suggestion I could give at this point is for you to get the proper OEM service manuals for your engine and drive, the Seloc will tell you nothing of help with your problem.

 

[Gary H NC]

Re: OMC Cobra How much shift chatter is normal?

Hard to set idle out of the water but guessing i would start around 900 to 950 rpm on the muffs.
The Cobra shift adjustments are very critical.Also the lower shift cable may need to be replaced if you don't know how old it is.
A factory service manual is a MUST,the Seloc or Clymers are no good except for very basic info.
Here is a link to the manual,I know its expensive but it will be the best money you ever spend.Also you may email the seller and ask if he has other ones that may be smudged or in not new condition.I have bought several from him for around 40 to 50 bucks.
"http://cgi.ebay.com/ebaymotors/1992-3-0-4-3-5-0-5-7-5-8-OMC-COBRA-SERVICE-MANUAL_W0QQcmdZViewItemQQcategoryZ26453QQihZ010QQitemZ200168553072"

Copy and paste the link then remove the quotes......

 

[a70eliminator]

Re: OMC Cobra How much shift chatter is normal?

Definately get the Service Manual, you'll find the idle speed RPM for the 5.8 OMC Cobra is 550-600 in gear, so it would be advisable to adjust while on the water. Also, it is normal to have a slight vacuum at the vent opening near the choke housing, it's the opening that has a compression looking nut on it with a screen inside.