Johnson 6 HP 1967(CD-24) Prop confusion..

[JANDREWB]

I have a still to be water tested 67 Johnson 6HP that I recently bought used and am tuning up. I went to order a new prop for it, and it came in ( a Michigan Wheel make) It turned out to not work at all. The aft portion of the hub had no portruding boss to put the shear pin through that would hold the prop in place on the shaft. The MW prop bushing was just totally flush with the prop itself with no way to hold it in place on the shaft. The Part no for the Johnson prop should have been 380958 which translates to the MW Prop #012005. After a lot of calls one helpful parts dealer believes he solved the problem. I am looking for confirmation in the forum of his solution.

He states the parts catalog drawing for the 1967 HP CD-24D model is wrong (this one shows the shear pin and portruding boss on the prop) the part number however is right. Johnson apparently never updated the drawings in the parts catalog, just the part numbers. The prop that has the portruding boss is really from a pre-1965 motor and therefore the lower unit on the motor I have (my upper unit has the plate identifying it as CD-24) is not original and from another older unit.
On one hand it seems he is right in as much I can identify a different type of paint (white not green) as original on the lower unit. However it seems so odd that a lower unit of a pre-65 Johnson should be able to work on a 67, above all since the HP does not match.(5.5 in those days)

Anyone think the 64 lower units would work, and therefore correct interpretation? Does anyone have a 67 CD-24 with no protruding boss that the part diagram "mistakenly" shows for that model?

The prop for this older LU unit costs $125 (as opposed to the $75 for the CD-24 original LU) Any place to get one cheaper? Thanks for the help.

 

[jay_merrill]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

I just changed this whole post because I am rereading yours and am a little confused.

Where is the shear pin hole in the drive shaft your motor? Is it forward, close to the LU housing or is it at the aft end of the prop shaft, near the tip?

If the hole is near the LU housing, it is the newer style and the prop should have two indented slots in the face of the bushing, on either side of the hole for the propshaft, at the front of the prop.

If the hole is at the aft end of the prop shaft, with another hole next to it for a cotter key, it is the older style and the prop should have a machined portion of the rear that has a hole in oit for the shear pin to pass through the prop end and the prop shaft.

I belive that the '67 had the newer style prop shaft and I just looked at the BRP site for a parts explosion on a '68 6hp (the oldest that they show) - the prop depicted in that diagram is wrong.

 

[walleyehed]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

From '54-'65 they built a 5, a 5.5 and a 6hp...likely the same LU.
I don't have my app books here or I'd give ya the P/N. What Diam. and Pitch are you looking for?

 

[DJ]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Jay is correct. They moved the cotter pin position about that time. It's one or the other.

 

[jay_merrill]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

I have a pair of sixes with each of the two prop shafts. Give me a day to get a couple of digital pics and a photobucket account and I'll post pics of the shafts and the props that go with them.

I started to answer you previously by telling you that your motor might have an older LU on it. What threw me was the prop that you were describing but as I reread it, I think you are wanting one of the older style props. What you may have is a '67 6hp with a 5-1/2 LU on it. Its easy to swap them by pulling the long shift rod out of the 5-1/2 LU and replacing it with the bottom half of the two piece rod that the sixes have.

It looks like Michigan Wheel still stocks these props as part of their "Michigan Match" series. There are two available:

7-3/4 x 6-1/2 Part # 012067
8 x 7-1/4 Part # 012060

 

[F_R]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

The 5.5 and 6 horsepower motors have similar lower units that will swap as a complete unit. However, they are different inside. The 5.5 has a "shock absorber" or slip clutch built into the short pinion shaft below the water pump. That shock absorber has a heavy spring inside that winds up and releases whenever an underwater obstruction is hit, releasing and protecting the drive parts. Because of that, the propeller has no rubber shock hub and is driven by a stainless steel pin in the aft (nose) end of the prop.

However, the 6hp no longer has the shock absorber below the water pump, instead has a full length drive shaft going all the way down into the pinion gear. Since it does not have a shock absorber, it must have a rubber cushion hub in the propeller to protect the drive parts. The cushion hub propeller is driven by a stainless steel pin in the forward end of the prop. The props are not interchangeable.

Yes, I have noticed that the draftsmen did not change the pictures in the 6hp parts books. The part numbers should be correct though. Bottom line short story is if it has a shock absorber it takes the 5.5 prop with the pin in the nose. No shock absorber, it takes the cushion hub prop with the pin in the forward end, next to the gearcase.

There are other differences in the units if anybody gets into swapping parts. The gearcase head and seal and the shift rod, to name a couple. But you can swap the whole lower unit and shift rod as a complete unit. Often the 6hps get swapped to 5.5s to eliminate the troublesome and very expensive (obsolete) shock absorber when the spring breaks and locks up the lower unit.

 

[jay_merrill]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

F.R., do you happen to have a parts diagram for the 5.5hp LU with the spring? I would love to save it to my HD for reference purposes.

I took the LU off of a late 50s model Johnson 5.5hp that I own to put on my '67 6hp, which some clown at a "repair shop" had broken the LU casing on, trying to change a water pump. This LU is one with the old style propshaft - it has the shear pin and cotter key at the end of the shaft with no threaded portion for a screw-on type prop nut. Instead, it uses the rubber, press fit prop nut to hold the shear pin in place. All I did to make this work is to open the gear case up, remove the long shift rod and replace that with the short, bottom portion of the shift rod out of the original 6hp LU. I know that I did not swap the drive shafts because the 5.5hp motor is a long shaft and the 6hp is a short shaft. Apparently this works because I ran the motor for hundreds of hours afterwards with no problems.

 

[JANDREWB]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Excellent replies.
1) Just to clarify- Yes the hole in the shaft is in the aft part of the Lower Unit facing away from the motor.
2) Most of what all of you are telling me, I can verify now as dead on as you describe your own motors. What I have is clearly an LU unit from a different motor pre-1965. This is good to know and I will return the rebuild kit for a 67 gearcase for it (I just got it to have on hand, with some other tune-up parts)
3) By freak accident I found an exact match of the prop on Ebay with a pic to confirm. Only $49.
Thanks so much for the help, especially Jay.

 

[jay_merrill]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

YW. Glad you found what you needed.

 

[wbeaton]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Shock absorber is part number 12.

 

[F_R]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

x-ray view:

 

[jay_merrill]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Thanks for the diagrams guys. I just compared the parts explosion for the 5.5hp with the 6hp and it appears that the driveshaft lengths would, indeed, have to be different. That said, I am puzzled because I don't remember doing anything special in regard to the spring loaded pilot shaft when I made my swap. One possible explanation is that the 5.5hp motor was converted from a short shaft to a long shaft in about 1975, so that it could be used as a sailboat kicker. My dad owned the motor at the time and I didn't do the work. What I am wondering is if the shop didn't have the right long shaft and took the pilot shaft out to make it work with a long shaft out of a 6hp.

Regardless, I know that this swap does work because both the OP and I have a motor to which it has been successfully done. I am reluctant to take my LU apart just to see what is inside of it so, if anyone else can shed light on this, it would be appreciated. I love these sorts of mysteries because part of the solution to keeping these old motors going is to be able to mix and match parts. The fact that OMC built the motors so similarly over the years is also one of the reasons why I like the product.

BTW, one of the other swaps that I have wondered about is to put a 6hp powerhead on a late 50s 5.5hp motor. I have no idea at this point if the engine base will fit the older motor but it might be a nice conversion if it works. I have a third, non-running 6hp and I still have all the other parts from the 5.5 so I may try this someday. If it works, I'll do a thread about it.

 

[Chinewalker]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

There are some subtle differences in the 6hp powerhead that make it difficult to swap onto the older 5.5 chassis. Different cylinder head arrangement, different bosses for the recoil, etc. It is possible to swap in the needle bearing crankshaft and rods,and the 2-ring pistons to achieve some of the benefits of the 6hp... From a performance aspect, though, you're not likely to notice any difference between the two...
- Scott

 

[F_R]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Jay, I can tell you this much:

The drive shaft is the same diameter (.437") in both 5.5 and 6hp. We know this because they use the same bearing plate, impeller and carbon seal assemblies. However, the lower end of the shafts are different, flat sides where it enters the shock absorber on a 5.5, and full length with a key to directly enter the pinion gear on a 6hp.

The lower shaft on the shock absorber is .550" diameter. This means that the cast-in pinion bushing in a 5.5hp gearcase is for a .550" shaft.

Since a 6hp shaft is .437", the cast in pinion bushing for a 6hp gearcase is for a .437" shaft.

So, obviously, a .437 (6hp) shaft cannot be used in a 5.5hp (.550") gearcase because it is too small to fit the pinion bearing. And vice-versa.

The propeller shafts are interchangeable, if the prop shaft bearing head is also swapped. Or the 5.5 bearing head can be trimmed so as to not interfere with a 6hp prop. I did just such a swap not 6 months ago.

 

[jay_merrill]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Maybe another possibilty ... The LU that came off of my 5.5hp has the oval shaped cavitation plate that you would expect on this motor, rather than the slightly squared off ones on the later 6hp engines. Could it still be a 6hp LU in which the prop shaft was swapped for the older one with the shear pin at the aft end?

PS: FR, just reread your post and now understand that the two propshafts can be swapped. I'm still kind of curious about the oval cavitation plate v. the squared off one. Any thoughts as to whether there was ever a 6hp LU with the oval cavitation plate. At this point I'm in curiosity mode, trying to figure out just what it is that I have!

 

[jay_merrill]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

I think I found part of the answer to this riddle - my motor is a CD-22M, not a CD-24, which makes mine a 1965, not a 1967. I found the old 6hp LU, plus another one that I had, along with a long drive shaft (the one that was in the 5.5hp) and a short drive shaft that probably went with the extra LU. I'll post pics of all of this stuff later.

What I am thinking at this point is that the first couple of years of the 6hp used the old LU setup, but had the two piece shift rod. What this discovery doesn't answer, however, is why the OP's motor has, at a minimum, the older style prop shaft.

More to follow - need to go pick up the tyke now.

 

[F_R]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Found some more information for you:

305215 prop shaft fits 5.5hp 1958-1964, Plus 6hp 1965
305261 prop shaft fits 6hp 1966-1976

376787 drive shaft fits 5.5hp 1956-1964, Plus 6hp 1965
381026 drive shaft fits 6hp 1966-1975
387466 drive shaft fits 6hp 1976
(All drive shaft numbers are for short shaft)

So you appear to be correct, the 1965 6hp seems to have the 5.5 gearcase.

 

[jay_merrill]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Here are a few pics of what I have.

First is the motor, a 1965 CD-22M. The LU on it came off of a Johnson 5.5hp, about 1957 (I need to look). I painted this motor to match a 1969 Johnson 6hp that I own.

Second is the original LU from the 1965 6hp (original white paint), along with another LU that I think I remember buying off of EBay. The "housing and retainer assembly" that sits under the water pump base has been taken out of this LU, revealing the large area where the pinion shaft & shock absorber assembly is located.

Third is the bottom end of one of the drive shafts that would have been used with either of these LUs. Above the blue tape (holding impeller key in place) is the machined portion of the shaft. where it engaged the pinion shaft & shock absorber.

Forth is of a long & short gear shift rod for the 5.5hp, and a long & short drive shaft for the 5.5hp or early 6hp motor. On the early 6hp motors, the shift rod was changed to include an upper and lower portion.

 

[Nailknot85]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Bumping a 5 year old thread for my first post woot.

It was mentioned that the driveshaft carbon seals into the LU are the same for the 5.5's and 6's, is that accurate or are there 2 different sizes available?

I am having some woes with my 1967 cd-24d. I had the lower unit apart last winter as part of a mini "overhaul" and was sent the wrong size carbon seal for the driveshaft into the LU.

The internal diameter I measured for the new seal I was sent corresponds fairly closely to the diameter of the driveshaft for an early model 5.5hp at 0.518" having measured the old seal's ID at .424"



I now have an oil leak coming from the lower unit that I believe to be attributed to the seal.

Honestly I pretty much shelved the motor since the winter and haven't put a full hour on it yet due to carb. tuning issues.

Is

 

[kfa4303]

Re: Johnson 6 HP 1967(CD-24) Prop confusion..

Hi Nails. Here's the seal kit you need for a '67 6 hp lower unit. You don't need any special tools to do the job other than a seal puller and some 3M 847 gasket sealant, which you usually have to order offline, or get at a store like Grainger's. Here's a link on how to do a basic reseal job. Btw, I posted some links regarding your carb issues in your other thread too.

http://www.iboats.com/mall/partfind...&gd_poid=110555&gd_row=3&session_id=308142776

http://forums.iboats.com/showthread.php?t=277190&highlight=lower+unit+seal+kit+installation