briggs and stratton drive surgery

[Murray Campbell]

Hi..I'm going to open up my drive to find out what's going on, but I'm having trouble finding anything about what the innards are like.

The engine is a 5hp Briggs and Stratton, the drive is also stamped 'B and S'. It has its own oil. The shift lever rides on a collar on the drive shaft, the shaft moves in and out of the tranny to give forward, neutral and reverse. It has been popping out of forward for a while, and now won't go into gear properly at all.

I'd really like to fix this thing. Any suggestions for info sources, or any clues about what's on the inside?

Thanks so very much...

murray

[donald branscom]

What is the engine on? Lawnmower ?
Just take it apart slowly and make sure that if ther are thrust washers you write down the location.
You can also get PDF service manuals online.
It might have a wet clutch.
When you drain the oil put it in a clean pan and see if there are metal particles in the oil.

[Murray Campbell]

Hi Donald..

It's on a boat and it looks like it was manufactured as a marine gear. I haven't heard back from the Briggs people yet, maybe they still have some manuals around? The internet search isn't going so well.

I think it is a wet clutch. Some local dock walker said something about there being leather drums that turn on each other.

m.

[donald branscom]

Hi Donald..

It's on a boat and it looks like it was manufactured as a marine gear. I haven't heard back from the Briggs people yet, maybe they still have some manuals around? The internet search isn't going so well.

I think it is a wet clutch. Some local dock walker said something about there being leather drums that turn on each other.

m.
Leather drums?

Some kind of drums but i do not think they would be leather. Maybe.
Usually wet clutches have friction plates with plain metal plates in between OR two cone shaped pieces of metal.
A drum with a band around it is more likely, just like old hydramatic car transmissions.
Does not matter.I think you are on the right track.
Just carefully and slowly dismantle it and make notes.

This project is very interesting to me personally.
what kind of boat? How large? Gear reduction?

Could you post a photo perhaps? That would be great.
Very interesting.

[Murray Campbell]

First try at posting a photo, we'll see how this goes...

<imgsrc="http://www.flickr.com/photos/12733109@N05/1333254537/"border="0">

rats, looks like that will take a bit more figuring out...anyway you should be able to get the photo at that address or I can email you some.

the boat is a 17' displacement hull, pretty heavy with a little cabin forward...no idea what the reduction is

[donald branscom]

Try this web page it has many FREE downloadable manuals for Briggs and Stratton.
http://shop.briggsandstratton.com/BShopProductListingPage.asp?MECID=100&LRID=1&CATALOGID=56B2B9AF-283C-11D4-8886-00B0D0203414

"OK now you know what to do - and you know how to do it - so get down to it." Quote from SF blues musician , the great Jonny Nitro.

ha...ha...ha..

[Murray Campbell]

exactly, i've been looking through there...haven't found anything that matches the drive yet, i will get down to the boat tomorrow and have another look for any other numbers stamped on the drive...

thanks donald,

m.

[AlanL]

Leather drums?

Some kind of drums but i do not think they would be leather.


If it is an older model then that sounds right. The pressure pads would be leather.

Older marine installations on smaller launch engines were often like this. Seen quite a few in the past. Not so much now.

[Murray Campbell]

thanks guys, i'll have a go at it this weekend...i'll try to take a photo if i'm not too greasy and busy cussing!

[Bob Adams]

If that's the shift lever sticking up, it looks like there might be a shift dog right on the output shaft. How about a closer picture?

[donald branscom]

First try at posting a photo, we'll see how this goes...

<imgsrc="http://www.flickr.com/photos/12733109@N05/1333254537/"border="0">

rats, looks like that will take a bit more figuring out...anyway you should be able to get the photo at that address or I can email you some.

the boat is a 17' displacement hull, pretty heavy with a little cabin forward...no idea what the reduction is

About the image posting.
What i do is I get the JPG. on my desktop.
Then I go to www.tinypic.com it is a photo posting service.
There are others too.
Then when the page opens I click on browse and select my jpg.
Then I click on UPLOAD.
Wait a minute then you will see 4 lines of HTML code.
Just pick the appropriate one and then hit command "C" (copy)
Then go to Wooden boat forum and go to the thread you want to post to and put your text curser at the end of your messege and hit command "V" (paste) and you will see the HTML code from tinypic.com and when you hit submit the photo will appear on the post. Copy and paste means that whatever you copy goes to a CLIPBOARD function of your computer (you cannot see it) and saves the information untill you paste it. The computer erases the info when you log out. But it only copies one thing at a time. Just takes a little faith.

Reduction (gears) means the engine instead of being driven right off of the crankshaft will have gears inside that will reduce the speed and be on an output shaft that is not the crankshaft. 2:1 for instance.

[donald branscom]

Let me try that code that did not work and modfy it.
Nope cannot do it.

Here it is:
http://i18.tinypic.com/5227z82.jpg
Veeeeerrrry COOL !
Now that is what i call a piece of machinery !
Whoooooo !!!
That lever is like the lever on a standard transmission of a car.
Just like a sprint car. A in and out box.
That aluminum cone shaped case on the back of the engine is the gear reduction. To drain the oil you need to loosen the upper left bolt and then loosen the bottom bolts and the oil will drain out.
Thats what it says in the Briggs and Stratton literature.
If you go to that website i gave you and click on "complete list" and then go to the last entry it shows that thing in the pdf file pages.

Anyway I really like this photo and I think other forum members will like this project too. Email me the photos and I will post them if you do not like doing it.
Then you acn copy and paste the photo to YOUR desktop from Wodden Boat forum.

One more thing ...that yoke on that lever has a pin sticking out of it on each side and I think a piece could be missing that it was supposed to pivot on.(not sure). See underneath it looks like something was there. Maybe they did not care about reverse? That box might be a reverse gear? You could make your own pivot bracket no problem.
Wish i were there to see it.
<a href="http://tinypic.com" target="_blank"><img src="http://i18.tinypic.com/5227z82.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[donald branscom]

That exhaust pipe looks like trouble because the engine will vibrate and it needs a flex type exhaust between the engine and the solid exhaust going overboard.

Just my opinion.

[AlanL]

That exhaust pipe looks like trouble because the engine will vibrate and it needs a flex type exhaust between the engine and the solid exhaust going overboard.

Pretty common style of installation. But including a flexible portion will probably reduce noise, since a fair amount of vibration would be transferred down the exhaust pipe to the boat's hull and be returned as noise.

Often, flexible connections are only used when the exhaust uses water to cool the emissions first. In this case, the engine is air cooled and so that will not be the case. I can't tell, but hopefully there is a muffler to reduce noise, and in that case is there any reason that you can't use a shorter exhaust and have it sticking up, Murray? That way, you reduce the amount of asbestos(?) wrapped plumbing in your cockpit, your reduce the noise transferred through your hull, with a muffler the engine noise is reduced, and fumes are directed over people's heads and mostly carried away by the wind.

[donald branscom]

thanks guys, i'll have a go at it this weekend...i'll try to take a photo if i'm not too greasy and busy cussing!

No need for cussing.
Just get a nice cold drink and some music and something to put your knees on and a sun shade and enjoy the discovery.
Before you loosen the bolts put some liquid wrench or lube on the night before and rap the bolt head with a hammer a couple times - then try to loosen.

[Cuyahoga Chuck]

I think you are missing a piece of the cooling shroud. On later models of that engine there is shouding over the entire head to keep the cooling air down amongst the fins.
I think the aluminum case is just the special adapter that allows the gear reduction (the black oval case) to bolt up to the engine.

[Murray Campbell]

Thanks for all the comments!

The engine model is a 23FB, and from the PDF manual it looks like the aluminum casting is a 6:1 reduction.

Donald, I'm completely baffled trying to find the PDF for the drive itself, if you've managed to find it could you please let me know where it is?

The yoke on the shift lever pivots on a fitting beneath the shaft that isn't visible. The two posts on either side are threaded and have lock nuts..they engage the collar which pushes the shaft in and out. When it was working there was forward, reverse and neutral.

I'll take some photos of progress when I get down to the boat this weekend.

The exhaust along the cockpit isn't a great idea. In my personal 'museum of horrors' I now have a plastic gas jerry can with a side that is nearly melted through...thank god i noticed it before blast-off.

There is a muffler aft. I may try to add a flexible section, as the pipe does rattle noisily at certain rpm. It looks like the original exhaust went forward into the house and then up through the roof of the cabin. Probably everyone who's owned this thing has hearing aids now. I use earmuffs, and if i don't figure out how to quiet it down i may end up bolting on an outboard, even if it is sacrilege. There is a starter/generator...it may kick out enough electricity to run a blower fan for fresh air, then I might be able to get a more soundproofed engine box without overheating the thing. Just an idea...

[AlanL]

Air cooled engines I've been associated with (mostly 3 cylinder Listers, so really noisy) have mostly been inside the cabin. In these cases the air out-flow was contained within a large canvas chute from engine box to cabin roof. On the outside-top of the cabin there was normally a large vent or a box through which the hot air would be ventilated. The exhaust pipe was then within the canvas chute and enclosed within a large diameter pipe, from engine box top, through the cabin roof and out about two-three feet above the cabin. The muffeler'd exhaust then protruded from there. In some cases the engine box and large diameter pipe were lined with sound dampening insulation.


Air inflow was then either taken from the bilge if it was open enough, through a vent in the side of the engine box, or via a chute from the rear of the engine box, connected to the rear wall of the cabin. A ventilator was on the outside. The purpose of this was to try and capture cooler air and accentuate air flow out through the cabin top. The result was that the engine was more than tolerably quiet.

[donald branscom]

Thanks for all the comments!

The engine model is a 23FB, and from the PDF manual it looks like the aluminum casting is a 6:1 reduction.

Donald, I'm completely baffled trying to find the PDF for the drive itself, if you've managed to find it could you please let me know where it is?

The yoke on the shift lever pivots on a fitting beneath the shaft that isn't visible. The two posts on either side are threaded and have lock nuts..they engage the collar which pushes the shaft in and out. When it was working there was forward, reverse and neutral.

I'll take some photos of progress when I get down to the boat this weekend.

The exhaust along the cockpit isn't a great idea. In my personal 'museum of horrors' I now have a plastic gas jerry can with a side that is nearly melted through...thank god i noticed it before blast-off.

There is a muffler aft. I may try to add a flexible section, as the pipe does rattle noisily at certain rpm. It looks like the original exhaust went forward into the house and then up through the roof of the cabin. Probably everyone who's owned this thing has hearing aids now. I use earmuffs, and if i don't figure out how to quiet it down i may end up bolting on an outboard, even if it is sacrilege. There is a starter/generator...it may kick out enough electricity to run a blower fan for fresh air, then I might be able to get a more soundproofed engine box without overheating the thing. Just an idea...

Trust me, it is not 6:1 Maybe to turn a cement mixer.
It is more likely to be 2:1. If it is a gear reduction.

That exhaust has got to go as far as i am concerned.
Just cut it off with a sawzall or unscrew it and get rid of the whole mess. Also you will notice the pipe comes out of the engine and goes
down then back up. Water and condensation is probably sitting in that low spot . Get some of that flexible exhaust stuff metal spiral hose.and attach a car muffler. Otherwise something is going to break. It is just a matter of time.
that should quiet it down.

Make sure there are no rust holes in the bottom of that gas tank.
You could just use a boat fuel tank and that way it would keep the gas tank away from the engine. The boat fuel fitting on the gas tank fits onto a male fitting. i would try to get one of those fittings and put it on the carb. You could just use a short piece of fuel hose to attach it to the carb fitting. Then the fuel tank won't vibrate and that will also help bring down the noise. That fuel tank probably resonates noise.
The wiring looks tidy.



Having that inboard engine with the shaft deep in the water can save you and your boat.

[donald branscom]

This website has alot of info. http://www.smokstak.com/forum/showthread.php?t=37295

Talks about FB and FC engines.
Also a book showing the early engines "The Legend of Briggs and Stratton"
About $10.
Some FB's had specials shrouds (only 5) but 3 are known.
There was a connection with Briggs and harley-Davidson.

Here is a #23 with original color green .Check out the sheet metal.
http://i7.tinypic.com/52mml5c.jpg
<a href="http://tinypic.com" target="_blank"><img src="http://i7.tinypic.com/52mml5c.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[donald branscom]

Engine number 23 FB. The F stands for flange mounting and the B stands for ball bearing (mains) thats good.
Called an "early " engine.

About 1939. Ebay has an ad for sale showing a boat with a briggs and stratton engine.

[Tylerdurden]

Don't get to flipped over the exhaust. If its noisy, break the union and slip in a short piece of hose (high temp) w/ some clamps.

Chances are that wear in the bearing clearances are causing your issues. Pull the drive apart and head over to Kaman bearing or some other bearing house, Match up the bearings an seals and give it a go.
That crap will last forever with proper care.

[geeman]

This is a very interesting project.I will follow this one.I've been "designing/thinking" about an air cooled motor on my boat for several years.

[donald branscom]

OK it is time to hear something about the surgery.
The doctor needs to come out and give us a little report. Right?

[Murray Campbell]

Hi all, life got in the way, I just got down to pop the drive open yesterday.

It is an extremely simple affair but I can't figure out the problem. Everything looks fine on the inside. I'm not having a lot of luck with the html coding for photo posting but here are the url's for three photos we took (maybe someone literate could do something magic??)

The prop shaft has a tufnol disk attached to it. The disk tapers forward and aft. When the shaft is pushed forward this tapered disk slides into a matching taper on the inside of the forward gear which is driven off a smaller drive gear on the crankshaft. When the shaft is pulled aft the aft taper slides into a gear which is spinning backwards as it engages an idler gear which switches the direction. In the central, neutral position the disk is in between the gears and spins freely. There is no mechanism to hold the disk engaged in either forward or reverse. I am starting to think that it relies on the thrust from the prop to hold it in gear once it is engaged????

Everything looks fine on the inside, I was told that the transmission was rebuilt recently and it looks like the tufnol has very little wear.

When the shift lever pushes the shaft forward the shaft begins to turn. If you push quite a bit harder the engine rpm drops and then comes back up, and the shift lever stays forward momentarily and the shaft spins. It feels right. Then the lever pops back into neutral.


This is the unit split open...

http://s223.photobucket.com/albums/dd315/murraycamp/?action=view&current=Mattcell024.jpg

This is the forward view. On top is the driving gear which engages both the forward gear and the idler for the reverse gear. The large gear below is the forward gear, it is tapered and hollow and the tapered disk slides forward into it.

http://s223.photobucket.com/albums/dd315/murraycamp/?action=view&current=Mattcell025.jpg


This is the aft view showing reverse idler gear, empty bushing where the shaft for the driving gear goes, and the reverse gear...the tufnol disk on the moving shaft is visible inside the reverse gear.

http://s223.photobucket.com/albums/dd315/murraycamp/?action=view&current=Mattcell026.jpg

There is a thrust bearing behind the forward gear, it looks fine.

The prop seems to turn freely but i am wondering if i have an alignment or cutlass problem which is making it too hard to turn and not allowing the prop thrust to keep the unit in gear? Or there may not be enough travel in the shaft for it to move far enough forward to engage properly.

ps the shaft with the small drive gears is not the crankshaft but is in line with it, they must be coupled somehow in that aluminum casting next to the engine...it has a little bit of a funky feel to it when you turn it but I thought that was because it wasn't supported by the bushing on the aftermost plate which we removed. The engine runs well so i really think the main crank bearing is fine. I decided it didn't make sense to look for the problem way back there so i didn't remove that housing, but maybe that was a mistake..?

[ion barnes]

Sounds like a cone clutch, and its out of adjustment. Its something like the dog clutch in the bottom end of an outboard. The prop does not provide the contact, but a heavy spring would.

[Murray Campbell]

Found an identical drive in pieces at a local machine shop. It still has the stamp on it:

Twin Cone
Marine Reverse Reduction Gear
model BM 618
2:1 10Hp at 2800 RPM
N Bennet Machine Works Seattle

[donald branscom]

I am posting your photos.
Looking at them I am impressed at the quality of the components.
I can tell you that even the new Honda's are not that good.
I am still wondering about those pivots for that gear lever. They are missing in the original photo. Maybe that is why it would not shift.
http://i5.tinypic.com/4mm8777.jpg
<a href="http://tinypic.com" target="_blank"><img src="http://i5.tinypic.com/4mm8777.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[donald branscom]

From the photos it is hard to tell how that clutch works.
Just a dark object in side of that large gear. But it looks like that black thing is supposed to expand and make contact with the inside of that large gear. is that black thing in the middle of that large gear made of more than one piece? Is it metal?
Just cannot see any details from photo.

OK ....I have it figured out. When you move the big lever back and forth it allows the big gear to move back and forth contacting one of the two smaller gerars ,forward and reverse. So that black thing
in the middle of that big gear must have friction material on the face and or edges to grab tha big gear. So until that big lever gets the blocks that it is supposed to pivot on ,it cannot work.

[Murray Campbell]

nope, that's not quite right, i'll try again... :-)

there are two large gears you see, one is forward and one is reverse, you see one in each of the last two pictures....the black think on the inside you are looking at is a solid disk of tufnol fixed to the drive shaft..it has a conical taper on it's forward and aft face....the shift lever rides loosely on a collar on the drive shaft and pivots on a solid mounting, moving the shift lever moves the whole shaft in and out of the unit....as the shaft moves in and out it presses the conically tapered tufnol disk either forward into the 'ahead' gear (which has a matching taper inside it) or aft into the reverse gear....the tapered disk and matching taper on the gear grip each other and the shaft turns...in neutral the disk is spinning freely in the space between the two large gears and not engaging either

both of the large gears (forward and reverse) are fixed in place, as are the small drive and idler gears, all that stuff is engaged and running all the time, all that happens is the tufnol cone tapered disk either moves forward or aft (to engage either the forward or reverse gears)..the shaft moves forward or aft with the tufnol disk fixed to it, once the disk engages with a gear it starts turning



the smaller gears are the drive gears from the engine and the reverse idler gear

the shift lever moves things just fine...perhaps the travel of the shaft isn't adequate?

murray

hope that's a better explanation, my previous post might help as well

[Excalibur]

The shaft that slides in and out obviously slides in and out into SOMETHING. Pilot bearing maybe? Anyway, it's either worn or out of alignment. Or maybe even reversed (a classic error when rebuilding a tranny). The thing that I can't see is how the cone clutch is kept engaged. The cone will try to force itself back out of engagement if not held in, and I don't think the prop will develop enough thrust to do that, especially at idle. This is done of some tractors (like my Farmall) by moving the shift lever itself into a detent. Any sign of something like that? I think the dip in rpm during engagement is due to wear or misalignment allowing the tufnol disk to contact both gears for a bit.

Edit. Went over the posts again, and I now think my above opinion is a little off. There appears to be a fair amount of wear on the end of the movable shaft. If it is out of alignment, the initial movement may be due to the shaft itself contacting the gear instead of simply going through the hole, thus the shaft begins to turn. More pushing forces the end of the shaft (now beveled due to wear), into the hole where it belongs, and engagement is now at the tufnol disk where it should be.

[donald branscom]

How can the lever work without the fulcrum block for the lever to pivot on?
http://i12.tinypic.com/68asri1.jpg
I do not think that if you find out something is worn .001 thousdandths it won't work. this is a very well made piece of crude machinery. But i wonder if that flexable disk has gotton hard from sitting?
<a href="http://tinypic.com" target="_blank"><img src="http://i12.tinypic.com/68asri1.jpg" border="0" alt="Image and video hosting by TinyPic"></a>

[Ron Williamson]

What if those pins move the shaft and the pivot is out of sight in the shadow of the trans.
IIRC Tufnol isn't flexible,more like Bakelite.
R

[donald branscom]

What if those pins move the shaft and the pivot is out of sight in the shadow of the trans.
IIRC Tufnol isn't flexible,more like Bakelite.
R

See the rectangular white block with the rectangle hole beneath the shift lever? I beleve something was mounted on that block. That is why that block is there.

[andrewe]

Some questions: Did reverse work before you stripped it down? In the absence of any obvious alternative I assume the shaft thrust keeps the cones engaged,this does not require much force. It has been `rebuilt`recently. Has someone tried a fix?Tufnol is not the sort of material I expect to see here. Bronze would be more normal. Is there any sign that the `forward´cone has bottomed out in the gear? Any wear on the front edge of the cone? I suspect the cone is worn.Your symptoms seem to idicate this. What was the other one you saw made of? This is more diagnostic than solution, but hope it helps
Andrew

[Eric D]

Don, that rectangle is not tapped so what would mount on that? I agree that it looks feasible though.

[andrewe]

Murray,I assume that the shaft has enough free movement to allow engagement? A silly thought,but is there anything impeding the shaft further back? Bit of rope between the prop and `P´bracket........?
That would also fit the symptoms.
Andrew

[donald branscom]

Don, that rectangle is not tapped so what would mount on that? I agree that it looks feasible though.

Good point Eric D. Nothing like being there in person right?

I imagine some old timers are just sitting back laughing at us young guys struggling to figure it out and hoping it does not get !@#@$ up right?

[Excalibur]

Don,
You are thinking that this is a first class lever and that the fulcrum is in the middle, yes? I think that this is a second class lever, and the fulcrum is at the bottom end. The shift lever is mounted to that rectangular block. The pins that you point to are where the shift lever is attached to the output shaft and they float as they move in the horizontal plane along with the shaft. I expect that there is a bearing pressed onto the shaft there and that those pins go into the housing that receives the outer race. There may also be a couple of circlips that keep the bearing set from sliding.

[Murray Campbell]

Hi all, thanks for having a look. My work has been keeping me out in the mountains and away from the internet.

Excaliber has the right idea on the shift lever arrangement...the pivot is under the shaft..those two bolts on the side engage a horseshoe shaped sort of half-bushing that rides loosely over a collar which is fixed to the shaft...the horseshoe piece pushes against the collar to move the shaft in or out. No bearings there. You can keep it in gear by physically holding the shift lever forward but it gets hot there in a hurry as there is no bearing. There is no evidence of any detent or spring to hold the shaft forward or aft and one couldn't act through the shift lever anyway as there is no bearing there and it would be smoking hot all the time.

I checked for line around the prop shaft...had the same thought but it is clean.

Having been away from it a few days i am now convinced that a) prop thrust does hold it in gear and b) i think i have an engine alignment problem which is making the prop work harder to push that shaft into place.

Thurman, your comment about the wear on the end of the moving shaft and the possiblity of the shaft engaging the gear and causing a bit of spin before the cone engages....that rings true to me and i wonder if poor alignment might be throwing the moving shaft out of wack with the hole in the drive gear!!?? There was a bit of metal colour to the oil.

There is little to no wear on the cone and the other transmission i've seen also uses tufnol as a material.

I'm not home for a couple of weeks, when I get there I'm going to try to tidy up the alignment and see if that helps...The stuffing box is a self aligning type and i thought it was close enough but maybe not.

But then, who knows??????????????????????????

thanks so much guys...

[Excalibur]

If it is an alignment problem, could it also be off at the shift lever? That block looks pretty old and a little beat up, and if the shift lever was out of position it may be pulling the shaft out of alignment. Is there any kind of flex joint on the prop shaft, or is the shaft solid from the stuffing box to the trans? If it is, then its the stuffing box that needs adjusting, since as you said, there is no bearing on the shifter and a lot of friction there would be noticed. Good Luck!

[Oscarvan]

Somehting has to keep the pressure on the disc.....