Redband 50hp Gearbox problem

[Bosunsmate]

Hi
Ive bought a Mercury 1970 Redband 50hp (500) that was seized. I got the powerhead off after dealing to a few seized in bolts and after getting hold of the mercury flywheel puller ive pulled her crankcase apart. The top big end con rod bearings had come apart and seized the top cylinder. Ive order a piston and needle bearings and will hopefully get away with a light hone on the cylinder.

I went to change the impellor in the meantime but when i dropped the leg the gearshaft didnt come apart at the lower leg and it ended up pulling the shaft right up and out of the lower leg. Its now stuck in forward gear and putting the shaft back in is not doing anything.

Is there anyway to fix this instead of pulling the propshaft off? After dealing with the rest of the motor id say itd be pretty good at not letting me pull it apart
Serial # 2947660
Thanks

 

[Bosunsmate]

Re: Redband 50hp Gearbox problem

Well i decided to go for it and remove the prop shaft to get to the fallen off cam shaft.
I removed the prop nut by using a 24mm and chocking the prop with some wood against the anti cavitation plate.
I then heated up the splined washer and knocked that out with a screwdriver. I then heated the prop shaft where it joins on to the prop for quite a while and then knocked it with a rubber mallet and it came loose.
I then heated up the gearcase cover for quite a while- the big nut looking round thing and also bent back the locking trim tabs. I took a risk and got a cold chisel and rubber mallet and knocked it loose. it turns anti clockwise. I then removed the locking tab ring and shims. Im now left with the Carrier assembly to remove. Im not sure if you have to remove the driveshaft to do that, i cant see how you can do it without removing the driveshaft but the manual doesnt mention it so im wondering if im not doing something thats so obvious they havent included it in the manual or something?

The heat i used was candles

 

[oldman570]

Re: Redband 50hp Gearbox problem

The prop shaft, carrier bearrier bearing housing and rear gear, should be able to slide out of the housing without removing the driveshaft. The carrier bearing housing is probly corrided to the outer housing if any water has set in the LU very long. If this is the case then you might be better off getting a good used LU to replace the one you have as the cost of the parts to fix that one will be high and harder to find. Being the top end has troubles also , you could be money ahead just geting another motor in the long run. The best way to find parts would be to find salavage dealers there and contact them as to parts that they have for the motor. There is a sticky on here for salavage yards but most are in the USA and the shipping would cost more than the motor is worth. JMO
Oldman570

 

[carholme]

Re: Redband 50hp Gearbox problem

The only thing that happened here as far as the LU is concerned is that the E clip has fallen or broken off the short shift shaft and allowed the shaft to come out of the gearcase.

As you have it disassembled to the point you have, there are two choices:

1. Remove the bushing housing that the shift shaft fits into and then re-assemble the shift shaft and cam or

2. Remove the bearing carrier by clamping the end of the prop shaft in a soft jawed vice and tapping the gearcase off the carrier. This procedure is in the manual.

Here is the parts list for your engine which is a model 1500100:

Mercury Parts, MERC 500-7/8

See the bushing housing as item 41 under GEAR HOUSING ASSEMBLY, COMPLETE (PAGE 1)

Here is the condensed version of the service manual for your engine. Download it soonest to your computer as the link is short lived.

Small Engine Repair Reference Center Home

See page 284 for the bearing carrier removal:

Disassemble gearcase by removing
gearcase housing cover nut (61-Fig.
M12-61 or M12-62). Clamp outer end of
propeller shaft in a soft jawed vise and
remove the gearcase by tapping with a
rubber mallet. Be careful not to lose key
(59) or shims (47) on early models. Forward
gear (4()) will remain in housing.

If you look at items 56/57/58 and 59 under GEAR HOUSING ASSEMBLY, COMPLETE (PAGE 2), you will see that the spring pressure against the cam is what has pushed the cam forward when the shaft came out and this is why you cannot re-align them.

Gerry

 

[Bosunsmate]

Re: Redband 50hp Gearbox problem

Thanks for that.
Pretty good to have two options before getting cornered. I have left penetrating oil on it overnight so I will look around for a vice tonight. I figure i will try and get the carrier out as i tried removing the bushing housing but thats seized well too.
I cant find the key that i was meant to be careful not to lose, i can see the hole its come out of so i will be using/ attempting to use my grinder to make one at some stage.
Those links were better than the Kiekhaefer manual and much lighter too.
I will post what happens and some photos for those wondering what the cam etc looks like right in there

 

[carholme]

Re: Redband 50hp Gearbox problem

You shouldn't have a problem removing the carrier as the only thing holding it at the moment is the Oring between it and the housing. Going this route, you will also have to remove the pinion nut at the bottom of the driveshaft to enable you to remove the forward gear to see the shift cam.

Good luck with it.

Gerry

 

[Bosunsmate]

Re: Redband 50hp Gearbox problem

Update, i have got a problem unfortunately.
I couldnt budge the carrier so i worked on the gear-lever bushing and eventually got that to move. I could fish around and locate the cam in the hole and tried turning it but nothing happened. Soon afterwards i saw the sliding pin floating around so no way i can put that back together using that small hole, itd probably be even hard key hole surgery.
So i went back to the carrier and i cant budge it. Im thinking it will need some very hot heat and a sliding hammer with penetrating oil sitting on it the rest of the time. Im going to switch back to the powerhead rebuild and move back to this once ive got the tools to try further so please add any other suggestions to the attempt on it list if you want.
Im assuming its the front and back of the carrier where its contacting and seizing to the housing wall.
Since the prop comes out with the carrier i cant see how a three legged puller would help but perhaps it might?
Thanks

 

[oldman570]

Re: Redband 50hp Gearbox problem

You might try useing blocks of wood with a hole bored in them big enought for the prop shaft to go thru, and using the nut and washer as a puller to get the shaft, carrier housing, and every thing broke loose or removed from the LU. WD 40 or Power blaster should get the corrision to loosen things up. Use of a heat gun or other nonflamble heat source (heat lamp, hair dryer) for heating the LU case would be my first choice of heating, as the LU will expand and damage to the LU case is less than a torch. JMO
Oldman570

 

[Bosunsmate]

Re: Redband 50hp Gearbox problem

Thanks Oldman, sounds good, il give that a go tomorrow. Il be able to leave it sitting with the tension on it then too while im away so it will be getting no rest.
Ive a good long spanner for putting tension on that nut,
Il report back,

 

[emckelvy]

Re: Redband 50hp Gearbox problem

Dunno how far you are now with disassembly of your lower unit, but there is a way to get the shift shaft reinstalled without taking the gearcase apart. Here's an old thread which explains how to do that:

http://forums.iboats.com/mercury-ma...lling-shift-shaft-into-lower-unit-264376.html

HTH & G'luck with the repairs..........ed

 

[Bosunsmate]

Re: Redband 50hp Gearbox problem

Update.
I tried Oldmans method. Finding a bit of wood that was thin enough took a while as if it was too big i would never of got enough purchase on the nut and would of risked stripping the threads. I ended up finding just a normal bit of timber around the house and also used the nut and washer that came on the prop shaft. I used a little heat from candles as i had no other option but i placed them further away and i also tapped on the o-ring areas with a soft mallet when it was under compression and heat.

I tightened it, heated and then tightened and then using another spanner as shown in the photo for more torque i heard a little crack. I saw the wood had cracked a bit but i didnt think it would go anywhere so i tightened again, i kept on tightening and it was getting easier so i figured i had put the prop through the wood- but no, i looked in the prop shaft and there was the bearing carrier coming out of its cave.

I could believe my eyes, I had heard that these were often not possible to do without breaking the casing, let alone in a 1970 Redband salted, so i unwound it to see if it was actually out and there it was. I lifted it right out and then the key somehow appeared from somewhere too! Very productive session.
I have a few things to do but will get on to removing the rest tonight. Carholme says there is a nut to remove off the driveshaft to pull that out, ive seen it so my sights will be on that.
I can see the sliding pin and the camshaft at the end of the LU, the only thing i havent seen is the spring but it must be there somewhere, tucked up like a worm in there somewhere i suppose.

I have never got this far into an outboard gearbox before so i will probably ask a few questions in due course about reassemble and il post some photos. The local marine dealer here is my nemis after a few encounters of being charged much more than he quoted so thanks a lot everyone. I might ring him for a quote then ring him to say ive done it myself!

 

[Bosunsmate]

Re: Redband 50hp Gearbox problem

I didnt use much torque at all, probably about that used on a car tyre lug nuts

 

[carholme]

Re: Redband 50hp Gearbox problem

Good for you for sticking with it and getting it done! Hope the rest goes OK.

Gerry

 

[Maxz695]

Re: Redband 50hp Gearbox problem

I believe the spring is actually in the propshaft. Be sure to not grab the driveshaft in a delicate place where the water pump and seal go when removing the pinion gear nut

 

[Bosunsmate]

Re: Redband 50hp Gearbox problem

Max i think you are right as there just seems to be this sliding pin and pressing on it moves the clutchdog and it springs back, its under quite some compression.
Does this mean i dont need to take the pinion gear nut off (as getting enough purchase on the driveshaft is hard)?
Since ive got the sliding pin back in do i just need to line up the shiftshaft into the cam and then put the carrier bearing back in (with new o-ring)?
Im not sure what this e clip thing is thats being mentioned as i havent come across a clip in dismantling

 

[Maxz695]

Re: Redband 50hp Gearbox problem

Bump!!!

 

[Maxz695]

Re: Redband 50hp Gearbox problem

View attachment 176042reset the cam and shift shaft screw her down and reassemble as long as you can align the cam No do not remove the pinion gear. I have a bunch of leftover O rings I,m not using if you send me the diamiter I can mail you one if i have it. FREE. The E clip is on the shift shaft (Pictured) itself it,s like a C clip that keeps the shaft from coming up out of the cam. It may have fallen off. I have one on my spare shift shaft if you need it or I can send the part number if I can find it EDIT PN 53-29641 http://www.ebay.com/itm/290603173432?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 If your ring isn,t there I would shake the hell out of the LU to make sure the clip didn,t break and end up where the cam is. If unsure at that point remove the pinion gear and foward gear to check for the clip or clip pieces ad I see slight nicking of the main gear on the propshaft indicating metal somewhere. Better at this point to be safe than sorry.

 

[Bosunsmate]

Re: Redband 50hp Gearbox problem

Great! thanks, i had bad thoughts about cracking something here unnecessarily at the last hurdle. I will get an o ring and hopefully start the rebuild tonight or early next week (if engineering supply shop is shut). Thanks for the Xmas offer Max but i just talked to the shop and they have one for one hundred and fifty cents! so il grab that as im keen to get started tonight.
Il post how the rebuild goes, the shift locking cam at the top of the gearbox is confusing me, im picking i must put it in a certain way into the cam otherwise it wont lock into gear but i guess my manual will mention that. Its a shame it doesnt have a keyed edge for matching up (if it does need to be matched up.

 

[carholme]

Re: Redband 50hp Gearbox problem

Bosun;

If you look at page 287 of the manual I sent you, you will see Fig. M12-64 which is the correct setup for the reverse lock cam, the item next to your thumb in the above picture.

Gerry

 

[Maxz695]

Re: Redband 50hp Gearbox problem

your C clip is gone see my edit in the previous post and pic. Get a new clip the position of the cam don,t mean a thing it can do 360 and still be put back into the correct position. Make sure you get the clip or the shaft will end up poping out again on the next impellor change. Find the old one as it will screw up the gears as well. Optional The oring on the bottom of the waterpump base could be changed now later or never but the propshaft seal on the carrier is recommended before reinstalling it. After re reveiwing your photo in a blow up I think i see the clip at the bottom of the shaft where the cam splines are. It looks to be in bad shape. Consider getting a replacment