Old Bravo lower W/ new Bravo upper?
 

Can I bolt an older (pre 1990) Bravo lower to a newer (post 1995) Bravo upper? The only real difference I can see is an oil hole in the newer drive. Thing is, some of the IMCO lowers have this oil hole blocked.
So, can I run an older lower with a newer upper?
Can I also do this visa-versa? (newer lower W/older upper)?
Thanks,
Gordo

Re: Old Bravo lower W/ new Bravo upper?
 

Also,
I have seen a newer "replacement" lower that had the "boss" for this oil hole, but the hole was not there.
Can I drill out this oil hole to use with newer upper? Do I even need to?

Re: Old Bravo lower W/ new Bravo upper?
 

I don't think so,the old bravo upper has a oil vent hole in top cap and fill hole in the side where its normally vented. As far as I know if you put a new upper on a old lower no oil could get to the top from the bottom and it would melt down because there would be no oil passage between the two. I have a old style upper in real good shape with good looking gears and bearings I'd like to sell if anyones interested,Smitty

Re: Old Bravo lower W/ new Bravo upper?
 

You can put an newer lower on an older upper. Simply put a plug in the extra oil in the newer lower. I've run one that way for 2 years.

Re: Old Bravo lower W/ new Bravo upper?
 

I've done this too with no problems.

Re: Old Bravo lower W/ new Bravo upper?
 

What does that hole connecting the upper to the lower do,allow oil to drain back,let oil from churning in lower pump to the top or is it a vent? I have a nice early upper I just could have sold a few days ago to a friend :( but didn't think it would work,at least I know now though,Smitty

Re: Old Bravo lower W/ new Bravo upper?
 

Thanks Payton.
Now, is it possible to run a newer upper with older, (non oiler) lower if I simply plug the upper hole?

Re: Old Bravo lower W/ new Bravo upper?
 

no you can not run newer with older its an oil hole and provides improved oil circulation on the drive which inturn lets them run cooler I wouldnt recomend "plugging it" to anyone bravos need all the help that they can get

Re: Old Bravo lower W/ new Bravo upper?
 

So heres the big question,once you've plugged the new style lower and bolted a old style upper on it would the drive work exactly like a old style upper and lower (no better/no worse than what pre-91 bravos came from the factory like),just without the extra cooling a newer one would have OR would it create a new problem,Smitty

Re: Old Bravo lower W/ new Bravo upper?
 

That is what I was told by the company that I bought my new style lowers from. They are known for doing performance upgrades on Bravos. The lowers I bought had been replaced with some shorties.

GOODT tell me if I was told wrong. And how can it be fixed?

Re: Old Bravo lower W/ new Bravo upper?
 

Ive never mixed the too was told back in the early 90s that the new style did mix with the old and that they tend to over heat...

so ive never tried I know if you have a warr issue with that set up merc will say its on you and that its got to be hard on the drive lube......

maybe some other techs have seen it or done it and they can tell you more

Re: Old Bravo lower W/ new Bravo upper?
 

thanks Joe

Re: Old Bravo lower W/ new Bravo upper?
 

Thanks guys for all the info.

Ok, going against recomendations, and just for fun, (also with not much to lose here), I am going to try to drill a non-oiler lower to see if I can "create" a newer style oiling lower.
I'll let y'all know the results.

Re: Old Bravo lower W/ new Bravo upper?
 

I have installed a new upper on an old lower without the hole in the pad. It did have the pad, so when I plugged the upper it would support the sealant I put in there. There is another hole in the older uppers that needs to be drilled in the new upper.. I would think it would work like the pre 90's bravo's.. I never got any feed back on the drive I modified, so I dont know for sure if it worked or not.

Gordo, you are on the right track.. drill the hole and complete the oil circulation.. you will be better off, I believe. Let us know how it works..
And where you got the extra long drill bit..

Dick

Re: Old Bravo lower W/ new Bravo upper?
 

Dick, Since you mentioned "extra long drill bit", I assume you've tried this before.
So, I'm drilling this perfectly straight hole, (rare for me) into the boss where the hole would be in the newer lowers, and I run out of drill bit length. Pisssed me off, so, I ran a small circle of RTV around the hole I had just drilled so it would seal the oil hole in the upper and bolted em together. Filled w/ gear lube from bottom up like normal and bolted it onto the boat. As of this evening it has about 4 hard hours on it and still running strong.
We'll see how long it lasts...

Re: Old Bravo lower W/ new Bravo upper?
 

Gordo,
never tried drilling one. but I think it would take a very long bit. On the older uppers there is an extra hole in the front of the vertical shaft hole.. that leads to the upper cavity.. hard to discribe where to drill it.. Not sure if it makes any difference.. but I matched the old upper to the new one.. and drilled the extra hole.. but didnt try to drill the lower.. that would be the best solution...

Dick

Re: Old Bravo lower W/ new Bravo upper?
 

The lower I am working with is actually a newer model (dual water pickup), but it was to replace an older (pre-1989) lower that was damaged so it came as a "non oiler" lower.
This being the case, I didn't have to "line up" the upper and lower. The boss is already there for the oil hole, just no hole. I'm working on the longer drill bit, but I would like to know if I will eventually drill into an oil cavity or gally, or will I just drill out the bottom of the drive?

Re: Old Bravo lower W/ new Bravo upper?
 

If you drill it straight.. it will come out into the lower just in front of the front propshaft bearing race... I have a few I can try and take some pics..

Imco's case has a large relief where the hole comes out. I assume to catch more oil from the gears..

The hole I am taking about in the previous post is in the tunnel (I'll call it that) where the vertical shaft goes up into the upper case. If you look in that hole from the bottom. You can see a hole on the back side of that tunnel. The old case has another hole in the front part of the tunnel that leads to the cavity that the oil hole we are trying to match is connected..

See I told you it is hard to describe.. Too bad I didnt take a pic of it.. LOL!!

Let me see if I have time to get something to show it.. but in the mean time get the long bit.. Real LONGGGGGGGGGGGgggggggggg!

Dick

Re: Old Bravo lower W/ new Bravo upper?
 

LMAO !!!
Ok, in search of a looooong bit.
Let's hope I started my hole straight n true.
Tomorrow I'll look at an upper and lower sitting in the shop. I'm sure if I have it sitting in front of me it will all become clear.
Thanks for the help and advice Dick. I'll keep you up to date on how things go.

Re: Old Bravo lower W/ new Bravo upper?
 

Our electricians at work have 1/4" and 5/16" drill bits that are 10" or 12"long,they are either getting them from a electrical supply house or our local V.I.P bolt/drill bit dealer. I think vip is a national deal,I'll check into it more if you don't find the bit you need,Smitty

Re: Old Bravo lower W/ new Bravo upper?
 

Here you go,VIP has 1/4 drill bits 12" and 18" looooong,Smittyhttp://www.valleyindprod.com/shopping/index.php?cPath=161_180

Re: Old Bravo lower W/ new Bravo upper?
 

http://www.valleyindprod.com/shoppin...?cPath=161_180
browse as a visitor,go to special drills, they have a 1-800# to order but find your part# first because you'll probably be talking to a operator or order taker,Smitty

Re: Old Bravo lower W/ new Bravo upper?
 

Thanks Smitty...

Re: Old Bravo lower W/ new Bravo upper?
 

Thanks for the link Smitty

new bravo 1 lower replacing 1990 bravo lower
 

So if i understand everybody correctly all i have to do to use a 2000 bravo one lower on a 1990 bravo one upper is plug the oil hole on the new lower? What do i use to plug the hole is my next question?

If there is no hole in the upper housing then just tap the hole i the lower and install a small stainless set screw with a hex socket (?) that you would screw in with and allen wrench.. Use some red locktite on it and make sure it is flush with the top of the lower case. The smaller the set screw the better, in case you want to ever use it on a newer upper..

Hope this helps.
Dick

thanks
 

thanks, I will give it a try.

I am doing the same this week to two drives; old uppers w/ newer lowers. It appears the thread size that would fit without drilling is 5/16-18. That's what I am going to put in anyway. Now I have to find of SS set screws, that should be fun :rolleyes: