Stainless Engine Bolts?

[aussierob]

Hi Everyone,

I'm Rob from Australia. I have a 1980 FBC, and love it.
I'm currently doing some major work on the Velvet Drives and engines (350 Chev).

I'm going to repaint the velvet drives, as there's loads of surface corrosion from ~40yrs of use. I'm in the process of taking them back to bare metal, and will do a gasket overhaul at the same time (the internals, and overall operation has been flawless, so i see no reason to to a total rebuild. They weren't leaking fluid either but figured it's prudent while they're out.

I know the common approach is to assemble then repaint as a whole, as with engines.
I'm just wondering if anyone has any experience using Stainless fasteners instead of the carbon steel ones?
Then i could paint / reassemble without worrying about paint so much - mostly for the fittings.
From a corrosion standpoint they seem to hold up fine in areas where they have been used previously (coupling bolts, etc).

Thanks in advance.
Rob

[Tony Meola]

Problem you have with using stainless engine bolts to install things like heads, manifolds etc, is two fold. You have to try and isolate two dissimilar metals which will be tough with the heat from the engine that will probably destroy any isolating material, then there is the issue of the tensile strength of the bolt. Stainless would not be as strong as normal engine bolts and you would have to be careful you do not snap them.

Not sure if the boat is used year round or if you lay it up. If you have lay it up, like we do up here in the North East we normally spray the engines down with a protective coating for the 5 months out of the year we lay them up.

The best way to keep corrosion down is to use the boat as much as possible so the engines get hot and stay dry.

[scot]

I use a lot of SS bolts. Water pump, trans -to- bell housing mount, pulleys, alternators, starter mount, oil pan, etc. Never had a problem.

But as Tony mentioned, don't try them on heads, manifolds, etc. SS fastners are not as strong as carbon steel and cannot be torqued to the required amount on these components. They "may" stay in one piece, but will be stretched beyond their capacity.

[aussierob]

Problem you have with using stainless engine bolts to install things like heads, manifolds etc, is two fold. You have to try and isolate two dissimilar metals which will be tough with the heat from the engine that will probably destroy any isolating material, then there is the issue of the tensile strength of the bolt. Stainless would not be as strong as normal engine bolts and you would have to be careful you do not snap them.

Not sure if the boat is used year round or if you lay it up. If you have lay it up, like we do up here in the North East we normally spray the engines down with a protective coating for the 5 months out of the year we lay them up.

The best way to keep corrosion down is to use the boat as much as possible so the engines get hot and stay dry.

Thanks Tony and Scot.

Our winter here is very mild - we still use the boat throughout Winter (at least, if i didn't have the powertrain sitting on my deck at home we would)! No freezing or anything like that to deal with. We can still find ourselves in shorts on the water in the depth of Winter when the sun is out.

OK - so perhaps bellhousing and other accessories which are likely to be changed out more frequently (water pump etc) might be the way to go. Thanks!

Perhaps i should stick with a engine enamel type paint for the velvet drives.

I was really keen to use a metallic paint - a little like colour-coding to the hull (i have a metallic blue hull wrap). I know it's somewhat pointless, but the itch to do it is there, even though touch-ups might be tougher to manage.

Maybe the bellhousing can go metallic with stainless bolts, and the trans can go black (the long blocks are brand new, so i'm not going to repaint those for no reason). That said, the velvet drives are basically bulletproof and are unlikely to need to come apart again too.

Lots to think about. Cheers!
Rob

[Rawleigh]

Just add Tef-gel tot he threads on assembly to protect them.

[aussierob]

Just add Tef-gel tot he threads on assembly to protect them.

Thanks for the tip Rawleigh - will do.

[Tony Meola]

Rawleigh

I am not sure what the engine heat will do to the tef gel. I find that some of these products do not mix well with high heat. It may render it useless. I would ask the Tef Gel folks before using it in a high heat application.

[Rawleigh]

Tony: I wasn't thinking of really high temp things like the manifold. I was thinking bellhousing or transmission bolts. High temp anitsieze on the other bolts.

[Tony Meola]

Rawleigh

Just thought you were putting it on everything. I understand now.

[Bill Fuller]

Rob,
One suggestion.
When you set up the forward clutch pack on the velvet drives, set the clearance on the loose side of the spec.
Foe instance, if spec is 0.030" to 0.055", set the clearance at about 0.050. These are not the exact specs but close and gives you an example.
The first one I ever did I set the clutch pack at the tight end of the spec and the clutch pack did not completely release in neutral.
Consequently the props would turn a small amount when in neutral. I real pain! After 2 years and about 500 hours, still dragging! Removed the trans and reset the clutch pack to about 0.003-0.005 below the loose spec. No more drag. After about another 3,500 hours all was still good. At that time I repowered with diesels.
Since that time I have reset the clutch pack on quite a few Velvet Drives that have been rebuilt and set up at the tight end of the spec.
Good luck with your projects
Bill

[aussierob]

Rob,
One suggestion.
When you set up the forward clutch pack on the velvet drives, set the clearance on the loose side of the spec.
Foe instance, if spec is 0.030" to 0.055", set the clearance at about 0.050. These are not the exact specs but close and gives you an example.
The first one I ever did I set the clutch pack at the tight end of the spec and the clutch pack did not completely release in neutral.
Consequently the props would turn a small amount when in neutral. I real pain! After 2 years and about 500 hours, still dragging! Removed the trans and reset the clutch pack to about 0.003-0.005 below the loose spec. No more drag. After about another 3,500 hours all was still good. At that time I repowered with diesels.
Since that time I have reset the clutch pack on quite a few Velvet Drives that have been rebuilt and set up at the tight end of the spec.
Good luck with your projects
Bill

Thanks Bill. These are such great transmissions, and i've read a few things like this with the velvet drives getting people caught up.

I've inspected everything and i'm not actually going to disassemble the main drive units. I've removed them, but i've found no reason to totally rebuild them. So i'm basically replacing oil seals / gaskets, doing a bare metal respray, and fixing up a few odd things such as the breathers missing and no oil temp sensor.

I have everything out / apart now, and the main assemblies are quite good. No major imperfections in the gears anywhere, no massive play in any shafts, they're really in quite good condition.

The output bearings are sloppy when everything is disassembled, but i think that's by design, and are not when everything is bolted up.

I had no reason for concern so this was more a preventative measure while replacing the motors. I almost could have simply stripped and repainted! But that seemed a little lazy, and i would be haunted by transmission fluid in the bilge for my laziness hahaha. But it was a good opportunity for inspection too, since i didn't know the history of the boat, now i'm learning all of her secrets!

Thanks again for the note.

Rob

[Bill Fuller]

Rob
Sounds like a good plan. Maybe replace the bearings just because you are in there.
Bill

[aussierob]

Rob
Sounds like a good plan. Maybe replace the bearings just because you are in there.
Bill

Parts are a little tough to come by here in Australia, but i agree, may be worth doing the output bearings at least.
Though i don't have a shop press to do the inner one of the pair. But may be able to work something out.

The inner seems fine, but the outer i am a little concerned about the play (even though i think it's by design).

Rob

[Rawleigh]

Are they tapered bearings?

[aussierob]

Are they tapered bearings?

Yes - they're tapered, and face each other with a spacer between them.

[Rawleigh]

The pre-tensioning should take care on any play, unless you see any pitting, scarring or discoloration on the rollers or the race..

[aussierob]

The pre-tensioning should take care on any play, unless you see any pitting, scarring or discoloration on the rollers or the race..

I did carefully inspect everything, and am very pleased with what i found (ie - nothing). There are a few scratches in a planetary gear from a piece of dirt or something it looks like, but very minor and not worth replacing. The teeth are still in great shape.

I've never looked at a velvet drive before, but i started adult life as a mechanic, so know enough about what i'm looking at to fudge my way through it (have a service manual i found too, though it's from a different box, it still gives me torque settings etc).

I'm replacing all gaskets, seals, the breathers (which were missing), oil temp sensor etc which was damaged but not connected to anything anyway, and a bare metal respray. Should be like a brand new trans! Corrosion on the outside was the only real issue i had.

I haven't started on the port drive yet - doing one at a time, so any mistakes i make, i only make once. So far the only mistake was removing a snap ring that didn't need to be removed, so can't complain! :D

Rob

[Rawleigh]

Sounds like you have got it under control Rob. I like my Velvet Drives.

[aussierob]

Sounds like you have got it under control Rob. I like my Velvet Drives.

Thanks Rawleigh - they're great units!!!

Now i just need the rain to stop so i can get to work... i'm working on an outdoor area with a pergola. However wind / rain can still get in there (we don't have a garage - converted it to more house a number of years ago).

I'm keeping everything covered in oil to ensure no corrosion from the poor weather.

Rob