Stainles v aluminium

JSP · 17 March 2009, 16:03

The mount bolt for my engine go through the transom and then through 2 box sections, one on the top 2 bolts and one across the bottom 2.
I was going to do away with the box sections and just put a large stainless plate across all for bolts but I've decided to stick with the box section.
The box section that's on there now is only mild steel and needs replacing.............So which is best, Stainless Steel or Aluminium box section. Aluminium will be the lightest but at this kind of size it doesn't really matter.

And does anyone know of a good retailer? Or anyone got some laying around somewhere and want to do JSP a favour

jyasaki · 17 March 2009, 16:36

If the section is supposed to provide stiffness for the motor mount, I'd go stainless. It can be thinner than aluminum for the strength, so the weight tradeoff isn't as great as you'd think.

jky

Leapy · 17 March 2009, 16:42

Quote:

Originally Posted by jyasaki

I'd go stainless...

Agreed. Strength for strength aluminium is about 30% lighter but over the sort of size your talking about not worth the trip

martini · 17 March 2009, 17:02

I've got 2 stainless plates 8mm thick drilled for the same purpose, nothing fancy as they were only a temporary measure. I was going to hang on to them in case they came in handy 1 day but I may let you have them if you really wanted them. I think they are 100mm wide but not sure.

JSP · 17 March 2009, 17:07

Thanks for the replies lads

Quote:

Originally Posted by martini

I've got 2 stainless plates 8mm thick drilled for the same purpose, nothing fancy as they were only a temporary measure. I was going to hang on to them in case they came in handy 1 day but I may let you have them if you really wanted them. I think they are 100mm wide but not sure.

Martini,
that's very kind of you but I have already bought the bolts to fit. Thanks anyway

Arse about tit way of doing it I know but saw them and bought them. Got 316 A4 M12 bolts as you recommended

JSP · 17 March 2009, 18:32

Only stainless box section I can find is in 304. Would that be ok for the job? Sorry I know sweet f-all about this kind of thing.

martini · 17 March 2009, 18:48

Quote:

Originally Posted by JSP

Only stainless box section I can find is in 304. Would that be ok for the job? Sorry I know sweet f-all about this kind of thing.

I don't think it's really commercially available in 316. 304 won't exactly corrode but it will stain and probably leave brown streaks down the inside of your transom

JSP · 17 March 2009, 18:57

Quote:

Originally Posted by martini

I don't think it's really commercially available in 316. 304 won't exactly corrode but it will stain and probably leave brown streaks down the inside of your transom

Balls!

You know ya stuff mate, as far as strength, for this kind of application any way, would box section offer me that much more strength than a thick plate of stainless?

jyasaki · 17 March 2009, 23:04

Quote:

Originally Posted by JSP

Only stainless box section I can find is in 304. Would that be ok for the job? Sorry I know sweet f-all about this kind of thing.

http://www.onlinemetals.com/stainlessguide.cfm

jky

martini · 18 March 2009, 00:01

Quote:

Originally Posted by JSP

Balls!

You know ya stuff mate, as far as strength, for this kind of application any way, would box section offer me that much more strength than a thick plate of stainless?

None whatsoever!

yoyo · 18 March 2009, 10:46

I suggest that the box section should have spacer's running thro where the bolts are otherwise the box section may/will distort when the bolts are tightend.

Downhilldai · 18 March 2009, 21:36

Quote:

Originally Posted by yoyo

I suggest that the box section should have spacer's running thro where the bolts are otherwise the box section may/will distort when the bolts are tightend.

Or:
Just get some flat plate.

JSP · 19 March 2009, 15:16

Well who ever put the engine on the back used box with no spacers and it's lasted a good few years with out going flat

A plate would look better, just didn't want to upset anything by changing from the box section. Need to get shorter f'ing bolts now !!

yoyo · 19 March 2009, 17:09

Quote:

Originally Posted by JSP

Well who ever put the engine on the back used box with no spacers and it's lasted a good few years with out going flat

I suppose it depends on the wall thickness of the box section.

Anyway, why are you bolting lumps of steel to your transom…are you concerned of the SR’s strength or what..

You were recently complaining that the back end is already too heavy, lumps of metal aint gona help ya...

JSP · 19 March 2009, 19:34

Quote:

Originally Posted by yoyo

I suppose it depends on the wall thickness of the box section.

Anyway, why are you bolting lumps of steel to your transom…are you concerned of the SR’s strength or what..

You were recently complaining that the back end is already too heavy, lumps of metal aint gona help ya...

JSP · 21 March 2009, 10:08

Got some plate coming and fresh bolts. Thanks to those who know what they're talking about

Anyone need any M12 x 140mm A4 316 Stainless bolts?

htc1 · 26 March 2009, 15:00

Its also worth bearing in mind the long term corrosion problems you would get with disimilar metals (s/s bolts throught Ali plate) if you did follow that route.