Transom bolts bending. CMC jackplate laying over!

[Revolution141]

Bought a Cmc hydraulic jackplate 2.5 years ago. Have had problems from day one with plate dropping on port side. Spoke to dealer who said I needed upgraded plastic guides and aluminium outer plates (replaces washers) after swearing to me over the phone that this was the plate I needed for my application. I made it very clear I was racing my 21' v hull with 300xs offshore and it would cop a hiding. When I ring him back to tell him of the problems I'm having he treats me like an idiot for not buying the stainless version??? Sells me upgraded guides anyway and assures me it will fix my problem. Needless to say nothing has changed and it got to the point now I have drilled and tapped holes through side of plate to bolt off level. Can't adjust with hydraulics now though. Anyone with similar issues?What size mounting bolts are 300xs owners using through transom? I'm on my 3rd set of 1/2" stainless bolts as they keep bending. Want to go to larger diameter bolts but can't cause my heap of junk jack plate doesn't have enough clearance for bigger nuts and bolts.

[BUSHWACKER]

If I were you I would contact CMC direct.

[danrad]

Have a friend that kept stretching the SS boats at the transom causing the jackplate to move on the transom. He swithed to aircraft grade steel boats. He never had the problem again.

[Euroski]

Have a friend that kept stretching the SS boats at the transom causing the jackplate to move on the transom. He swithed to aircraft grade steel boats. He never had the problem again.

I would do that... was told SS bolts are soft compared to steel bolts.

[VELOCITOY]

SS bolts are a no-no in a high-strength/high-torque/sheer application...Fastenal has what you need in the industrial section of the catalogue...never did like the CMC stuff...

[myron]

Allisons come with 9/16 fine thread bolts on the top

[Bryan1257]

uh oh, just put 1/2 all thread rods 10 inches long on my bracket today! However I was just makin sure everything lined up.

[fast fun 2]

Weve used CMC stuff on a few offshore race boats, no issues. Call CMC direct

[Revolution141]

Funny.... Merc supply the motor with 1/2" stainless bolts for rigging????The other thing that ****s me is the holes in trim bracket are sloppy for 1/2" bolts. I know they can't be exactly 1/2" or bolts would be almost impossible to line up but still I think the holes are a fraction too big. Merc 6 drives use stainless studs to mount also.I know some offshore race cats that use the high tensile steel bolts but they also need replacing every 12 months cause they rust.I'm sure bigger stainless bolts would solve my problem. Will probably just cut my loses with this heap of $hit jack plate and make something myself.

[spbutler]

I have a CMC that is probably at least 10 years old and have had no problems. I'm not sure what size bolts and what they are made of but they aren't stainless. Are you using lock washers and big enough backing plates.
As everyone else said call CMC. I don't think I have any play in my holes.

HYDRAULIC UNIT
(Item Numbers - 65001, 65002, 65006, 65201,61001, 61002 and 61006)
1. One Hydraulic Power-Lift unit2. One wire assembly3. One Power-Lift position indicator gauge(65001, 65006, 65201, 61001, and 61006)4. One Power Dial Control (65006 and 61006)5. Four 1/2" -13 x 3 stainless steel hex head cap screws6. Four 1/2" -13 stainless steel hex nuts7. Four 1/2" stainless steel lock washers8. Four 1/2" stainless steel flat washers

[modvp]

What type of stainless steel bolts are you using? If you're using type 316 SS, I would consider using 304 SS. 316 is more resistant to corrosion due to the presence of molybdenum, higher nickle and lower chromium content but it makes for a slightly "softer" bolt. 304 (lacks molybdenum), and due to it's slightly higher chromium and lower nickle content makes for a stronger bolt. For that reason, I opted to use 304 SS for my transom/jack plate bolts.

[FUJIMO]

Its become more common that a rigger, when drilling a transom for a new outboard bracket, jackplate, I/O transomplate, large swim platform, etc., to drill larger size holes than are needed for a particular size mounting bolt. It makes it easier for them, given the large number of nuts, bolts & washers that have to go in at the same time, "and line up", all with caulking on them, to slip right in, without having to use a hammer. This is common practice these days. With this said, my experience with offshore outboard race boats has found, that NO brand of single engine "adjustable" aluminum setback bracket, hydraulic OR manual, can take the brutality of offshore abuse. In a race that requires you first, to finish, they just don't cut the mustard. The bolts that hold them on, are just part of the bigger problem.

[loop]

316 or 304ss is not strong enough for his application
use 17-4 stainless bolts or studs. MUCH stronger and corrosion resistant too.
If not use grade 8 steel

[modvp]

What type of stainless steel bolts are you using? If you're using type 316 SS, I would consider using 304 SS. 316 is more resistant to corrosion due to the presence of molybdenum, higher nickle and lower chromium content but it makes for a slightly "softer" bolt. 304 (lacks molybdenum), and due to it's slightly higher chromium and lower nickle content makes for a stronger bolt. For that reason, I opted to use 304 SS for my transom/jack plate bolts.

I checked my bolts, I have the numbers mixed up...I am using 316...not 304. I had 304 SS and changed to 316. I would definitely consider using something harder like what was suggested by loop.

[Greg G]

Go to 17-4 for that application ...........

[Brabender]

210... 220 whats the difference,
Fujimo sounds like he's onto something

[Revolution141]

Never heard of 17-4? What's the difference from 316? Tensile strength, corrosion resistance etc??I tend to agree that no jackplate on the market will last long in offshore (race) applications. That's why I will probably just make my own setback that I can lift and lower engine on the bolt holes. I don't often raise or lower engine height. Where it's at now is the best for all applications.

[modvp]

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

304 Stainless Steel
T-304 is the most commonly used stainless in the world. You can find it in everything from forks and knives to backsplashes. It is weldable, machinable with the right techniques, and has good corrosion resistance, but is not for use in salt water environments. This material is hardenable by cold work.
<tbody>
304 Stainless Steel (annealed condition)


Minimum Properties
Ultimate Tensile Strength, psi
73,200


Yield Strength, psi
31,200


Elongation
70%


Rockwell Hardness
B70


Chemistry
Iron (Fe)
66.5 - 74%


Carbon (C)
0.08% max


Chrome (Cr)
18 - 20%


Manganese (Mn)
2% max


Nickel (Ni)
8 - 10.5%


Phosphorus (P)
0.045% max


Sulphur (S)
0.03% max


Silicon (Si)
1% max

</tbody>


316 Stainless Steel
Also known as marine-grade stainless steel, T-316 is similar in machinability and weldability to T-304, but has far superior corrosion resistance. It has a far higher yield strength than both 303 and 304, meaning that it will not bend as easily. This material is hardenable by cold work.
<tbody>
316 stainless steel (annealed condition)


Minimum Properties
Ultimate Tensile Strength, psi
89,900


Yield Strength, psi
60,200


Elongation
45%


Rockwell Hardness
B91


Chemistry
Iron (Fe)
65%


Carbon (C)
0.08% max


Chrome (Cr)
17%


Manganese (Mn)
2%


Molybdenum (Mo)
2.5%


Nickel (Ni)
12%


Phosphorus (P)
0.045%


Sulphur (S)
0.03% min


Silicon (Si)
1%

</tbody>




17-4 Stainless Steel
Also known as a PH, or precipitation-hardening, grade of stainless, this alloy is used a great deal in the aircraft industry in part due to its strength, and also because there are a wide range of heat treatments to choose from to reach a specified hardness or other properties. This alloy is very similar to 15-5 except that 17-4 tends to have more ferrite, and is slightly more magnetic.

<tbody>
17-4 PH Stainless Steel Condition A (annealed)


Minimum Properties
Ultimate Tensile Strength, psi
160,000


Yield Strength, psi
145,000


Elongation
5%


Rockwell Hardness
C35


Chemistry
Iron (Fe)
69.91 - 78.85%


Carbon (C)
0.07% max


Chrome (Cr)
15 - 17.5%


Manganese (Mn)
1% max


Niobium (Nb) + Tantalum (Ta)
0.15 - 0.45% max


Nickel (Ni)
3 - 5%


Phosphorus (P)
0.04% max


Sulphur (S)
0.03% min


Silicon (Si)
1% max

</tbody>

[mr_velocity]

totallystainless.com sells grade 8 stainless bolts, I think they're from ARP at least the smaller ones I used for the steering were.

[Revolution141]

17-4 it is then. Excellent bit of info modvp. Thanks

[modvp]

You're welcome; I never new 17-4 existed until this thread (specifically the info by loop).

17-4 it is then. Excellent bit of info modvp. Thanks