Merc 250 Pro XS
1. Should mounting bolts and lock nuts be 316 stainless, Grade 5 or Grade 8? Have Grade 8, 1/2" diameter bolts in thread count 20's now. Having some rusting on grade 8 nuts.
2. To keep nuts tight (prevent loosing) can I use a 2nd lock nut (mounted nylon 1st/backwards due to length of bolt) or Jam nut?
Thank,
Bill
I would use Mercury factory bolts which has the FINE threads on them and BRASS nylock nuts.
Don:
What is your thought on using jam nuts to prevent lock nuts from loosening? Are factory lock nuts brass? Can you look a 1and 2 above.
He is going to tell you to use the Mercury Marine bolt kits. The nuts are brass.
OK, Thanks Savage. Are these 20 thread count nuts and bolts?
1/2"-20 Fine Thread STAINLESS bolts. Many of the Mercury bolt kits carry are ABP (F593C Rating).
I do not recommend utilizing "other" hardware, simply due to the potential liability. If you use the exact specified hardware, from the manufacturer, and something goes awry in that area, your legs are (lets say) on more solid ground.
Stainless fine-thread bolts, Stainless washers on the jackplate or boat side (of appropriate size/thickness), brass locknuts, and specially sized (and hardened) washers for the TRANSOM bracket. That last washer is EXTREMELY critical, especially when mounted to a jackplate or setback plate.
Final torque when mounting to a jackplate is 90 lbs/ft (engine to jackplate) using the specified fasteners.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Does Mercury recommend F593C grade 304 or 316 or 17-4 stainless bolts? How much thread should protrude past the fastened nut? What about the bolt washer nut setup for a jackplate to outboard motor? Is a stainless (grade?) washer required inside the jackplate to motor mount? What thickness and is it hardened?
I have seen both types in their kits over the years. Traditionally, we want to see 5 threads protrude beyond the nylock (although in theory, two threads is sufficient).
I do NOT recommend double-nutting LOCKNUTS. See Post# 8 (above).
Also keep in mind that the Transom Brackets require a special Hardened Stainless Washer, specific dimension in OD to properly provide clamp load between the bracket and a JACKPLATE.
All of these items are provided in the OEM bolt kits.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Thank you. Do you know the length of the bolt that goes between the jack plate and merc motor mount?
That will depend on the Jackplate used. In most cases you end up with a 2.5" bolt kit (and may potentially have to swap out the upper bolts for 3" bolts).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Thank you!
What is the part number for the kit . Has a buddy that's going to change plate's this fall on his boat.Originally Posted by Savage
Just be aware those bolt kits DO NOT provide the proper hardened washer.
"Better to remain silent and be thought a fool than to speak out and remove all doubt."
I purchased F593C 1/2-20 x 3" long 316 stainless steel hex bolts, 3/16" thick Stainless steel 1/2" washers and 1/2-20 Brass Nylock locking nuts for mine. https://www.fastenal.com/products/details/11128575
Reviving due to repower
Current - 1995 xri 200
repower- 2018 pro xs 225
is the motor plate thicker on the pro xs?
cmc jackplate
From looking at pictures seems the Pro xs motor plate is 5/8” and the XRI is 1/2”
cmc jackplate 1/2”
this picture is my current xri / jackplate setup bolt length
yes sir it is , should have the updated much beefier clamp on those engines
.................................................. ...the scariest thing in life is the unknown ...................................
joe. Would that qualify to a 2.5” bolt kit?
xri looks to be 1/2”
cmc looks to be 1/2”
pro xs looks to be ? 5/8-3/4??
Bolts come in 1/2" increments, so you could just measure what you have currently and add 1/2" to determine the length.
Tom- Respectfully, it would be considerate to ask this question in ONE place. In the last 24 hours I've received an email, a PM, and now see a post... all with the same question.
One last time: Using MERCURY bolt kits (ONLY), you need a 2.5" Bolt Kit (67755A22) and then also need TWO (2) 3" bolts. Mercury's next size up is 3.5" and that won't work.
As indicated in the Email, Rhonda can set you up with these items if you drop her an email.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Reply With Quote
