need help on volvo prop shaft

[raskill52]

i just bought a 18 donzi 1976 has a 280 volvo out drive.the problem i
have is that the threads inside the shaft that secure the cone are
pulling out and i can not get the required torque.they are 5/16x20 do not want prop to come off.any suggestion other than replacing shaft????
frend of mine told me to go to this site.he said you guys got your stuff
together.any help would be geatly hulpful first time user of this site
hope i am doing this right thanks glenn gaskill

[mrfixxall]

i just bought a 18 donzi 1976 has a 280 volvo out drive.the problem i
have is that the threads inside the shaft that secure the cone are
pulling out and i can not get the required torque.they are 5/16x20 do not want prop to come off.any suggestion other than replacing shaft????
frend of mine told me to go to this site.he said you guys got your stuff
together.any help would be geatly hulpful first time user of this site
hope i am doing this right thanks glenn gaskill


you could either drill the hole deeper and get a longer bolt and lock it down or if theirs enough room you could drill the hole bigger, tap it and install a helicoil or ihave done this for many years,i didnt know that volvo made a cone with the hole in it so i driled out the center of the cone and screwed in a set screw,i first used blue loctight on the prop shaft threads and then locked down the set screw against the prop shaft..if your spinning a left hand prop you womt lose the prop because its spinning in the direction where the prop cone will stay tight..

[BlownCrewCab]

Well, If you strip out a 5/16 then it's already the right size to tap for 3/8-16. (I don't know if you can switch the bolt out)

[raskill52]

thanks alot good input great site

[BERTRAM BOY]

Which way does the prop turn, right or left?
You have a lot less to worry about if it spins left. You still have to be carefull, but the prop nut probably won't come off while you're going forward.

[raskill52]

it was left but no matter what i did it pulled real hard to right
so i got a right hand wheel to take care of that but that is when i
found the shaft problem i had a 1966 sweet sixteen 25 years ago
it had the same problem with a lefty i put a right hand wheel and
with a little adjustment it went straight
thanks for help

[MOP]

Going to 3/8" is very easy much hassle at all, you will need to drill the cone hole and recess for the new bolt. To make holding the shaft easy leave the prop on sans hardware lower it on to a soft block of pine, that holds it nice and firm while you drill/tap. Go with a bolt at least 3/8' longer to get into virgin material, tap it with a regular tap then a bottoming tap it is worth the extra effort.

[Conquistador_del_mar]

Going to 3/8" is very easy much hassle at all, you will need to drill the cone hole and recess for the new bolt. To make holding the shaft easy leave the prop on sans hardware lower it on to a soft block of pine, that holds it nice and firm while you drill/tap. Go with a bolt at least 3/8' longer to get into virgin material, tap it with a regular tap then a bottoming tap it is worth the extra effort.

This is excellent advice, and the way I would personally approach the problem. Bill

[raskill52]

thanks alot people 3/8 is the way i will go i will be checking site to see
if i can help someone out 1 last question to be safe what size drill bit
do i run in before taping 3/8 thread maybe dumb question but better than
being sorry thanks again good people raskill52

[mrfixxall]

that depends on the % of threads you want, at 60 % stregnth is for a shallow hole you use a 5/16 drill bit 75 % stregnth you use a 21/64 which is the srgongest..now if your bolt is stripped then use the 5/16 because the threads are already gone and the hole is now to big for the 21/64 drill bit.

when drilling the prop shaft you need to use a drop of oil and drill really slow,the prop shaft is stainless steel and when it gets hot it goulds and good lick drilling through it so take your time drilling it..again when your threading it take your time,it you feel the tap binn back it out and blow the threads out..you dont want to brake the tap off in the hole.