Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

[TheRealTeeHill]

Hello All,

I am in the process of stripping and servicing my twin sea horse and have got to the flywheel/magneto... I have a harmonic puller but the bolts supplied, 1/4" and 5/16" are too big (and probably too weak). I understand that I need grade 8 bolts for the strength but what diameter, length and TPI? I have measured the inside diameter of the holes and they are around 5mm, don't know if this helps at all?

The part I am looking at is #5 (Part # 0582388) on this diagram and it is the three holes on top around the crank shaft hole that I need to size bolts for.


Thanks in advance, Tee.

 

[F_R]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

Well I dunno, I can't say that I've ever specifically checked a 1984, but they have been 1/4-20 threads for at least 30 years.

 

[TheRealTeeHill]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

Well I dunno, I can't say that I've ever specifically checked a 1984, but they have been 1/4-20 threads for at least 30 years.

Thanks for the response. Everywhere I read says 1/4" or 5/16", well I have a 1/4" and 5/16" bolts in my hand an they're are not going to fit The service manual says nothing past "use a proper puller blah" no mention of the threads

 

[kfa4303]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

should be 1/4" x 20. OMC have been using that size as long as I can remember too.

 

[TheRealTeeHill]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

I have measured the inside diameter of the holes and its 5mm, noway will a 1/4" fit.

Does anyone know what standards are used on this engine? Its a Belgian one I believe. If I can confirm the standard I will just move down from 1/4" in the standard increments till I find the right one.

 

[Vic.S]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

I have measured the inside diameter of the holes and its 5mm, noway will a 1/4" fit.

Does anyone know what standards are used on this engine? Its a Belgian one I believe. If I can confirm the standard I will just move down from 1/4" in the standard increments till I find the right one.

I have a 1984 Belgium built 6hp Evinrude

The holes are 1/4"

A 1/4" Whitworth bolt screws in ... I dont have any 1/4" UNC bolts AFAIK but the threads are the same diameter and pitch (20tpi)... so I'd be pretty sure they are infact 1/4" UNC

The inside diameter of the holes are 5.0mm as close as I can measure them and that tallies with 1/4" UNC.

I think you had better go take a closer look.

You may have 1/4" BSF bolts (26tpi) ????? or even UNF (28tpi)

 

[boobie]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

Try running a 1/4" x 20 tap in the threads once and see what happens.

 

[TheRealTeeHill]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

Thanks for the responses guys

The puller I bought describes the bolts included as [5/16"x4", 1/4"x3", 5/16"x2", 1/4"x2"] with no mentions of standards. I will head to the fastenings shop tomorrow and grab some 1/4" grade 8 Whitworths and the same UNCs.

Can anyone offer some guidance on the suitable length of the bolt? Will getting bolts with shanks be better than ones without?

Thanks again for the help.

 

[Vic.S]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

The depth of the holes/thickness of my flywheel is approx 3/4". At one point a screw threaded in by 1" would hit something.

But my 6hp has CDI ignition. I believe your 4 hp as points so very different inside

Bend a small hook on the end of a piece of thinnish wire and use that carefully to determine the thickness of the flywheel. Choose the longest bolts that will not pass quite all the way through.

BTW Bolts have plain shanks..... those that don't are called "set screws"


Be careful if you run a tap through as suggested. You dont want to damage anything inside

 

[Tim Frank]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

I have a 1984 Belgium built 6hp Evinrude

The holes are 1/4"

A 1/4" Whitworth bolt screws in ... I dont have any 1/4" UNC bolts AFAIK but the threads are the same diameter and pitch (20tpi)... so I'd be pretty sure they are infact 1/4" UNC

The inside diameter of the holes are 5.0mm as close as I can measure them and that tallies with 1/4" UNC.

I think you had better go take a closer look.

You may have 1/4" BSF bolts (26tpi) ????? or even UNF (28tpi)

Whitworth threads have a 55 degree thread angle, UN are 60 degree. Pitch is the same on 1/4 " . A Whitworth bolt will go into a UN tapped hole....vice versa won't work.

 

[Tim Frank]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

Thanks for the responses guys

The puller I bought describes the bolts included as [5/16"x4", 1/4"x3", 5/16"x2", 1/4"x2"] with no mentions of standards. I will head to the fastenings shop tomorrow and grab some 1/4" grade 8 Whitworths and the same UNCs.

Can anyone offer some guidance on the suitable length of the bolt? Will getting bolts with shanks be better than ones without?

Thanks again for the help.

The 1/4 x 3" should be fine and would almost certainly be UNC. The BSW should be 2nd choice.
I always use a locknut, to set the depth and then snug up to eliminate slack.

Edit: But as Vic says, he has used the BSW succesfully, and on a 4 HP, should not be a problem if that's what you have. Most times the FW will pop on those small OBs if someone holds them up by the FW rim and you give the centre nut a rap with a deadblow hammer.

 

[SolingSailor]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

Gotta be 1/4" - 20 tpi. That 1/4" measurement is the outside of the bolt threads -- by measuring the hole, you are measuring the diameter minus the thread depth. If you are using a harmonic balancer puller, the bolt length is not very critical, as you can compensate using the center bolt setup.

 

[F_R]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

It is NOT Whitworth. I'd bet the farm on that. And I'd almost bet it on not being Metric either---even though it was made in Belgium. Dag-Nabbit, it's 1/4-20. Good old US of A bolt size.

 

[boobie]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

Agree 100%.......

 

[kbait]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

I've pulled flywheels on LOTS of J/E motors, including several Belgian made.. Every single one is 1/4 x 20 unless it'd been stripped/re-tapped.

 

[TheRealTeeHill]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

Thanks guys, I'll be heading to the engineers shop shortly and will be getting 3 x (1/4" x 20). I'll let you know how it goes when I'm back

Cheers

 

[TheRealTeeHill]

Re: Flywheel Puller Bolt Size? Johnson 4HP Sea-Horse 1984 J4BRCRM

They fit! God knows what 1/4" bolts were supplied with the puller!

Now to get the flywheel off

Edit: The flywheel is off. Thanks for all the help guys

 

[Bazmond]

Hi all, I'm having a similar sort of problem, I think I'm just going to drill and re-tap them. Any view on this? Like is it advisable and what size would you go to? Bigger obviously lol, any input appreciated.

 

[Tim Frank]

You probably will not get many responses since responders will notice that you have re-opened a 5 year old post which will be closed when the mods spot it.
Best to start a new thread of your own as the forum rules request.