As some of you may know, I bought an Ulster Rep. in 2016, with a Pettit body and a Pigsty engine. I received it here in the US after much work. I have now found that the off side bolt of the starter mount (1930 post bacon slicer but still rear mounted)has blown out. I have now heard that 12 volt is not advised because of this issue. I need a new crankcase. But should I convert from 12 volt to 6 volt? I have heard that 12 volt puts unnecessary stress on the mount because of the stress when the starter engages.
Why a new crank case ? You could get a new lug welded back on, and the whole area beefed up - probably cheaper and quicker than getting a "Good" crankcase And it may be possible with a minimum of engine stripping down. I can't see why a 12 volt starter would put more load onto the crankcase, the power output of the starter motor is likely much the same. Was there any possibility of a water leak into one of the cylinders causing the piston to 'hydraulic' and then put excessive load back through the starter?
I’ll be watching this thread with interest as I’m keen to understand why it failed. I’m just a silly civil engineer so the mechanical guys will know a lot more than me but I wonder why 12V systems would be more prone to cause a failure, after all the loading caused by compression in the pots does not know if it’s a 12V or 6V system being applied. Maybe the 12V can draw a higher cranking amperage and this spins the engine faster? My guess is that if it’s a race engine it’s running a higher compression and this in turn puts more load on the starter. Did the onside bolt fail as well?
(10-04-2018, 07:28 AM)steve davidson Wrote: Hi Erich,
I’ll be watching this thread with interest as I’m keen to understand why it failed. I’m just a silly civil engineer so the mechanical guys will know a lot more than me but I wonder why 12V systems would be more prone to cause a failure, after all the loading caused by compression in the pots does not know if it’s a 12V or 6V system being applied. Maybe the 12V can draw a higher cranking amperage and this spins the engine faster? My guess is that if it’s a race engine it’s running a higher compression and this in turn puts more load on the starter. Did the onside bolt fail as well?
More shock loading with 12v into 6 v starter.Torque reaction will try to pull up Rh side of casting.
Where is the gearbox bolt, looks to have been missing which wont help.
Crankcase is repairable without strip down, I have a scrap crankcase here and can send you th corner you need.
Been there.
I found, after I had built my engine, that I had crack by the starter motor stud.
I took the engine out and my friend Nick, a man with TIG skills, welded it back up on the bench. I then redrilled and tapped the starter stud hole by mounting a wooden board across the gearbox top face and used a power drill in a vertical stand, ensuring a new, square hole.
Not a disaster and very fixable. Just find a good TIG welder.
(10-04-2018, 09:50 AM)Ruairidh Dunford Wrote: Drill and tap for two cap screw either side of the existing hole. This can be done without removing the engine, if sufficient body dexterity exists.
Drill and tap into what, there is jus a big broken hole
(10-04-2018, 12:37 PM)Charles P Wrote: Been there.
I found, after I had built my engine, that I had crack by the starter motor stud.
I took the engine out and my friend Nick, a man with TIG skills, welded it back up on the bench. I then redrilled and tapped the starter stud hole by mounting a wooden board across the gearbox top face and used a power drill in a vertical stand, ensuring a new, square hole.
Not a disaster and very fixable. Just find a good TIG welder.
C
With you there Charles, Tig welders (good ones) are our friends
10-04-2018, 01:53 PM (This post was last modified: 10-04-2018, 01:54 PM by Ruairidh Dunford.)
(10-04-2018, 01:18 PM)Zetomagneto Wrote:
(10-04-2018, 09:50 AM)Ruairidh Dunford Wrote: Drill and tap for two cap screw either side of the existing hole. This can be done without removing the engine, if sufficient body dexterity exists.
Drill and tap into what, there is jus a big broken hole
I can, and have, repaired similar using two cap screws into the remaining metal on several engines Gene. If you feel it is not possible you should consider alternatives, if you find yourself in a similar situation.
