One way bearing or something else?

bklein

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I'm inexperienced at debugging this stuff. I am restoring my and my son's trucks. His was thrashed of course. The one way bearing seems to hold one direction on the motor shaft, but the starting shaft needs to get help to move towards the crankshaft to engage it. What pushes it towards it? Or is the thing surrounding the crankshaft pin supposed to stick out more? I don't know which thing is the cause of poor engagement. IMG_7082.jpg IMG_7080.jpg IMG_7081.jpg
 

olds97_lss

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The crankshaft is actually 3 pieces. The crank, a spring and a pin. Either your pin is worn down, or, it's gummed up keeping the spring compressed. The spring presses the pin against the flat disk with the groove in it and catches the groove. When it starts, either the shaft/disk with a groove spins with the engine, or the spring is compressed and the pin slides around the disk.

I don't know the HPI engines that well, but here's one like it:
https://rc4me.us/product/hpi1493/

 

bklein

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13
I remember seeing in a video someone replacing that spring as it had broken in two pieces. I'll try to get that spring and pin out, see if they are good, and then see if things work better once reassembled. Seems a little scary to me that the pin can be what the slotted circle thing hits first. The slot is wide enough to capture the collar the spring and pin are surrounded by - but it doesn't protrude from the crankshaft so that doesn't happen. Is the slotted circle thing supposed to slip forward with a tilt of the chassis or is it always under pressure by the pin? If held back, then it is constantly spinning with the crank even after starting, correct?
 

olds97_lss

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The slotted circle thing should have pressure on it pushing away from the crank via the pin/spring in the crank. When the engine is running, either the starter shaft (slotted circle thing) will spin with the crank, or the hardened pin will slide along it's surface and compress the spring. The issue with yours is the spring is compressed and stuck due to being gummed up, the spring wasn't put back in, the spring is broken or the pin is worn down, or the pin is broken.
 

bklein

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The slotted circle thing should have pressure on it pushing away from the crank via the pin/spring in the crank. When the engine is running, either the starter shaft (slotted circle thing) will spin with the crank, or the hardened pin will slide along it's surface and compress the spring.
Ok, thanks, mine's definitely stuck back then.
 

olds97_lss

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@olds97_lss

YOU HAD ME AT "SLOTTED CIRCLE THING" ......
LOL!

I've only had 2 HPI engines in my life, one was the old single needle 15FE, the other was whatever came in my savage-x when I got it used. It ran awful and had zero compression when I got it, so I never really tore it apart, I just replaced it with an LRP28S3. I have never seen an engine apart in person that had that starter shaft/pin/spring thing like the HPI engine has. All of mine had a nipple on the crank that keyed into something solidly and spun the "starter shaft" all the time or the OWB all the time.
 

olds97_lss

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Is there a good parts diagram somewhere with names?
I don't know what engine you have specifically, but here's a parts list for one like it:

111595 - NITRO STAR F4.6 V2 ENGINE WITH PULLSTART
https://www.hpiracing.com/en/parts/111595/std

And a manual which has a parts explosion for it:
https://www.hpiracing.com/assets/documents/instruction_manuals/111598-f46_v2-glb-m-v1.pdf

I wasn't making fun of you, was just using what you called it so you knew what I was talking about. I wasn't sure what to call it either, so I searched one up and got the name from HPI's site. :)
 

olds97_lss

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If you upload a photo of the top of the cooling head and sides of the engine, we can likely sort out what engine you have specifically and find the manuals/explosions for it.

I'm guessing to get that pin out, your going to have to dig further into the engine. Pull out the sleeve for the piston, mark the piston so you know which way it goes when you put it back, remove the piston and con-rod, knock the crank out of the engine. Then use heat/solvent on the pin area to get the pin to come loose. You can try dealing with it in the engine, but would be easier with it out of the engine.
 

ELWOOD

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@bklein
AS FOR THE PIN AND SPRING STUCK IN CRANK , I HAVE HAD LUCK WITH PUTTING A COUPLE DROPS (NOT SPRAYING) CARB OR BRAKE CLEANER RIGHT ON TOP OFF PIN AND COVER CRANK SO PIN DOSEN'T FLY OUT . SOME TIMES A LITTLE HEAT SAY FROM A SOLDERING IRON CAN WORK ALSO...
 

bklein

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Guys, no hurt feelings at all. Thanks much for your help. More questions to come ( like why am I doing this?). I’ll return after I get this pin free.
 

bklein

Member
Messages
13
If you upload a photo of the top of the cooling head and sides of the engine, we can likely sort out what engine you have specifically and find the manuals/explosions for it.

I'm guessing to get that pin out, your going to have to dig further into the engine. Pull out the sleeve for the piston, mark the piston so you know which way it goes when you put it back, remove the piston and con-rod, knock the crank out of the engine. Then use heat/solvent on the pin area to get the pin to come loose. You can try dealing with it in the engine, but would be easier with it out of the engine.
Got it out with 300 degrees heat gun and PB lubricant and pushing down letting up on it several times. Spring is intact but really gunky. My engine head says .25 HPI 3.5.
 
Last edited:

ez2frag

Member
Messages
20
That pin set up is one of the worst designs for roto start engines. Too many little pieces that can end up in the rotating assemble, and grenade the engine. SH engines have a lot better set up as well as Nova's. JMHO
 

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