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ct1 175 crankshaft questions


Chunkstyle
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hi guys --

i'm a novice working on rebuilding the engine on my old ct1 175 & was wondering if somebody could please answer a couple questions:

1. while i've got the case cracked, i'm also replacing as many of the bearings as i can, as insurance. in the crankshaft area of the case, water got in so that there was sludge in there that rusted the left side crank bearing somewhat. since the lower connecting rod bearing is in that same area and down low, i'm wondering if i've got to replace it as well, even though it's not easily removable. it doesn't look rusted, but it's hard to see it well, between the crank counterweights, and there is some rust on those weights nearby. and i figure that it's probably one of the highest-stressed bearings in the entire engine, so i don't want to skimp on it.

if i do need to replace it, how bad a job is it to press out that pin & reassemble everything? my clymer manual seems to show it as a pretty big/precise deal, with v-blocks & dial indicators & alignment tools, etc.

2. when i was splitting the case, with a puller threaded into those holes behind the magneto, it took a little more pressure on the puller than i expected and a lot of tapping of the case halves to get it apart. the clymer manual said just "hand pressure" on the puller. and now that it's apart, it looks like the crankshaft bearings are possibly a press-fit onto the crank. is that supposed to be the case, or is something messed up here? and how do i get the case back together while having to press the case halves-with-bearings onto the crank? it took some pounding with a brass hammer to drive the crank out of the left-side bearing once the halves were split.

thank you for any help or advice you can offer!

drew j.

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  • Moderator

1 Not a job you do at home. They should be balanced.

2 Probability just crud. Carefully pull the cases together using the crankcase screws or slightly longer ones. The last owner may have used sealer to join the half's making it harder to part them.

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The crank is a definite no go for the diy fix, simple as that. Unless of course your an engineer with the experience and kit to press up crankshafts leave well alone.

Thats the dull bit done with, 'hand pressure' i thought that when i split one of these. I wouldn't want a slap from the fellow that dreamed that up. As to the bearings they are a doddle with a heat gun. A proper one though, the ones that strip paint not your sisters hair dryer.

The cases being ally will expand quicker than the chromium steel bearings and they will come out, they should drift out though. When you put them back its the old heat the cases, freeze the bearings trick, it all fits easy then. Heating the cases makes the seals a doddle to fit too. You cool the crank too, then as you add the bearings to the case they warm and expand making the crank a dodle to fit. Really it will litterally drop in, if you have really got a good temp difference the bearings will rattle in the cases till they warm up. Best of luck getting them out then, LOL

Be VERY carefull when you order the crank bearings, when they turn up they are easily mixed up be carefull. Also don't forget the O ring that fits on the crank under the primary drive gear spacer. Make sure you use a good quality liquid gasket on the centre mating face on the cases too. Be a bitch to have it leak later.

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