Saito 100 suspect bearings

[Ian Mat]

I recently purchased a Saito 100 from Ebay to put in the Top Flite Corsair I'm building. I ran the engine as soon as I received and all was well, huge amounts of compression, tons of power and smooth tick over. I was very pleased, especially for the price I paid, however I did notice that there was a tiny amount of side to side play in the crank shaft when I was turning the prop... should I be concerned?

[Mr.B.]

Do you mean side play or end play?

I've only just changed the bearings on John's Saito 100 (amongst other parts). No biggy.

[Ian Mat]

Mr. B. Its not end float, it definitely side to side. You can feel it when you grab the prop and rock it. I reckon the guy that sold it may have crashed a model a damaged the bearings. The rest of the engine is fine. I might bring it tomorrow and ask you to work your magic on it. I reckon its definitely worth saving!

[Guest]

I have a Japanes magnum 90 4 stroke which developed a lot of side play - so i changed the bearings and guess what - side play still there. came to conclusion i wasnt strict enough in keeping the large props balanced and this resulted in the front crankshaft bearing housing being opened up slightly. I should really have stripped the engine down and tried to shim the housing but as model and engine getting on a bit - I just fly as is.

[Stevo]

All of my Saitos (50, 56, 72 and 100) have no play at all. Changing a bearing is quite easy... be armed with an oven and an oven glove

[Shaunie]

I would think you need to check whether the play is in the bearing or between the bearing and spindle or if the bearing is loose in the housing.

If it's the bearing, change it.

If it's at the spindle does it have a collet type prop driver as sometimes they don't load up against the bearing correctly.

If it's the most likely which is loose in the housing then some loctite bearing fit will take the slop out.

Shaunie.

[Ian Mat]

Mr B flies at the same club as I do and he has plenty of experience in rebuilding Saitos, so we will take a look at it sometime next week! I'm hoping it's just duff bearings, because the engine runs beautifully apart from that.

[will -0]

Mr B, do you have any hot tips for removing prop drivers on Saitos? Mine is currently resisting all approaches by pullers etc.

[jrman]

"do you have any hot tips". I think you have answered your own question. As you tighten up the puller apply some (a lot of) heat with a hot air gun to the prop driver/collet and with a sharp tap on the end of the puller the driver and collet should pop off. I always leave the nut on in order to stop the driver and collet disappearing into the depths of the workshop!

[will -0]

|I'll give that a go

So far it's Saito2, pullers 0

[Paul Harris 5]

One thing to watch out for with crank bearings is that once they start to go the small amount of side to side movement can enlarge the bearing support hole in the end of the crank case, so that when you eventually do change the bearing the new one is then loose in its housing so you still get crank movement.

This can be fixed with some thin shim but its best to fix the bearing before it has time to damage the crank case as well.

Paul

[Mr.B.]

will-o,

As jrman says, a bit of heat and a sharp tap with a hammer. Do protect the end of the crank.

What sort of puller are you using?

On some saito's (such as the 100) the way the cam drive gear is machined on the crank means that you must remove the cam box before extracting the crank.

[will -0]

Latest one I tried was one like this:

http://www.ebay.co.uk/itm/CAR-VAN-BATTERY-TERMINAL-BEARING-WIPER-ARM-REMOVER-PULLER-6-28MM-REPAIR-TOOL-/391142579837?hash=item5b11ea1e7d

but it bends while the saito stands firm.

I have the cam box and everything else removed as the purpose of the excercise is to replace what's left of the bearings.

[ROY DAVIES 1]

First remove the cam gear noting where the indexing marks are. Load up the puller and apply heat either with a small gas lamp or in the cooker to the bearing / collet area. Your safe with this until the assembly smokes. Heat off, wrap the assembly in a towel or similar and also wear gloves hold the PULLER firmly and give the shaft end a sharp hit with a hammer and it should fall to pieces before your very eyes. Leave the propnut almost fully on while doing this to save damage to the shaft threads and dropped bits disappearing. 'Loctite Bearing fit' will take up to 6 thou' clearance in a fit, you may need heat to remove a bearing on a future repair if you need to do so. Heat the case up when you refit a new set as pressing them in a cold case may stretch or distort the openings and you may face a worse state of 'slop' than before

There is a small possibility in severe cases where the housing has worn a lip through a loose bearing which will hinder the removal somewhat.

[GONZO]

To accentuate the effects of heat(expansion) on the prop driver pop the whole lot in a plastic bag and leave in the freezer overnight. Remove from freezer and plastic bag then heat the prop driver. The crankshaft will remain cold (smaller) for some time whilst the prop driver (aluminium) will heat up and expand much quicker.

[Mr.B.]

try a beefier puller

**LINK**

or simular.

[Shaunie]

Most methacrylates such as bearing fit or nut lock give up quite easily with a bit of heat and I find no problems disassembling things if you get them nice and toasty!

Shaunie.