Bolts 101, fixin broken ones and other shop mayhem

[Master Hack]

In this new educational program we explore the methods of fixin broken studs in an aluminum block. (courtesy of Scrap yard engineers education and training department). Your instructor for this highly advanced class is none other than Egor our head design and engineer.
The subject of this cluster errr ahhh I mean project is Franken"s GX390, which sheared of 3 studs in the block.

Your homework is to study this info on bolts vs cap screws. There will be a pop quiz on this subject.

Hex Bolts vs. Hex Cap Screws - Portland Bolt

What are the differences between a hex cap screw and a hex bolt?

www.portlandbolt.com

So stay tuned and watch us f**K up err ahhh I mean repair this block.

 

[ezcome-ezgo]

 

[Master Hack]

I want to take this opportunity to thank the academy for this recognition! Also I would like to thank Egor, NR Racing, The chinese bolt manufacturer and of course my mother, for all their support. A special thanks to my Father without all his help and learnin none of this would be possible. I will treasure this award for all time!

 

[Denny]

I think the reason for the failure is the letters floating around in the crank case. Were you eating your Alphabits cereal when you assembled that engine?

 

[Master Hack]

Were you eating your Alphabits cereal when you assembled that engine?

Just a tip (from Egor) NEVER assemble an engine while eating alphabet soup during cold season!

For more advanced tips and tech you can subscribe to Egor's newsletter/blog thingy.
Contact him directly...
I'm not his effen salesman!

 

[Master Hack]

The Forensics team from the Skunkworks has been investigating the failure of the propulsion unit thingy. The NTSB, FBI, CIA, IRS, are all involved.
The focus of the investigation has zeroed in on the CVT gizmo. The CVT manufacturer came over from China and quickly placed the blame on the use of a Comet belt. Their beliefs are that the OEM belt (made from Yak scrotums) allows for more stretch, Bla bla, Bla bla...

The question has been brought up, The HP rating.

This was copied from the hongdong sales material:
Suitable for 8hp-16hp engines with 1" straight crankshaft and 1/4" keyway.

SO:
Is running 180% (or so) of the "max rated" power responsible for the failure?
There is a lot of tork yanking on that chain, which is ultimately transferred to the engine case via 4 bolts on the CVT.

 

[Denny]

You should have went with the Longdong CVT system. It seems to work better for inserting long male studs into the female holes.

 

[Master Hack]

Well thats a valid point, however is has been well established that all the CVT systems are all the same no matter which Dongwerks the came from.
And thank you fro that very descriptive explaination!

Despite all the seriousness here, the question remains.
Is the extra power creating too much tork stress on the 8mm studs? If so, why those and not the 4 bolts that hold the CTV back plate on?
This is a serious problem! There must be a government grant program to study this problem!

 

[Denny]

I myself think there is too much flex in the crank case and side cover. In talking to the space aliens about this very problem last night. Their analysis showed that the higher stresses induced by increased horsepower causes the crankcase and cover to flex independently of each other. Then combined with the harmonics coming from the crankshaft causes the nuts to loosen. When you combine the loose nuts with the flexing it makes for disaster. There is even an engineering failure analysis paper that they wrote somewhere. But it is one of their planet wide secrets that they will not disclose.

 

[Master Hack]

l can buy the cover flexing, doe to tork transmitted via roller chain from the dirt drivind surface to the crankcase cover. The CVT belt also transfers tork to the crankshaft.
Nothin a bunch more $$$ can't fix.
Billet crankshaft cover and a divorced CVT plate are called out in revision 854A.

 

[bob58o]

Did you yank on your crank?
I believe crank yanking is proper play when assembling. I forgot what what proper end play is? Something like 0.010” on a small block, not sure on the big boys. They make crankshaft washers if end play is too loose. If end play is too tight, a thicker gasket.


That’s all I got. Not sure if any of that will help or even applies to your bolts?

What about the Tellurium on the gears?

 

[ezcome-ezgo]

Too much wooble in your wobble

 

[bob58o]

I myself think there is too much flex in the crank case and side cover. In talking to the space aliens about this very problem last night. Their analysis showed that the higher stresses induced by increased horsepower causes the crankcase and cover to flex independently of each other. Then combined with the harmonics coming from the crankshaft causes the nuts to loosen. When you combine the loose nuts with the flexing it makes for disaster. There is even an engineering failure analysis paper that they wrote somewhere. But it is one of their planet wide secrets that they will not disclose.

Here’s Jody from ARC…
“All of our Billet side covers come with not only a O-ring but come with a shim/gasket kit to set the proper crank end play on any Honda/Clone block. They will help control crank and block flex because we use duel crank bearings which give you 4 points of contact on the shaft. This helps by controlling the up and down flex from the combustion and the twisting flex caused by the torque pulling the clutch. This will take stress off of the crank journal. It also helps control block flex by using all 4 dowel pins in the block. The Billet side cover is 5 times more ridged than the block its self and will not stretch, flex or twist like the OEM side cover. This flex/twist leads to sidecover bolts backing out, gasket failure, block fatuge and eventually block failure. Another plus with the Billet side cover is the pre-threded vent holes. These can be used for duel vents or a pulse to run the fuel pump.”

 

[Master Hack]

Yeah, I got all that BS and that's all good stuff, and will solve a lot of problems. My biggest concern was why they say the stuff about electric start and studs. I think both of those have been put to rest.
Stay tuned for the ongoing saga. To be continued. (some day)

 

[Denny]

Here’s Jody from ARC…
“All of our Billet side covers come with not only a O-ring but come with a shim/gasket kit to set the proper crank end play on any Honda/Clone block. They will help control crank and block flex because we use duel crank bearings which give you 4 points of contact on the shaft. This helps by controlling the up and down flex from the combustion and the twisting flex caused by the torque pulling the clutch. This will take stress off of the crank journal. It also helps control block flex by using all 4 dowel pins in the block. The Billet side cover is 5 times more ridged than the block its self and will not stretch, flex or twist like the OEM side cover. This flex/twist leads to sidecover bolts backing out, gasket failure, block fatuge and eventually block failure. Another plus with the Billet side cover is the pre-threded vent holes. These can be used for duel vents or a pulse to run the fuel pump.”

So the Space Alieums were correct in their conclusions. I might have to wear my tinfoil hat more often to communicate on a regular basis with them then.

 

[Master Hack]

So, Egor got tired of my prorcrastination and started working on the mobile blue scrap heap.
Stay tuned for more fun and excitement!

 

[Master Hack]

Today's episode of Egor's workshop. We explore the innards of a GX390 and continue stripping down the propulsion unit in preparation of rethreading metricated bolt holes. With broken studs innem.
Here's a $0.050 flywheel puller:
A piece of .750 x 1in bar stock drilled at 2.244 inches for studs. Fits the ARC 'wheel and probably others.
I little heat and a couple turns of a wrench and off. And $20 less than a bought one.



When the crankcase cover comes loose, the crank end play gets outta whack, and things go to hell quickly.
We were problably only fractions of a second away from things getting really ugly. As the flywheel started acting like a grinding wheel.

 

[panchothedog]

Yeah, you got real close to UGLYVILLE. Not a pleasant place to visit.

 

[Master Hack]

On this episode of Egor's gararge, we look at CVT mounting options.
A brief recap for those just tuning in...
The CVT is mounted on a 3/16 steel plate which is in turn mounted to the engine. (GX390 + 40 series CVT)
The engine is making too much Tork for the current arrangement. The Crankcase cover is getting pulled off the engine, cus Tork is Pi$$ed off.
The plan is to attach the CVT plate to the engine mount and have it divorced from (not physically attached to the engine)
Does anyone else have this problem and what was the solution?
This is the second time this same time this happened. I gotta fix this!
l'll listen to all suggestions. I'll still do it my way, but at least l'll listen! I'm purdy stupid like that!

Here's the plan as devised by the engineering dept, here @ the Mountain Top Labratory.

The CVT plate (green) has a 3/8 plate welded to it and that is bolted to the engine mounts through that blue thing with 3 holes innit.
the new plan is to cut off the blue thing and replace it with the bar stock (brown) then weld it to the engine mounts. There are 2 5/8 x 1 pieces of bar stock unna dare.



the engine and engine and CVT are mounted so that the thing moves as a unit. adjusting the chain is easy.
View from front (looking back)
Once this is assembled and welded, l'll remove the bolts, so that the only connection to the engine is the belt.



So Waddaya think?

 

[Whitetrashrocker]

Use a plate like this to hold the driven. It uses the motor mount holes and slides with the engine keeping the distance for the TC belt.