30 Series Converter Failure

[GT20Modding]

So my converters crank pulley came off while driving and I just re-assembled it and went on my way. About a week later of driving it it comes apart once more but this time it was more destructive. Snaps a bolt off in output shaft and warps part of the converter. Pics attached.

 

[GT20Modding]

The motor on this is http://www.nrracing.com/product-p/eng-rac-212-level2.htm (Hemi , Balanced, Tuned and dynoed. Peak HP 12.29 at 5250 and Peak Tq 13.22 at 4000. 22 LB Spings. Head Milled .050) on a Trailmaster Mid XRX frame. I would like to find a replacement crank pulley that won’t do this.

 

[bob58o]

Do you know how fast you were turning the engine when it blew?
The description say the MOD2 cam is for 7000+ RPMs. I found it interesting that it made peak HP at 5250. I guess I just figured it would be a bit higher.

 

[GT20Modding]

I don’t have any idea.


Sent from my iPhone using Tapatalk

 

[KartFab]

I would like to find a replacement crank pulley that won’t do this.

30 series is only rated for 8 hp, and per the quote on the page that engine is putting out 12-15ish hp depending on what dyno you have it on.

with that said, you can either go back to a stock engine, or get a different series torque converter for the engine you have now (e.g. 3/4" to 1" adapter) https://www.amazon.com/Everpert-Eng...=8-3&keywords=3/4"+to+1"+adapter+engine+shaft

Then run the 1" bore drive unit for the 40 series, properly space the engine shaft away from the jackshaft and run a 40 series driven unit. Will require some research for reverse wound or outboard installation of the driven unit as the 30 series runs a 6" driven, and the 40 is a 7.5" driven iirc, and it needs more space between the jackshaft and engine shaft.

Another option is to run a race clutch or centrifugal clutch on tthe engine shaft, and run it to maybe a 20 tooth jackshaft sprocket in, and an 8-10t jackshaft sprocket out.

You may find that you can actually rev the **** out of your engine, and a torque converter was holding the rpms down.

 

[GT20Modding]

Hey Kartfab. FYI I’m a fellow Grant as well. Thanks for that I’ll look into a 40 series with that adapter. Ok after re-reading your post I realized I had a brain fart. You mean run a 40 series on both ends. Got it. Maybe I’ll do a racing clutch. I have a 3-d Motorsports manual clutch but my parents don’t like the idea of that. After I asked them and bought the 400 dollars worth of parts. Then they put their opinions in.

 

[itsid]

I'f you're willing to try...
I'd get a new series 30 bell from mfgsupply.com and the lighter flyweight.
(that increases engagement speed without using weaker springs)

but in the end, it also lessens the centrifugal force pressing against the bell,
maybe enough so, that it doesn't come flying at you

'sid

 

[KartFab]

Hey Kartfab. FYI I’m a fellow Grant as well. Thanks for that I’ll look into a 40 series with that adapter. Ok after re-reading your post I realized I had a brain fart. You mean run a 40 series on both ends. Got it. Maybe I’ll do a racing clutch. I have a 3-d Motorsports manual clutch but my parents don’t like the idea of that. After I asked them and bought the 400 dollars worth of parts. Then they put their opinions in.

You dont really need a race clutch. A centrifugal clutch with jackshaft works great, You might even be able to put it on the existing jackshaft and backplate from the torque converter. E.g. 10t or 12t clutch to 20t jackshaft in might cost you only $40-$60 and you can still use your torque converters jackshaft out sprocket.

Just something to think about. The 30 series torque converters can really hold the engine's power at 5-5500k even if your engine can rev higher. The centrifugal clutch or race clutch wont do that.

 

[Clifton]

The first time you say the pulley flew off, which means the bolt came out.
The second time you say the bolt broke off, my guess is that it broke because it had vibrated partially loose again.

There have been a number of cases of the bolt vibrating loose and the driver flying off, to help prevent this: use the longest bolt that will fit in it, use a lock washer, use loctite, and the torque specs on that bolt I cant find atm, but I know you can't hold the pulley with your hand and achieve the proper torque, you need a "strap wrench" or, do as I did and use an old leather belt

 

[GT20Modding]

Will an electric impact achieve the proper torque?

 

[Kartorbust]

It can but I would use proper specs instead of just relying on an impact.

 

[Tpdingo]

The trick that many people use is to open the sparkplug up, shove a bunch of string down the sparkplug hole and then you can tighten it up no problem!

 

[landuse]

The trick that many people use is to open the sparkplug up, shove a bunch of string down the sparkplug hole and then you can tighten it up no problem!

Rope is a lot easier than string. Just don't use nylon as it can smear in the bore when being compressed