K301 oil pan bolt torque

[Fred's 123]

So, I was installing the oil pan on my freshly rebuilt K301 (Cub 123), and decided to look up the torque spec for the oil pan bolts. I found the following link, specifying 35 ft.lb.

http://cubfaq.com/kohlertorquespecs.html

Four helicoils and two broken OEM bolts tells me there's something way off in this torque spec, as I never got beyond 25 ft.lb. without spinning or breaking a fastener. I compared my three torque wrenches, and they're all dead-nuts with each other at 20 ft.lb., so I don't think it's a miscalibrated torque wrench.

Seems to me the Cub Cadet FAQ simply cannot be right, if I'm breaking two factory fasteners at only 70% of the recommended torque spec. I think I helicoiled four holes which likely didn't need it, and that the fasteners stretching was my sole problem.

I'm not sure what grade the factory bolts are, but I see another source putting grade 5 at 23 lb. oiled or 30 lb. dry. Seems you need to go grade 8 to achieve the torque spec listed, and I know the factory bolts are not grade 8.

Seems to me maybe these torque spec's are aimed at hotrod pulling motors, not factory spec's. Does anyone know the factory spec for this fastener? I'm going to need to try to find this odd sized fastener (3/8 NC x 1.25") locally tomorrow, which will be a big challenge if I need to go grade 5 or grade 8.

[Matt G.]

If you aren't using grade 5 fasteners, that's why you are twisting them off. The helicoil should be stronger than the original threaded hole, particularly if it's an aluminum pan.

You can buy 1.5" bolts and trim them to the correct length.

[Fred's 123]

Thanks. I was able to find some grade 5 bolts 1-1/4" long at a local HW store, so it looks like I'm good to go. I'll be torquing to 23 ft.lb., per this table:

http://raskcycle.com/techtip/webdoc14.html

Frankly, I'm surprised folks aren't bending their oil pan castings or damaging the block castings torquing to 35 ft.lb. with grade 8!

[Matt G.]

There's a torque table in the service manual, too

Who said anybody's putting grade 8 bolts in there? That's totally unnecessary. The only danger would be pulling the threads out.

[Fred's 123]

Originally Posted by Matt G.

There's a torque table in the service manual, too

Not in my original 1965 service manual, at least that I can find. I've read it cover to cover several times, looking for that torque spec.

In any case, I installed grade 5 with oiled threads and torqued to a more sane 23 ft.lb. All seems good. Got the engine back in and fired her tonight. Just gotta fine tune the timing and governer, now.

[Matt G.]

It's for sure in the 1x8/9 and later manuals, which you can grab from the tech library.