Need advice for putting the tranny back in

[Torxhead]

Thats not good. Looks like the back of the crank has a bad hole. If I am correct, that is a 7/16"-24 bolt and will require a 29/64 hole to accept a heli-coil. If that stripped hole is any larger, a heli-coil is not advisable. There are inserts that will go in there though, just not a heli-coil. You could also just replace the crank, but it is only a Jeep.

 

[Hedgehog]

ONLY A WHAT! Them there's hangin' words!

Disclaimer, no violence is not necessary this was a case of over the top humor.

 

[hdgapeach]

Looks like Liquid Steel to me.

I think you're right. JB welded the hole, re-tapped and called it good.

Don't know if it's doable but, I'd look into oversizing the hole with good threads and bump up a bolt size.

 

[steel]

Thanks for the heads up guys. I'm going to go talk to a guy tomorrow who knows a thing or two about motors and see what he thinks. My 3 options are Gerry-rig it, rebuild the motor with a new crank, or find a rebuilt/salvaged motor. I'm leaning towards getting it Gerry-rigged then finding a AMC 304 on the web, which would be a hell of a lot easier if I wasn't on an island in alaska, but as long as the financial adviser is ok with it I'll find the right motor.

 

[Hedgehog]

As I said before, you have another option. Weld the hole, it doesn't need to be welded closed, just add material to the ID. Then use the proper flywheel hole as a guide, drill out and re-tap to the stock size. I've done it many times .... not to a crank shaft though.

 

[tarry99]

Thanks for the heads up guys. I'm going to go talk to a guy tomorrow who knows a thing or two about motors and see what he thinks. My 3 options are Gerry-rig it, rebuild the motor with a new crank, or find a rebuilt/salvaged motor. I'm leaning towards getting it Gerry-rigged then finding a 304 on the web, which would be a hell of a lot easier if I wasn't on an island in alaska, but as long as the financial adviser is ok with it I'll find the right motor.

First off the Crankshaft has been heat-treated so drilling and re-tapping can be done but not normally with your Standard HS tap and die set........... Welding the hole up is also nothing you want to do. The biggest problem is getting the part in a suitable location with some room to perform the surgery correctly....without pulling the crank from the motor. You'll only get one chance at getting the new hole in there at 90 degrees to accept the heli- coil.

Talk to someone that grinds & repairs cranks or rebuilds motors in your area.......might be easier to get them to fix it.

 

[Hedgehog]

Definitely good advice.

I know a crank shaft is a hard piece of metal, but is is really heat treated? Why do I ask? An engine is a VERY hot hostile environment. I imagine a heat treatment could easily be destroyed in such a place, but I'm also easily convinced that I'm wrong on this subject.

 

[Neuner]

Definitely good advice.

I know a crank shaft is a hard piece of metal, but is is really heat treated? Why do I ask? An engine is a VERY hot hostile environment. I imagine a heat treatment could easily be destroyed in such a place, but I'm also easily convinced that I'm wrong on this subject.

Been a long time since my metallurgy classes for engineering and manufacturing but remember some of the basics. A lot of factors go into the complicated equations including temperature ranges, number or quenches and durations of quench and heating depending on the metal molecules, desired strength vs flexibility, etc.. Metals are usually at a high of 800-1000 degrees during this process. The operating temperature of an engine is mild in comparison but the cycle of heating and cooling thousands of times is usually included in the equations for consideration some how.

 

[Lumpy Grits]

Definitely good advice.

I know a crank shaft is a hard piece of metal, but is is really heat treated? Why do I ask? An engine is a VERY hot hostile environment. I imagine a heat treatment could easily be destroyed in such a place, but I'm also easily convinced that I'm wrong on this subject.

The operational temps of an engine is no way near the temp need to affect heat treatment.
A good tig welder could do the welding with ease. The trick is get'n your 'junk' to the welder.
LG

 

[Hedgehog]

In a the not to distant past they would refurbish crank shaft bearing surfaces by essentially spraying liquid metal on a spinning crank, then machine a new bearing surface on, rebalance and reinstall. This was done during WWII for aircraft engines and it worked very well. I can't see why a similar process (TIG) wouldn't work for new threads. In reality we aren't talking about adding much metal. .... Sorry if I'm beating a dead horse here, I'm just thinking out loud.

 

[Torxhead]

That bad hole may not need any welding as the tap drill size for a heli-coil is larger than the bolt. A ream to that size may be all that is needed along with a countersink to get the tap started. Not really sure just how hard of a metal that crank is but a high speed steel ream and tap can be done in heat treated metal to a point depending how hard it is.

 

[koda]

Hey guys. I finally got a chance to continue putting my jeep back together. It's a 79 cj 7 with 258 and t-150 trans. I started off swapping out the transfer case with a salvaged one I found. While I was it it I decided to do the clutch and pilot bushing. I'm having a hell of a time getting the transmission back in. I get it up and within half of an inch or less from getting the bolts started, but can't get it any closer. I know the clutch, flywheel and pressure plate are lined up, but can't get that last little bit. I tried getting it close, then turning the transmission output hoping it just needed the splines to line up. Anybody have any hints to get them together. Thanks

To your original issue, I had a the exact same problem when I was trying to put mine back together. I could get it within a half an inch but couldn't get it to go the rest of the way. After doing some forum reading, there was a suggestion to have someone pump the clutch pedal while you pushed the tranny back in. I had my kid get in and slowly pump the clutch and was able to slowly work it in.
Hope this helps.