D750 Main Bearing Carrier Bolts

[Schmotown]

I am reassembling my B7100 with the D750 engine. I am installing the original bolts on the (3) main crankshaft carrier bearings and torquing to 23 ft. lbs. Im using a "click type" torque wrench correctly set to 23# but it feels like the bolts are stretching. I switched to a beam type torque wrench and it feels like they are still stretching and I cannot reach the 23 ft lb mark on the scale. I stopped because this doesn't feel right and I dont want to snap a bolt.

Wondering if these are a one time use bolt.

Thanks for any input.

Larry

 

[TheOldHokie]

I am reassembling my B7100 with the D750 engine. I am installing the original bolts on the (3) main crankshaft carrier bearings and torquing to 23 ft. lbs. Im using a "click type" torque wrench correctly set to 23# but it feels like the bolts are stretching. I switched to a beam type torque wrench and it feels like they are still stretching and I cannot reach the 23 ft lb mark on the scale. I stopped because this doesn't feel right and I dont want to snap a bolt.

Wondering if these are a one time use bolt.

Thanks for any input.

Larry

I would be would be more worried about the threads in the crankcase. Whatever it is it doesnt sound right.

Dan

 

[Schmotown]

I would be would be more worried about the threads in the crankcase. Whatever it is it doesnt sound right.

Dan

Thanks, I need to do some research on these bolt.

 

[TheOldHokie]

Thanks, I need to do some research on these bolt.

If you cant pull up 23 lb-ft there is ZERO chance of snapping a bolt. Check the internal threads in the crankcase. I suspect they have pulled out.

Dan

 

[Lil Foot]

Agreed!

 

[North Idaho Wolfman]

If you cant pull up 23 lb-ft there is ZERO chance of snapping a bolt. Check the internal threads in the crankcase. I suspect they have pulled out.

Dan

The main carriers on these engine do not thread in to the block, they thread into themselves.

 

[North Idaho Wolfman]

I am reassembling my B7100 with the D750 engine. I am installing the original bolts on the (3) main crankshaft carrier bearings and torquing to 23 ft. lbs. Im using a "click type" torque wrench correctly set to 23# but it feels like the bolts are stretching. I switched to a beam type torque wrench and it feels like they are still stretching and I cannot reach the 23 ft lb mark on the scale. I stopped because this doesn't feel right and I dont want to snap a bolt.

Wondering if these are a one time use bolt.

Thanks for any input.

Larry

They are not one time use bolts, none of the engine bolts are.

 

[TheOldHokie]

View attachment 165593


The main carriers on these engine do not thread in to the block, they thread into themselves.

View attachment 165598

Whatever - check the internal threads.

Dan

 

[Lil Foot]

The main carriers on these engine do not thread in to the block, they thread into themselves.

Then I would suspect them.

 

[Schmotown]

Check the internal threads in the crankcase. I suspect they have pulled out.

Dan

Dan,
I am referring to the bolts that connect the two bearing halves that encase the crank bearings. Are you referring to the single bolt that locates the main crankshaft carrier bearings in the block?
Larry

 

[North Idaho Wolfman]

The chances that he has stripped out the threads in those would be really really slim to none.
I've never seen any of those carriers stripped.

 

[TheOldHokie]

The chances that he has stripped out the threads in those would be really really slim to none.
I've never seen any of those carriers stripped.

Why wont they tighten?

 

[TheOldHokie]

Dan,
I am referring to the bolts that connect the two bearing halves that encase the crank bearings. Are you referring to the single bolt that locates the main crankshaft carrier bearings in the block?
Larry

I sm talking about whatever does not tighten.

 

[Schmotown]

Why wont they tighten?

Wolfman's comments makes sense, I think I'm being too cautious. I'll do a mock-up on my vise and torque a couple of bolts to 22# and see what if "feels" like when the torque wrench clicks before going back to the engine. I'll report back. Thanks.
Larry

 

[TheOldHokie]

Wolfman's comments makes sense, I think I'm being too cautious. I'll do a mock-up on my vise and torque a couple of bolts to 22# and see what if "feels" like when the torque wrench clicks before going back to the engine. I'll report back. Thanks.
Larry

Have you never tightened a bolt?

 

[North Idaho Wolfman]

Nevermind the crotchety old man behind the curtain!

 

[Schmotown]

Have you never tightened a bolt?
View attachment 165599

Mr. Hokie,

I'm 78 YO and if memory serves correctly I think I can recall tightening at least one bolt or maybe two, maybe.....

Anyway, I removed the bolts from the carrier and the bolt that won't torque is stretched, photo is attached. I'll replace all six and hope that the female threads are okay.

Thank to all for their replys.

 

[TheOldHokie]

Mr. Hokie,

I'm 78 YO and if memory serves correctly I think I can recall tightening at least one bolt or maybe two, maybe.....

Anyway, I removed the bolts from the carrier and the bolt that won't torque is stretched, photo is attached. I'll replace all six and hope that the female threads are okay.

Thank to all for their replys.

View attachment 165620

Those look like some sort of torque to yield bolts.

So only one of them will not tighten?

Dan

 

[Schmotown]

I've searched for any specs for those bolts and don't find any info. The web says that TTY bolts were first used in the mid 80's. My tractor is an 1984 so not sure. Mr. Wolf says that they are not one time use bolts which sounds right due to the tractors age.

All 6 of the bolts felt odd while torquing to specs. The pull on the wrench did not feel linear, too much rotation of the bolt with very little movement of the foot pound scale. Torqued tons of bolts in my job so I know when something doesn't feel right and it's time to stop and find out what the problem is.

Thanks, Larry.

 

[North Idaho Wolfman]

You have the old style of bolts, and yes they are know to stretch over time.

This is the newer style of bolts.
They are a replacement, and they are getting very hard to find.

Kubota #15381-04540 BOLT, BEARING CA

BOLT, BEARING CA

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