Overhauling trans cross member threads

[amc78cj7]

The stock trans crossmember is held on by 4 bolts (3/8") on each side of the frame. When I went to remove these 7 of the 8 bolt heads snapped off. As a result I have drilled out the remaining bolts, albeit some may be slightly off center by maybe 1mm. I drilled them to 5/16. Would you just retap these holes knowing that some of the old bolt thread might still be in place? Would you overdrill and use a heli-coil/threads? Overdrill and go with 7/16 bolts instead of the stock 3/8? There is really no access to the inside of the frame so making new nutserts from the back side is not really an option.

 

[bax]

Yes I would just re-tap and go with original size. The bolts are loaded in sheer so after everything is snugged up there is really not much load on the threads.

 

[zimzimma]

If you have access to a welder, another option is using weld nuts. Mcmaster-Carr has them in 3/8-16, 50 for $13. When I broke all the heads off of the bolts holding on the fuel tank skid plate these worked well.

 

[broncnaz]

Heli coil would be pretty hard to do because the frame is not thick enough to hold them. As was said either try to retap in the current size or just go up to the next size. If they are a little off it doesnt matter there is adjustment availible in the crossmember.

 

[amc78cj7]

If you have access to a welder, another option is using weld nuts. Mcmaster-Carr has them in 3/8-16, 50 for $13. When I broke all the heads off of the bolts holding on the fuel tank skid plate these worked well.

Thanks, but I don't think the weldnuts would work well in this application since the outer frame surface has to be flat (no weld pool) and there is no access to the inner frame to get a wire.

 

[farnorthdan]

when we removed the crossmember holding up my Tcase one of the bolts broke. We drilled it out and used a though bolt and nut, worked great.

dan