Bolts as bell housing fasteners?

[logician]

I noticed that that the 2.7L engine (magnesium case) in my race car uses bolts instead of studs for the upper two fasteners attaching the 901/911 transmission to the engine. Is that the way that the earlier cars with 901/911 transmissions came? Is there any reason not to use studs there instead, maybe clearance problems?

-Juan

[911SCfanatic]

I would think you would want to use studs so that you're not repeatedly threading bolts into/out of the magnesium. Over time, I would imagine that using bolts would be hard on the threads.

[Henry Schmidt]

Early cars came with two bolts ( one allen at the starter and one 10x15mm on the other side) and you can use studs if you like.

[Walt Fricke]

If you Helicoil the case threads you can avoid the issue of wear in screwing into and out of the magnesium alloy case. At least one of my cases had this done to the two upper threaded holes before I got it - don't know if this was factory or a repair. Sometimes, at least for guys who pull the engine without pulling the tranny, having a bolt or two can make lining things up easier, though I prefer studs.

Walt Fricke