Why not just lower my tailshaft to get my transmission to “fit” in the tunnel?
This is not a good practice, even though some people will tell you “it’s just fine”. A little bit (1/2”) is probably fine, but much more than that, and here’s the issues
you’ll have to consider:
- Fan to shroud clearance
- Distributor to firewall clearance (GM)
- Lower hanging exhaust
- Unacceptable driveline angles
Keep in mind that lowering tailshaft changes the angle of the engine also. The front of the engine will be higher (fan to shroud clearance, and distributor to firewall clearance).
This, in turn, affects the angle of your headers/manifolds (lower hanging exhaust). Also consider that if you currently have a complete exhaust system, the pipes may no longer bolt up properly to your
headers/manifolds. Lower hanging exhaust also means lower ground clearance. This is also not an acceptable appearance option.
Now the bad news. Your driveline angles will be all messed up, and you can EXPECT driveline vibration problems to work out.
So, do yourself a favor, and don’t lower the tailshaft to get the transmission to fit. If you’re only lowering a little, then you can probably get by ok. But anything more than 1/2”
(give or take a bit), you will need to address the above issues.
So, what are your options? Unfortunately, not many. If the transmission won’t fit with a properly driveline angle, you’ll need to open or “lift” up the tunnel. Here’s some pics of some solutions; both quick-n-dirty, and very elegant.