trans-to-bell hsg mounting question

[jocko]

Just noticed the oddest thing - was under the truck to grab one of the 1/2"-13 trans-to-bell mounting bolts (chev 3 speed to 283 arrangement) so I could run to home depot and grab so loonger bolts to help slide the trans in/out - and noticed that of the 4 mounting bolts, the top 2 were inserted from the rear-to-front (i.e. thru trans into the bell orientation - which is what I expected all 4 to be like) but the bottom 2 were inserted from front to rear (i.e. inside the bell hsg side first then thru the bell and into the trans mounting ears). In other words, when I was behind the transmission looking forward - the bottom of the 2 bottom bolts wetre showing, not the heads.

Is this normal?

Also, does it mean the bottom 2 bell housing bolts holes are NOT threaded and that the 3-speed mounting ears are threaded??

Hmmmm.
Thanks, assuming someone has seen this before, but if nobody has, I'm curious what the bottom 2 bolts are actually threaded into, if anything... It appears that the trans has the 2 lower mounting bosses threaded - which worries me because if they are, then the bell hsg must not be - and I'm getting ready to swap transmissions and use the stock bell hsg. If the 1/2" bolts go THRU the bell and the threads are in the trans, then that bell hsg is gonna be junk for the new trans (T5). Never seen a mounting setup like this on a manual trans.

[jocko]

well, i guess if what i'm worried about is true, all I'd need to do is run a bolt thru and then put a nut on either the trans side or inside the bell - if there is enough room. Cripes, this is weird.
I do have a spare bell that has the bell-to-frame mounting positions (like our trucks do) but it has the correct smaller opening and I want the bigger opening (i.e. the incorrect one for a T5) so that I can use the Hamilton adapter plate and solve for input shaft length AND bell index ring size with one adapter. If I don't have BOTH of those problems, then the adapter won't work and I'd need to get the input shaft cut down a bit I believe. Gotta get the whole thing completely apart to see what I'm really working with first though.

Brings up another question - if a T5 is swapped onto a stock bell hsg (i.e. one that has the bell-to-frame mounts like old cars tend to have) is the rear corssmember that normally goes with a T5 required? If yes, should the mid/bell-frame mounts not be utilized connected? (Once read that it is not a good idea to have triple mounting points in the driveline (i.e. engine side mounts, bell hsg mounts, AND a rear trans crossmember - either use the rear crossmember without the bell hsg-frame mounts or vice versa (bell-frame mounts without the trans rear crossmember). Anyone know?

[jocko]

Hey, it's embarrassing when I keep replying to myself! But found a 4-speed cutaway in the assembly manual (an incredibly handy, but difficult to find what you want because it's completely disorganized manual...) that showed exactly what I found on my 3-speed (top 2 trans-to-bell bolts mount thru trans into bell hsg and the bottom 2 trans-to-bell bolts actually mount from the bell hsg side, through it and screw into threaded lower mounting ears on the trans).

Seems this would wreak havoc on the average trans swap because the bell would never have threaded lower mounting holes for the trans (i.e. all modern transmission mount the mounting bolts the same direction - thru trans into 4 threaded bell hsg holes - most moder trans, including muncies, bw's etc - have no threaded holes in the trans for the mounting to the bell, etc). I GUESS it would be ok to use a bolt thru from the bell hsg side then mount a nut on the trans side or vice versa... when mounting a newer unthreaded trans into an older unthreaded (lower 2 holes) bell hsg??? THoughts? I don't know any other way to do it (other than replace the bell hsg with a newer one). Surely someone has run across this problem before...

[geezer#99]

OK I'll bite. Stop talkin' to yourself. You gettin' old timers disease. LOL!!
You're right on the bolts. Not sure why though. No problem putting a bolt in to hold your bottom tranny mounts in place. You might need to drill out the ears on your T5 to use a bigger bolt top and bottom.
As far as mounting your motor and tranny why not side mount motor, side mount tranny at the bell and install one at the back of the tranny too. I did on a 56 with no problems. Had a front mount on the motor though. I never noticed any diff. It's still running like that for 25 years.

[jocko]

yep, will have to drill out the T5 to 1/2" bolt size since T5's are metric. As for why not 3 separate mount locations in line - unless all 6 locating points are perfect and the frame is perfect, etc - there will be extra stress on SOMEthing in the line - whereas with only 2 mounting points, the bell-trans mounting surface would be perfectly true (stress-free). BUT, it's probably nothing that amounts to a hill of beans - as evidenced by your 25 trouble-free years!

I suppose I will have to use a nut on the lower mounting bolts since when I have the T5 and old bell hsg mated up, I'll have no threads in the bell OR the trans at the lower mounting holes. Shouldn't be a problema.

Thanks, I was gettin lonely....

[geezer#99]

If you think about it all the mounts aren't solid. Rubber flexes a bit. The one on the tranny end could be rubber mounted on the attachment points on the frame. Just peace of mind. T5 etc. would be longer and heavier hanging back there.
I tried a torque strap on the driver's side front of the motor once. Kind of like running solid mounts. Crazy torque steer when I was pedal to the metal.

[padresag]

use either the bellhousing mounting or trans rear mounting but not both.
does it matter how it is bolted together just as long as it is secure. it is centred securely (trans) into the b/housing by the frt brg retainer; that aligns it up' the bolts just hold it together. as long as the bolts and or nuts clear the pressure plate then there is no problem. tighten them up and go for a drive
ron

[geezer#99]

Another thought Jocko. Is your crossmember and brackets for your emergency brake gonna be in the way?