55.2-59 Help with my automotive ignorance pls

[Phungki]

So I might have a line in a donor vehicle which is pretty cool since I’m getting close to that stage of the build. I’ve been researching of course the ins and outs the best I can on this forum and other google searches. The vehicle is supposed to have a running 350 but who knows how good lol.
I’ve read that whatever angle the engine/tranny points down is the same angle that the rearend points up. If I’m wrong pls correct me on it. I’ve also rear that ppl shift the motor to the passenger side to allow for steering and headers. Makes sense sorta. Doesn’t that put it out of alignment with the rearend? I thought Chevy rearend were centered. Mine is out of a 76 trans am. Or is it just not important?
Also what mounting brkts, engine and transmission, should I be looking to using? A link would be helpful. My truck was a 6 cyl manual transmission. So I’m pretty sure a 350 with a auto tranny won’t bolt right up either. I’m not sure what transmission is in it yet just know it’s automatic. It’s coming out of a 70 something Monte Carlo.
Your advice is always appreciated
Except if you tell me to make my own brkts. Not going to happen

[mongocanfly]

Driveline angles need to match....a typical setup would be engine angle down 3deg..rear diff up 3deg..
No need to offset engine unless you have clearance issues,but offset is really no different than up and down..
I'm satisfied you'll need v8 mounts..but more info on the truck you have is needed...

[Phungki]

Right, 56 GMC stepside

[Phungki]

Originally Posted by mongocanfly

Driveline angles need to match....a typical setup would be engine angle down 3deg..rear diff up 3deg..
No need to offset engine unless you have clearance issues,but offset is really no different than up and down..
I'm satisfied you'll need v8 mounts..but more info on the truck you have is needed...

So when you say “offset is really no different than up and down” what exactly do you mean?

[1project2many]

Hmmm... for whatever angle is between the driveshaft and trans there has to be an "un-angle" at the other end. If you shift the engine or the rear end side to side the angle and "un-angle" (or cancelling angle) work out automatically because everything is tied to the frame rails. But when you look at the "up and down" between trans and driveshaft, then between driveshaft and rear, that requires a little thinking.

These show why you need cancelling angles at both ends and show some of the checks that will apply to the design and construction phase.

https://www.youtube.com/watch?edufil...&v=gmV4qwLfOMY

https://www.youtube.com/watch?edufil...&v=DDmz0tibVGM

https://www.youtube.com/watch?edufil...&v=TUFzehQBDPI

[Phungki]

Originally Posted by 1project2many

Hmmm... for whatever angle is between the driveshaft and trans there has to be an "un-angle" at the other end. If you shift the engine or the rear end side to side the angle and "un-angle" (or cancelling angle) work out automatically because everything is tied to the frame rails. But when you look at the "up and down" between trans and driveshaft, then between driveshaft and rear, that requires a little thinking.

These show why you need cancelling angles at both ends and show some of the checks that will apply to the design and construction phase.

https://www.youtube.com/watch?edufil...&v=gmV4qwLfOMY

https://www.youtube.com/watch?edufil...&v=DDmz0tibVGM

https://www.youtube.com/watch?edufil...&v=TUFzehQBDPI

Great thank you. Any idea on mounting brkts for engine and transmission?

[mongocanfly]

if you offset the engine and trans and keep engine and trans centerline parallel (lines a and b) to the pinion centerline ,then the angles cancel each other out....red marks.
same as with 3deg up ,3deg down...the angles cancel each other out
but I don't think youll need to do any offsetting
those videos above show what happens when its not right

[mr48chev]

56 trucks were designed for small block V8 engines so it is basically a bolt in an if you decided to keep the three speed and get a cast iron 56 --------V8 bellhousing with the clutch fork on the drivers side it could actually be a bolt in that used to be done in a day all the time back in the 60's 70's and 80's when a lot of guys were driving those trucks as daily drivers.

The automatic makes things a little more time consuming as you have to remove the crossmember under the bellhousing for clearance and install new mounts in the front and a new crossmember under the trans.

If you aren't putting the axle on top of the spring to lower it a bunch you can set the pinion angle to match the angle of the stock rear end and come out real close to perfect. If you were just changing engine and trans and not the rear axle pinion angle wouldn't even be in the discussion.

[Phungki]

I’m not keeping the original trans. I’m opting for power brakes under the cab instead of the manual transmission.
I have to remove the entire transmission crossmember? Seems like a substantial part to the integrity of the frame. I’ve found other trans cross members that can replace it but it seems wimpy in comparison. Or can I just notch it? I’m sure it will be more clear when I go to mock it up but I don’t want to have to stop and wait on a part. I rather have what I need there at the time.

[_Ogre]

x-member is substantial as it supports the spring brackets and cab mounts, along with the bellhousing motor mounts found on our trucks. when the po cut mine out, the front of the cab sagged down to the frame. pretty much frame flex without it, as there is no bracing from front to back over the driveline
when i rebuilt truk i fabbed up a substantial trans mount x-member to support the cab mounts.

[Phungki]

So if I went with a Sbc and a 700r4 transmission I need to remove the existing trans x-member and fab up a new one?
Has anyone used the under cab mount master cylinder w/brake booster kits available? Did you have figment issues with the trans x-member?

[Ironworking]

Originally Posted by Phungki

So if I went with a Sbc and a 700r4 transmission I need to remove the existing trans x-member and fab up a new one?
Has anyone used the under cab mount master cylinder w/brake booster kits available? Did you have figment issues with the trans x-member?

Do you really want to have your MC under the truck? Imagine having to check the fluid or servicing any of the parts. Some things the factory designers did were just not top notch. A MC under the floor was common place back in those days. It was nonsense too! IMHO

[Matt_50]

Unless you want one of those slick clean firewalls and pop open your hood at shows... I think most of us just mount the MC on the firewall.

[MiraclePieCo]

Originally Posted by Ironworking

Do you really want to have your MC under the truck? Imagine having to check the fluid or servicing any of the parts. Some things the factory designers did were just not top notch. A MC under the floor was common place back in those days. It was nonsense too! IMHO

I've put MCs under the floor. I just fab'ed a simple plate in the floor for access.

[Phungki]

I have been thinking about putting it on the firewall as well.

[Russell Ashley]

I recently had to pull my distributor out to repair it and it made me glad that my MC was under the floor and not in my way. If your brake system is all new how often will you have to add fluid, especially if you have four wheel disk brakes. Yes, if you ever have to work on the master cylinder it will be more trouble, but the clean firewall and access to your steering and shift linkage is worth the trouble to me, not to mention the possibility of getting brake fluid on your firewall paint.

[Phungki]

Originally Posted by Russell Ashley

I recently had to pull my distributor out to repair it and it made me glad that my MC was under the floor and not in my way. If your brake system is all new how often will you have to add fluid, especially if you have four wheel disk brakes. Yes, if you ever have to work on the master cylinder it will be more trouble, but the clean firewall and access to your steering and shift linkage is worth the trouble to me, not to mention the possibility of getting brake fluid on your firewall paint.

Yeas there seems to be pros and cons to either way. I think it will be tight with dual exhaust with having it under the cab which I do intend to have. I’m still debating the whole thing and taking in every ones advice.
Thank you for yours

[dsraven]

what kind of truck are you building?
-show truck with super clean engine area and lots of chrome? hood up all the time to show off the goodies? in that case stick the master under the floor and make a nice looking trans cross member, engine mounts, steering parts etc etc.
or
-a nice looking truck that will turn heads but you're not polishing valve covers every weekend? put the master on the firewall where you can get at it and also where the pedal linkages and etc are easier. no farting around with residual brake vales and a bunch of linkage pivots that wear etc.
just my opinion, it's your truck.
a small block chevy engine (or a big block for that matter) will all have the same bell housing bolt pattern and engine mounting configuration points. you could literally take a 283 engine out and slip a 400 in and the truck wouldn't know the difference until you hit the gas pedal.
the old trucks used a bellhousing that had the rear engine mounts under it, as you know, so when you install the automatic you will likely want to get rid of the old cross member under the trans to allow room for the automatic. like ogre says, fab up a substantial mount in the area somewhere so the frame flex doesn;t screw with the cab mounting and crack the floor or make the doors close different all the time. a welder could easily make something for you once you have the engine and trans hing in there as a mock up situation.

[Phungki]

It will be a very nice driver, that’s my plan anyway. Not a real show truck by any measure but I could take it to the local shows and not hide my head in shame...hopefully. But again that’s not why I’m building it anyway. Kind of a bucket list thing for me I guess.
I can’t wrap my head around how a different auto transmission will sit on the old crossmember and why I have to replace it. I’ll just have to drop it in and see what’s what I guess. Seems like the old cross member drops down a bit but maybe not enough?

[dsraven]

yeah, prolly not enough room under the trans to get the thing in there as a unit, can't totally remember. anyway, you could cut the center out and weld on some flanges to allow you to bolt it back together after, possibly just a little lower for clearance.or just fab up a whole new bolt on part from channel or tubing with flat bar on the ends to fit the flange on the frame.

[Phungki]

Originally Posted by dsraven

yeah, prolly not enough room under the trans to get the thing in there as a unit, can't totally remember. anyway, you could cut the center out and weld on some flanges to allow you to bolt it back together after, possibly just a little lower for clearance.or just fab up a whole new bolt on part from channel or tubing with flat bar on the ends to fit the flange on the frame.

Yeah having no experience doing this particular type of thing I’ll just have to see what needs to be once I try to put it in.

[_Ogre]

i installed a 03 mustang hydroboost under my floor then added a remote reservoir from a nissan quest (ford joint venture)
if i had it to do over, i'd use the stock mc and cut the back off, then remote mount the new mc a foot back
look at orrieg's build

[Phungki]

The more I think about it, the more I think I’m going to just put in on the firewall. I can appreciate all the work you guys have done to clean up the firewall but it’s not as important to me to be obstruction free. I haven’t ordered anything yet as far as MC goes so I’m still pondering. Appreciate the pics tho. Truk is sweet

[Ironworking]

Originally Posted by Phungki

The more I think about it, the more I think I’m going to just put in on the firewall. I can appreciate all the work you guys have done to clean up the firewall but it’s not as important to me to be obstruction free. I haven’t ordered anything yet as far as MC goes so I’m still pondering. Appreciate the pics tho. Truk is sweet

I got my MC at Oreilly's for around $40. I got the swinging brake and under-dash mount for less than $80 here https://www.ebay.com/itm/Universal-U...72.m2749.l2649

And it all went reasonably well.

P.S. I made me a template from the bolt pattern and that helped immensely. Also, on my 58, i only needed the first two holes, so i cut the rest of that bracket off.

[mongocanfly]

keep in mind the firewall wasn't designed for the weight and force of a firewall mount master...id seriously look at firewall reinforcing if you go there
ive got a buddy that mounted his on firewall..and its amazing how much flex the firewall panel has when he gets on the brakes just from bleeding...hes added some brace rods but its still moving...he said hes gonna fab a plate to try and spread out the load some