[Accuracy]

Hi all.
First post here. But I was looking at my neighbors 74 firebird for sale. He doesn't know much about it because it was a project car from a relative .(I know. Typical story) It has a 350SBC

It has a down lower right reverse 4 speed shift pattern. Some research leads me to believe it could be a truck transmission like sm465 , because the throws do feel kind of long. It also needs a lot of clutch just to get the car moving. Like it has no power down low. I wasn't sure if it was a timing issue or perhaps someone regeared the rear-end drastically juat to work with the 6.55 first gear if it was indeed a sm465

First gear doesn't seem to run out of speed/gear too soon , and 4th seems to cruise around 60mph no problem. It just needs a lot of throttle and clutch to get it moving in 1st. Other than that it seems to drive fine. Except sometimes when I accelerate it feels like a bowling ball in the trunk just rolled and slammed into the left side of the car , with a bang. I'm thinking thats not related to this transmission but Maybe just a bad axle or wheel bearing. Or diff perhaps.

Any one have any ideas of whats in this car before I start bothering him to tear around his car again?

I have attached a picture of the shifter. It is round and straight and comes out of the floor on the correct location.

I am a little worried buying this from him as a project because I don't know how much "custom" work was done to get this odd transmission in there. And if it'd turn into a money pit just to drop a muncie back in.

 

[Injuneer]

Wow! Never heard of the SM465 (SM = Saginaw Michigan), had to look it up. Yes 😵‍💫 , it really has a stump pulling 6.55:1 1st gear. And from the looks of it, with option for two different power takeoffs, it's probably a real “boat anchor”. What rear axle gears do you think it has?

https://en.wikipedia.org/wiki/Muncie_SM465_transmission#/media/File:Munchie_SM465_Transmition.jpg

 

[Accuracy]

Haha yeah. I will go back and try to take pictures of it if I can not find any ID on the casing. No idea of the rear end

 

[EdKnecht]

The shifter does look suspiciously to be right in the center of the hump… yeah 465’s are stump pullers for sure. The shifter on the 465 is pretty big And comes right out of the top of the trans…not sure it would even fit…..although that shift boot looks frickin hugh…

 

[Accuracy]

Yeah. May just be the angle of the photo tho. Heres the orig size. Compared to a factory unit. If not a gm truck trans what else could it be? Japanese one? Haha

 

[joeq]

LOL. A 465? I have that in my 83 C-30 6.2 diesel dually truck. Like mentioned above, I would be surprised if it fit the tunnel.. Plus the crossmember mod, along with the driveshaft and yoke. some-one must've had a lot of extra parts, and time to fab that. And why? Were they pulling a boat with it?. You need-ta crawl under there and snap a couple pics of it, from a couple angles. Amazing what some of these cars had-ta endure in their lifetime.

 

[Aus78Formula]

One of those, Just because it was there in the shed, mods. Probably needs tons a torque to get moving normally which is not the usual place for a high-winding SBC.

 

[joeq]

Granny low needs no torque at all. It's mostly useless.

 

[Accuracy]

Update for those who were curious. I ended up buying the car. The seller offered me a price where I couldn't refuse and just bought it as is.

Brought it home, changed all the fluids.

All I could see on the transmission was 13-52-065-914 and a 88 circle . Headers got in the way of reading any other codes or tags. Upon research looks like this is a 1988 T5 5speed. Potentially pointing to from a ford mustang or Capri?

I found out the rear diff is a POSI 2.41 so makes sense why it was a dog to get moving.

Transmission mount is wild. Looks like previous owner welded in a mount on crossmember at about 30 degrees clockwise. And put a 1/4 2x4" rubber pad down between it.

TL;DR -
Ended up being 5 speed. Not 4. 5th gear is missing. Feels like neutral. Reading online seems like common for snap ring failure and 5th gear sliding out if place.


Is it safe to keep driving without the 5th? Or will I potentially blow up the trans or ruin a potentially good gear,

 

[joeq]

Congrats on your new acquisition. A 2nd gen FB to play with. Lots of parts availability for ya, as long as you have the "long green". (Or in todays currency, would that be bitcoins?)
Anyway, you went from one end of the tranny spectrum, to the other. A 465 is practically indestructible, and a T5 is made of glass. Not rated for anything more powerful than a snail on crutches. But as long as you keep it a 2bbl carb., and don't push on the go pedal too hard, you'll; probably be alright. At least that's what I've been told. I have 2 T5s. A WC, and a non WC. Haven't been able to test them out...yet.
You mention something about the rear mount, and made me think of what I had-ta do, to make mine work.

If your T5 is from an 80s F body, then for some God forsaken reason, GM engineers decided to tilt the tranny CCW about 7° (?), and the bolt pattern on the chebby bellhousing provided that angle. But they tilted the tailhousing mount back the other way, to make it fit the flat cross member. I'm using a WC T5 behind my light duty 301T motor, (in an 84 T/A) and used a conventional BOP bell housing, which necessitated a "wedge" to bolt it to the cross member. Sounds like yours might be the same way. It may sound bush, but it's the logical option, compared to others. At least you got a stick shift.
Here's a photo of my rear mount

It's not pretty right now, but in the "experimental" stages. You'll notice the problematic torque arm that also needs ta be hooked to the tail. Fortunately you don't have-ta deal with that.
Anyway, good luck with your project. As for driving it W/O 5th? If it's not making any noises, you should be OK. And with a 2.41 gear, (?), who needs an OD anyway?

 

[Accuracy]

Congrats on your new acquisition. A 2nd gen FB to play with. Lots of parts availability for ya, as long as you have the "long green". (Or in todays currency, would that be bitcoins?)
Anyway, you went from one end of the tranny spectrum, to the other. A 465 is practically indestructible, and a T5 is made of glass. Not rated for anything more powerful than a snail on crutches. But as long as you keep it a 2bbl carb., and don't push on the go pedal too hard, you'll; probably be alright. At least that's what I've been told. I have 2 T5s. A WC, and a non WC. Haven't been able to test them out...yet.
You mention something about the rear mount, and made me think of what I had-ta do, to make mine work.

If your T5 is from an 80s F body, then for some God forsaken reason, GM engineers decided to tilt the tranny CCW about 7° (?), and the bolt pattern on the chebby bellhousing provided that angle. But they tilted the tailhousing mount back the other way, to make it fit the flat cross member. I'm using a WC T5 behind my light duty 301T motor, (in an 84 T/A) and used a conventional BOP bell housing, which necessitated a "wedge" to bolt it to the cross member. Sounds like yours might be the same way. It may sound bush, but it's the logical option, compared to others. At least you got a stick shift.
Here's a photo of my rear mount

It's not pretty right now, but in the "experimental" stages. You'll notice the problematic torque arm that also needs ta be hooked to the tail. Fortunately you don't have-ta deal with that.
Anyway, good luck with your project. As for driving it W/O 5th? If it's not making any noises, you should be OK. And with a 2.41 gear, (?), who needs an OD anyway?

Haha thanks I'm actually excited. Finding lots of small issues. But it'll be a project that's for sure. Yes! My trans mount looks exactly like that. So seems like mine did come out of a late 80s camaro. I changed the trans oil with atf and seems to shift well. It grinds putting it into reverse seems to be the only issue

 

[ZumpTA]

It grinds putting it into reverse seems to be the only issue

Sounds like a bad synchronizer. Try shifting into 1st or 2nd before Reverse, sometimes that helps.

 

[Accuracy]

Sounds like a bad synchronizer. Try shifting into 1st or 2nd before Reverse, sometimes that helps.

Hmm yeah, I'll try that out!

 

[Injuneer]

I don't think all the T5’s have a synchro in reverse. See this article, scroll down to paragraph under 7th photo (not counting the header photo at the very top):

T5 Manual Transmission

I was working on the truck the other day because it was having clutch issues. While waiting for some parts to get in I decided to take a look inside the transmission. Why? I wanted to see what c…

somanyhobbies.wordpress.com

Also read the paragraph below the 8th photo for an explanation of why the T5 reverse does not have a synchro, while the T56 does have a reverse synchro (and a reverse lockout).

 

[joeq]

Haha thanks I'm actually excited. Finding lots of small issues. But it'll be a project that's for sure. Yes! My trans mount looks exactly like that. So seems like mine did come out of a late 80s camaro. I changed the trans oil with atf and seems to shift well. It grinds putting it into reverse seems to be the only issue

You probably don't know if it's a world class, or non-world class T-5, but the older T5s took gear oil. The WC uses a composite syncro assy, which requires the ATF. Maybe the ATF is affecting your reverse (?).

 

[Injuneer]

This thirdgen.org site has a good thread on the T5, including detailed lists if part #’s for various applications (e.g. post #6). Also a lot of posts debating the gear oil vs. ATF vs motor oil (there are apparently some shop manuals out there that recommend motor oil, because that's what GM used to achieve a higher fuel economy number).

T5 FAQ - Everything we know about the T5 - Third Generation F-Body Message Boards

Transmissions and Drivetrain - T5 FAQ - Everything we know about the T5 - Lets see if we can come up with a definitive list of everything known about the T5. I'll try to keep it neat, but I'm just going to list things as they come to me right now. GM used the Borg Warner T5 5-speed overdrive...

www.thirdgen.org