Avanti T5 conversion

[MarcD]

My ‘66 Avanti (327/Powershift automatic) is pleasant to drive, but I know it’d be a blast with a manual trans, preferably a five-speed. I’ve  seen articles on converting Studebaker Avanti’s using t-56’s and six -speeds, but i prefer the lighter and more compact World Class T5. I’ve converted early Mustangs and a Datsun V8 240Z using T5’s; with a moderate power engine (and a 68 year old driver) they’re plenty stout. I’m thinking a bellhousing/trans from a late ‘80’s Camaro/Firebird would be a good bolt on to the existing Chevy engine, but not sure about shifter location or rear trans mount.

I’ve accumulated all the manual shift pedals and clutch linkage parts needed, but would really appreciate hearing from someone who’s done this installation. Past experience tells me there’s lots of details involved and parts choices to make.

Thanks!

Marc

[Avanti83]

Did a T56 in my 74 that was originally a four speed. There is no reason that you can't use a five speed although the 6 speed put the shift handle in the correct location. The five speeds have several positions so you can find one close. SBC's up through the early 90's use the same bell housing configuration so you just bolt it on. A couple of words of caution, some early cranks were not drilled for the output shaft bearing - check yours. Secondly, some T5 bell housings were indexed at an angle. Find one that the shift lever is straight up, generally most were.

I'd chose an hydraulic throwout bearing for this setup, however I used the standard T56 hydraulic on mine as the 6-speed setup is pretty easy to install once a housing is built. The T5 is entirely different. 

I've got a ton of pictures and forum posts both here and on the SDC website about what I did.

Muck around in Bob's site and I think you'll most/all of what you need. We still need to use this resource more.

https://www.studebaker-info.org/rjtechdec2017p1g.html

As an aside - modifying the rear mount is trivial and also change to urethane mounts when you convert and after you've driven it for a while you might want to change the rear gears and add a posi if you don't have one now. I won't drive a manual in these cars without a posi. No fun and I'm 77 yo. sweetolbob on the other site FYI

Let me know what you need and I'll try to point you to where the data exists. It's available.

Underside

Topside

Edited January 15, 2020 by Avanti83

[MarcD]

Hi Bob

Thanks for the quick reply and words of advice! Your beautiful work was part of my inspiration to pursue the conversion, and I also reviewed the Spring/summer ‘09 article.

My ‘66 (80k miles)actually has the original, somewhat tired 327, which I plan to retire to a display stand and replace with an ‘89 Camaro 305/World Class T5 driveline currently residing in a friend’s garage. I know the 305 gets no respect with the hot rodders, but my dad had an ‘89 Firebird with same driveline, and it had enough suds for me!

The big question is will the shifter align well with the console opening? The Camaro WC T5 is the “furthest back” shifter ‘box (compared with the S-10 and Ford T5), but I do believe the Camaro used the canted bell housing, with the shifter assembly aligned straight up. May I ask what your concerns were about that setup?

I believe the critical dimension will be the distance from the bell housing end to the centerline of the shifter itself. The Avanti magazine article is a T-56 behind a Stude engine with an adapter plate; that may not be the same set of dimensions as an SBC Avanti II, like ours. 

Do you happen to know what that bellhousing-to-shifter CL length is on your T-56 setup? That would be REALLY good to know!

My car currently has the Stude tapered axle open diff rear end with 3.76 (I think, been a while since I looked) gears. Your advice about a posi, along with the notorious tapered axles on an old car has me considering other options.

I await input, comments and laughter as appropriate!

Thanks,

Marc

[Avanti83]

Marc

I found this on T56 dimensions on-line.

 32 1/2" long    25 1/2" Bellhousing flange to Trans mount
        Wiring hookups include backup lights, VSS, CAGS, and
           Reverse Lockout (none of the wiring hookups are necessary
                                    for proper transmission operation)
        Shifter is located on the Tailshaft 29" back from front of
            bellhousing flange

I'd have a hard time measuring mine currently as it's in storage. It's in my polebarn but put away for the winter.

When I first started to think about a T5, I was told to look for the non-canted one. There was no explanation but the comment stuck with me so I passed it on. You have one so you'll know if there's an issue. I was lucky enough to buy the T56 on craigslist new from a guy building a drag car drag car that wanted to change to an auto and it wasn't selling so he gave me a good deal. It made the decision easy. I did need a special flywheel to bolt it to my 74 engine but you won't have that problem with your setup.

If your rear end is in decent shape you might just want to try it. I believe the newer 44's (flanged axles) have a heavier axle and higher spline count as well as bigger brakes. If you have a pick a part locally the drive shafts from 70-90's Camaro's had length variations that were in the ball park to get me going. I did a custom length as the ones I found were just not close enough. You can probably find an Avanti rear end if you put out the word.

Good luck, I don't have many miles on the 74 but it's a blast to drive, brings back the "old days".

Keep asking if I can be of further assistance.