1970-W30

Every now and then somebody asks about a replacement transmission for their 61 to 63 Cutlass to replace the troublesome, inefficient factory stock automatic. The readily available T5 5 speed overdrive is a great, lightweight (77 lbs.) transmission for these cars. The problem is that the transmission tunnel is pretty small, so a bit of modification is needed before the T5 will fit.
I used a T5 from an 84 305 V8 Camaro (tag #1352-70), it has a 2.95 first gear and a .73 fifth gear overdrive. I’m not finished with the project yet, the T5 is just bolted to the bell housing, no clutch or flywheel installed yet. I just wanted to do a dry fit to see what needed to be modified to get it to fit. As the pics show, a 2x8 inch area out of each side of the tunnel needed to be taken out to get the T5 to fit, besides a 4x5 inch hole for the shifter. The shifter for this GM T5 is located 21 inches back from the front of the T5, almost a perfect position to allow me to use the factory console without having to modify or move the console itself. The shifter boot will be held down by the removable modified spare shifter plate I found in a wrecking yard out of another 63 Cutlass, making it look factory installed.
If a T5 out of an S10 is used, two things have to be taken in account, first, many of the S10 T5s have a very low 4.03 first gear, way to low to be useful, secondly the shifter is located to far forward, requiring a shifter stick with a very long backward sweep so it can be reached without having to stretch for the shift lever. In my opinion, it’s not worth using an S10 T5.
I put the drivers bucket seat back in temporarily and a trial fit indicates a 10” long lever either straight or maybe with a 2” backward sweep is going be a perfect fit. In my case, a 61-63 Skylark, air cooled 2 speed auto had been previously put in the Cutlass, it is a full 13 inches shorter than the T5 replacement. When I have the front driveline shortened, I’ll have the shop use the GM T5/350Turbo yoke that came with the transmission, the factory yoke does not interchange. The Camaro T5 is mounted 17 degrees offset, because of the offset drilling in the Chebby bell housing, thus the shifter has a 17 degree bend the other way in it, not good when the trans is remounted straight up. The shifter is also one piece, with an ugly screw on stick, no way to easily modify it. What I did was buy a used shifter without a lever, from a Mustang T5 on Ebay, these Mustang shifters are straight up and designed to use a bolt on lever, aftermarket levers in various configurations, chrome, round, flat etc. are readily available. The 17 degree tilt is built in the transmission crossmember mount also, so a modified mount has to be made. By now you might be thinking, why not use a straight up Ford T5? A couple of reasons come to mind, first an adaptor plate would have to be used, from GM bolt pattern to Ford pattern, that’s $200 plus shipping from D&D. The plate also moves the trans back another 5/8 of an inch or so, space is already very tight, the farther back you go, the smaller the hump area. And lastly, there is a big price difference, my GM T5 was only a $100 from Craigslist. Admittingly that was a super buy for a T5!
Also, I almost forgot to mention, after 50 years, the pedal pads are usually shot, no repros are made, but pads from a 3 speed 58 Buick Special from Steele Rubber fit almost perfectly, a little grinding to remove the sharp edge and square up the pedals are all that’s needed to get them to fit!
This is what I have into the project so far to make the change from an auto transmission to manual, I’ll be under a thousand all in when I’m finished;

Clutch linkage, pedals, bell crank assembly. Ebay $200
New clutch fork pushrod swivelEbay $10
Output yoke: came with T5 $0
Boot; 4” x 5” Summit SPE-6283 $10Rebuilt Clutch/Pressure Plate/ Bearing $125
1984 Camaro 305 V8 T-5 trans. Craigslist $100
Brake & clutch pedal pads (Steele Rubber) $51
Shifter, bolt on stick style/no leverEbay$32
Used flywheel, bolts$125
10” chrome shift lever Summit or Ebay$94Lokar white 5 speed ****$25
Labor to shorten drive shaft ??
3 Qts Red Line MTL fluid$45
Machining to lighten flywheel??
New carpet, (a might as well)Ebay$155

young olds

keep us updated with install pics

young olds

what did you do about the angle cast into the mount pad on the tail housing?

1970-W30

The modified transmission cross member was finished and trial fit today. I modified the angled tail housing mount pad by grinding down the low end of the pad about 1/4 to 1/2 inch and using 4 flat washers on the other side to almost eliminate the angle. The rest of the angle was taken care of by the cross member mods as the pictures show. There are two sets of holes for the cross member in the sub frame, the rear set for line up the cross member just right for the T5 transmission. So now the dry fit of the T5 is done, next is the final installation of the flywheel, pilot bearing, clutch assembly and having the driveline shortened approximately 12.5 inches. The console required moving back a little over an inch or so to get shift lever near the center of the hole.
A 10" Lokar shift lever will place the shifter right about where I like it.

joe_padavano

I'm afraid that the flat plate you used on the crossmember will make a nice leaf spring, but not such a great crossmember. There's a reason why the stock crossmember has a channel shape. You might want to consider adding some vertical webs to the flat part to increase stiffness.

1970-W30

Yes, that thought had crossed my mind, welding a piece of 1/8" thick x 3/4" angle iron on the flat plate, I'll do that when I take it back apart for the final time to install the clutch, pilot bushing and flywheel.

1970-W30

Well, the project is finished, I did have to move the console back a little bit to get the shifter located correctly. Even though the shifter and boot in the console isn't, it "looks" factory correct. I'm pleased with the project, with the 5 speed it feels like the engine picked up a bunch of horsepower and freeway cruising at 80 is now only 2450 RPM not 3400 RPM like it was previously....... Finding a stock 63 Cutlass clutch assembly was impossible, Phoenix Friction Products came up with a 10" pressure plate from a late Ford flathead V8, part # NCA0779. It was a direct bolt on with out having to have the flywheel re-drilled. The 10" disc (1 1/8x26 spline) came from Speedway Motors #910-15644.

young olds

looks good

joe_padavano

Nicely done. To confirm, that's the F-body tailhousing and shifter location? Are your seats all the way back in that photo? I've got the bench in my wagon and need the shifter to clear it, even with the seat forward (not that I'll ever drive it that way).

young olds

if your keeping the bench do an s10 tail. 1970-w30, how did the driveshaft come out?

1970-W30

Joe, yes it's an "F" body, 84 Camaro, tail shaft and shifter location. The seats are all the way back. A Ford tail shaft would have located the shifter forward about 1.5 inch compared to the F body tail shaft. Ideally, a GM T5 with the Ford tail shaft would have been perfect for me, I wouldn't have had to move the console back any, but money wise, I had to draw the line somewhere. As it is now, I still have a bend to the back in the shifter lever and it feels very comfortable, an S10 tail shaft housing would require a stick with a major back bend in it to avoid a long reach for it, but would easily clear a bench seat....
The driveline did give me problems, the original driveline has a floating carrier bearing, not a problem because the trans output yoke is bolted to the trans output shaft so it can't move. The T5 has the conventional sliding yoke, which means the front shaft could now drift backwards and the rubber carrier bearing support can move out of its housing. Not good. The front of the back driveline section is where the factory slip yoke is located. I had the front section shortened 13 inches to compensate for the longer trans length and had a carrier bearing that was solidly connected rubber unit installed. The new carrier bearing assembly had an inch lower mounting pad, which required more fabricating for the carrier bearing cross member, and combined with the shorter shaft made the angles wrong, plus the driveline shop did not balance the shaft correctly. Had the shaft assembly re-balanced, and got the front u-joint angle to 1 degree, now it's Ok. If I had to do it again, I would have a one piece driveline made up utilizing the factory constant velocity u-joint assembly. It's definitely a pain because of the factory pinion angle and transmission pinion angle relationship, there's only so much you can do to adjust the pinion angle on the factory rear end, hence the constant velocity u-joint to compensate for that. I still might have a one piece made up, I have an extra spare constant velocity u-joint assembly.