Manual Transmission Swap

cadzilla500

cadzilla500

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Maggie Valley, NC
What vehicle(s) do you drive?
1979 Malibu
I'm needing some input on converting my 517" caddy powered Malibu from a TH400 to a 5/6 speed. I'm tired of the old car just sitting in the barn and it's time to resurrect it in pro touring/autocross form. Any help would be greatly appreciated.
 
I would also be interested in hearing some more about this. I know that CadCo sells Chevrolet bellhousing adapters. QuickTime actually has an BOP bellhousing for tremec transmissions, but it is pricey. And then, from what I can tell there are a few flywheels floating around on the forum; I had one for a while but I sold it to another member. You'll also have to whip up a transmission crossmember. That's all the Cadillac specific stuff you'd need.

Otherwise you'll need a new pedal assembly, clutch lines and reservoir, and most likely a custom length driveshaft. And potentially a hole in the floor if your car is column shifted like mine.
 
If you want a 5 speed the TKO600 will fit a Standard BOP manual flywheel housing. I have used that as well as a BOP Quick Time for both the TKO and currently am installing a T56 Magnum.
I've always had my cranks drilled for a pilot bearing but there are adapter bearings that fit the torque converter pilot available. Some cut the trans input shaft off but I always drill the center of the crank deep enough to not need to cut the shaft. I had to run a spacer between the flywheel housing and the tranny on the TKO to get the throw-out bearing height correct. Have not finished the T56 Magnum install yet but have it mated up to build mounts. The TKO will more than likely fit with no floor mods, not so lucky on most T56 swaps. IMG_1948.webp
tko600 02.webp
IMG_4428.webp
 
Here's a pic of the other header. It might be worth pointing out that I just used a hand drill and I think it was a 5/8" bit to drill the pilot hole in the crank deep enough to not bottom out the trans shaft. Here's also a pic of an input shaft bearing made to fit in the converter pilot bore. If you look at the transmission mount you can see how much farther back the mount is on the T56 vs where it used to bolt up with the TKO.
IMG_4426.webp pilot brg.webp
 
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Thanks for the info. What are the benefits of the Quick Time bellhousing over a new/used aluminum one?
 
The Quick Time is an SFI piece and are said to be very accurately made. Both of mine have not required any offset dowels to be aligned with the crankshaft center line. My TKO didnt shift great and I did not check the alignment when I installed it with the Pontiac housing. If you are going with a TKO the stock aluminum one is fine, just check the alignment. I you want a 6 speed no factory housing will work without an adapter. They work for some, but I prefer to not go that route. The aftermarket T56 Magnum is probably needed to handle the torque on a modified Caddy. The TKO600s also aftermarket only are good too. Just going off memory I think the Magnum is good for 700 ft-lbs and the TKO around 600 ft-lbs. I happen to have a Quick Time housing and an aluminum Pontiac housing that will work with the TKO.
 
Was thinking of doing the same thing. BUT, what trans is going to be able to handle the HP AND TORQUE of the little Cad?
 
The Parts Place sells a G body manual transmission conversion kit on ebay. I think you need a BOP bellhousing.
They have pedals and linkage. I don't know how well the T56 fits in the G body trans tunnel. There is a wide ratio version of the M-22 called the M23Z made by AutoGear that has a 2.96 first gear and direct 4th. It wouldn't require trans tunnel surgery.
 
cadzilla500 said:
Thanks for the info. What are the benefits of the Quick Time bellhousing over a new/used aluminum one?
Click to expand...
Date codes if you're racing. Don't know why a piece of stamped steel needs a date codeo_O:confused:. Maybe to sell parts;)!
An aluminum bellhousing would NEVER contain a clutch explosion. And a steel one would not contain it either without a block saver.
 
That M23Z tranny sounds like a bunch of fun. Does anyone know if it has straight cut gears like the old rock-crusher Muncie 4-speed?
 
To piggy back on this thread, I am looking to drop an SM465 behind my newly acquired BBC. It is getting stuffed into an old Toyota Land Cruiser(FJ55) with a tow centric build-up. My SM465 has the cast iron bellhousing.

I looked through this thread:
https://cadillacmagazine.com/forums/threads/manual-trans-caddycarlo.18195/

It recommended lightly modifying a dorman 690-035 for use as a pilot bushing.

My BBC came with a thicker BOP to GM adapter bolted to the back.

My understanding is I can free hand drill the crank with ~5/8" bit to help clear the tip of the transmission. Anyone know how much I need to drill in?

What to do for a flywheel. Is there an off the shelf solution with minimal machine work? Or is Cad Company's version the only game in town?

Last part is will the standard chevy release bearing, fork, pressure plate, and clutch disc work?
 
I thought about doing this on my truck as it was a stick to start with, but the expense and limited availability of parts turned me away. You need a vendor flywheel, and then there aren't many trans that can handle a big Cad. Especially if you want 4WD like I needed.
 
MIHELA said:
I thought about doing this on my truck as it was a stick to start with, but the expense and limited availability of parts turned me away. You need a vendor flywheel, and then there aren't many trans that can handle a big Cad. Especially if you want 4WD like I needed.
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The only part that seems like it is limited is the flywheel.
The clutch parts are off the shelf chevy.
The bellhousing can be stock chevy with BOP adapter. This adds about $100 to the parts list.
The dorman bushing above was recommend with a light bevel put on it.

I think the SM465 will survive behind the cady. It was used in 1 ton and larger trucks. ;)

My 'truck' will be 4wd but more for snow conditions than any true offroading. But the rig(Toyota FJ55) will be on the light side: removing 750lb engine for cady, S10 blazer in size minus the roof from the doors back and minus any body overhang past the rear tires. It normally starts at about 4000lbs, I'll be shocked if I sniff that after the full body rework and drivetrain swap.
 
The SM465 is fine. Down the road you could even swap to an NV4500 if you wanted. For me I would have had to find one first! I had an Nv3500 that would have broken in half.
 
I had an 88 1/2t 4x4 silverado that I had a 500/nv4500 in. I used the turboglide pilot bushing,which I believe is the Dorman one you guys are speaking of. I shortened my input shaft 1/4 in and everything was good..
I had used a Cadco flywheel. The machining quality was like artwork. Very well made. I used that setup for 4 or 5 years and never any issues.
With 3.42 gears and 265/70/16 tires, the 500 would still accelerate from 30mph in 5th gear better than an old 2.2l 5-speed s-10 lol.. And I saw 17-18 mpg on the highway a few times
 
MIHELA said:
The SM465 is fine. Down the road you could even swap to an NV4500 if you wanted. For me I would have had to find one first! I had an Nv3500 that would have broken in half.
Click to expand...
I thought about an NV4500 for about five minutes. I've gone one in one of my other FJ55s and like it.

But two things are stopping me from that route:
  1. Most of my towing/driving is in 'mountain' roads... think scenic Tahoe roads. I rarely get out of third gear in my S10(NV3550) or FJ55(NV4500)
  2. Cost and availability. I could get fresh rebuilt for ~$2500. The last $500 one I bought cost me more than $2000 to get rebuild and resolve issues:eek:

kzhurley said:
I had an 88 1/2t 4x4 silverado that I had a 500/nv4500 in. I used the turboglide pilot bushing,which I believe is the Dorman one you guys are speaking of. I shortened my input shaft 1/4 in and everything was good..
I had used a Cadco flywheel. The machining quality was like artwork. Very well made. I used that setup for 4 or 5 years and never any issues.
With 3.42 gears and 265/70/16 tires, the 500 would still accelerate from 30mph in 5th gear better than an old 2.2l 5-speed s-10 lol.. And I saw 17-18 mpg on the highway a few times
Click to expand...
That is great information. I'm still debating gears and tire size. I'm looking at ~33" to 35".
 
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