Transmission Upgrade To A Tremec TKO600

The Cobra has been driving great for 15 years. Not a lot of miles on it, but around 1000 per year - all local stuff; no cross country trips yet. Rowing the gears is fun, but I've always felt I was short one. The four speed toploader has worked great and has no problems. My main issue is I run close to 3000 RPM when cruising at 60 MPH. I've been thinking about getting a Tremec TKO for quite a few years to get overdrive. I finally pulled the trigger and got one (the Tremec TKO600 with 0.62 overdrive).

As I'm putting the TKO behind an FE block, I also needed to get the short input shaft kit and install it on the tranny. I also chose to take advantage to upgrade to an input shaft concentric hydraulic secondary throw-out bearing. With the Toploader I had simply used the stock mechanical throw-out fork and bearing, but had connected the fork to a hydraulic secondary slave cylinder which was then attached to the frame of the car. While this worked fine (though I did break the shaft on the slave cylinder once and had to speed shift home), I've always wanted to change to a concentric throw-out bearing. It was the right time to do it.

This page documents the tranny upgrade.

First things first - remove the shift boot and shift lever.

Here's a "before" picture - the drive train as it has been since the original build.

Step 1 - remove the drive shaft - all 13" of it!

The tranny crossmember has been removed - I've got it supported by a regular car scissor jack.
As a side note - I am working from the pit in my garage. I've got the car positioned such that the jack is right at the edge of the pit

I put a steel pipe over the shifter hole in the tranny tunnel and looped a couple nylon straps around the tranny and around the pipe. I then moved the car backwards over the pit, removed the bolts holding the tranny to the bell housing, pulled and lowered the tranny into the pit.

With the Toploader removed, one can see the clutch fork, throwout bearing, and, on the left, the slave secondary cylinder that pulls on the clutch fork. This is all being replaced by the new input shaft concentric hydraulic throwout bearing.

Just another view of the removal process.

Here's the old Toploader (red, on right) and the new Tremec TKO600 (on left). It's pretty clear the TKO was based on the Toploader - almost all dimensions are identical - bolt placement, shifter location, length, etc. The TKO has a bit more hardware up top, relative to the flat top of the Toploader, but there's plenty of room in the Cobra's tranny tunnel. It's also nice to have the shift linkage all internal on the TKO as opposed to the external Hurst box on the Toploader.

The Toploader has a 10 spline input shaft, whereas the TKO comes with at 26 spline. Hence, a new clutch plate is required. Also, the standard input shaft on the TKO is too long for and FE application, so I had to buy the optional FE short input shaft kit.

The Toploader - a great tranny - a bit greasy and dirty from 15 years of use, but still in great shape. This will go up for sale after it's cleaned up.

The new Tremec TKO600 as received.

Here's a close up view of the old secondary slave cylinder attached between the frame and a Heim joint mounted on the end of the clutch fork (the Heim joint was added after the shaft on the first slave cylinder broke; it was simply mounted to a hole in the clutch fork which did not allow for sufficient movement).

Slave cylinder removed.....

Just in case I need to remember, there was a return spring attached to the end of the clutch fork.

The bell housing (FE stock, along with the clutch fork and throw out bearing) has been removed. This took quite a bit of work, because the starter had to be removed first (no pictures, but can be seen behind the flywheel at the right). Accessing the three bolts holding the starter was an exercise in flexibility and patience. However, simply taking the time, 1/12 of a turn at at time, and the bolts finally came out and the starter was free - at least to sit in place because it is tight enough in there that to truly remove it would likely require pulling the engine.

The drive line tunnel at this stage of the removal. I've got a scissor jack supporting the engine, though it turned out that was superfluous - with the headers and exhaust, the engine balanced, or at least, supported itself.

The clutch and clutch plate have been removed. Although it might not have been necessary, I chose to replace the pilot bushing as long as I was here. For those who have never removed one of these, the secret is to use hydraulic pressure... fill the hole in the pilot bushing with grease (any 'ol grease will do, but pack it in removing all air. For the Ford, the pilot shaft is 0.67" which happens to be very close to the diameter of a 3/8" drive socket extension. Place the socket extension into the pilot hole and hit it modestly with a hammer. Some grease will spurt out, but if the fit between the socket extension and pilot hole is tight enough, a few whacks, along with a few re-packs of grease, and the pilot bushing will back out.

One pilot bushing removed. Clean up and remove all the grease. I hit the flywheel with some break cleaner to get rid of any excess grease, etc. The removal of the old tranny is complete. Time to begin re-assembly with the new TKO.

Again, the standard input shaft that comes on the TKO is too long for an FE application, so I ordered the FE short input shaft kit and installed it. Four bolts on the input bearing retainer and some delicate pull, twist, tip, pull and the input shaft comes out (without losing any of the seventeen loose roller bearings inside the tranny!).

Here is a comparison of the standard TKO input shaft (top, with bearing still in place) vs. the short input shaft required for the FE application (bottom). I had to pull the bearing off the original input shaft and re-install it on the FE input shaft.

The FE input shaft kit also came with a new (shorter) input bearing retainer. The bearing race from the original retainer had to come off and moved to the new retainer. The race was a tight fit into the retainer, but a little grip using a rubber strap wrench pulled it right out. It just pushed into the new retainer with finger pressure.

I borrowed a bearing splitter from Autozone and was able to pull the input bearing off the standard input shaft. A jerry-rigged bearing insert tool made from PVC pipe allowed me to press the bearing onto the short input shaft.

The seventeen roller bearings go around the inside of the back end of the input shaft (where the red grease shows on the original shaft on the left). With ample grease, these were set in place in the short input shaft. Once all seventeen were installed, they tended to hold each other in place.

Being very careful not to knock any of the roller bearings out, the short input shaft was maneuvered into place.....

.... and the new bearing retainer was installed. I didn't get any pictures, but I installed a Tilton 6000-series hydraulic throwout bearing (Tilton 60-6102) on to the front of the tranny before installing this in the car. Looking on the web, and talking with a couple people at various tranny shops seemed to indicate this would not work on an FE. The impression was there was not enough distance between the input shaft bearing retainer and the clutch diaphragm for one of these to fit. However, I measured the "A" and "B" distances as shown in the throwout bearing installation instructions, and saw no issues - so I ordered one. It fit just like it is supposed to.

A new pilot bushing is installed (RAM Pilot Bushing BU50D).

A new clutch plate for a 26 spline input shaft was ordered from ClutchMasters (part #CD04173-00-D). I re-used the old ClutchMasters clutch (07-050-HD00). I also had to pick up a new alignment tool from Summit (Centerforce Clutch Alignment Tools 50048).

The clutch has been installed.

The bell housing is back in place. I kept the rubber boot for the clutch fork - the two hydraulic lines for the new throwout bearing will pass through the boot. Even though the lines are braided, the boot will help prevent wear. I also re-installed the starter. Again, it took time, but it actually went on easier than it came off (probably some learning on my part involved).

The next step is the new tranny itself, so in preparation I cut a new hole in the top of the tranny tunnel for the shift lever. This ended up being bigger than required (the top of the TKO sat lower than I expected in the tunnel), but the shift boot still covered the hole.

With a little muscle I was able to lower the TKO into the pit, then lift it up onto the floor under the car.

I put long studs into the two lower mounting holes in the bellhousing. I then was able to shim the front/back of the tranny up a bit at at time using 2x4 blocks until it was roughly in line with the studs, then slid the tranny forward carefully aligning and passing the input shaft through the clutch plate and into the pilot bushing. I also fed the throwout bearing hydraulic lines out through the clutch fork boot. Once it was all aligned, the two top mounting bolts were installed, the studs removed, the bottom two mounting bolts installed, and all bolts sequentially and incrementally tightened until the tranny was firmly attached to the bell housing.
This shot still has a 2x4 in place for a tranny mount.

The new position for the tranny mount did move back 1-2 inches, so I had to trim the cross member to fit (the tranny tunnel tapers at that point), but the angle brackets on the frame were long enough to accommodate the move.

The TKO came with a new driveshaft yoke. The new configuration required a slightly shorter driveshaft. I had Midwest Driveshafts rebuild my original driveshaft with the new yoke, shorter length, and while they were at it, put in new U-joints (the old ones were fine, but since we're here...). After putting this new driveshaft in I got to thinking I might have been able to get by with the original - I never checked the old vs. new yoke - the old yoke might have worked just fine in the TKO - something I have yet to confirm either way. Oh, well - new driveshaft.

And here it is - all 12.5" of drive shaft. I did have to take the drive shaft safety hoop out to get the drive shaft installed.

With the drive shaft safety hoop back in place and the speedometer cable installed, we're down to hydraulics and controls. The pig-tail loop on the back of the tranny is for an electronic speedometer. I'm not using one of those, so this was capped and taped off.

The old (Hurst) shift lever worked fine, so was mounted to the tranny. The boot was shifted an inch or so and re-installed. Tremec was offering a promotion of a free shift-ball when I bought my transmission, so I opted for their black ball. Whether I keep this or go back to my wooden Cobra-insignia shift ball is yet to be determined.

As I was already using a hydraulic clutch, I have a Tilton master cylinder for the clutch in place. For an 11" diaphragm clutch, when using the Tilton-6000 hydraulic throw out bearing, Tilton recommends a 13/16" bore master cylinder. The one I have in place is 3/4" - the difference is 17%. Before I went and ordered a new one, I decided to try to make this one work - it seems to be working fine. But, Tilton also strongly recommends installing a stop to prevent over travel. This shows my initial attempt at such.

Here's the clutch stop I built. It simply attaches to the firewall and has an adjustable lag bolt that sits behind the arm of the clutch pedal. The first one I made was too long and didn't allow enough pedal travel, so I had to remove it, cut it and re-weld the box.

I threw together a "tool" that allowed me to put incremental pressure onto the clutch while checking the adjustment. The "tool" attached to my roll bar and had a "foot" to push on the pedal. A turnbuckle at the top end allowed me to incrementally lengthen the rod and push further on the pedal. Tilton's instructions are to jack the rear wheels off the ground, put the tranny in first gear, and push the clutch until one can just turn the wheels. The pedal stop is to be adjusted to allow 1/4" additional movement of the pedal. This turnbuckle arrangement allowed for pretty precise adjustment.

Here's the pedal stop after adjustment. At this point I added Tremec's HP Manual Transmission Fluid, changed the engine oil (that time of year), and fired the beast up. A couple quick trips around the block (it's still early spring and cold here in Illinois) and all seems to be working well. The overdrive is just what the Dr. ordered!
The one remaining item is the speedometer drive/driven gears - I guessing the speedo is reading about 20-25% too high. Hence, I've got a little homework to do and some final tuning to do. Note for future reference: I ended up with a 19 tooth driven gear (pink).

	First things first - remove the shift boot and shift lever.
	Here's a "before" picture - the drive train as it has been since the original build.
	Step 1 - remove the drive shaft - all 13" of it!
	The tranny crossmember has been removed - I've got it supported by a regular car scissor jack. As a side note - I am working from the pit in my garage. I've got the car positioned such that the jack is right at the edge of the pit
	I put a steel pipe over the shifter hole in the tranny tunnel and looped a couple nylon straps around the tranny and around the pipe. I then moved the car backwards over the pit, removed the bolts holding the tranny to the bell housing, pulled and lowered the tranny into the pit.
	With the Toploader removed, one can see the clutch fork, throwout bearing, and, on the left, the slave secondary cylinder that pulls on the clutch fork. This is all being replaced by the new input shaft concentric hydraulic throwout bearing.
	Just another view of the removal process.
	Here's the old Toploader (red, on right) and the new Tremec TKO600 (on left). It's pretty clear the TKO was based on the Toploader - almost all dimensions are identical - bolt placement, shifter location, length, etc. The TKO has a bit more hardware up top, relative to the flat top of the Toploader, but there's plenty of room in the Cobra's tranny tunnel. It's also nice to have the shift linkage all internal on the TKO as opposed to the external Hurst box on the Toploader.
	The Toploader has a 10 spline input shaft, whereas the TKO comes with at 26 spline. Hence, a new clutch plate is required. Also, the standard input shaft on the TKO is too long for and FE application, so I had to buy the optional FE short input shaft kit.
	The Toploader - a great tranny - a bit greasy and dirty from 15 years of use, but still in great shape. This will go up for sale after it's cleaned up.
	The new Tremec TKO600 as received.
	Here's a close up view of the old secondary slave cylinder attached between the frame and a Heim joint mounted on the end of the clutch fork (the Heim joint was added after the shaft on the first slave cylinder broke; it was simply mounted to a hole in the clutch fork which did not allow for sufficient movement).
	Slave cylinder removed.....
	Just in case I need to remember, there was a return spring attached to the end of the clutch fork.
	The bell housing (FE stock, along with the clutch fork and throw out bearing) has been removed. This took quite a bit of work, because the starter had to be removed first (no pictures, but can be seen behind the flywheel at the right). Accessing the three bolts holding the starter was an exercise in flexibility and patience. However, simply taking the time, 1/12 of a turn at at time, and the bolts finally came out and the starter was free - at least to sit in place because it is tight enough in there that to truly remove it would likely require pulling the engine.
	The drive line tunnel at this stage of the removal. I've got a scissor jack supporting the engine, though it turned out that was superfluous - with the headers and exhaust, the engine balanced, or at least, supported itself.
	The clutch and clutch plate have been removed. Although it might not have been necessary, I chose to replace the pilot bushing as long as I was here. For those who have never removed one of these, the secret is to use hydraulic pressure... fill the hole in the pilot bushing with grease (any 'ol grease will do, but pack it in removing all air. For the Ford, the pilot shaft is 0.67" which happens to be very close to the diameter of a 3/8" drive socket extension. Place the socket extension into the pilot hole and hit it modestly with a hammer. Some grease will spurt out, but if the fit between the socket extension and pilot hole is tight enough, a few whacks, along with a few re-packs of grease, and the pilot bushing will back out.
	One pilot bushing removed. Clean up and remove all the grease. I hit the flywheel with some break cleaner to get rid of any excess grease, etc. The removal of the old tranny is complete. Time to begin re-assembly with the new TKO.
	Again, the standard input shaft that comes on the TKO is too long for an FE application, so I ordered the FE short input shaft kit and installed it. Four bolts on the input bearing retainer and some delicate pull, twist, tip, pull and the input shaft comes out (without losing any of the seventeen loose roller bearings inside the tranny!).
	Here is a comparison of the standard TKO input shaft (top, with bearing still in place) vs. the short input shaft required for the FE application (bottom). I had to pull the bearing off the original input shaft and re-install it on the FE input shaft.
	The FE input shaft kit also came with a new (shorter) input bearing retainer. The bearing race from the original retainer had to come off and moved to the new retainer. The race was a tight fit into the retainer, but a little grip using a rubber strap wrench pulled it right out. It just pushed into the new retainer with finger pressure.
	I borrowed a bearing splitter from Autozone and was able to pull the input bearing off the standard input shaft. A jerry-rigged bearing insert tool made from PVC pipe allowed me to press the bearing onto the short input shaft.
	The seventeen roller bearings go around the inside of the back end of the input shaft (where the red grease shows on the original shaft on the left). With ample grease, these were set in place in the short input shaft. Once all seventeen were installed, they tended to hold each other in place.
	Being very careful not to knock any of the roller bearings out, the short input shaft was maneuvered into place.....
	.... and the new bearing retainer was installed. I didn't get any pictures, but I installed a Tilton 6000-series hydraulic throwout bearing (Tilton 60-6102) on to the front of the tranny before installing this in the car. Looking on the web, and talking with a couple people at various tranny shops seemed to indicate this would not work on an FE. The impression was there was not enough distance between the input shaft bearing retainer and the clutch diaphragm for one of these to fit. However, I measured the "A" and "B" distances as shown in the throwout bearing installation instructions, and saw no issues - so I ordered one. It fit just like it is supposed to.
	A new pilot bushing is installed (RAM Pilot Bushing BU50D).
	A new clutch plate for a 26 spline input shaft was ordered from ClutchMasters (part #CD04173-00-D). I re-used the old ClutchMasters clutch (07-050-HD00). I also had to pick up a new alignment tool from Summit (Centerforce Clutch Alignment Tools 50048).
	The clutch has been installed.
	The bell housing is back in place. I kept the rubber boot for the clutch fork - the two hydraulic lines for the new throwout bearing will pass through the boot. Even though the lines are braided, the boot will help prevent wear. I also re-installed the starter. Again, it took time, but it actually went on easier than it came off (probably some learning on my part involved).
	The next step is the new tranny itself, so in preparation I cut a new hole in the top of the tranny tunnel for the shift lever. This ended up being bigger than required (the top of the TKO sat lower than I expected in the tunnel), but the shift boot still covered the hole.
	With a little muscle I was able to lower the TKO into the pit, then lift it up onto the floor under the car.
	I put long studs into the two lower mounting holes in the bellhousing. I then was able to shim the front/back of the tranny up a bit at at time using 2x4 blocks until it was roughly in line with the studs, then slid the tranny forward carefully aligning and passing the input shaft through the clutch plate and into the pilot bushing. I also fed the throwout bearing hydraulic lines out through the clutch fork boot. Once it was all aligned, the two top mounting bolts were installed, the studs removed, the bottom two mounting bolts installed, and all bolts sequentially and incrementally tightened until the tranny was firmly attached to the bell housing. This shot still has a 2x4 in place for a tranny mount.
	The new position for the tranny mount did move back 1-2 inches, so I had to trim the cross member to fit (the tranny tunnel tapers at that point), but the angle brackets on the frame were long enough to accommodate the move.
	The TKO came with a new driveshaft yoke. The new configuration required a slightly shorter driveshaft. I had Midwest Driveshafts rebuild my original driveshaft with the new yoke, shorter length, and while they were at it, put in new U-joints (the old ones were fine, but since we're here...). After putting this new driveshaft in I got to thinking I might have been able to get by with the original - I never checked the old vs. new yoke - the old yoke might have worked just fine in the TKO - something I have yet to confirm either way. Oh, well - new driveshaft.
	And here it is - all 12.5" of drive shaft. I did have to take the drive shaft safety hoop out to get the drive shaft installed.
	With the drive shaft safety hoop back in place and the speedometer cable installed, we're down to hydraulics and controls. The pig-tail loop on the back of the tranny is for an electronic speedometer. I'm not using one of those, so this was capped and taped off.
	The old (Hurst) shift lever worked fine, so was mounted to the tranny. The boot was shifted an inch or so and re-installed. Tremec was offering a promotion of a free shift-ball when I bought my transmission, so I opted for their black ball. Whether I keep this or go back to my wooden Cobra-insignia shift ball is yet to be determined.
	As I was already using a hydraulic clutch, I have a Tilton master cylinder for the clutch in place. For an 11" diaphragm clutch, when using the Tilton-6000 hydraulic throw out bearing, Tilton recommends a 13/16" bore master cylinder. The one I have in place is 3/4" - the difference is 17%. Before I went and ordered a new one, I decided to try to make this one work - it seems to be working fine. But, Tilton also strongly recommends installing a stop to prevent over travel. This shows my initial attempt at such.
	Here's the clutch stop I built. It simply attaches to the firewall and has an adjustable lag bolt that sits behind the arm of the clutch pedal. The first one I made was too long and didn't allow enough pedal travel, so I had to remove it, cut it and re-weld the box.
	I threw together a "tool" that allowed me to put incremental pressure onto the clutch while checking the adjustment. The "tool" attached to my roll bar and had a "foot" to push on the pedal. A turnbuckle at the top end allowed me to incrementally lengthen the rod and push further on the pedal. Tilton's instructions are to jack the rear wheels off the ground, put the tranny in first gear, and push the clutch until one can just turn the wheels. The pedal stop is to be adjusted to allow 1/4" additional movement of the pedal. This turnbuckle arrangement allowed for pretty precise adjustment.
	Here's the pedal stop after adjustment. At this point I added Tremec's HP Manual Transmission Fluid, changed the engine oil (that time of year), and fired the beast up. A couple quick trips around the block (it's still early spring and cold here in Illinois) and all seems to be working well. The overdrive is just what the Dr. ordered! The one remaining item is the speedometer drive/driven gears - I guessing the speedo is reading about 20-25% too high. Hence, I've got a little homework to do and some final tuning to do. Note for future reference: I ended up with a 19 tooth driven gear (pink).