Trans swap
Thread Starter
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
Trans swap
So I got everything inside the house right now, was going to start today but it's a bit rainy and damp, and I have a 4 day weekend, so there's time to spare.
Ended up getting a TREMEC TKO 600 with the .64 od, a Centerforce DF clutch(This will be my 4th one I've owned, it's an excellent clutch), and went with the Quicktime SFI bellhousing(a very sturdy unit that's compact and very well built, and is known for not having alignment issues. It also has 2 different ring inserts for the trans opening to use different size trans/input collars). I'll be doing the rear later on, maybe in a few weeks. Going with a Detroit True Trac and 3.55's.
The TREMEC is a good trans too, and a few things for those who don't know and never check the instructions on anything.
First, you MUST check bellhousing alignment to make sure you have no more than .005" of runout. If you do have more than that, the input shaft will bind and it will at the very least shift hard, worse it will tear up the pilot and/or input shaft bearing, create a vibration and possibly break the trans. This is true of any trans really, and is perhaps the most overlooked part of trans installs.
Second, they're designed for a light ATF oil, they recommend either GM Synchromesh or a Dexron III/Mercon ATF. I plan on running Torco MTF myself, which is just a better, higher dollar version of the above. I do a lot of hard driving and live in an area where the climate sees changes in temperature across the year of around 100* F between summer and winter, so I like to run better oils.
Third, they do NOT need an aftermarket shifter. All the TREMECs come with a hurst billet aluminum shifter installed, and all it needs is a stick/handle. The stick from my Toploader Hurst shifter bolts right up. The reason they do not need an aftermarket shifter is because the trans has built in internal shifter stops to prevent overshifting and fork damage. Adding an aftermarket shifter with stops may result in not being able to get into gear, and it voids the warranty.
The trans itself(for those who don't know) uses 4615 steel, and will take a crapload of abuse. They're rated at 600ft-lbs of torque, but that's a constant load rating over a period of time. They will take substantially more power over short periods of time and still last a long while. They just need to be treated properly. The only complaint I have against these transmissions is that they still use a brass blocker ring and spring loaded detents to operate the synchro mechanism. That's why they're hard to shift over 6,500rpm(which TREMEC advises against doing). It would be nice if they at least used carbon fiber blocker rings instead, but the brass ring and detent setup is a proven design none-the-less. The Toploader uses the same design, and mine lasted for a good 150,000 miles before it finally started showing signs of synchro wear in the 1-2 shift, and that was with NUMEROUS shifts above 6,000rpm, typically at 6,300-6,500. The Toploader blocker ring and detent design is substantially less refined than that of the TREMEC, so complaints in shifting that people have are usually a result of operator error or poor maintenance.
Anyway, right now with a 3.00 gear and no overdrive it manages about 20-22mpg at 65mph with a 25.6" tire. So after the swap I'll let you guys know what the mileage change was with just the trans swap, then again after the 3.00-3.55 gear change.
Ended up getting a TREMEC TKO 600 with the .64 od, a Centerforce DF clutch(This will be my 4th one I've owned, it's an excellent clutch), and went with the Quicktime SFI bellhousing(a very sturdy unit that's compact and very well built, and is known for not having alignment issues. It also has 2 different ring inserts for the trans opening to use different size trans/input collars). I'll be doing the rear later on, maybe in a few weeks. Going with a Detroit True Trac and 3.55's.
The TREMEC is a good trans too, and a few things for those who don't know and never check the instructions on anything.
First, you MUST check bellhousing alignment to make sure you have no more than .005" of runout. If you do have more than that, the input shaft will bind and it will at the very least shift hard, worse it will tear up the pilot and/or input shaft bearing, create a vibration and possibly break the trans. This is true of any trans really, and is perhaps the most overlooked part of trans installs.
Second, they're designed for a light ATF oil, they recommend either GM Synchromesh or a Dexron III/Mercon ATF. I plan on running Torco MTF myself, which is just a better, higher dollar version of the above. I do a lot of hard driving and live in an area where the climate sees changes in temperature across the year of around 100* F between summer and winter, so I like to run better oils.
Third, they do NOT need an aftermarket shifter. All the TREMECs come with a hurst billet aluminum shifter installed, and all it needs is a stick/handle. The stick from my Toploader Hurst shifter bolts right up. The reason they do not need an aftermarket shifter is because the trans has built in internal shifter stops to prevent overshifting and fork damage. Adding an aftermarket shifter with stops may result in not being able to get into gear, and it voids the warranty.
The trans itself(for those who don't know) uses 4615 steel, and will take a crapload of abuse. They're rated at 600ft-lbs of torque, but that's a constant load rating over a period of time. They will take substantially more power over short periods of time and still last a long while. They just need to be treated properly. The only complaint I have against these transmissions is that they still use a brass blocker ring and spring loaded detents to operate the synchro mechanism. That's why they're hard to shift over 6,500rpm(which TREMEC advises against doing). It would be nice if they at least used carbon fiber blocker rings instead, but the brass ring and detent setup is a proven design none-the-less. The Toploader uses the same design, and mine lasted for a good 150,000 miles before it finally started showing signs of synchro wear in the 1-2 shift, and that was with NUMEROUS shifts above 6,000rpm, typically at 6,300-6,500. The Toploader blocker ring and detent design is substantially less refined than that of the TREMEC, so complaints in shifting that people have are usually a result of operator error or poor maintenance.
Anyway, right now with a 3.00 gear and no overdrive it manages about 20-22mpg at 65mph with a 25.6" tire. So after the swap I'll let you guys know what the mileage change was with just the trans swap, then again after the 3.00-3.55 gear change.
6th Gear Member
Joined: Aug 2007
Posts: 5,896
From: Elk Grove, CA
Cool
I didn't know that about the shifter. I'll have to keep that in mind, although I really did like the Modern Driveline Slik Shifter when I checked it out at Hot August Nights. Not so much the positive stops as the smoothness of the shifter.
I didn't know that about the shifter. I'll have to keep that in mind, although I really did like the Modern Driveline Slik Shifter when I checked it out at Hot August Nights. Not so much the positive stops as the smoothness of the shifter.
Thread Starter
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
I've played around with it, and the shifter has a very positive feel to it. Shifting is a tad notchy, but the trans is also sitting in the box, dry with no lube. Even dry it still shifts better than the Toploader does at the same temperature. The synchros also need a bit of rotation to work, which ain't gonna happen sitting in the box. I was thinking that I'd need to get a good aftermarket shifter, but was surprised when the instruction sheet said that the trans itself has internal positive stops.
That overdrive and MUCH lighter oil(ATF as opposed to 85-190) should make a big mileage difference.
That overdrive and MUCH lighter oil(ATF as opposed to 85-190) should make a big mileage difference.
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