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Old 09-17-2018, 05:41 AM
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Masfel74
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Default Tremec transimmion

Hello everybody!
I write from Italy.
I'm going to install a Tremec gearbox on my '69 Corvette; actually I have the original manual M20 4 speed and I'd like to mount a 5 or 6 speed gearbox.
I found that the most common modify is with Tremec gearbox. Initially I opted for the 5 speed (Tremec TKO600) because I just look for a relax 5 gear for long travels; now I'm considering also the Magnum with 6 speeds...
Any suggestions?
I saw that it's possible to install TKO600 without cut or drill, just using conversion kit; do you know if this is possible also with the Magnum?
Thanks a lot for your help

PS; I'm sorry for my english...
Old 09-17-2018, 09:07 AM
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gkull
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I brought a 6 speed vette and the double over drive ZF transmission was so hopelessly over geared that it didn't have the power accelerate in 6th gear. It could actually go faster in 5th gear. I think that it came with a 3.43 rear end and I changed it to a 4.10 and it ran so much better

I installed the tko 600 in my 79 vette also with 4.11 rear end and it has the ability to cruise very nice at 200 Kph
Old 09-17-2018, 09:27 AM
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Masfel74
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thank you for the answer.
no drills or cuts for install the tko 600, right??
Old 09-17-2018, 09:59 AM
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gkull
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Originally Posted by Masfel74
thank you for the answer.
no drills or cuts for install the tko 600, right??

I convertedmy 79 vette auto tranny to the 600. I had to cut the sheet metal under the console to fit the shifter block. Minor modification from a 4 speed car it is probably nothing unless the shifter is physically in a different place

the kits can come with a different cross member. Bolt on type. The mounting point of the tail shaft was different than my auto tranny. If you have a solid cross member it would be great to take it out
Old 09-17-2018, 06:32 PM
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scottjamison
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Originally Posted by Masfel74
Hello everybody!
I write from Italy.
I'm going to install a Tremec gearbox on my '69 Corvette; actually I have the original manual M20 4 speed and I'd like to mount a 5 or 6 speed gearbox.
I found that the most common modify is with Tremec gearbox. Initially I opted for the 5 speed (Tremec TKO600) because I just look for a relax 5 gear for long travels; now I'm considering also the Magnum with 6 speeds...
Any suggestions?
I saw that it's possible to install TKO600 without cut or drill, just using conversion kit; do you know if this is possible also with the Magnum?
Thanks a lot for your help

PS; I'm sorry for my english...

I have the TKO600 and love it.
The 5th gear ration (0.56) is like an overdrive and on the highway it is awesome to cruise easy at 80mph.
No cutting necessary. I used the perfect fit from Silver Sport Transmission.

https://shiftsst.com/articles/cat/ge...erfectfit-kit/
Old 09-17-2018, 07:06 PM
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cagotzmann
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Originally Posted by Masfel74
Hello everybody!
I write from Italy.
I'm going to install a Tremec gearbox on my '69 Corvette; actually I have the original manual M20 4 speed and I'd like to mount a 5 or 6 speed gearbox.
I found that the most common modify is with Tremec gearbox. Initially I opted for the 5 speed (Tremec TKO600) because I just look for a relax 5 gear for long travels; now I'm considering also the Magnum with 6 speeds...
Any suggestions?
I saw that it's possible to install TKO600 without cut or drill, just using conversion kit; do you know if this is possible also with the Magnum?
Thanks a lot for your help

PS; I'm sorry for my english...
Here is my install notes. T56 Magnum 6 speed in my 78 corvette. Rear Gear is a 3.08 with a ZZ383 Runs fine in any gear. Nice to curse @ 74MPH @ 1800 RPM, Great gas mileage for a C3 Corvette.

https://www.corvetteforum.com/forums...-corvette.html
Old 09-18-2018, 05:35 AM
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Gordonm
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I installed a 5 speed Tremec in mine years ago. I did make the cross member removeable at the time. No other mods were needed and everything bolted up fine. Later iput in a T56 and the fit was a lot more work. The crossmember had to be heavily modified. The shifter came up In the wrong location so I modded the console. I have seen others that have modded a shift lever so it comes up in the stock location.
Since this I have done over a dozen swaps from automatics to 5 speeds and 4 speeds to 5 speeds. The auto cars are easier due to a removeable crossmember. No mods are needed as the yprovide a bracket that bolts to the stock member. The 4 speed to 5 speed cars are ok to do without a removeable crossmember but the fit is real tight and takes some time and patience. Plenty of overdrive with the TKO. The install is easier with the TKO than the 6 speed.
Old 09-18-2018, 01:47 PM
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OldCarBum
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I'm getting ready to order my auto to manual kit from Silver Sport Transmissions.
Their kits come with everything you need and no cutting.
Their prices do seem a bit high but when I started trying to pull all the parts needed from different vendors I found the SST kits were actually cheaper.
I looked into other kits as well and even though their advertised prices were less, by the time you added everything needed to their "base kits" the prices were equal to or in some cases more than SST.
Old 09-18-2018, 06:02 PM
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scottjamison
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Originally Posted by OldCarBum
I'm getting ready to order my auto to manual kit from Silver Sport Transmissions.
Their kits come with everything you need and no cutting.
Their prices do seem a bit high but when I started trying to pull all the parts needed from different vendors I found the SST kits were actually cheaper.
I looked into other kits as well and even though their advertised prices were less, by the time you added everything needed to their "base kits" the prices were equal to or in some cases more than SST.
Yep. Same realization I came to.
They are super cool too and will help you with choices for flex plate, clutch, etc if you need it.
Old 09-18-2018, 06:21 PM
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OldCarBum
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They have been very helpful and patient with me and all my concerns.
Old 09-20-2018, 09:05 PM
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drwet
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I have a TKO 600 in my '79. I converted the car from an automatic which meant some relatively minor modification of the floor. The swap is well worth it. I love the way it drives now. I did not use a kit. I put all the parts together myself over the course of about a year. I figure I might have saved $100, if that.
Old 09-21-2018, 08:50 AM
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Metalhead140
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The tko kits from the vendors come with a special shifter and require no cutting, or you can do as I did and some of the others above and use the standard box and open up the hole in the floor a little to suit. I cut and welded an offset in the shifter stub so that it comes through the console like stock, and covered the opening in the floor under the console with a larger rubber boot. I used the factory Corvette bellhousing and z bar clutch release (after repairing all the pivots) and it works great. I didn't modify the crossmember at all.

The 6 speed requires some cutting, and from memory you cannot reuse your factory bellhousing and clutch release arrangement, adding cost and complexity to the conversion. I don't personally see the need for the additional gear. All depends on personal preference!
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Old 09-21-2018, 09:19 AM
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Automatic cars require cutting (as drwet said). The auto shifter doesn't go through the floor like a manual. Cars that were originally manual should not need cutting if you get the right shifter setup.

I also converted a 79 from automatic to a TKO 600 - I love it. I am running a 3.73:1 rear end. I probably would not run less than a 3.55:1 ratio rear with a TKO, but really rear gearing just depends on the RPM range where your car makes power. Just try to make sure you think about that aspect of the conversion.

Last edited by cooper9811; 09-21-2018 at 09:22 AM.
Old 09-21-2018, 11:48 AM
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Hello Mastfel74
Like "drwet" above I completed a TKO project buying part by part.
I would recommend buying a kit - especially if I lived in Italy.
My project started as a 1978 automatic with a 3:08 axel ratio.
I purchased the TKO-500 (3:27 1st gear ratio)
A vehicle is easier to drive and easier on the clutch if the axel ratio X 1st gear ratio = 10 +/-
A TKO-500 --- 3:08 X 3:27 = 10.0716 (Good combination)
A TKO-600 ---2.87 X 3:55 = 10.1885. (Good combination)
The single overdrive gear ratio of a TKO is enough overdrive for most older cars.
If the two overdrive gear ratios of a T56 six-speed are to be efficient especially at cruise speeds in 6th gear, many times EFI, a minimum of a 3:55 Axel gear ratio and a smooth running camshaft at engine speed of less than 1800 RPM are required.
A 350 engine with a modifications, and a 3:08 Axel ratio is very happy with a TKO-500.

Old 09-21-2018, 01:10 PM
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Originally Posted by cooper9811
Automatic cars require cutting (as drwet said). The auto shifter doesn't go through the floor like a manual. Cars that were originally manual should not need cutting if you get the right shifter setup.

I also converted a 79 from automatic to a TKO 600 - I love it. I am running a 3.73:1 rear end. I probably would not run less than a 3.55:1 ratio rear with a TKO, but really rear gearing just depends on the RPM range where your car makes power. Just try to make sure you think about that aspect of the conversion.
The floorpans in 75+ cars are different than 68-74. I had to cut in my 78, as, like you said, there's a unique floorpan for the automatic vs the manual. I believe the earlier cars do not require cutting.
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Old 09-24-2018, 02:44 PM
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Originally Posted by Metalhead140
The tko kits from the vendors come with a special shifter and require no cutting, or you can do as I did and some of the others above and use the standard box and open up the hole in the floor a little to suit. I cut and welded an offset in the shifter stub so that it comes through the console like stock, and covered the opening in the floor under the console with a larger rubber boot. I used the factory Corvette bellhousing and z bar clutch release (after repairing all the pivots) and it works great. I didn't modify the crossmember at all.

The 6 speed requires some cutting, and from memory you cannot reuse your factory bellhousing and clutch release arrangement, adding cost and complexity to the conversion. I don't personally see the need for the additional gear. All depends on personal preference!
I agree on the 6th gear. I was cruising at 60mph over the weekend at 1700rpm in 5th and even 80mph without feeling like I was pushing the RPM too high.
It is important to note that the TKO600 mirrors the Muncie gear ratios (at least very closely if not exactly) for 1-4. 5th is 0.56 I believe so it is like a massive overdrive. I already don't use 5th on regular streets usually. Just the highway.
Old 09-24-2018, 03:33 PM
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The TKO600 comes with either a .82 or .64 fifth gear ratio. I have the .82 and 3.54 gears and it's great.

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Old 09-26-2018, 11:06 AM
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Masfel74
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Thanks to everybody for answers and for share experiences. I thought about the 6 spees just for more sport driving 'cause there is a big jump from 4th to 5th with 0.64. But considering:
1. I don't want to cut anything
2. At least my first need is to reduce rpm in highway
3. I have the 427 and quite short final ratio (3.70)

I'll buy the TKO 600 with 0.64 5th gear. and of course the complete conversion kit.

Thank again!
Old 09-26-2018, 06:50 PM
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I wish I had a gear between 4th and 5th in my car - kinda wish I'd done T56 since I had to cut the floor anyway. But not your problem...

On 45->60mph the 5th (0.64) is a bit low and then I have to downshift. 4th is a bit high. I'm running 3.70s. But I'm already into this transmission and am not about to dump the cash in for a T56.
Old 09-26-2018, 07:30 PM
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That was the reason I went with the close ratio TKO-600.
1 to 1 4th gear and the .82 5th gear.
Between 4th and 5th I will only see a 450 rpm difference.


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