[scott70]

I think I’m going to pull the trigger on a tkx trans for my 70 gto.Might be a loaded question but anybody prefer MDL or silver sport? I noticed silver sport has a short throw shifter available. I’m going to order the shifter handle that looks like the original competition plus hurst that’s in it now. I have no experience with either company and have never tried a tkx. I’ve gotten estimates from both and MDL is a few hundred more. Thanks

[VCho455]

I got mine from Modern just as they were a lot closer to home so shipping was less. Otherwise I didn't see much difference 3 years ago.

[gtorich]

Scott, i got my tkx from siliver sport two years ago..............they have some sales every now and then with free shipping.

I have the 2.87 with the .68 overdrive..............im running a 3.42 rear, P255/60/15 tire, usually running about 70 mph or so, im at 2200...........455...........very happy with the trans

Rich

[jhein]

Wherever you get it, you're gonna love it. It's one of the best upgrades I've made.

Get a price from Jody's Transmission. I thought he was very competitive and great service.

[Gator67]

I picked up a TKX from Silversport for my son's '79 TA. If you're not aware, Silversport modifies the transmission to accommodate their proprietary shifter so that it ends up in the right spot (which it did). I had mixed feelings about it, since it kind of locks you into Silversport and the particular car you purchase it for. I don't know if MDL does this or uses an adaptor on the shifter stub, or something else, to get the right offset. Also, Silversport's parent company (Wharton Automotive) also owns Mcleod, so if you buy a kit from them, chances are it will include a McLeod clutch set-up. I had to exchange the clutch hat because it was so out of balance. The second one was better but still needed work to balance. The kit also comes with their own hydraulic throw out bearing. It seems to function well enough, but it doesn't seem as well made or as beefy as the Tilton unit I run on one of my other cars (same thing with the clutch MC). Time will tell. I've never bought anything from MDL, but I have used Bowler (for a T56 Magnum). When I shopped, Bowler was definitely more expensive, but they put together kits with more expensive components. I've also been impressed with Bowler's customer service and their patience addressing questions and issues.

[scott70]

I believe Mdl and silver sport do their own proprietary modifications to get the shifter in the correct place for BOP A bodies. SS is having a discount til the end of the month I think. They do offer a McLeod clutch as part of their kit. I’ve always used centerforce and had no problems so at the point I don’t know which clutch kit I’d use. I’ll be staying with my original bellhousing , clutch fork etc. .. not converting to hydraulic clutch.

[soupman]

I used Modern for my TKX, I used a hurst straight lever to put in the correct position. Modern also make’s their own clutches too which I ended up buying from them.

[65madgoat]

American Powertrain the best to buy from. Their White Lightning shifter is super too. Not a fan of Silver Sports shifter configuration

[PDC]

Lots of opinions on gearing - all valid of course. And all combo dependent. I had an older TKO with the 2.87 1st and .64 OD with 3.42 ring gear. 1st Gear was 2.87 x 3.42 = 9.81 overall gear reduction. Think in terms of the OG Muncie M-22 with the 2.21 1st Gear. In order to get 9.81 out of the hole, you’d need to run that M-22 in front of a 4.44 ring gear. Most folks back in the day had 4.11s behind their M-22 which equaled 9.08 overall reduction in 1st. Think about how much fun you could have with a Buick / Olds / Pontiac 455 (or a well build Chevy 454) in front of an M-22 with 4.11s out back. Add more cam, aluminum heads, better exhaust - you really don’t need more than 9.0 overall gear reduction with a long stroke, big displacement, low(er) RPM engine for crazy off the line acceleration.

What that means is that with the 2.87 1st in the TKX, you could run somewhere between a 3.08 and a 3.23 (common GM ring gear ratios) to replicate that M-22 + 4.11 ring gear combo.

I personally found that the 2.87 in front of 3.42s (9.81) was hella overall reduction in 1st gear. And I still found that dropping down to .64 made the car feel a bit ‘lazy’ at any speed below 80 mph. For example, 75 mph was just below 2K rpms - which was great for long distances - but if you needed to downshift to pass a car, the tach jumped from 1900 to 3200 at the exact same 75 mph. I didn’t care for that.

I ended up rebuilding my TKO with the .81 main shaft and dropping my ring gear back from 3.42 to 3.23. (I honestly could have gone back to 3.08) That gave me 9.27 overall gear reduction in 1st (still even deeper than 4.11s with an M-22) and had 2.61 in OD. 75 mph was a comfortable 2400 rpms. At that point, I could floor it without downshifting and accelerate if I needed to pass a car or just speed up. If I did choose to downshift, the tach only jumped a few hundred RPMs - not 1200 like with the 1:1 - .64 drop.

My current car has a T-56 with the 2.66 1st gear and the .81 / .64 OD gears. I currently have a 3.73 out back but I am seriously considering backing that down to 3.42. FWIW, I really like spitting the difference with basically 2 OD gears. I never really cared for that BIG drop between 1:1 and .64 in the older TKO trans. The difference between .64 and .68 doesn’t seem like much on paper, but I’m betting it gives you a bit more reasonable drop between 4th and 5th in the TKX offering.

[64speed]

I have the TKO600 with the .64 overdrive 3.70 gears and a 26 inch tall tire. The speed limit thru town is 30-35 at which of course I drive in 4th but on the side road home the speed limit is 50. Once I get some speed and RPM up I can shift to 5th at 45 mph and never lug the engine or lose my ability to gain speed. Engine rpm in 5th at 45-50 is just above idle. I feel like my rear gears are a little too deep to be ideal but it makes it really easy to take off and drive 1st is just a little short. When I went to the beach in March I put 22 gallons in the tank and drove 232 miles to the hotel (interstate 90%) and then drove around Myrtle Beach when I got there another 25-30 miles and I still had about 3 gallons. The TKO and the RTX gauges are the best upgrades to the car I have made.

[Formulajones]

The most popular package I've done here is the tko with a .64 and 3.73's.

I've done them with 3.50-ish gears as well. In Fact our daily had 3.55's with a .64 for a few years and it was fine, used it all the time at 35 mph.

I've since put the original 3.73's back in the Z so I could use the 3.55's in another project and quite honestly I can't tell much difference in overdrive. Darn thing got 22 mpg on the last trip with the big fat 780 Holley on it cruising at 75 mph lol.

[scott70]

I’m going to do the 2.87 / .81 OD. With my driving style , 3.31 gear and 255/60-15 tire I think it will be good. It’s about a 500 rpm drop from 4th to 5th which is good enough for me.

[jhein]

Originally Posted by scott70

I’m going to do the 2.87 / .81 OD. With my driving style , 3.31 gear and 255/60-15 tire I think it will be good. It’s about a 500 rpm drop from 4th to 5th which is good enough for me.

That is the exact combo I have. Same trans gears, rear gear and tire. As I recall, you and I both rarely if ever drive at Interstate speeds. 55 mph is really the highest speed limit I encounter. The .81 OD is perfect for 65 and even 70 mph cruising. Even 75 mph @ ~2500 rpm is still very comfortable.

[scott70]

Originally Posted by jhein

That is the exact combo I have. Same trans gears, rear gear and tire. As I recall, you and I both rarely if ever drive at Interstate speeds. 55 mph is really the highest speed limit I encounter. The .81 OD is perfect for 65 and even 70 mph cruising. Even 75 mph @ ~2500 rpm is still very comfortable.

Yes,, most highway driving around me is a 60 mph limit which means I’ll be cruising 65. If I hit the interstate ( rarely) it would be 75 and like you said that still manageable .

[Formulajones]

That's a lot of money to spend for a small gain. If you guys are really driving that slow (55 mph) why are you even looking at overdrives? For as little as you drive these cars and cruising at the old speed limits I wouldn't even be thinking about an overdrive.

[jhein]

Originally Posted by Formulajones

That's a lot of money to spend for a small gain. If you guys are really driving that slow (55 mph) why are you even looking at overdrives? For as little as you drive these cars and cruising at the old speed limits I wouldn't even be thinking about an overdrive.

Well, for a 55 mph limit I will go up to 65 (my local LEOs ignore that here and in most places I think). That's around 2700 rpm in 4th gear vs 2150 in 5th. That's a pretty big difference. Plus you also get the 2.87 1st gear, that turns my 3.31 rear into the equivalent of a 3.77 when compared to a Muncie with it's 2.52 1st gear. It works for me. Your driving habits are different and if I used my car like that I'd most likely get the .68 too.

[Formulajones]

Yeah 65 starts to get in that realm of "do I want one or not" type of deal. I'd do the overdrive with anything that speed or more. They just make the car a pleasure to drive any distance.

Honestly I find I use 5th more than I thought I would anyway, even cruising around town at 35-45 mph and still have plenty of ooomf to accelerate from there with itty bitty engines so I'm okay with it.

[scott70]

Originally Posted by jhein

Well, for a 55 mph limit I will go up to 65 (my local LEOs ignore that here and in most places I think). That's around 2700 rpm in 4th gear vs 2150 in 5th. That's a pretty big difference. Plus you also get the 2.87 1st gear, that turns my 3.31 rear into the equivalent of a 3.77 when compared to a Muncie with it's 2.52 1st gear. It works for me. Your driving habits are different and if I used my car like that I'd most likely get the .68 too.

My 2.20 first gear with the 3.31 is obviously doable but the 2.87 should be much more pleasant. So you get a 550 rpm drop going to 5th?

[jhein]

Originally Posted by scott70

My 2.20 first gear with the 3.31 is obviously doable but the 2.87 should be much more pleasant. So you get a 550 rpm drop going to 5th?

I'm rounding slightly. If I use my tach that's what it looks like, but it's hard to get a really precise reading with the resolution of the tach needle. You need a really flat, level surface and then get in a steady state with zero acceleration or deceleration and then try to get an exact reading from the tach. Maybe it's me but it's not as easy as it seems to get the resolution down to the tens of MPH. When I use an online RPM calculator I get 509. So it's in that ballpark.

I'm sure you've used them, this is the one I use:

https://purperformance.com/p-29669-rpm-calculator.html

[Silmendoza]

Originally Posted by 65madgoat

Do it and don't look back. No point having a weak 4 speed with no OD anymore these days.

Makes the car so much more fun.

Plus with the new TKX you don't have to cut your floor. So every reason to do this swap today.

The guy installing this said the shifter is not clearing the opening on the floor, any ideas? 69 GTO original 4 speed, swapping with a Tremec TKX...