Seeking opinions on which direction to go for a manual swap. I have an 84 automatic car that I would like to put a manual transmission in. It already has a Dana 44 from a later ZF6 car with 3:45 gears in it. I have all the parts to put a 4+3 in but grafting in the shifter mounting points on the trans tunnel seems daunting and the 4+3 doesn't seem to be regarded as a great feeling transmission anyway. So I'm looking at used ZF6s and the TKX swap kit from Silver Sport. Used ZF's seem to be going for around $2.5k near me and the TKX kit would be about twice that. ZF seems easier, but the gear rollover noise in the ZF gives me some concern. I don't know if it's something that would end up bothering me in the long run. No plans for outrageous power in the future, a reasonably built 383 would probably be the upper limit. Don't plant on racing road or drag and its not going to be a daily driver.

So roll the dice on a cheaper used ZF? Or spend the money for a new TKX?

 

Personally, neither. I'd sell the whole car and buy a ZF6 car instead.

That said, SST kits are highly regarded in the C3 world. I know Richmond 5 speeds were the go to swap for C4s for a time. I think tHX is a 5 speed too though.

 

https://www.corvetteforum.com/forums...m_content=post

 

I've considered this, but the later interiors don't do it for me, so I'm left with 89 cars only. And the cost difference between selling mine and buying a nice clean 89 with the 6 speed is more than what it would take to put a ZF6 in mine.

From the folks here who have done the TKX swap in a C4, it sounds like it is a good transmission and significantly better than the 4+3. I guess I'm just wondering if the extra cost for the TKX is worth it over a ZF6.

 

performance or driving wise no the tkx is not worth the cost.

the only consideration you should make is if you install a zf (used) and it gives you trouble in a week, or 10 years, are you willing to take it out again and find another to swap in.

chances are you’ll never have an issue, but that’s the main consideration.

we’re going to assume together the new tkx will come with a warranty and chances are will be trouble free for the life of your ownership.

zfs are amazing, I have driven many and they have all felt fresh and tight.

 

I have not heard any downsides to a TKX transmission... As to the swap in a C4 I can't say.... NO problems with the transmission.. I have f them in my Fox mustang and 65 C2...
Can you say that about a ZF or the 4+3??

 

BTW the best ZF transmission is in the year 1989 -- you should look at those, it doesn't come with the new interior or softer body panels. The 2-1 downshift synchro is much quicker in the 1989 ZF, and it's also the stronger overall version. And they can be bought reasonably well, and most C4 issues worked out. Problem is the Z51 is usually not a real Z51 but usually FX3 with FE07 springs/swaybar but it can be retrofitted properly.

 

I'm still updating this here and there: https://www.corvetteforum.com/forums...-swap-kit.html


Unless you put in a taller rear diff gear I don't think the TKX is going to work for you.
Plug your info here and see: https://tremec.com/aftermarket/resou...io-calculator/

Otherwise the TKX in my 86 is a HELL of a lot of fun, money well spent for a new trans with a warranty that
I'll probably never break. And if I did the parts are cheap and plentiful and it's easily repaired.
That said I second just buying a ZF car unless you're like me and really hung up on the early ones.

 

I did my own Black tag ZF swap a few years ago and made a thread about it here.
I've been really happy and ZF is a great transmission, I've been satisfied.

 

Although the ZF6 is a wonderful transmission, it isn't a M22 Rock Crusher and they aren't making any more of them, ever.
There are already some early versions of the ZF6 where there are NO new internal replacement parts available at all.
The only good news is that there were many thousands of the ZF6s made and installed in Corvettes, so finding another one when and if you have troubles with your existing one won't be all that difficult.
Just things to consider.

Crabs

 

I'll second what Wolf said. I put a TKX in my 86 also to replace the 4+3 with a bad o/d unit. It was money well spent. I absolutely love it. I originally was going to put in a ZF and had one ready to go, but decided on the TKX. No regrets.....

 

I swapped my 85 from auto to ZF6 about 6 years ago. At the time, C4s were seriously dirt cheap and it didn't make a ton of sense financially to do that versus buying a car that was already a manual. I ended up finding some really bad floor damage during a stereo upgrade and needed to gut the interior to fix it. There was no better time to do a swap. All in, with pedals, clutch (hydraulic TOB conversion), flywheel, transmission and a Dana 44, the swap cost me around $3000. I got lucky with an unknown condition ZF6 and a Dana 44 that had the batwing chopped up for less than $1500 so that put me money ahead.

Present day, C4s have gotten a little more expensive, and clean 6 speed cars definitely command a premium. If you want an 89, you have a limited pool of cars to choose from. I feel like manual swaps now make financial sense for anyone who can do the work themselves. You can focus on getting a car that has all the options you want, in really nice condition for much cheaper than a 6-speed car and take those savings to do the swap.

TKX vs ZF6 is a tough choice. I love the ZF6 but I definitely worry about parts availability. I plan on purchasing another good transmission to keep as a spare so that if I need to repair my current transmission I can take my time looking for parts and not be without my C4. The TKX is a great transmission, it is light, strong and shifts beautifully. I've driven a handful of cars with them and they just make so much sense. They were literally designed to be swapped into various classic cars and trucks with almost no clearance issues. You will spend more than a ZF6 for sure, really you will spend more than two ZF6s. But the transmission will likely outlast every other drivetrain component in your car. Several companies sell a kit with pretty much everything you need to install it into an automatic Corvette and that has some value too. It took me a while to track down all the individual parts I needed to make the swap correct. I did go the extra mile and wired the car up exactly per the 89 FSM diagrams. This makes issues easy to troubleshoot potential issues and makes the swap feel seamless. The only thing that would tell you my car was originally an automatic is the RPO code on the storage compartment label.

 

I appreciate the input from everyone, the TKX swap threads are helpful to understand what all is involved.

It does seem like the ZF is still a decent option if you can find one for a reasonable price. I'll try and see if I can locate one locally.