Jump to content
HybridZ
Sign in to follow this  
260DET

Tremec TKO Sequential Clutchless Shifting?

Recommended Posts

260DET    25

Have a TKO 5 speed lying around and am wondering if it can be fitted with a sequential shifter and a engine rev up downshift device, upshift ignition cut is no problem, the Haltech ECU will take care of that. It's for a circuit race LS3 Z, basically I want a setup where the clutch is only operated to get moving and to stop.

 

Am looking for experienced info, I know that there are sequential adapters for the TKO but have no idea how well they work or don't. Real info would be great, there don't seem to be many in the US using this sort of equipment for some unknown reason.

Share this post


Link to post
Share on other sites
260DET    25

OK, so everyone likes the idea of doing all those things with your feet when changing gear, rather than concentrating on more productive things. Like checking out the scenery or else concentrating on your lines and those around you on the circuit :)

Share this post


Link to post
Share on other sites
Chickenman    4
Posted (edited)

Have a TKO 5 speed lying around and am wondering if it can be fitted with a sequential shifter and a engine rev up downshift device, upshift ignition cut is no problem, the Haltech ECU will take care of that. It's for a circuit race LS3 Z, basically I want a setup where the clutch is only operated to get moving and to stop.

 

Am looking for experienced info, I know that there are sequential adapters for the TKO but have no idea how well they work or don't. Real info would be great, there don't seem to be many in the US using this sort of equipment for some unknown reason.

Biggest   problem is the synchronisers. Race transmissions don't have synchronizers, they have dog rings. Really hard to make it work with synchronizers. If you want clutchless upshifts and downshifts, you may want to look at a used racing Jerico 4 or 5 speed with proper dog rings.

 

And TKO trannies aren't the fastest shifting around ( due to slow synchronisers and heavy gears ), so it makes what you want to do doubly hard.  As far as auto Rev up on downshift, your Haltech may be able to do that... but really, the easiest way is to train your right foot. 

 

Here's a video of James Courtney ( Aussie V8 Super Cars ) and his heel and toe technique. These are sequential shift dog boxes, but James is a right foot braker and likes to use the clutch on downshifts. It's not necessary to use the clutch at all with these gearboxes, but it is easier on the box. These guys know how to Heel and Toe properly!!

 

https://www.youtube.com/watch?v=P1ZuynAYMLo&list=PLTlMnJOh8l3Y3F1-6AWvU0H8NGYXSQAvg&index=3

Edited by Chickenman

Share this post


Link to post
Share on other sites
Chickenman    4

I had a race  ( many moons ago ) when the clutch slave cylinder failed after a couple of laps. Small bore Datsun with a synchro box. Very small and lightweight gears and synchro's. Very fast shifting for a synchro box. Ran whole race with no clutch pedal. Downshifts were easy, but upshifts were a PITA. A slower shifting box would have been even worse... FWIW.  

Share this post


Link to post
Share on other sites
260DET    25

Thanks chook, I've been looking at all options that avoid double declutching as my clutch leg is a bit wonky. I presently run a sequentially shifted 4L85E behind the LS3, it works OK and certainly helps when racing but at 116kg it's just too heavy. The alternative choices have been narrowed down to a Powerglide auto with a Gear Vendors over/under drive which in total is about 50kg lighter, four speeds with the right spacing are fine.

 

Problem yet to be solved is how to sequentially shift such a combo with a single lever and nothing else.

Share this post


Link to post
Share on other sites
hooahh3    0

if what i've learned about the GV overdrive is right, it should be do able with just the push button switch.

Manual valve body in the PG.

go first

hit button for GV

move to 2nd and hit button to turn off GV at same time

hit button again when 4th is needed

 

Don't exactly quote me on this as i've only been able to piece together this information; i'd like to do a GV myself but can't do the 2500$ for one any time soon. so the 4l60E is staying around awhile longer. It would be awesome to have the full manual aspect though. especially an auto/manual for just cruising around

Share this post


Link to post
Share on other sites
Chickenman    4
Posted (edited)

Thanks chook, I've been looking at all options that avoid double declutching as my clutch leg is a bit wonky. I presently run a sequentially shifted 4L85E behind the LS3, it works OK and certainly helps when racing but at 116kg it's just too heavy. The alternative choices have been narrowed down to a Powerglide auto with a Gear Vendors over/under drive which in total is about 50kg lighter, four speeds with the right spacing are fine.

 

Problem yet to be solved is how to sequentially shift such a combo with a single lever and nothing else.

 

If you go manual, you are going to have to get a box with Dog Rings. A 4 or 5 speed Jericho and Haltech can take care of  flat shift on up-shifts no problem. . There are sensors that work on the shift lever that detect  when  you pull on the gear lever. They are very accurate. You can get either Torque load sensors or linear motion sensors. They work on both sequential and H pattern shift levers. This is what the Aussie V8 Supercars use. 

 

You can pick up a good used Jericho 4 or speed from shops that sell used Nascar parts. You can get some pretty good deals if you shop around. All the major Nascar Teams sell off used parts. The junior leagues such as Infinity series are a bit cheaper. For the 5 speed, check out SCCA used forums. 

 

If it's in your budget, a used 4 speed Jerico from a Nascar team may be your best bet. You can use a sequential or H pattern shifter. Sequential would naturally be preferred, but could be added later. Then a shift sensor on the shift lever. Transmission with dog rings is going to be the biggest expense. 

 

Downshifts just manually blip with your right foot. Note: Make sure you over rev and catch the change on the down swing of revs. A dog box will just fall into gear when you do it properly. No need for fancy Rev-up software. Your right foot and brain are more adaptable than any software programming. 

 

The secret to clutchless downshifting is the over rev. Most people don't give a hard enough blip. You have to get the engine RPM range ABOVE the engagement RPM for the lower gear. A slight but swift pressure on the lever, and the gear will just fall into place. Swift movement of shift levers with a dog box is essential. Dog boxes are made to with stand a " Crunch " on gear changes. What they don't like is too slow of a shift, that gives you some " Fine ground coffee " and 10 cents change. Dog boxes take commitment on gear changes. But when you get it right they will literally shift like butter.  

 

For  upshifts with no clutch, it can be easy. You don't really even need the flat-shift hardware and software. Just do a  quick, slight lift of the accelerator and pull the shift lever. Speed of shifting is the secret. Do everything quick and with commitment, and the Dog Box will be happy. 

 

One other thing. Always try and shift ( up and down ) at the top of the Rev range. This is where you will have minimal shock loads from Torque differential between gears. Dog boxes don't like to be shifted at low or medium RPM's. Fat part of the torque curve is the worst place to shift a Dog Box. 

 

I have some links for shift lever sensors for flat shifting. Gotta run right now, but I'll post them up later this evening. 

Edited by Chickenman

Share this post


Link to post
Share on other sites
Chickenman    4
Posted (edited)

Here's a good video of proper Dog Box up-shifting with no clutch and no Flat Shift. All controlled by drivers right foot. Unfortunately, not so good of an example for downshifts as this is a fairly tight and slow Stage. 

 

Note: This is a Turbo rally car. Ignore what's he's doing with the brake pedal. Turbo AWD rally cars are always using left foot braking to load the Turbo and to set up the car for corners. rally drivers left foot brake much more than Road Race drivers.

 

https://www.youtube.com/watch?v=H98vSNz6vrw

 

Edit: Here is another video by a company in Australia that makes Dog Gear conversions for street cars. Note that this driver is extremely experienced. Clutchless Dog box shifting is harder on the street than in racing. Note where he says, " the faster you go, the faster you shift ". Note the general speed of the shifts. He is not being brutal on the shift lever, but he is committed and shifts are quick and clean. 

 

https://www.youtube.com/watch?v=n_1jO64tuQA

 

Some companies such as Liberty, make Face-plated or Pro shifted gear sets. These are NOT the same as Dog rings  and are NOT recommended for clutch-less shifting. Liberty specifically warns users about attempting to clutch-less shift with these type of modifications. They are not suitable for Road Racing.  G-Force? Personally I wouldn't use them. Very bad reputation and experiences with Road Racing users.

 

Jericho, Sainz, Weisman  and a couple of others are the big players for purpose built Road Racing transmissions.  

Edited by Chickenman

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

×