Sequential manual transmissions

Lately I've been getting into the thought of sequential manuals for street cars, where normally you only see them in race cars. I saw a video of the Caterham 620 with a sequential box and it was insane.

 

 

Now, while many know what I'm talking about, let's clarify that we're not talking about automated manual transmissions (egear, PDK, F1) or torque converter based transmissions (tiptronic).

 

We're talking about the same kind of transmission in bikes.....I get the terminology confused but terms like straight cut gears, dog clutches, "crash box", that stuff is what you normally hear when talking about sequentials. You push forward to downshift and pull backwards to upshift.

 

Curious to hear from those here who have driven these types of track cars -- what it's like to drive, how it would be like in normal life (e.g. reversing), and the practicality of it for street use.

 

I heard the new Huayra or Zonda offers the option of a sequential box along with standard manual or dual clutch auto. Pretty sweet!

they can be used, but they are loud and wear quickly compared to standard trans, have to be refreshed more often.

Never driven one but I've been told the clutch slips under load to absorb the shock of the shift, so it wears out much faster too.

Because of the drum that does most of the work it is impossible to mis-shift, that's an advatage. On the flipside it makes it impossible to skip a gear. On any high speed burst you can't just throw it in neutral and then select a lower gear while braking like you can with a H pattern. You have to go through every gear on the way back down. Good for the track or strip, not really for the street.

 

Agreed on the noise and wear, the straight cut gears are usually made of a softer steel that is less brittle than covnentional helical gears. This prevents shear and cracks because of the instantaneous power uptake but also means that it will wear at a much higer rate. My brother worked at BMC&G rebuilding Porsche Cup car sequentials and from what I recall rebuilds were usually done after around 48 hours of use. Sometimes less, sometimes more depending on the monetary constraints of the team.

 

The other pro/con is clutch wear. A dog box that most sequentials use has no syncros. That means you are only using the clutch pedal to disengage while downshifting. Upshifts are much faster, but the clutch and trans are put through a lot more abuse because of the lack of power interuption.

 

A dual clutch sequential sounds interesting. I'm curious how it would work. I wonder if it would use a drum style gear selector or if the whole process would be automated. I'm guessing the latter. Also curious as to whether it will have straight or helical gears.

 

I've never had a dentist put a drill in my mouth, but I'm guessing the sensation is close to what I experienced while watching that vid. I've heard the high pitched whine plenty of times, but that grinding cannot be good or normal. Made me cringe.

I couldn't watch the entire POS video, it gave me a headache, I wouldn't want that in my street car.

I can't imagine that is 100% right.

I've done the Skip Barber cars with sequential shift and loved it. It didn't sound anything like that either.

 

I'd kill to put a sequential box in my Porsche - for weekend driving or track.

 

I wouldn't want it on a daily driver.

I couldn't watch the entire POS video, it gave me a headache, I wouldn't want that in my street car.

 

I have driven sand rails with sequential that didnt sound as annoying as that car.

Here's a street driven sequential that is actually a sensible four seater. Doesn't even have a clutch.

Is a sequential transmission different than a Lenco or Jericho? I know the shifting is different, but is the engineering the same?

Is a sequential transmission different than a Lenco or Jericho? I know the shifting is different, but is the engineering the same?

 

Lenco is a planetary drive, not even remotely the same thing. Jericho makes a number of clutch and clutch less shift transmissions as well as solenoid shifted, so that depends.

 

When I think sequential its like a road race or rally car, push forward to downshift, pull back to upshift. And not no, but hell no would I ever want one in a car that didn't require wearing a helmet to drive.

These transmissions are loud by nature but the rattling you hear in the video is the reverse handle seen at the bottom of the shift knob. Lou installed it in his ZO6 in a hurry. It wouldn't normally make that noise.

I always thought sequential transmissions were sweet. I love that whine you hear with them and they look like a blast to drive when you watch hill climb videos or similar racing events.

I would love on in my diablo but it would make me want to drive the car hard and fast 100% of the time in which I am sure a ticket would ensue.