620R - clutch and sequential gearbox lifespan/cost

[Dicko_4]

Hi everyone,

I'm currently looking into a few options for my next car and one option is the Caterham 620R.

I've recently been looking into the 620R on YouTube and the online forums etc and I'm amazed by it. If I went down the 620R route I would obviously have a second car as a daily. It would be used mainly for road use/euro trips etc and I know people will say its too much for the road and try to talk to me into the 620S but there's something I love about the idea of a sequential and the bangs/flames from the side exhaust. I like the idea of having something with so much character and performance so it feels "special" every time I take it out. Yes I know its a marmite car to drive on the road and I NEED to drive one first to see if I like it but I wondered if anyone knew how long the sequential gearbox lasts and how much they are to rebuild? Also same question woth regards to the clutch?

Thanks

John

[DCL]

Reliability of the Sadev is a question that comes up quite often and the answer is that it is really down to how skilled you are, or how much money you are willing to spend on a good paddle shift.

Generally they are very good if you change the oil frequently. But ham fisted bashing through the gears will require regular servicing and replacement of the dogs. On the other hand, a well set-up Geartronics paddle shift may never need anything other than oil changes before you get bored with the car.

But my advice would be to think of them as motorsport racing 'boxes designed to withstand 15 minutes of hell between checks and oil changes - they are designed to be stripped down and inspected each season. Use them in a road car and you're only using 10% of their potential capacity, but that doesn't mean they will be 90% more reliable.

Edited by DCL on Saturday 23 January 09:10

[Dicko_4]

DCL said:

Reliability of the Sadev is a question that comes up quite often and the answer is that it is really down to how skilled you are, or how much money you are willing to spend on a good paddle shift.

Generally they are very good if you change the oil frequently. But ham fisted bashing through the gears will require regular servicing and replacement of the dogs. On the other hand, a well set-up Geartronics paddle shift may never need anything other than oil changes before you get bored with the car.

But my advice would be to think of them as motorsport racing 'boxes designed to withstand 15 minutes of hell between checks and oil changes - they are designed to be stripped down and inspected each season. Use them in a road car and you're only using 10% of their potential capacity, but that doesn't mean they will be 90% more reliable.

Edited by DCL on Saturday 23 January 09:10

Thank you for your reply. Do you know roughly how often the sadev need an oil change/servicing and how much this usually costs? The paddle shift seems interesting especially if it helps preserve the gearbox. Does the paddles shift upgrade on the sadev work in the same way as the standard with gearknob - I.e flatshift on upshifts and use the clutch for downshifts/1st gear?

Thanks

John

[DCL]

The Sadev manual recommend changing oil 'every meeting' and that hints at its intended use. No mileage is quoted beyond 1st service which is recommended at 50 Km (30 miles).

Personally, I change it every time I use the car (every track event) but I know of others that treat it like a conventional gearbox. Used as a road car I would suggest every 1000 miles would seem a sensible compromise. With dog boxes, the debris is generated at every shift and you don't want that floating around the 'box any longer than necessary. They do have magnet plugs, but it can take time to collect the particles up.

It takes just over a litre of 75W140 synthetic oil, so about £20 a go if you do it yourself.

'Easy shifts' help with clutch-less up shifts, and generally they protect the box. Downshifts require the use of the clutch, or a high degree of skill. Paddle shifts can do clutch-less up and down shifts by controlling the engine RPM precisely, usually with a combination of auto blip and limiter. The throttle is opened automatically and the engine limited back to synchronise to the new gear ratio. When working correctly they effectively prevent dog wear.

If you click on my profile there's some youtube clips showing a Sadev up and down shift using a Geartronics paddle shift.

Edited by DCL on Sunday 24th January 18:22

[mr momo]

Do Caterham still do their 6-Speed manual. If so, have a go. I had the 6 speed on an old SLR and it just suited the car.

[upsidedownmark]

The other thing to consider is that (without the clever paddleshift gubbins), sequentials generally don't like part throttle or less than full RPM shifts. Usually it's just a timed ignition cut that is calibrated for the full throttle, full rpm upshift scenario. Consequently anything else is mistimed, and so rough as guts and not kind to the mechanical bits, which doesn't fit really well for a road car. Disclaimer - I haven't driven the 620R personally (but would expect the same)

[Boggo]

upsidedownmark said:

The other thing to consider is that (without the clever paddleshift gubbins), sequentials generally don't like part throttle or less than full RPM shifts. Usually it's just a timed ignition cut that is calibrated for the full throttle, full rpm upshift scenario. Consequently anything else is mistimed, and so rough as guts and not kind to the mechanical bits, which doesn't fit really well for a road car. Disclaimer - I haven't driven the 620R personally (but would expect the same)

+1 Motorsport boxes and road driving isn't the best idea

[I Like Tea]

I’ve never really understood this argument. Motorcycles have used sequential dog engagement ‘boxes for as long as I’ve known, without needing oil changes multiple times a year and will do 10s of thousands of miles without failing. Why is a sequential gearbox in a road going Caterham going to be any different?

Change the oil once a year and enjoy

[upsidedownmark]

I suspect you're trolling, but a few significant factors:

- A motorbike, engine and drivetrain all weigh a LOT less than even a caterham, so a lot less inertia, and less loading on the components
- Motorbike transmissions, dog or otherwise are designed for general use. Dog/sequentials on cars are generally designed for motorsport, not for general use.
- Most motorbike riders are shifting with a clutch in the 'traditional' manner. Some are doing 'manual' clutchless with a lift on the throttle, and some are using flat shifters. FWIW my bike also hated part throttle / rpm shifts on the flatshifter. You could of course do the same with your caterham instead of banging the lever, but..
- Chain drive (a lot more 'play' in the transmission)

[Boggo]

upsidedownmark said:

I suspect you're trolling, but a few significant factors:

- A motorbike, engine and drivetrain all weigh a LOT less than even a caterham, so a lot less inertia, and less loading on the components
- Motorbike transmissions, dog or otherwise are designed for general use. Dog/sequentials on cars are generally designed for motorsport, not for general use.
- Most motorbike riders are shifting with a clutch in the 'traditional' manner. Some are doing 'manual' clutchless with a lift on the throttle, and some are using flat shifters. FWIW my bike also hated part throttle / rpm shifts on the flatshifter. You could of course do the same with your caterham instead of banging the lever, but..
- Chain drive (a lot more 'play' in the transmission)

+1 again!

[jm doc]

There are many cars out on the roads with clutchless boxes, they are very much routine and are used in many extremely high performance cars. I've never understand why the box on the caterham in particular needs down changes with a clutch.

I'm sure someone will come along shortly and point out to me where I am going wrong with this.

[DCL]

jm doc said:

There are many cars out on the roads with clutchless boxes, they are very much routine and are used in many extremely high performance cars. I've never understand why the box on the caterham in particular needs down changes with a clutch.

I'm sure someone will come along shortly and point out to me where I am going wrong with this.

The simple answer is they're not engineered to do it in the factory Caterham . Be that a cost factor, or a belief that the driving experience should be as raw as possible, I don't know. But Sadev is very capable of doing a very smooth clutch-less change up and down. https://youtu.be/Qglr6TJ9Wr0

[BertBert]

jm doc said:

There are many cars out on the roads with clutchless boxes, they are very much routine and are used in many extremely high performance cars. I've never understand why the box on the caterham in particular needs down changes with a clutch.

I'm sure someone will come along shortly and point out to me where I am going wrong with this.

I have to ask what's a clutch less box in a road car?

[upsidedownmark]

I'd hazzard a guess that most of what people think are clutchless boxes (i.e. flappy paddles) are actually dual clutch systems, but with computer actuated clutches.
In a dual clutch system you separate odd and even gears onto different shafts which are individually clutched. Only one shaft is engaged at a the computer pre-selects the next gear up/down depending on what's going on, and when you pull the paddle it switches one clutch in and the other out. Hence the extremely fast/seamless shift. As to why they're not on a caterham, they're bigger, heavier, more complex and don't exactly add to the driving.

Of course I'm sure that there's some exception that breaks the rule, but I'm not aware of any production cars that don't use a clutch to shift - as much as it is possible to program a computer (or a driver!) to make clutchless up/down shifts with a dog box. Just that for *most* applications there are other ways of doing it that I guess you could say are more appropriate..

Edited by upsidedownmark on Tuesday 26th January 09:59

[I Like Tea]

upsidedownmark said:

I suspect you're trolling, but a few significant factors:

- A motorbike, engine and drivetrain all weigh a LOT less than even a caterham, so a lot less inertia, and less loading on the components
- Motorbike transmissions, dog or otherwise are designed for general use. Dog/sequentials on cars are generally designed for motorsport, not for general use.
- Most motorbike riders are shifting with a clutch in the 'traditional' manner. Some are doing 'manual' clutchless with a lift on the throttle, and some are using flat shifters. FWIW my bike also hated part throttle / rpm shifts on the flatshifter. You could of course do the same with your caterham instead of banging the lever, but..
- Chain drive (a lot more 'play' in the transmission)

Sorry you thought that, it was not my intention. Was merely trying to offer a counter point to what I considered a negative view of sequential gearboxes to help the OP make an informed decision. Some further thoughts based on my experiences.

A Suzuki Hayabusa plus rider is about 340kg, so about half the weight of 620R, so yes you make a good point. However there are plenty of examples where bike engines and gearboxes have been used in cars of similar weight to the Caterham.

I used to run a Radical Prosport with a built Hayabusa engine making about 200bhp and weighing 500kg, so similar to the Caterham. Running ultra soft slicks on sticky tarmac it was launched hard 4 to 6 times a meeting. This is when the gearbox sees the highest torque and the 1st to 2nd change is also the most violent. Lots of other stuff broke on that car but not the gearbox. I changed the oil at the beginning of each season and I think once mid season after the clutch failed.

In a series I used to race, there were a lot of 7esque cars, many running Hayabusa engines and all 500kg or over, there was a 500kg min weight limit so lighter cars had to ballast up. Never saw a gearbox failure, a number of engine failures though.

A sequential box also protects the engine from missed gear over-revs. I cost myself a couple of engine re-builds over the years from missing a 4th to 5th change and getting 3rd on the 6 speed Caterham box, that couldn't have happened with a sequential.

If I was buying a Caterham at that price point I would have the sequential box every time. Firstly, as the OP says, for the experience of having the most extreme factory Caterham. Secondly, if I didn't like it, it's easy to swap out for an H-pattern box, either store the sequential for resale or sell it to cover all the swap costs. Hope that helps the OP and if you do dismiss the sequential I won't be offended . Caterhams are amazing cars, so glad I owned mine, whatever you buy will be brilliant.

[upsidedownmark]

I stand corrected
All very good points/counterpoints also. IMO (and it is just opinion), it's the 'road use' that goes hard against the sequential. 99% of the shifts are going to be out of the window its designed to work in. Even though my inner child still thinks they're very cool.

[I Like Tea]

Yes, what is the threshold for too extreme for a road car, is a 300bhp Caterham too extreme? You could argue any Caterham is too extreme and before you know it you've bought a Porsche Boxster

[upsidedownmark]

That's a personal choice. My point was simply that while it's surprising how well a dog box with a simple rev cut shifts when at the intended point (foot flat, near max rpm), it's equally impressive how badly they shift when you're out of that window, and those bad shifts aren't just uncomfortable, they're bad for the oily bits.

[jm doc]

BertBert said:

jm doc said:

There are many cars out on the roads with clutchless boxes, they are very much routine and are used in many extremely high performance cars. I've never understand why the box on the caterham in particular needs down changes with a clutch.

I'm sure someone will come along shortly and point out to me where I am going wrong with this.

I have to ask what's a clutch less box in a road car?

A car without a clutch PEDAL. Do not to confuse pedal with pedant. Judging by the thread responses, that vast majority seemed to understand the meaning of the post. I'm sorry if you struggled.

[jimhcat]

I have a 620R and although I don't use it much on the road now, I never had an issue with the sequential box and part throttle shifting when I did road miles. With the factory setup I always used the clutch and heel and toe for down shifts and don't remember it being too clonky.
I have now got a flappy paddle system on my car and this allows for clutch-less changes up and down. I do tend to use the clutch when changing down at low speeds like when returning to the pit lane a it smooths the process slightly.
I had my Sadev box serviced while it was out of the car for the modifications and there wasn't any major repairs required to it, just seals etc.
I know of one 620R that has done a lot of road miles as well as numerous track days and I don't think he has had his box serviced at all.