Caterham 620R Paddle Shift Conversion
Discussion
Hi, I've had my 620r since 2018 and have thoroughly enjoyed this maddest of Caterham's. However it's not been without its issues, and I am now, about to be on my third clutch. I use the car both on the road and track, I have done about 10,000 miles.
I've tried to always make quick, positive, flatshifts on the way up and clutch downshifts. Maybe I just lack talent!
Anyhow, I can't keep changing the clutch every 18 months so I'm now looking into converting to a paddle shift. From what I read, this could solve the problem of the clutch and protect the Sadev sequential gearbox damage.
I know there's been a fair bit of discussion on this topic and I have been reading up on it.
I would really appreciate any current input from people who have made this conversion on a 620 R or are thinking about it. Thanks.
I've tried to always make quick, positive, flatshifts on the way up and clutch downshifts. Maybe I just lack talent!
Anyhow, I can't keep changing the clutch every 18 months so I'm now looking into converting to a paddle shift. From what I read, this could solve the problem of the clutch and protect the Sadev sequential gearbox damage.
I know there's been a fair bit of discussion on this topic and I have been reading up on it.
I would really appreciate any current input from people who have made this conversion on a 620 R or are thinking about it. Thanks.
I've done a fairly lengthy thread on here and on my Facebook page about fitting the Geartronics paddle shift. (Links are in my profile). So perhaps I am biased towards Geartronics as it works superbly, but the market keeps evolving.
But firstly, it maybe easier to just upgrade your clutch to a solid multiplate and live with clutch use on the downshifts. There is something nice about gear sticks, and paddle shifts are not for everybody. Secondly, if you do go for a paddle shift, you should get some advice about whether you go for gearbox ECU (GCU), or use the MBE. My experience would be to go for the GCU as it is simple to set-up, maintain, logs shifts, and generally easier to understand what is happening. But there will be others that think differently.
But firstly, it maybe easier to just upgrade your clutch to a solid multiplate and live with clutch use on the downshifts. There is something nice about gear sticks, and paddle shifts are not for everybody. Secondly, if you do go for a paddle shift, you should get some advice about whether you go for gearbox ECU (GCU), or use the MBE. My experience would be to go for the GCU as it is simple to set-up, maintain, logs shifts, and generally easier to understand what is happening. But there will be others that think differently.
I'd echo geartronics. Ideally you want a closed loop system that detects that it is actually in gear.
I spoke to geartronics about a system but just couldn't stretch my finances at the time. Wasn't long out of Uni. I did come a war very impressed though. They offered a demo in their car and went into great detail about the pros and cons of all the competitor systems - a balanced view as well.
I had a cheaper system (open loop) system fitted. Worked great for about a year until it found a false neutral and detonated 3rd 4th and the selector forks. The resultant bill would paid for the geartronics system.
I spoke to geartronics about a system but just couldn't stretch my finances at the time. Wasn't long out of Uni. I did come a war very impressed though. They offered a demo in their car and went into great detail about the pros and cons of all the competitor systems - a balanced view as well.
I had a cheaper system (open loop) system fitted. Worked great for about a year until it found a false neutral and detonated 3rd 4th and the selector forks. The resultant bill would paid for the geartronics system.
It's the upshift mainly - they're so fast that the standard clutch with springs eventually break up. Solid clutches can help but are harder to use and drive smoothly. A good paddle shift that controls and matches the RPM across the change is really the only way to get a good change consistently.
DCL said:
I've done a fairly lengthy thread on here and on my Facebook page about fitting the Geartronics paddle shift. (Links are in my profile). So perhaps I am biased towards Geartronics as it works superbly, but the market keeps evolving.
But firstly, it maybe easier to just upgrade your clutch to a solid multiplate and live with clutch use on the downshifts. There is something nice about gear sticks, and paddle shifts are not for everybody. Secondly, if you do go for a paddle shift, you should get some advice about whether you go for gearbox ECU (GCU), or use the MBE. My experience would be to go for the GCU as it is simple to set-up, maintain, logs shifts, and generally easier to understand what is happening. But there will be others that think differently.
Thanks, DCL, that's really useful advice.But firstly, it maybe easier to just upgrade your clutch to a solid multiplate and live with clutch use on the downshifts. There is something nice about gear sticks, and paddle shifts are not for everybody. Secondly, if you do go for a paddle shift, you should get some advice about whether you go for gearbox ECU (GCU), or use the MBE. My experience would be to go for the GCU as it is simple to set-up, maintain, logs shifts, and generally easier to understand what is happening. But there will be others that think differently.
I've already given the go-ahead for a new clutch by Williams Caterham who service my 620r. At £2630 inc VAT, it was more than I was expecting, but everything is these days. So I'm afraid I've missed the boat for a solid clutch.
But I'm certainly very interested in having a look at your threads and getting a lot more information about the paddle-shift upgrade. Interesting what you say about a paddle shift not being for everyone. I imagine that I'm going to love it - especially if it saves the clutch and gearbox.
Anyhow, thanks again for the advice. Much appreciated.
BertBert said:
I'm curious as to why manual shifts would be so harsh on the clutch. It's not used on the way up and if you use the clutch on the way down presumably you can blip and equalise revs?
Confused!
Yes, I know that doesn't seem intuitive Bert Bert, but as DCL said, it seems to be the upshifts that cause the problem. Confused!
This is the second time I have experienced clutch failure and on both occasions, it was an upshift I think from 4th to 5th that caused the failure. I'm quite willing to accept that my skill might be a factor in this, however, there is nothing in the Caterham manual to advise on how precise a shift you need. From what I have learned from other sources, it needs to be rifle shot quick and right at the end of the rev range.
take-good-care-of-the-forest-dewey said:
It doesn't need to be paddle if you prefer using the gear stick. You can actuate off the gear lever.
It's a bit cheaper too.
Interesting, I hadn't thought of that. Though the notion of being able to make shifts while still holding the wheel does have particular appeal, particularly for track days. It's a bit cheaper too.
But I guess I need to go and try a paddle shift to really know. It sounds like Geartronics are a helpful outfit so might start there.
DCL said:
It's the upshift mainly - they're so fast that the standard clutch with springs eventually break up. Solid clutches can help but are harder to use and drive smoothly. A good paddle shift that controls and matches the RPM across the change is really the only way to get a good change consistently.
Interesting. I would expect it to be self limiting as it were. You shouldn't be able to make the shift unless you have lifted enough. But maybe you can. So the geartronics gets the throttle lifted more? before the shift happens to reduce the shock?Sounds like the need for a more robust clutch to me, but if the geartronics did the job, why not?
Mostly a curious response - in what way does the clutch fail? I'm guessing not the friction surface.
No experience of the 620, or how it's set up, but a lot of motorbikes and flatshifters - which are just a timed ignition cut - would I be right in thinking the R has something similar - i.e. strain gauge on the lever detects the push and interrupts spark for a predetermined amount of time. If the time is correct, and you need pretty much the same rev drop for every gear, it's beautifully smooth (i.e redline, full bore, every time..) If you're on part throttle/part rev, the result is pretty nasty. I was always much happier just burping the throttle. Without the flatshifter/ignition cut device, it doesn't release the outgoing gear until it unloads the teeth and with a little finesse the result is pretty smooth. However if you've got the device, then it fires and releases the gear anyway, possibly prematurely, so you can still get a nasty bang..
Of course motorbikes weigh less, have less power and more free-movement in the chain to help with all of that..
Main problem I could see with beefing up the clutch is that the failure moves downstream - I seem to recall hearing of problems with the propshaft? Which I'd not fancy a whole lot..
No experience of the 620, or how it's set up, but a lot of motorbikes and flatshifters - which are just a timed ignition cut - would I be right in thinking the R has something similar - i.e. strain gauge on the lever detects the push and interrupts spark for a predetermined amount of time. If the time is correct, and you need pretty much the same rev drop for every gear, it's beautifully smooth (i.e redline, full bore, every time..) If you're on part throttle/part rev, the result is pretty nasty. I was always much happier just burping the throttle. Without the flatshifter/ignition cut device, it doesn't release the outgoing gear until it unloads the teeth and with a little finesse the result is pretty smooth. However if you've got the device, then it fires and releases the gear anyway, possibly prematurely, so you can still get a nasty bang..
Of course motorbikes weigh less, have less power and more free-movement in the chain to help with all of that..
Main problem I could see with beefing up the clutch is that the failure moves downstream - I seem to recall hearing of problems with the propshaft? Which I'd not fancy a whole lot..
Edited by upsidedownmark on Wednesday 4th May 18:05
Several question to answer in that lot. Taking the 620R clutch first - it is a heavy duty AP road unit and it doesn't wear out or start to slip. There are sveral modes of failure, but generally it involves the clutch breaking the metal parts - usually the lugs that press on the springs break off and the hub is free to rotate.
As soon as load is detected on the gearstick, a switch in the gear box asks the ECU to cut ignition and when torque disappears, the dogs can disengaged and the next gear is engaged. That not to say it's synchronised with the next ratio, but simply there was a moment when the dogs were unloaded and aligned allowing the change. In practice that may mean the engine was too slow, or too fast for the next gear. If it was too slow for example, it hammers the clutch as it goes from overun to fully power in 20 odd milliseconds . . . you get the idea.
Geartronics paddle-shift uses closed loop involving engine RPM and gear positions. It also knows the gear ratios so it can target the correct RPM more like an RPM limiter to achieve the upshift, and uses both the throttle (blipper), and limiter at the same time to target an engine RPM for downshifts.
A system that uses a predetermined time has little hope of doing anthing other than an approximation. The problem for the 620R clutch is that the re-application of power is very fast and the clutch can go from fully unloaded to full torque in 20 ms or so. That is much faster than any throttle response that the clutch was designed to deal with.
It maybe that torque recovery could solve the issue, but CATs don't like it and exhaust noise might make that unusable on track. So I guess Caterham have decided the clutch issue is the best compromise, as it is not an immediate problem at the point of sale.
As soon as load is detected on the gearstick, a switch in the gear box asks the ECU to cut ignition and when torque disappears, the dogs can disengaged and the next gear is engaged. That not to say it's synchronised with the next ratio, but simply there was a moment when the dogs were unloaded and aligned allowing the change. In practice that may mean the engine was too slow, or too fast for the next gear. If it was too slow for example, it hammers the clutch as it goes from overun to fully power in 20 odd milliseconds . . . you get the idea.
Geartronics paddle-shift uses closed loop involving engine RPM and gear positions. It also knows the gear ratios so it can target the correct RPM more like an RPM limiter to achieve the upshift, and uses both the throttle (blipper), and limiter at the same time to target an engine RPM for downshifts.
A system that uses a predetermined time has little hope of doing anthing other than an approximation. The problem for the 620R clutch is that the re-application of power is very fast and the clutch can go from fully unloaded to full torque in 20 ms or so. That is much faster than any throttle response that the clutch was designed to deal with.
It maybe that torque recovery could solve the issue, but CATs don't like it and exhaust noise might make that unusable on track. So I guess Caterham have decided the clutch issue is the best compromise, as it is not an immediate problem at the point of sale.
Thanks DCL for your answers to ‘upside down mark’ questions. Very informative and concise. It really does seem that a Paddle shift conversion is the only viable long-term solution. I’ll get it back on the road for the summer and then continue my research and look at a conversion during the winter.
If you need any information on both clutches and or paddle shifts for a 620 give Andy a call at www.pgmsussex.com There is some info on the website but he is always happy to explain the finer details on the phone.
bluecob said:
If you need any information on both clutches and or paddle shifts for a 620 give Andy a call at www.pgmsussex.com There is some info on the website but he is always happy to explain the finer details on the phone.
Brilliant, thanks bluecob!Just finding out more. From the description, am I right in thinking that as standard the 620r has a flat shift option being a (simple) throttle cut from a strain guage on the gear stick? And that is the setup that breaks clutches?
If so I understand it much more. I'd assumed we were talking about manual sequential shifting. Load the lever, lift the throttle new gear engages.
A closed loop system then will definitely improve it. Back in my radical racing days, the earlier open loop paddle shift system definitely was bad for the gearboxes. Then they implemented a closed loop system and it was much better.
If so I understand it much more. I'd assumed we were talking about manual sequential shifting. Load the lever, lift the throttle new gear engages.
A closed loop system then will definitely improve it. Back in my radical racing days, the earlier open loop paddle shift system definitely was bad for the gearboxes. Then they implemented a closed loop system and it was much better.
BertBert said:
Just finding out more. From the description, am I right in thinking that as standard the 620r has a flat shift option being a (simple) throttle cut from a strain guage on the gear stick? And that is the setup that breaks clutches?
If so I understand it much more. I'd assumed we were talking about manual sequential shifting. Load the lever, lift the throttle new gear engages.
A closed loop system then will definitely improve it. Back in my radical racing days, the earlier open loop paddle shift system definitely was bad for the gearboxes. Then they implemented a closed loop system and it was much better.
You probably mean this, but for clarity all the systems cut ignition on an upshift. They don't touch the throttle position. If so I understand it much more. I'd assumed we were talking about manual sequential shifting. Load the lever, lift the throttle new gear engages.
A closed loop system then will definitely improve it. Back in my radical racing days, the earlier open loop paddle shift system definitely was bad for the gearboxes. Then they implemented a closed loop system and it was much better.
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