Quaife sequential gearbox changing gear on it's own
Discussion
I have an Elise race car with a Quaife sequential box and flatshift system fitted. I've only just bought the car and was out testing yesterday.
Maybe twice a lap, the car would change down a gear without me having touched the gear stick. I think it was only doing it from 5th doe to 4th. Obviously I was concerned about buzzing the engine, so stopped driving once I was sure it was a mechanical problem and not (new) user error.
I have two other symptoms which may be related. The first it that the gear leaver was not clicking back to the centre position after a gear change. It felt like it wasn't springing back firmly enough to click back in. The second was that the clutch felt to be going, as in 1st gear the car would crawl forward or stall if I tried to stop when in gear with the clutch pedal in. It may be the clutch cylinder rather than the clutch itself. I doubt the clutch is related to the issues with the gear change as the quaife system does not use the clutch one I'm moving.
I will speak to Quaife tomorrow and alto ATF who fitted it last year, but any ideas in the mean time would be appreciated. My mechanic thinks it could be the cable linkage between the gear stick and gearbox sticking inside the sleeve, but I would like a few other thoughts before I have the whole thing taken out of the car for inspection.
Maybe twice a lap, the car would change down a gear without me having touched the gear stick. I think it was only doing it from 5th doe to 4th. Obviously I was concerned about buzzing the engine, so stopped driving once I was sure it was a mechanical problem and not (new) user error.
I have two other symptoms which may be related. The first it that the gear leaver was not clicking back to the centre position after a gear change. It felt like it wasn't springing back firmly enough to click back in. The second was that the clutch felt to be going, as in 1st gear the car would crawl forward or stall if I tried to stop when in gear with the clutch pedal in. It may be the clutch cylinder rather than the clutch itself. I doubt the clutch is related to the issues with the gear change as the quaife system does not use the clutch one I'm moving.
I will speak to Quaife tomorrow and alto ATF who fitted it last year, but any ideas in the mean time would be appreciated. My mechanic thinks it could be the cable linkage between the gear stick and gearbox sticking inside the sleeve, but I would like a few other thoughts before I have the whole thing taken out of the car for inspection.
Sounds to me like the lever/cable failure to return will be the cause of your shift problems.
The clutch will be related to either the master or slave cylinders so is not the clutch as such.
So start by looking for fluid leaks or has the fluid level dropped. If you sit with the car running in gear and the clutch pedal on the floor will the car start to pull away or does it just sit there dragging slightly. If it just sits there with a constant drag then it has to be an adjustment issue. If it pulls away then likely an internal leak in the master cylinder.
Steve
The clutch will be related to either the master or slave cylinders so is not the clutch as such.
So start by looking for fluid leaks or has the fluid level dropped. If you sit with the car running in gear and the clutch pedal on the floor will the car start to pull away or does it just sit there dragging slightly. If it just sits there with a constant drag then it has to be an adjustment issue. If it pulls away then likely an internal leak in the master cylinder.
Steve
If you have worn dogs, it is possible for the dog ring to get fired out of one gear and into the next one when put under load. However, this is unlikely as the shifter barrel/plate should be held fairly firmly in position by detents. But, if your gear lever is not springing back to centre, then there is something wrong there too, which could well be leaving the selector barrel/plate "floating" and as a result you could get "phantom" shifts. Any-which-way the box probably needs to come out for a look-see!
the shaping of the dog itself is critical to the operation of the system. They are deliberately undercut behind the tooth end to cause the dog to pull tighter into the dogring when torsionally loaded. if the dogs have worn (usually on the ends of the dogs at the corners) and they are now no longer undercut, they will tend to push apart rather than pull together
the shaping of the dog itself is critical to the operation of the system. They are deliberately undercut behind the tooth end to cause the dog to pull tighter into the dogring when torsionally loaded. if the dogs have worn (usually on the ends of the dogs at the corners) and they are now no longer undercut, they will tend to push apart rather than pull together
Edited by anonymous-user on Sunday 4th August 12:53
Max_Torque said:
But, if your gear lever is not springing back to centre, then there is something wrong there too, which could well be leaving the selector barrel/plate "floating" and as a result you could get "phantom" shifts. Any-which-way the box probably needs to come out for a look-see!
Logically, to me, this feels likely. I think the selector barrel isn't locked in place. Whilst it could be wear on the dogs due to miss-use, the gearbox only has about 2-3 hours on it from new and I don't think I've done anything to abuse them (although I am new to a sequential, so no guarantees!).Thanks for the input. I'll talk to ATF Power and Quaife tomorrow and get their ideas before setting my mechanic lose.
The Wookie said:
Might also be worth checking the engine mounts, I've had one shear before and the resultant fore/aft motion of the engine and box when going on and off the throttle was effectively making it change gear by itself
Ah, yes, good call. Basically, is the engine moving and pulling on the cable, making it change gear. An easy one to check before the gearbox gets stripped - THANKS!Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff