Extra power / gearbox ,clutch
Discussion
wessexrfc said:
I'm just going through this now after my standard box let go. I was running about 420bhp with about the same torque. I've upgraded the clutch and gone for the strengthened gear box c/w oil cooler and lightened fly wheel (thanks Andy). I will try to update once the car is back on the road with the costs. Reasons for doing this? Reliability, and looking to take the car to a "safe" 500bhp ish.
sounds good , I'm just trying to gauge if it's track work or the way one drives to see why at 400lb/ft Torque which is supposedly still to be 'safe' ( 3r in my case ) that a lot of people are breaking 5th gear and the clutch seems to end up slipping .. 
t it's self at 400ft 414bhp. At donnington the other week in the second session. verba1 said:
sounds good , I'm just trying to gauge if it's track work or the way one drives to see why at 400lb/ft Torque which is supposedly still to be 'safe' ( 3r in my case ) that a lot of people are breaking 5th gear and the clutch seems to end up slipping ..
Regarding the gearbox, it was made for a car that runs little over 200lb/ft. Even a standard noble putting 350 through it is a lot of extra stress. mrpbailey said:
verba1 said:
sounds good , I'm just trying to gauge if it's track work or the way one drives to see why at 400lb/ft Torque which is supposedly still to be 'safe' ( 3r in my case ) that a lot of people are breaking 5th gear and the clutch seems to end up slipping ..
Regarding the gearbox, it was made for a car that runs little over 200lb/ft. Even a standard noble putting 350 through it is a lot of extra stress. well let me put my spin on this power rating thing...
I have an ST220.. it runs around 230bhp AND has a quaife lsd fitted (why I bought it lol)... it still suffers with grip issues just putting the 250ish ftlb to the road.
My noble runs a genuine 600ftlb + and has run over 530ftlb for over 3 years now and lots of miles (around 15k)... its had a load of dyno runs in that time and I almost exclusively run it on full boost as Im not particularly kind on the car, I have on a number of occasions given the car FULL throttle through 1st gear WITHOUT wheelspin, which I think shows whist I have huge amounts of torque, I also have huge amounts of traction and as such punish the gearbox very heavily.
Additionally we have our tame scotish racing driver who is doing 45min races with slicks and 500ftlb and isn't exactly destroying a box at every race.
I think this shows the box actually can take the power, you just have to give it a fighting chance... Its widely accepted that gearbox losses are actually a % of your engine power rather than a fixed amount... so if we assume it saps 10% (lots of people recon its lots more but I have my doubts) then at stock ST220 power its having to expel 22bhp of energy (mostly heat and some noise)... at 400bhp that figure is 40bhp... at 600bhp thats 60bhp.... thats a HUGE amount of energy, were is it going as you can't destroy energy, clearly its heat.... I think its this that is killing boxes, so if we can manage the heat regardless of power then the box should be ok.
I run my box a little overfull, and run cooling on track to help get rid of this heat....worked so far on mine but I am expecting it to break sat some stage as Im probably going to keep creeping the torque up until I find the real limit of the box power wise.
I have an ST220.. it runs around 230bhp AND has a quaife lsd fitted (why I bought it lol)... it still suffers with grip issues just putting the 250ish ftlb to the road.
My noble runs a genuine 600ftlb + and has run over 530ftlb for over 3 years now and lots of miles (around 15k)... its had a load of dyno runs in that time and I almost exclusively run it on full boost as Im not particularly kind on the car, I have on a number of occasions given the car FULL throttle through 1st gear WITHOUT wheelspin, which I think shows whist I have huge amounts of torque, I also have huge amounts of traction and as such punish the gearbox very heavily.
Additionally we have our tame scotish racing driver who is doing 45min races with slicks and 500ftlb and isn't exactly destroying a box at every race.
I think this shows the box actually can take the power, you just have to give it a fighting chance... Its widely accepted that gearbox losses are actually a % of your engine power rather than a fixed amount... so if we assume it saps 10% (lots of people recon its lots more but I have my doubts) then at stock ST220 power its having to expel 22bhp of energy (mostly heat and some noise)... at 400bhp that figure is 40bhp... at 600bhp thats 60bhp.... thats a HUGE amount of energy, were is it going as you can't destroy energy, clearly its heat.... I think its this that is killing boxes, so if we can manage the heat regardless of power then the box should be ok.
I run my box a little overfull, and run cooling on track to help get rid of this heat....worked so far on mine but I am expecting it to break sat some stage as Im probably going to keep creeping the torque up until I find the real limit of the box power wise.
The gearbox can take the power, i run 580ftlb torq, but they wont last much more than a year, always 5th gear, as again mine has just started to slip on the main shaft in 5th, all otber gears have been fine, the problem is they will never be reliable running big power amd without doubt 5th is the weak link, now i hixe no secrets and have decided to see if they can be splined together instead of frozen in, and look at making 5th gear a dog tooth, which will make 5th gear noisey but solve the issue, just waiting to see if its poss
Just to clarify, my box done 30,000 miles in 9 years, with 540lb/ft, over 30 races now, ranging from 10 - 45 minutes, and only just broke last month.
If you are smooth with gear changes and careful to lift while flying over kerbs, you shouldn't brake them.
When it did brake, it wasn't during a race either but the different between my car and a road car is the weight, my box has 540lb ft to deal with but only 1050kg plus driver, a road car could quite easily be subjecting a gearbox to the same force with 440 ft lb and 1200kg plus driver.
They should last a few years of abuse IMO.
If you are smooth with gear changes and careful to lift while flying over kerbs, you shouldn't brake them.
When it did brake, it wasn't during a race either but the different between my car and a road car is the weight, my box has 540lb ft to deal with but only 1050kg plus driver, a road car could quite easily be subjecting a gearbox to the same force with 440 ft lb and 1200kg plus driver.
They should last a few years of abuse IMO.
Hollowpockets said:
Just to clarify, my box done 30,000 miles in 9 years, with 540lb/ft, over 30 races now, ranging from 10 - 45 minutes, and only just broke last month.
If you are smooth with gear changes and careful to lift while flying over kerbs, you shouldn't brake them.
When it did brake, it wasn't during a race either but the different between my car and a road car is the weight, my box has 540lb ft to deal with but only 1050kg plus driver, a road car could quite easily be subjecting a gearbox to the same force with 440 ft lb and 1200kg plus driver.
They should last a few years of abuse IMO.
Sorry mate dont agree, you cannot call that box reliable and also 5th gear on a race track is used alot less and for less time, you cant compare the two ie mine has never had a problem on track, its worn off track from constant motorway driving and overtaking, my caterham runs big power never had a prob eith that box and its only on track. Graham do 200 laps of le man and the moulsonIf you are smooth with gear changes and careful to lift while flying over kerbs, you shouldn't brake them.
When it did brake, it wasn't during a race either but the different between my car and a road car is the weight, my box has 540lb ft to deal with but only 1050kg plus driver, a road car could quite easily be subjecting a gearbox to the same force with 440 ft lb and 1200kg plus driver.
They should last a few years of abuse IMO.
straight where 5th will be used constantly, see how u get on then?
Hi Craig, I'm not sure how you come to that conclusion, my most commonly used gears on track are 4th and 5th, my car has lots of low torque so I'm not making too much power at the top end for class rules and I only rev it to 6500 so I'm changing up the gears earlier than most would on track and staying in the maximum torque band 500-530ish most of the time, average speeds of over 100mph on Silverstone/Snetterton/Donnington also confirm im more often than not, in 4th/5th gear and into 6th on Silverstone. 45 minutes of racing through the gears and bouncing around over kerbs, is as good a test as any.
9 years, 30+ races, lapped Silverstone/Donington/Snetterton/Knockhill faster than any Noble has gone before it to my knowledge and it's only broken 5th gear once after all that, I can't see how that's not reliable. Even when 5th gear was broken I kept racing my two races at Knockhill and was shifting from 4th to 6th 3 times a lap, that's only a small twisty track and still use 5th there plenty.
Most people break them with nowhere near as much use.
Cheers
Graham
9 years, 30+ races, lapped Silverstone/Donington/Snetterton/Knockhill faster than any Noble has gone before it to my knowledge and it's only broken 5th gear once after all that, I can't see how that's not reliable. Even when 5th gear was broken I kept racing my two races at Knockhill and was shifting from 4th to 6th 3 times a lap, that's only a small twisty track and still use 5th there plenty.
Most people break them with nowhere near as much use.
Cheers
Graham
Guys thanks for the input very interesting reading.
I'm referring more to in my case a standard 6 speed box ( non strengthened ) only used on road . It has been on standard power for over 3 years and has recently been remapped to 380 bhp 400 lb/ft and i'm just wondering, as quite a few boxes at these torque levels are breaking , if it's worth taking the torque down as i don't really want to go through all the hassle and expense of getting it repaired if you see what i mean .
I'm referring more to in my case a standard 6 speed box ( non strengthened ) only used on road . It has been on standard power for over 3 years and has recently been remapped to 380 bhp 400 lb/ft and i'm just wondering, as quite a few boxes at these torque levels are breaking , if it's worth taking the torque down as i don't really want to go through all the hassle and expense of getting it repaired if you see what i mean .
Hollowpockets said:
Hi Craig, I'm not sure how you come to that conclusion, my most commonly used gears on track are 4th and 5th, my car has lots of low torque so I'm not making too much power at the top end for class rules and I only rev it to 6500 so I'm changing up the gears earlier than most would on track and staying in the maximum torque band 500-530ish most of the time, average speeds of over 100mph on Silverstone/Snetterton/Donnington also confirm im more often than not, in 4th/5th gear and into 6th on Silverstone. 45 minutes of racing through the gears and bouncing around over kerbs, is as good a test as any.
9 years, 30+ races, lapped Silverstone/Donington/Snetterton/Knockhill faster than any Noble has gone before it to my knowledge and it's only broken 5th gear once after all that, I can't see how that's not reliable. Even when 5th gear was broken I kept racing my two races at Knockhill and was shifting from 4th to 6th 3 times a lap, that's only a small twisty track and still use 5th there plenty.
Most people break them with nowhere near as much use.
Cheers
Graham
Hi Graham, im not trying to be argumentative, but its not track work that breaks them, ie when going through gears at max torque running evenly in each gear change it seems to handle it progressivly, its nailing it at lets say from 4k rpm to max say 6500rpm from 100 onwards tbat it breaks after time, mine has lasted close to 3 years, but that is hardly reliable, ive never broke a geatbox in 35yrs of driving and racing. I take it urs is brimmed with oil which helps big time, is urs also braced around cassing? My point was that in stamdard form and power there is little problem, Graham think you have got away with it so far, but honestly so many of us wouldnt break 5th it was reliable, ie not have to worry how hard you push it is what i would prefer. Come on mate, you capped the torque to compensate as you can run the same power as me. 9 years, 30+ races, lapped Silverstone/Donington/Snetterton/Knockhill faster than any Noble has gone before it to my knowledge and it's only broken 5th gear once after all that, I can't see how that's not reliable. Even when 5th gear was broken I kept racing my two races at Knockhill and was shifting from 4th to 6th 3 times a lap, that's only a small twisty track and still use 5th there plenty.
Most people break them with nowhere near as much use.
Cheers
Graham
I know if a solution comes up at a fair price you and me will be jumping at it :-)
I've capped my low down torque a huge amount still mainly as I'm worried about the box.... But then I'm still running over 600ftlb now and it hasn't broke.... yet...
Of the failures, to my knowledge as many have broken running less than 500ftlb as running over 500ftlb,
Let's change the question, when your boxs have bust, was you running oil cooling and high oil level at the time?
Of the failures, to my knowledge as many have broken running less than 500ftlb as running over 500ftlb,
Let's change the question, when your boxs have bust, was you running oil cooling and high oil level at the time?
Gassing Station | Noble | Top of Page | What's New | My Stuff