Lowering gearing?
Discussion
Beemer-5 said:
Many reviews of modern day Corvettes say the gearing in 7th, 6th and even 5th is too tall.
I find the gearing too tall on my 2009 Corvette.
Two answers it seems. More power or lower gearing.
Easiest way to lower the gearing would be what and at what cost, anyone?
Thanx.
Solution: change downI find the gearing too tall on my 2009 Corvette.
Two answers it seems. More power or lower gearing.
Easiest way to lower the gearing would be what and at what cost, anyone?
Thanx.
Cost: nil
....or have I missed something?
I'm very happy with the gearing on my 01Z06. I think 1-4 are a little shorter than the gears on the standard C5 , but 5&6 are both pretty tall. Same for the C6, and i believe similar for the C7, except you get another over-drive gear in 7th. This all helps with cruising economy.
If you want to go fast just use the lower gears, as said above. I can't remember exactly, but on track 4th is good for over 140mph in my car.
If you want to go fast just use the lower gears, as said above. I can't remember exactly, but on track 4th is good for over 140mph in my car.
Change diff ratios. Went 3:45 to 4:10 in the ZR1 despite having significantly more power than stock.
What's it done? Brought down MPG. Given me a mental car. As an idea. It has slightly more power than my Z06 but is a bit heavier. It'll leave the Z06 for dead up to 80 or so mph - if it hooks up. More importantly to me is what it's done to the car for driving roads around the Alps and such like. In affect its given me a much closer box. Ideal for mountain passes. Having just returned from a 2800 mile trip including a lot of gorge roads, as good as the Z06 is I would rather have been driving the ZR1 on them I often find myself wanting first and a half etc.
The down side is it runs out of oomph at a slower speed. Third gear pull from motorway speeds on a stock geared ZR1 is unbelievable. I've lost that as I'm now using 4th or 5th. Like most things if you gain somewhere, you loose somewhere else. Tbh I was getting a bit fed up with its gearing and was tempted to put the other diff back in but then I bought the Z06 so I kind of have the best of both worlds now.
The other alternative would be to change the gearbox ratios on only the gears you want to change.
What's it done? Brought down MPG. Given me a mental car. As an idea. It has slightly more power than my Z06 but is a bit heavier. It'll leave the Z06 for dead up to 80 or so mph - if it hooks up. More importantly to me is what it's done to the car for driving roads around the Alps and such like. In affect its given me a much closer box. Ideal for mountain passes. Having just returned from a 2800 mile trip including a lot of gorge roads, as good as the Z06 is I would rather have been driving the ZR1 on them I often find myself wanting first and a half etc.
The down side is it runs out of oomph at a slower speed. Third gear pull from motorway speeds on a stock geared ZR1 is unbelievable. I've lost that as I'm now using 4th or 5th. Like most things if you gain somewhere, you loose somewhere else. Tbh I was getting a bit fed up with its gearing and was tempted to put the other diff back in but then I bought the Z06 so I kind of have the best of both worlds now.
The other alternative would be to change the gearbox ratios on only the gears you want to change.
It certainly isn't a case of just changing down!
I have had many sports bikes and a simple sprocket change to lower the gearing has often had an amazing effect.
Bike and car makers have to consider noise and emission laws.
My Monaro 6.0 was badly over geared in 6th.
Several car magazines have criticised the high gears in Corvettes.
A lower set of gears can make a car feel like it has more power.
When a car can do 180 in 5th out of 6 or 7, it's over geared for street use.
I have had many sports bikes and a simple sprocket change to lower the gearing has often had an amazing effect.
Bike and car makers have to consider noise and emission laws.
My Monaro 6.0 was badly over geared in 6th.
Several car magazines have criticised the high gears in Corvettes.
A lower set of gears can make a car feel like it has more power.
When a car can do 180 in 5th out of 6 or 7, it's over geared for street use.
Beemer-5 said:
...
When a car can do 180 in 5th out of 6 or 7, it's over geared for street use.
I'd argue that it's over-geared for track use rather than street use... On the street, there are issues like fuel economy and noise levels that to many people are at least as important as maxing out at peak power in 7th!When a car can do 180 in 5th out of 6 or 7, it's over geared for street use.
I've never been convinced by the idea of just dropping the diff ratio to "improve" performance. Often you end up making 1st too low in order to improve acceleration in 6th/7th, and the rev drops between gears stay the same (they just happen sooner!). It's not really an alternative to closing up the ratios in the box. I'm with others, and would just drop down a couple of cogs then you've still got the high gears when you want them.
Changing the ratios in the ZF wasn't an option. Kurt White in the US did look into it as a group buy but no one could match ZF's quality so it wasn't an option. Being a breathed on LT5 with the limiter set just under 8k the diff swap works very well indeed, maybe not so much on on lower revving cars that run out of puff sooner. Just dropping down a couple of cogs is not the same at all. Why do you think they change the gearing of bike and cars at different circuits, perhaps they should just tell the driver/rider to change down
I'd say it matters on the road too, depending an what sort of driving you do. But that's the point most people don't do much driving of their Vettes anyway, let alone tracking them or even driving in anger on the roads. Some Vette owner at a meet I gate crashed near Bedford was busy telling me they don't handle. Really I replied, you tracked it then....no.
I'd say it matters on the road too, depending an what sort of driving you do. But that's the point most people don't do much driving of their Vettes anyway, let alone tracking them or even driving in anger on the roads. Some Vette owner at a meet I gate crashed near Bedford was busy telling me they don't handle. Really I replied, you tracked it then....no.
Edited by Gixer on Friday 13th June 17:20
Got it in one Gixer. Changing down is not the answer to what I am saying.
I have only ever lowered the gearing on cars in the past by fitting 2 inch smaller wheels in diameter and making sure tyre profile stayed the same or almost the same.
Not what I want to do with the Corvette. Bikes are much easier to do, with chain drive.
Many American-engined cars like my Monaro are geared too high for street use. At 70 mph, even with a 6 litre V8 it needed two gears dropped if I wanted real overtaking power. It was geared for 200+ in top, in theory.
Lowering the gearing can improve top gear performance, give you are a better top speed in a more realistic 6th, make the car livelier generally and the fuel consumption difference over a year of mixed driving will be what, £100-£200 extra maybe?
My mate wants to lower the gearing on his 2012 Viper V10 8.4 for the same reason. Geared for 100 mph at 1,950 rpm in sixth.
I have only ever lowered the gearing on cars in the past by fitting 2 inch smaller wheels in diameter and making sure tyre profile stayed the same or almost the same.
Not what I want to do with the Corvette. Bikes are much easier to do, with chain drive.
Many American-engined cars like my Monaro are geared too high for street use. At 70 mph, even with a 6 litre V8 it needed two gears dropped if I wanted real overtaking power. It was geared for 200+ in top, in theory.
Lowering the gearing can improve top gear performance, give you are a better top speed in a more realistic 6th, make the car livelier generally and the fuel consumption difference over a year of mixed driving will be what, £100-£200 extra maybe?
My mate wants to lower the gearing on his 2012 Viper V10 8.4 for the same reason. Geared for 100 mph at 1,950 rpm in sixth.
Perhaps someone should take a 'leaf' from a 1960's or '70's book. The very best transmissions for their time just had to be Muncies M21 transmission and Fords 'Top Loader' 4 speed. Both with similar closely set ratios in a big block car with 27" tall tyres and 3.08 rear end could easily hit the current national speed limit in first gear. My own 489 cu in Vette maxes out at 6400 rpm @ 75 mph. Thing is that big block cars had/have the torque to be able to pull really well off the line and make maximum use of the closely set ratios. A highly strung small block car would struggle with these ratios unless coupled with a 3.80 or 4.11 rear end. Cruising would be a nightmare. Modern computer controlled 'big' small blocks would surely benefit from a similar 'old fashioned' set of ratios?. Old school logic would be to use an add-on overdrive like the Hone unit or current Gear vendors overdrive. You then the have the best of both worlds. For the life of me I just can't see why people accept the ultra low first and second ratios of modern 6 speed gearboxes. These to my mind just seem to waste forward motion with excess wheelspin, a required gearchange at 30 mph or so and less than ideal upper gear ratios - too many gearchanges - not enough forward motion. Bring back a modern version of a Muncie but with a 'proper' 5th overdrive ratio so that 1800 rpm @ 70mph is a reality - junk all the late model 6 speeders!
Edited by roscobbc on Monday 16th June 22:59
Edited by roscobbc on Monday 30th June 08:19
I think the option of more power sounds good. My C6 Z06 now has over 600bhp and an additional 100+lbft of torque, and happily pulls the long gearing. I think with shorter gearing I would lose time with gear changes. 6th Gear is for high speed crusing only as 2,000rpm is over 100 mph, but it pulls 6th from 100 mph just as hard as my E46 M3 pulls 5th from the same speed! More power is quite inexpensive in these Corvettes so why not!
Gearing is less important in a car with a wide power band. It is in modified (bigger druation camshaft) engines where the power band is more narrow and peak torque is higher up the rpm scale that you really need lower diff gears.
It is also much more important to have the right gears in drag racing where really you want to be crossing the finish line with nothing to spare from the engine.
In my automatic C5 I just drive in 2nd and third rather than "Drive" around town or on the twisty roads. Keeps the rpms up and gives me just a little engine braking. I tend to only use top gear while the engine is warming or on dual carrageways.
On my old muscle car with big duration cam my peak torque was around 3500rpm. So low rear gears really helped keep me on the power band. So much so that I actually used less fuel cruising at 90mph (4000rpm) than I did at 70mph.
It is also much more important to have the right gears in drag racing where really you want to be crossing the finish line with nothing to spare from the engine.
In my automatic C5 I just drive in 2nd and third rather than "Drive" around town or on the twisty roads. Keeps the rpms up and gives me just a little engine braking. I tend to only use top gear while the engine is warming or on dual carrageways.
On my old muscle car with big duration cam my peak torque was around 3500rpm. So low rear gears really helped keep me on the power band. So much so that I actually used less fuel cruising at 90mph (4000rpm) than I did at 70mph.
I don't see any need for for a car with the grunt and rev range of modern Corvette to need a close ratio gearbox. Drivers will already be skipping gears in the 6-speed manual a lot of the time, let alone the new 7-speed. The more often you change gear in a manual, the slower the car.
5 USA said:
I don't see any need for for a car with the grunt and rev range of modern Corvette to need a close ratio gearbox. Drivers will already be skipping gears in the 6-speed manual a lot of the time, let alone the new 7-speed. The more often you change gear in a manual, the slower the car.
Certainly agree with your last paragraph - as for c/r ratio's - no, as you correctly say a 'modern' car with the grunt and rev range of a modern Corvette doesn't actually need a c/r set - but there again nor does an 'old school' early big cube/high torque muscle car in many cases - however it does still give the driver an option I guess of full-on 'gear swapping' if he wants 'fun' - or - short shifting at other times. Gassing Station | Corvettes | Top of Page | What's New | My Stuff