hotrodholty Posted May 30, 2008 Report Posted May 30, 2008 after my recent destruction of my 1st gear by way of a big burnout, i got thinking, does anyone sell gear sets for a 1600 sport box and can you get a straight cut 1st gear for it. iv got a standard box to throw in for now, so am going to rebuilt my sport box, be nice to know i aint gonna break 1st again
Supercharged Nat Posted May 30, 2008 Report Posted May 30, 2008 Im not sure if you can get just a stright cut first gear, as the others within the box would have to match (well atlest the pair for 1st gear- the main and lay). What i dont get is why do people fit straight cut gears when helical gears of the same size can transmit more power- 3 teeth in contact with each other compared to just one. unless the straight cut gears are so much bigger than the standard helicals that they are infact stronger... anyone care to add / enlighten me?
hotrodholty Posted May 30, 2008 Author Report Posted May 30, 2008 straight cut are stronger, than helical
MexDan Posted May 30, 2008 Report Posted May 30, 2008 Straight cut gears are stronger.. hence why they are used in race and rally cars. You can get gear sets from quaife and tran-x, but are pretty pricey. I doubt you would find a second hand straight cut box for that much cheaper... plus you never 100% know the quality of the gears inside the box. I have not found a place that sells just the 1st gear, if you do find one give me a shout as i need a new ratio. That ios also something to consider, straight cut 1st gears are pretty low ratio.. i have yet to find one below 2.5. Compare this to you sport box which probably has a 1st at about 3, it will make it much harder to pull a burnout if you have a smaller engine. I don't know what engine ur running. Crossflows can struggle with this, a decent modded Pinto would probably still be able to cope with that ratio pretty easily.. A standard rocket box can cope with up to 170hp being ragged through it... that would sort you problem far cheaper... depending, again, on what engine you are running!!
Admin Vista Posted May 30, 2008 Admin Report Posted May 30, 2008 Straight cut gears aren't stronger than helical gears at all, as stated above helical gears have more teeth in constant mesh and the load is much better spread ergo better able to sustain large torque and speed inputs. The reason race and rally cars favour straight cut gears over helical ones is that they don't produce end thrust and therefore gearing losses due to friction are lower. Don't believe me? Feel free to do some research but here's a quote from Wikipedia: - Spur gears make a characteristic whine at high speeds and can not take as much torque as helical gears because their teeth are receiving impact blows. Whereas spur gears are used for low speed applications and those situations where noise control is not a problem, the use of helical gears is indicated when the application involves high speeds, large power transmission, or where noise abatement is important
hotrodholty Posted May 30, 2008 Author Report Posted May 30, 2008 urban myth me thinks then along with "if the wind changes your face will stick like that"
petrolhead Posted May 30, 2008 Report Posted May 30, 2008 mexdan, I think you may have a misconception or I have misinterpreted what you have written. If you have a 1st gear ratio numerically below 2.5 you actually have a higher ratio 1st gear. 2.5 is a very long 1st gear that allows a lot of engines to pull 50mph in 1st if the diff/tyres combo is right. 95% of Ford gearboxes have a 1st gear 'lower' (ie higher in number) than 2.5:1 RS2 boxes have a 3.6 1st gear wich is actually pretty low. The sport gearbox had 3.3 1st gear I asked a transmission specialist about two weeks ago about straight cut 1st gear, he said No regards Petrolhead matt
MexDan Posted May 30, 2008 Report Posted May 30, 2008 mexdan, I think you may have a misconception or I have misinterpreted what you have written. If you have a 1st gear ratio numerically below 2.5 you actually have a higher ratio 1st gear. 2.5 is a very long 1st gear that allows a lot of engines to pull 50mph in 1st if the diff/tyres combo is right. 95% of Ford gearboxes have a 1st gear 'lower' (ie higher in number) than 2.5:1 RS2 boxes have a 3.6 1st gear wich is actually pretty low. The sport gearbox had 3.3 1st gear I asked a transmission specialist about two weeks ago about straight cut 1st gear, he said No regards Petrolhead matt Yes mate... that is what I meant.. got my highers and lowers the wrong way round Cheers
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