Just seen these on Newera parts :
O.S. Giken Close Ratio Gear Set. (new part)
Improve your RX-7\'s racetrack performance and shave seconds off your lap times at track days with this gear set! The following are standard ratios as fitted to RX-7\'s from 1st - 5th gear: 3.483 2.015 1.391 1.000 0.806 For making a close ratio box, the 1st 3 gears can be modified with an O.S. Giken kit to become: 2.714 1.742 1.267 This kit including layshaft and gear set is priced at: £1,090.00 The 4th and 5th gear ratios are not usually worth changing, as the difference is only marginal with the 5th ratio, whilst 4th stays the same: 2.578 1.772 1.289 1.000 0.821 If preferred, a 5 gear close ratio set is available at £1,695.00 Please note: For this item, lead time is approx 1-2 months from receipt of order, as these parts need to be made specially by OS Giken.
Now would this make the first 3 years taller....? How would that affect the drive (havent got GT4 handy at the mo!), guessing you\'ll be a bit slower off the line due to 1st gear being taller, but get a gain between say 40-100ish as the 1st 3 gears will be reaching greater speeds.
Is there a calc about that can work out what speeds would be at diff rpm with the new ratios?
Yes andy i have a very complex calc for performance which takes into account aero drag and various factors.. If i get a chance i will put it in for you but cant see a great differance really.
Scott
Cheers fella, havent got the cash for it or anything just interested to see the effect it has :)
Are they syncro or dog?
http://www.neweraparts.com/Parts/pictures/1129187825620//pic1129187864983.jpg
Heres a pic, you tell me :)
Dog are straight cut arent they, so guessing these are syncrho, my knowledge of gearbox\'s is a little lacking...:)
:D :D Yours and mine :wave
The \'other\' additional cost is the re-build. Sounds a good mod though, but wont make it any stronger, will have to look around and start saving and find some one who can re-con a gearbox and fit those parts at the same time, might be worth looking into buying a s/h one and start from there hmmmmm
lol, we better wait for an expert :)
Dont see much in the way of g/box experts............... anyone out ther?
Quote from: sdminusi have a very complex calc for performance which takes into account aero drag and various factors..
I\'ve got GT3 if that\'s any help :rollin
I\'ve tuned the Escudo to around 1800 bph, and tweaked to the gear ratios and spoilers to squeeze about 240mph out of it ;)
If only I could attach my Playstation to my Apexi Commander - I\'ve had it tuned in no time ;)
Cheers
Jon
Andy i have dumped that info in for you and it shows the following
4658 RPM in 1st gear would see you at 30 MPH OS GIL
5973 RPM in 1st gear would see you at 30 MPH Stock box
4983 RPM in 2nd gear would see you at 50 mph OS GIL
5778 RPM in 2nd gear would see you at 50 mph stock box
5799 RPM in 3rd gear would see you at 80 MPH OS GIL
6362 RPM in 3rd gear would see you at 80 MPH stock
Basicaly it will give you about an extra 10 mph in each gear
Also it will drop the g force of a perfect launch from 1.33 G to 0.98 G. Figures based on a stock twin at about 300 wheel hp
I am no expert but how i have worked out the shift points will be no good for a high rpm engine or a twin turbo. More for the circuit racer i feel
Hope this helps
Scott :evillaugh
Cheers Scott, good info matey :) Reading the ad I think circuit racing is what its aimed for.
Rememeber seeing Pip\'s orange 2nd gen circuit racer go up the drag strip, 1st gear seemed to go on forever :)
QuoteIf only I could attach my Playstation to my Apexi Commander - I\'ve had it tuned in no time
lol, like it :)
Good info Scott :cheers
Andy, did you find a somewhere local that has a 4-wheel laser alignment thingy?
Cheers,
Jon
No mate, but I havent really looked much to be honest...will start looking again soon.
Sorta lost interest a bit cos im not putting coilovers on for a little while
Quote "More for the circuit racer i feel"
I think that Scott has it here.
I tend to evaluate gear sets by the difference in RPM when you change gear, rather than trying to make sense of speeds in gears. After all, since 4th gear locks the input and output shaft together, we aren\'t really going to make any big changes to top speed unless we make wild changes to 5th. I calculate the RPM drop figure - e.g. 0.75 would mean that the changing from one gear to the next would drop the engine revs to 75% of the previous value, 6000 to 4500 for example.
From the data above, we have the stock ratio\'s at 3.483/2.015/1.395/1/0.806
This gives changes of 0.58, 0.69 , 0.72 and 0.81
0.58 drop from 1st to 2nd is a big drop. Thats 6000RPM down to 3480.
The first option quoted gives 2.714/1.742/1.267/1/0.806 and results in changes of 0.64, 0.73, 0.79, 0.81
The second option quoted gives 2.578/1.772/1.289/1/0.82 and results in changes of 0.69, 0.73, 0.78, 0.82
Thats 6000 to 4140 RPM from 1st to 2nd.
Experience says that anything around 0.75 feels close to drive. I\'m not one for the 1/4 mile, so the longer 1st doesn\'t really matter to me. It then all comes down to how wide the engine\'s torque curve is and how much grip you have.
I have a very close ratio ZF gearbox in an old rally car. The car has a prehistoric engine (boinger) with sidedraught carbs and the torque curve is very narrow. The close ratio\'s allow me to change gear without dropping off the power, and even with the long first is still spins the wheels on launch, so having a shorter 1st wouldn\'t really help.
The FD has fairly wide ratio\'s, a wide torque curve and comparatively good grip as standard, so I\'m thinking that this gearset will only really make a difference if you have a big single turbo with a very narrow torque curve, and spend all your time on the track where standing starts don\'t matter.
Only my thoughts
Keith
Thanks for the write up Keith, make some good points there :) Can see how it would be more suited to a single turbo after explaining it like that, re-inforcing what scott said about not being suited to twin turbos.
BTW when I was talking about Pips car, i meant the longer gears seemed a disadvantage, you could tell the car was quick just not suited for a 1/4 mile sprint.
No problem Andy. I\'ve got to organise some new tyres and new rear bushes before my MOT so I\'m going to be looking around soon. I\'ll let you know if I find one.
Cheers
Jon
Hi Jon
Talking of tyres and the lazer jobbie, I have a frend in Ilford if it is not to far for you, Goodwin Tyres ask for James, he is very helpfull and has some good deals.
Very interesting Keith, by jove I think I just about understand :wave
Quote from: John YorkeI have a frend in Ilford if it is not to far for you, Goodwin Tyres ask for James
You used him before then John? Do they have the laser guided-missle thing there?
Cheers
Jon
Found somewhere a bit more local; //www.airwaytyres.co.uk Might give them a try. They have a laser-giuded missle jobbie there ;)
Cheers
Jon
There is also Supertyres in Maldon,Essex.
They have the same machine but are much cheaper if you need most things adjusted, £80 or so i recall.
Cheers Andy K. Have you used them before then? If you have and were happy with them then I\'ll go there - I\'d rather go somewhere that\'s been recommended to me.
All the best,
Jon
Quote from: TonyBlairYou used him before then John? Do they have the laser guided-missle thing there?
Cheers
Jon
Jon
Yes and they have \'budget\' tyres and he kindly found my presant Yoko\'s [street legal slicks] for a very competitive price, with these lazer jobbies it is all about the guy that is setting it up, I first went to a [so called] reputable east of London store who did the bizo, took the car away, felt somewhat worse, took it back was unable to get any satisfaction from said company, had the car looked at by Goodwin [he loves \'propper\' cars and does them himself :) ]
and have seen a remarkable improvement, not bothered to go anywhere since.
I am sure there are plenty of lazer jobbie peeps out there, its all about them doing it correctly in the first place.
All these FD\'s suddenly finding their cars \'tail\' happy is a worry and I am convinced it is more about having the car set up in the 1st place rather than \'mostly\' driver error.
Me, I would rather go somewhere I was sure I was going to get a \'propper\' job done rather than save that 50p :cool
Many thanks for the commes John. Will take them under consideration.
:)
Cheers
Jon
65 miles to Ilford...not too bad, plenty of time to test set-up on the way back :D
Like you Jon be better to go to a recommended place as its one of those jobs where the equipment is only as good as the operator :) Also want a place that isn\'t patronising cos I wont really know what to ask for camber, toe in, etc wise, is there a general guideline for these settings?
Quote from: ScuttleRX65 miles to Ilford...not too bad, plenty of time to test set-up on the way back :D
Like you Jon be better to go to a recommended place as its one of those jobs where the equipment is only as good as the operator :) Also want a place that isn\'t patronising cos I wont really know what to ask for camber, toe in, etc wise, is there a general guideline for these settings?
Andy / Jon have a look at the stickie\'s under wheels tyres and suspension :cool
Ah yes *slaps wrist* should have had a look in there..!
Would be tempted to set up for a bias for oversteer but would probably end up getting myself in trouble :)
Yes i have had my car done there twice now, they are a good bunch and know what they are doing.
Looking at how they set mine up with one of those machines you\'d be a fool to get it wrong anyway.
The settings they make is up to you, i had std settings put on mine and it drove like a dream after.
Going back as soon as i can due to suspension changes, again.
Thanks for the comments Andy_K.
If you say they know what they\'re doing then I think I\'ll give them a try. However I hope they can handle set-up\'s that aren\'t just standard - my car is lowered :rolleyes:
Cheers
Jon
Just out of interest has anyone seen the 6-speed box offered by Rotary Extreme (Banner at top of Page)??
I\'ve got the details and ratio\'s at home, but i do know they\'re dog gears!!!will post these up when i get home. But for the time been here\'s a pic.
(http://i7.photobucket.com/albums/y283/icesurf3r/Odds%20and%20ends/greddytranny.jpg)