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kasim
09-05-2007, 10:32 PM
Hi guyz

am new to this

just wanted some information, basically ive recently got a new gearbox put in my audi a3 1.6, and ever since its using alot more petrol, its doin like 45-50 miles to £10. Before the change of the gearbox it was easily doing 70 miles to £10. i have paid 700 for the new gearbox, and just wanted to know what the problem could be????
a friend of mine said it could be the gear ratio, but the car is doing less revs than it used to with this new gearbox, but i am not that technical so i dont know. so thats why i need some help please.

guyg
09-05-2007, 11:00 PM
If you're now doing different RPM for a given speed and gear, either the gear or final drive ratios [or both] may be different from your old box.

Gear and final drive ratios are chosen to match the type and power curve of the engine, weight of the car and the effective diameter of the wheels.

Anyone out there know how many combinations are possible on an A3?

You may be doing less revs for a given indicated speed, but if the box was meant for a different car [e.g.a diesel or one that had larger wheels], you might not be going as fast [or faster] than you think!

It might be worth checking the accuracy of your speedo and odometer against a known car or borrowing a TomTom or similar GPS device that can indicate accurate time and distance to compare.

My Passat indicates 73 when the GPS indicates 70. A couple of MPH over is common, if you're much more than 5% out, your ratios are probably wrong.

Cheers

Guy

kasim
10-05-2007, 06:52 PM
thanks guy

the car does feel alot slower than it used to be, ive ask other people and they ve said its gta be the wrong gearbox, and some have suggested that its the gear ratios, ive paid 700 for this gearbox, and its taking the ****. the guys i got it done by said bring it down, but they just gona fog me off. is it the gear ratios???? can garages check dat???? how much does it cost to sort the gear ratios out????

thanks

S2AVANT
11-05-2007, 12:20 PM
Each gearbox has a code etched into it. This code the will tell you what ratios are in that gearbox. If you go to any dealer and ask them nicley what gearbox code your car should have (reg number / vin number at the ready) they can tell you.
You then need to compare that code with the code on your £700 box and see what you have. The dealer shoulb be able to tell you what your £700 gearbox is out of and the ratios.
Its far easier to change the box than the ratios as you have to remove and then strip the box to change them.