Modifying my Esteem's gearbox for better fuel efficiency

We had replaced the engine at around 2.5 lakh km from MASS in 2017 and duly endorsed the changes on the RC.

BHPian Sourav@1977 recently shared this with other enthusiasts.

Hello everyone,

I own a Maruti Esteem 2002 petrol model. It has done almost 2.72 lakh km on the odometer.

We had replaced the engine at around 2.5 lakh km from MASS in 2017 and duly endorsed the changes on the RC.

Now the engine is very peppy and almost in new condition but the rising fuel prices is now worrying me, and I am seriously thinking of modifying the gearbox to lower the fifth gear ratio from .79 to around .65-.7. OR to modify the FWD ratios.

My query is:

• Is the Maruti Esteem gearbox a direct swap into the petrol avatar or I need to modify the engine mounts?
• If any other gearbox fits my requirements eg. Tata Vista TDI ratios looks attractive.

Kindly suggest.

Here's what GTO had to say on the matter:

Back when I used to take my Jeep on the highway, I'd changed the final drive ratio to 4.2. It did make a difference and led to easier cruisability as in stock form, the Jeep used to scream even at 90 kmph. But it did lead to an offroading deficit, so I changed back to stock ratios when I got the Bolero 2.5L engine swap.

Not a good idea in your situation though. Don't mess around with an old car for marginal improvements (if at all).

Here's what BHPian Jaggu had to say on the matter:

Have you considered the engines power and torque figures and how it will work with changes in gear ratio. The petrol 1.3 litre engine is not really a torque monster vs the diesel so do double check the calculations before going ahead.

A better option would be to do a full overhaul of the gearbox and fill her up with new oil to reduce any transmission loss. With regards to the query if it will fit? Different engine most likely will mean different gearbox covers and mountings, and at the least you would need adapter plates. Input shaft and clutch assemblies also need to be checked if they are a match. Best is to go to an authorized dealer and go through parts manual and check the details of both.

Here's what BHPian Rahul Bhalgat had to say on the matter:

The new gearbox will have it's cost. And it may make a difference of just 1-1.5 kmpl. So it will still take another 50,000 to 1,00,000 km (or maybe more) for the cost of new gearbox to pay back. Are you going to retain the car that long?

If your existing gearbox has more than enough torque output in the first four gears, you can upsize the tyres to make the engine run at lower rpm for a given car speed. That will be easier to try, less costly and easily reversible option.

Another option is to check if the fifth gear pair and a few related parts from diesel gearbox can be fitted to the petrol gearbox.

Here's what BHPian Kosfactor had to say on the matter:

Esteem is geared tall as is, on city roads it needs frequent downshifts unlike the zen with a smaller engine. Esteem's 5th gear is also tall, you need frequent down shifts for overtaking in comparison to a Zen, again. I also think that the vacuum assist of the brakes will suffer if the rpm drops any further as well as the alternator output, and the lubrication system and the cooling system besides the engine produces its power higher up the RPM band, so no point running it at low engine speeds.

I think It is impractical to run a vehicle on highways to return 28 kmpl , I'd rather reach the destination than worry about extracting the maximum out of the fuel.

Check out BHPian comments for more insights and information.