Re:Re:Re:Re:Re:Re:My Jimny gen4 South Africa mods/build thread

Did you notice any difference in the way it stops? Maybe needs a little bit of a firmer push on the pedal, hopefully not too much firmer.

One of the reasons behind these questions is many years ago I did something similar with a Suzuki Swift, I was almost 20% wider on the tires with a very minimal increase in diameter, the impact on acceleration was not noticeable, but it took a heck of a lot more brake to bring it to a stop, (because the bulk of the rotating weight was further away from the center of rotation) and this eventually lead to warped rotors, and a brake upgrade.

The Jimny, like that Swift uses a relatively small solid rotor, I've started compiling a list of parts to upgrade the Jimny front disks to a more substantial vented system, just in case the need arises.

fordem wrote: Did you notice any difference in the way it stops? Maybe needs a little bit of a firmer push on the pedal, hopefully not too much firmer.

One of the reasons behind these questions is many years ago I did something similar with a Suzuki Swift, I was almost 20% wider on the tires with a very minimal increase in diameter, the impact on acceleration was not noticeable, but it took a heck of a lot more brake to bring it to a stop, (because the bulk of the rotating weight was further away from the center of rotation) and this eventually lead to warped rotors, and a brake upgrade.

The Jimny, like that Swift uses a relatively small solid rotor, I've started compiling a list of parts to upgrade the Jimny front disks to a more substantial vented system, just in case the need arises.

Currently I dont find any negatives in respect of braking. It feels like with std tyres.
BUT
Short town trips so far with jimny was with no loads etc. Vehicle empty with only driver.

I might take it for a long drive maybe over the weekend and drive some passes in our area to get a more substantial feedback.

The other aspect is that I am not aggressive driver and not hard on braking, so if there are minimal impact on braking I might not notice simply because of my driving style.

On the other hand an aggressive driver might pick up difference easier.

For me currently they feel pretty much the same as std wheels

Average km/L for last 13000 km was 13.2 km/L

When you brake, you convert kinetic energy into heat. Standard brakes are designed to cope with all manner of situations that a driver will incur. If the driving style you use does not promote brake fade then the slight increase in tyre diameter will not give you any problems.

If you still like the idea of vented discs then Martin has covered this in one of his tutorials.

Roger

oger

I don't know that I've experienced brake fade perse, which I'm defining as a gradual need to use more & more pedal pressure over several repeated applications, but that Swift certainly gave the impression it wasn't about to stop any time soon, and it was absolutely impossible to lock the front tires up, which was possible before the tire upgrade.

Upgrading the brakes using Brembo vented rotors, large calipers & pads and braided stainless steel flex made a huge improvement, and yes, it was driven hard.

By the way - it's not the increase in tire diameter that causes the issue - it's the increase in rotating mass, and the fact that the rotating mass is concentrated at the outer edge, rather than being evenly distributed - I'm not theorizing here - proven on the street experience.

If you increase the dia. of a tyre, you increase it's mass because there is more material in the tyre.

Roger

BUT - you can increase the mass of a tire without increasing it's diameter, and even do so whilst reducing it's diameter.

And the reason I am pointing this out is that on that particular vehicle, the wider tire/wheel assembly did not significantly increase either the diameter or the mass of the rotating assembly - it was a heavier tire on a lighter rim which essentially meant that the rotating mass was further away from the center of rotation.