Samurai 4:1 Rock Lobster Reviews

You don't need to cut the axle to change the diff. It's a simple case of pulling out the half shafts and undoing the ring of bolts.

Did 45000km on my rebuilt and modified SJ transfer. Same transfer as samurai. All good. As I said should be no more noise than stock in high range.
I found that the price for diffs or axles where higher than gears for my transfer case.
Changing diffs is a lesser job than rebuilding transfer case though.
Many gear sets available for your transfer case, from 4.16 to 6.5.

yakuza
Did 45000km on my rebuilt and modified SJ transfer. Same transfer as samurai. All good. As I said should be no more noise than stock in high range.
I found that the price for diffs or axles where higher than gears for my transfer case.
Changing diffs is a lesser job than rebuilding transfer case though.
Many gear sets available for your transfer case, from 4.16 to 6.5.

For my 2005 jimny transfer case I bought a gear kit. but here the noise from the aftermarket chain wheels are horrible. The 17% lower high range comes with a loud price..
On my 2005 car with 235's a 4.16:1 SJ transfer would not be possible due to the total ratio.

As far as I know currently you have Trail Gear reduction gearset installed into your 2005 transfer box. So the SJ related experience gained before this. Is it correct?
If so are you really saying that Trail Gear kit is very noisy? I thought they are manufactured to the highest standard. I'm wondering if anyone else had reported this issue as well. Any solution the reduce the noise?

I have a box made by the man in Scunthorpe.. It is noisy and uses old gears on new gears and have vibrating noises from within. I've quietened mine down considerably with some Lucas gear oil designed to do just that.

I understand that the new TG gearsets are quieter but not silent like a new box.

My Jimny is a daily now and with the radio on I am not bothered by the slight whine I have now.

The benefits of a rocklobster are massive off road. You actually have engine braking and can crawl over obstacles that would kill your clutch otherwise, if you could even get over them.

I'm on 235.75.15 Maxxis Bighorn 764's, so not massive tyres.

On road the reduction is likely not much better than you have on a 410 box.

The diff housing just needs a little grinding to get the later diffs in the earlier axles, it's no biggie.

Kirkynut

As I am in the fortunate position of having a standard Gen4 (which has the Gen3 transfer box as standard) and a Gen3 with a 4:1 Rocklobster and a 6:1 RockLobster, I decided to do some real tests with a sound meter to understand the actual noise rather than any subjective report.

Sound is measured in dB and each rise of 3dB represents a doubling of sound pressure. So 66dB is double the pressure of 63dB.

I drove the same 26 mile route at the same time of day and set the meter to average reading with the meter on the passenger seat.. This is to ensure any random peaks (me shouting at Landrover drivers etc) are excluded.

On average the RockLobsters (4.1 and 6.1) were around 3 or 4 dB higher. In terms of sound pressure reading, this is twice as loud in technical measuring terms.

However, you will note that I have used the term "Sound Pressure". The Human perception of sound is apparently different. The human ear perceives that the volume has doubled (twice as loud) when the sound pressure rises 10dB! (so 10dB is 8 times more sound pressure). Therefore in Human terms 3 to 4dB is not perceived as a big increase in sound by the human ear.

Certainly the noise is there, but tolerable. Both the 4:1 and 6:1 have a "jingle" which I think its the selector rings vibrating as I can kill the jingle by holding the selector lever (yes - they have new selector sheets fitted). The 6:1 (which is the Trail Gear version) has a whine at a specific road rpm which matches 40mph. Go slower than this and the box is actually all but silent. Go faster than this then the whine drops it level. Its just an annoying frequency just at this one specific speed. Both had an Castrol EP90 and Lithium grease mixture which is a way of decreasing noise.

Ah, yes, it can you hear that extra noise over the chatting with your passenger, the banter with your other greenlaning mates over the CB and the whine from them big off-road tyres...?