Gq info

[tkwj1966]

Hi new to patrols have just bought 2 patrols 4.2 diesel and 4.2 petrol,apparently the diesel has 4.6 diff ratios. what are standard ratios, are they different between petrol diesel how can i tell what ratios they are, is there any external identification have read the bible struggling to find this info.Also are the petrol diesel gearboxes different ratios? thanks

[Lepa]

i pretty sure standard diesel diff gears are 4.1. i believe standard petrol are 3.9 and the factory 4.6 gears are out of rd28t's. you will find that 4.6 diff gears with a n/a td42 will be difficult to highway drive on 33" tyres or smaller as you will be contantly changing 4th/5th on even the slightest hill. i've now have turbo'd my engine and drives 35s no worries. i pretty sure both gearboxes are the same.

[Reddo]

Check you compliance plate, it should read;
3.9
4.1.11
4.3
4.6

this should give you a rough idea on what is your diff ratio will be.

the tb/td gearbox are the same, the only difference is the bell housing

however
the rd30 carby, and rd28s have a smaller gearbox with different ratios. Both these models are either fitted with the 4.3, or the 4.6 ratio differentials

since gqs are getting old, it appears someone may have fitted 4.6s to your td42 (common), OR they have thrown out the rd2.8 and fitted the td42. check the plates on the engine bay, it should tell you what was once in the car from factory. if it is the latter, it might be a mod plate issue, as you will need to see an engineer about the motor upgrade...

all the information is on the ID plates. Read them and then make some assumptions on what someone may have done.

but in the end, you need to jack the rear up, and have someone turn both axles at the same time and count the revolutions of the pinion/axles ie;
4.1
should be one full rotation of the axle to 4.1 turns of the pinion. You will need to mark both and watch were it lands.