Outer Limits 4x4 Board

Been out of the game for a bit while working on the house. Any way the itch has returned and I am working through some bits and pieces.

On to the topic at hand - I am confused - Reading through the diff swap banter I am wondering why MQ diffs get a mention, but no mention of GQ?

Are the GQ's not a better choice since they have rear disc brakes standard?

Simon

gq rears are centred.

Sierra's are offset.

mk/mq fronts bolt up. spua. rears offset like sierra but needs custom mounts.

Pootrols have way too big centres for sierra's!

Thanks I recognise the need for custom mounting.

I had assumed (likely incorrectly) that a double card driveshaft would take care of the lack of offset - I assume this is wrong? What is the answer in the all the Hilux conversions that occur.

Being too big - are you generalising that both the MQ and GQ are too big for Sierras?

Simon

Aren't MQ Leaf and GQ Coil?

Also a wider track, necessitating a fair deal of fab work to get any mounts to match-up I would imagine.

Plus they are heavy as fark

CHOPZUKI ran Gq's in his sierra, have a look through members to find his thread. I've got a few pics saved if you need them.

A double cardan driveshaft is actually worse at correcting an offset diff than a normal uni. Double cardan joints are designed to bear all the angle, with the uni at the other end bearing as little angle as possible.

MK/MQ's bolt up to WT front. The front MQ centre is quite small. THe rear is big, for sure, but can be shaved pretty heavily.

They are also narrower than GQ, so they are a better fit if you want to build something legal/legalish.

Steve.

Steve - your double cardan comment has confused me. I don't fully understand why the situation is made worse.

I thought that people who put hilux diffs in use a double cardan to reduce vibration? Is that not the case?

Simon

some do, some dont... all depends on pinion angles etc...

im running hilux double cardans front at rear at the tcase end and havent had any issues what so ever - however it does mean custom driveshafts, which means you cant carry a spare (not cheaply).

simobimo wrote:Steve - your double cardan comment has confused me. I don't fully understand why the situation is made worse.

I thought that people who put hilux diffs in use a double cardan to reduce vibration? Is that not the case?

Simon

Double Cardinals have a very small range of operation before they bind. My Fathers Hilux had to have the factory double-Cardinal removed because its rather unflexy front suspension was still causing bind up issues.

Double cardan joints are a form of constant velocity joint. That's because they contain 2 unis and the velocity variations of each one cancel the other out.

That means that if the uni at the other end of the driveshaft is at an angle, the driveshaft will vibrate as the uni cycles though it's velocity variations.

The DC joints in patrols/hiluxes etc aren't there to allow for big angles, as highway star says - they often allow very little angle at all. They are there to allow mismatched angles when the transfer is tilted down at the back to make the rear angles equal - that makes the front driveshaft unequal so the front diff is rotated to point straight at the transfer and a DC is employed to take al the angle.

with an offset rear driveshaft, it's not possible to have all the angle borne on one end of the driveshaft so you'll get vibration with a DC. You might not with a normal uni at each end.

Steve.

i vote for GQ diffs...

the easy option isn't always the best option.

just because the MQ come close to bolting in - that's not enough reason to pick them. just pull the body off the car and move put a different transfer in there to sort out the diff offset issue.

really - how hard could it

Or you could buy mine on 60 series diffs already done and engineered. (Shamless plug)

MQ is a relatively easy conversion on a Wide Track. GQ's would be a bit of work.

What are you hoping to achieve? strength? width? ratio? budget?