Refreshing the diff, axles, driveshaft seals, bushes, etc.

[cib24]

Alright, after visiting Rotor Torque this weekend to diagnose my clunking issue we couldn't find anything wrong with the rear suspension. All wecould find were two things: (I) the lug nuts were not catching sufficiently cashing the wheels to move ever so slightly, and (II) there was definite play in the diff/axles which implies that it is all a bit worn.

What I would like to do this winter or next spring is refresh the diff, axles, driveshaft seals, bushes, joints, etc. to make it like new again to match the rest of the car.

Can anyone give me links or advice on where to buy appropriate parts, what else I should consider and any guides to help me go about doing this?

 

[JoeLanger]

There will be a bit of backlash in your diff, not sure if this is what you are describing?

New axles from rock auto
J auto pillow balls
Super pro bushes
Seals genuine Mazda.
Not sure on where to go for diff parts but I imagine you'll have to take it somewhere to get rebuilt.
That's about it really not much else to the rear.
Not sure if you wanna do the rear wheel bearing but they can be a pain to source and it's a big job to swap

 

[Chris_Ward]

If the wheel nuts aren't catching with enough threads I guess the only real fix for that is longer wheel studs, which will be easy if your doing wheel bearings anyway.

I had my diff checked over by TDI, so I have no doubt they could do the work for you if Rotor Torque can't. As for parts (bearings, seals etc) your really going to be using Mazda geniune parts or equivalents for the rebuild. Only real options for upgrade are if you want to change the diff pumpkin itself:
KAAZ 1.5 way LSD
Carbonetics / ATS /Across 1.5 Way LSD
Cusco Type RS LSD 1.5 Way
OS Giken Super Lock LSD Spec-S

You can also change the ring and pinion if you want to adjust your final drive ratio to change your acceleration / top speed.

There a couple of options for the diff rear cover:
1) The RX8 one with additional fins for cooling shown below (left) against the stock RX7 one (right):

2) The Greddy one that allows extra oil capacity, and also has take offs for an external cooler should you need it:

As for replacement suspension parts, depends if you want to stick with OEM or not.

For suspensions arms if you want to stick with OEM your looking at Mazda or J Auto for pillow ball bushes, and then PowerFlex, PowerFlex Black, SuperPro etc. for the poly bushes. Check out http://www.j-auto.net/ for a look through the options.

Alternatively you could look to move away from the OEM setup and look at either the hardrace or battle version arms that move away from the pillowball bushes and use spherical bearings, they also give you more adjustability which may or may not be useful to you with the amount of trackdays you do:

These are the battle version ones, you can buy them here, Hard Race equivalent here.

 

[Chris_Ward]

Just to clarify, when you say play in the diff / axles, do you mean rotational play, or play as in the axles move in and out?

Rotational play as Joe says is normally set by backlash, which is the shimming of the ring gear vs the pinion gear at the front of the casing.

In out movement can be anything from worn CV joints, worn axle retaining clips (the ones that hold the inner joint into the diff) or worn suspension bushes.

 

[richie2912]

For the shaft seals into the diff they are exactly the same as a Mk3 MX5 if i remember correctly.
https://www.mx5parts.co.uk/differential-side-seal-mk3-35-p-2375.html

 

[cib24]

Thanks guys for the great replies. So, to summarise what I have already done on the car:

Super pro diff bushes (3 years ago)
Powerflex poly bushes in the rear (3 years ago - squeaky)
J Auto pillowballs (Oct 17)
Wheel bearings (3 years ago)

I have a terrible clunk in my rear suspension despite this and I had the car on the ramp at Rotor Torque and we could find a culprit.

Maybe it's the toe links or maybe it is an axle. When rotating each wheel individually the driver's wheel would cause the axle/diff to make a clicking type noise. The passenger wheel wouldn't do that.

The clunk is driving me nuts and it's really loud now...no noticeable issues driving around or putting the power down.

 

[Paulm]

Almost completely unrelated, but the son in law had a clunking on his volvo. I thought it was a shit drive shaft, but on investigation the drive shaft bolt was found to be loose. Most cars i've worked on have had secondary retaining mechanisms, but not the volvo.
Any way proberly no use at all as ive not had the rear end appart yet im unsure on the fixing mech

 

[terry06]

Interesting topic as I have started to experience some rear end noise, more of a clicking than a clunk though. And only when going on/off the accelerator pedal and sounds like it is from the passenger side.

Before the rx7 I had a 350z and a common problem was a clicking rear axle caused by the cv's. The noise on the rx7 is similar although not quite as loud as that so that's where I'll be looking first but I'll be sure to check all of the above.

Did your noise start as a clunk or did it progressively get worse?

 

[JoeLanger]

Interesting topic as I have started to experience some rear end noise, more of a clicking than a clunk though. And only when going on/off the accelerator pedal and sounds like it is from the passenger side.

Check the tightness of your PPF nuts.

Not sure on your issue Roy as you've replaced a lot of stuff already, I'd just be checking all bolts for tightness.

 

[Copyninja]

have you got coilovers? sometimes the coilover top mount nut can come loose. which can cause clunking.