Caldina GTT rear diff noise

[sidewz]

Hi Guys

ever since ive had my GTT (97 manual), the rear diff has had a tendancy to clunk loudly if you are sloppy on the gear changes.
eg, if you push the clutch in when you still have power on.

I never thought much of it, but more recently its developed a rattle on deceleration.

I have just climbed under and had a look, and want to know what this is, and if its the source of the rattle.

These steel blocks are attached to the head of the diff, through the rubber mounting .
Looks like these blocks touch the sway bar when you decelerate, and the diff pitches forward.
When i push the clutch in, the rattle stops, which makes sense as the diff would be under no pressure, and would centre itself.

Presumeably the clunk on gear change is because the diff goes from being pitched back hard , and goes back past centre when its unloaded all of a sudden. If you unload it gently, it doesnt hit the sway bar.

So does this mean the diff mounts are stuffed?

Cheers
Dave

[cedwards]

I think they are anti resonance blocks.Basically vibrate in a way to cancel any resonant vibrations from the diff that would cause road noise.
Hard to tell but yours seem higher than mine when looking under back of car, also from your photo's it looks like it is adjustable??
My swaybar definitely lines up more with the sloped tops of the blocks and not with the corner as it seems to on yours.
Try loosening the top centre bolt and dropping it down a couple of mm's and see how you go. Someone may have stuck a trolley jack under it at some point forcing it up??

[sergei]

The mount itself looks exactly like on ST165-205 celicas, and they are notorious for breaking, when they break they make diff to make loud thumping noise under gear change or engine braking. If it was not for those steel blocks (that are not on celicas) you could see the mount properly to see if it is broken..

There is another possibility, if your car is lowered plus this mount is worn but not broken, it might cause the sway bar to contact with the steel blocks.

I would just chuck away those blocks, but you might care about extra vibrations under load between 1.8k-2.2k rpm (I have urethane diff mount and it vibrates like a bitch in that range, I just avoid loading it there).

[sidewz]

Thanks Cedwards.
Sergei is right, it is lowered a bit, so perhaps thats why it lines up different on the blocks.
I will try and move them, see if I can give them more clearance.

The diff certainly knocks on gear changes whenever someone else drives. i have learnt to ease off the gas a split second earlier so as not to create such whiplash to the system, which is probably better for my running gear anyway.
She's getting old now, done almost 200,000k....


Are the rubber mounts easy to get hold of as a spare part, and how about changing them?

Cheers
Dave

[sergei]

They are about $200 from toyota from memory, I have just filled mine with urethane for $90 but I would not recomend, unless, there is a way to make it a lot softer....
To replace them is about 2Hr job without hoist...
Although from the pics it looks a lot easier than on Celica.
Main point is to mark the position of the diff and put it back exactly the way it was (there is plenty of slack in the bolts to put it slightly on different angle), if you need to take it off to remove the mount (it looks like you don't)...