diff problem

[jnr 13b]

hi all
I really need some help.

I did the JDM diff conversion in about 1month ago.
i take eazy after the conversion.
I got the diff with all the JDM upper and lower trailing arm and pan hard rod( total of 5 rod). it come with tail shaft too. everthing fit find.

After worn in. i start to give it abit. I did a 4-5000rev launch and the car bounce all over the place.
I thought it might be the bushes. so i replace all 5 arms from the s series diff with locked diff centre. Which was all good before i killed it.(it would do on the spot burn out with 205 tyres).
anyway I try it agian and it still bouch all over the place.I can still do on the spot. but it bounce like a f**ken bunny.

so i replace the stock to a more stiffer stock. then put shit tyre on it.
try again. Still bounce a little at the start. but i can do on the spot.

does anyone know if there is anything else I can do to really fit the problem.

cheer

[upgarage]

adjustable arms and traction brackets

[crazy86]

Did you change the spring rate, or the ride height when you did the diff change??

[Monster]

CRAZY86 started, let me eloborate, in a solid rear axel car, when you lower it to a certian point, the geometry of the rear axel sits more to one side of the car to the other. This can be aleiviated quite simply with an adjustable pan hard rod which should re center the rear axel. Also if the rear spring rates do not match the damper rates, this will also make the rear end 'float' when a heavy launch is done

[jnr 13b]

sound like i need professional help.
I don't have anything adjustable in my rear.
but does it does not have the same problem with the S series locked diff?
the S series Ran prefect.
anyone know diff work shop that know what they are doing?
sydney?

[mattysshop]

adjustable panhard rod...pish posh...just bend your stock one in a vice

[RobertoX]

You may need to change the bearing for the pinion gear in the diff, this can cause tramp.

[ae86levint]

stuffed shocks can allow the axle to tramp also, how old are they?

[crazy86]

Just changing your diff will not cause the problems you have. Full stop. They may only exaggerate an already existing problem if the diff CW & Pinion are worn/different ratios.

If you have axle tramp, then it is usually caused by
1. Shocks not correctly matched to springs
a. Shocks too soft alowing springs to "over bounce"
b. shocks too stiff for the springs, stopping the spring from doing its job. The car "skips" over any bumps with slow rebound.

2. If you have adjusted your ride height, the diff pinion angle will be more "extreme". This can cause a "lashing" effect in your driveline. YOu can fix this with adjustable 4 link arms.
Also when you lower the car, this will move your diff to the left, changing alignment, therefore the need for an adjustable panhard rod.

Or you could need traction brackets. Im not 100% on how they work, so i will leave that for someone else.

Basically your problem is suspension related, and has nothing to do with your swap to a JDM T series diff.

The only help a diff specialist will give you is check the bearings and gears are in good nick. You should have done this before the install anyway.

[Monster]

Traction brackets are great!!! you cut holes in th underside of your rear, just where the upper links join into the car. Weld in the traction brackets on where the old ones used to be and get extended upper links. You see them alot in Japan, where the back seat used to be you'll see too rectangles sitting up into the cabin.
I'll post some pictires soon.