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jnr 13b
11th October 2005, 09:51 PM
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
11th October 2005, 10:23 PM
adjustable arms and traction brackets

crazy86
11th October 2005, 11:01 PM
Did you change the spring rate, or the ride height when you did the diff change??

Monster
11th October 2005, 11:14 PM
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
12th October 2005, 12:16 AM
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
12th October 2005, 08:16 AM
adjustable panhard rod...pish posh...just bend your stock one in a vice http://www.ae86drivingclub.com.au/forums/emoticons/laugh.gif http://www.ae86drivingclub.com.au/forums/emoticons/cool.gif

RobertoX
12th October 2005, 08:31 AM
You may need to change the bearing for the pinion gear in the diff, this can cause tramp.

ae86levint
12th October 2005, 12:19 PM
stuffed shocks can allow the axle to tramp also, how old are they?

crazy86
12th October 2005, 12:38 PM
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
12th October 2005, 02:22 PM
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.

http://www.ae86drivingclub.com.au/forums/emoticons/rolleyes.gif

jnr 13b
12th October 2005, 03:03 PM
Originally posted by CRAZY86@Oct 12 2005, 11:38 AM
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.
ok here the thing.
I don't know what spring rate or what height is the springs.
all i know that the shock is very stiff.
plus i try the soft on eas well.

so does any know if there us a diff or suspension work shop that know what there are doing?

Monster
12th October 2005, 03:38 PM
Ummm maybe because the T series rear end is alot heavier???

crazy86
12th October 2005, 03:56 PM
What are the rubber bushes like in the T series rear? Perhaps you should swap the S series links with the T series ones, and see what happens.
The weight of the T might make some difference, but i doubt it.

The only other thing i can sugget is that the change in geometry of the pinion angle (because the T diff has a longer neck than the S) is what is exposing weaknesses in your suspension setup

My car has gone from S to JDM T with no hassles, But i also replaced all bearings/bushings etc while i was there.

jnr 13b
12th October 2005, 07:49 PM
ok
nothing really really sound right so far.

but replace the adjustable trailing arm and pan hard rod sound like it might fix my problem.

apart from whileline
does anyone know where i can get adjustable trailing arms that is not too expensive?

jnr 13b
12th October 2005, 07:54 PM
I really don't think it a weight of the diff is my problem
and i have alway been running the same rubbers

crazy86
"The only other thing i can sugget is that the change in geometry of the pinion angle (because the T diff has a longer neck than the S) is what is exposing weaknesses in your suspension setup"

can you please go into detail with this please.
I did really understand what you are talking about

crazy86
13th October 2005, 12:00 AM
The T diff centre is phiysically bigger than the S series, so the distance between the diff centre line (through the axles) to the mounting point for the tailshaft is longer (thats why you had to use the shorter T series tailshaft)

This longer length, means that the effect of the pinion angle on the tailshaft is increased, therefore increasing the chance of the "whiplash" in the driveline mentioned earlier.

The increased effect will only be quite small compared to your original setup though.

As far as adjustable trailing arms, T3 and some other companys make them, but If i were you, i would start with an adjustable panhard rod, and buy a full set of poly bushes for the 4 link. All this stuff is available from whiteline. This will be much cheaper than geting adjustable everything, and hopefully will fix things for you. (provided your shock/spring setup is healthy and well matched. Best way to sort this is with adjustable shocks)

mattysshop
13th October 2005, 08:11 AM
yeh i would get a set of Super pro bushes..i can get you a set at better than trade price http://www.ae86drivingclub.com.au/forums/emoticons/wink.gif

jnr 13b
13th October 2005, 09:44 AM
Originally posted by Mattysshop@Oct 13 2005, 07:11 AM
yeh i would get a set of Super pro bushes..i can get you a set at better than trade price http://www.ae86drivingclub.com.au/forums/emoticons/wink.gif
can you find out how much they are. for 4of the trailing arms.
then I'll have to get some.

jnr 13b
13th October 2005, 09:48 AM
Originally posted by CRAZY86@Oct 12 2005, 11:00 PM
The T diff centre is phiysically bigger than the S series, so the distance between the diff centre line (through the axles) to the mounting point for the tailshaft is longer (thats why you had to use the shorter T series tailshaft)

This longer length, means that the effect of the pinion angle on the tailshaft is increased, therefore increasing the chance of the "whiplash" in the driveline mentioned earlier.

The increased effect will only be quite small compared to your original setup though.

As far as adjustable trailing arms, T3 and some other companys make them, but If i were you, i would start with an adjustable panhard rod, and buy a full set of poly bushes for the 4 link. All this stuff is available from whiteline. This will be much cheaper than geting adjustable everything, and hopefully will fix things for you. (provided your shock/spring setup is healthy and well matched. Best way to sort this is with adjustable shocks)
I did replace to a T series tailshaft.
plus to replace bush it'll cost me close to $180-$220 for them,
To get 4 adjustable trailing arm and bush from white line it only about $500.

crazy86
13th October 2005, 10:10 AM
Whiteline dont do adjustable trailing arms for the 86.

genkin
13th October 2005, 03:16 PM
can somebody explain to me how traction brackets work?

jnr 13b
13th October 2005, 04:08 PM
they do have the upper arm.
the lower arm is int he making.


yeah i also like to have more understandingon the traction braket too.

crazy86
13th October 2005, 04:40 PM
OK, Loki Boyracer and I were talking about this, and there are 2 mods you can do to your trailing arms.

BUT!!! This is just my understanding of what is happening, i might be wrong, and feel free to correct me if necessary!!!!!.

The first one is the mod Loki mentioned before, moving the body mounts for the upper arms further foreward, into a custom made "box" where the rear seat would normally be. This lengthens the upper arms to about the same length as the lower arms, improving the geometry of the 4 link rear end so the pinion angle doesnt change as much.

The Second, is the "Traction Bracket" mod. This involves adding a small bracket to the lower arm mounting point on the diff, effectively lowering the mount a couple of inches. This brings the lower arm back to "level" therefore returning the geometry to the "stock" setting before the car was lowered. Same idea as the front RCA's.


I might make some pics to help give you a better idea of what i mean.

See if these help.. Not to scale, and pinion angle doesnt change in the pic where it should.
http://www.ae86drivingclub.com.au/dcimages/4/8/4/3/79719.jpg

SPEEDCORE
13th October 2005, 04:58 PM
So ultimately you are trying to achieve the same angle on the trailing arms as the OEM suspension setup had?

crazy86
13th October 2005, 05:08 PM
Yep

jnr 13b
13th October 2005, 05:18 PM
Originally posted by CRAZY86@Oct 13 2005, 03:40 PM
OK, Loki Boyracer and I were talking about this, and there are 2 mods you can do to your trailing arms.

BUT!!! This is just my understanding of what is happening, i might be wrong, and feel free to correct me if necessary!!!!!.

The first one is the mod Loki mentioned before, moving the body mounts for the upper arms further foreward, into a custom made "box" where the rear seat would normally be. This lengthens the upper arms to about the same length as the lower arms, improving the geometry of the 4 link rear end so the pinion angle doesnt change as much.

The Second, is the "Traction Bracket" mod. This involves adding a small bracket to the lower arm mounting point on the diff, effectively lowering the mount a couple of inches. This brings the lower arm back to "level" therefore returning the geometry to the "stock" setting before the car was lowered. Same idea as the front RCA's.


I might make some pics to help give you a better idea of what i mean.
I'm trying the upper trailing arm first.
just so i can get pinion angle adjusted.

everthing else sound a bit hard to understand unless i get some picture in my head of what it look like.

crazy86
13th October 2005, 06:16 PM
Just remember that the first mod (equal lenght arms) requires permanant removal of the rear seats.

My first choice of those 2 would be the traction bracket mod.

Adjustable top arms will help your pinion angle though, as you say.

jnr 13b
13th October 2005, 10:50 PM
if not traction bracket and pan hard rod should help.

and if that does not fix my problem. then I'm going to run 155 tyres at the rear http://www.ae86drivingclub.com.au/forums/emoticons/wink.gif

RobertoX
13th October 2005, 11:59 PM
crazy86, your second method will also increase anti squat in the rear by introducing a convergence into the trailing arms.
I believe that this will reduce rear weight transfer under acceleration (good for drift) and as a result will reduce corner exit understeer (where handling is most affected by acceleration).

You don't achieve the same angles on all the trailing arms as oem (unless you also installed new brackets to the upper trailing arm diff mount to mount them lower)

A reduction in rearward weight transfer is also likely to reduce tramp by reducing loadings on the rear suspension. (in very lose terms just think of it as less forces fighting against each other).



I've never seen the first method you have mentioned there on a sprinter but I think that is a very good idea. The upper trailing arms on a sprinter are quite short! However it is a bit more extreme (IMHO) as it is a chassis modification, you can't just tack on extra mounts (safely) where you please without appropriate engineering ;D

mattysshop
14th October 2005, 08:12 AM
maybe swap over to a set of Jap trailing arms? i know the lower ones are longer than the T-18 items, i'm not sure if the top ones would be longer or shorter..but i difinetly know the lower ones on JDM cars are longer

RobertoX
14th October 2005, 12:19 PM
are you 100% sure on the trailing arms? pics?

t series isnt that much heavier than s series

and yes whiteline make adjustable lower trailing arms...

mattysshop
14th October 2005, 01:31 PM
100% sure the lower Arms are longer..i got one of my mates JDM disc rear end as i bent one of my t-18 type drum rear end..(don't ask how) and it was 2" longer..so i just pressed the old bent one straight..good as gold http://www.ae86drivingclub.com.au/forums/emoticons/smile.gif

crazy86
14th October 2005, 02:20 PM
I dont know about that, i have chopped and changed between my ADM and JDM lower arms and they all seemed the same to me.
Ill get the tape measure out tonight.

jnr 13b
14th October 2005, 02:58 PM
yeah i think the JDM and ADM is equal lenght?
if there are different it would only be something like 1-5mm different.
as far as i can see all four trailing arms and pan hard rod is the same in the JDM and ADM.

unless i can be prove wrong.

well I'm going to peddes to get a 24 points suspension check. not sure how they can help me but, one of my friend told me to should do that first.plus it only $14, so that is not that much

jnr 13b
14th October 2005, 02:58 PM
crazy86
thank for the diagram. I understand now.
cheer

mattysshop
14th October 2005, 03:21 PM
hrm...all this make me wonder if it's an after market arm? you know like a cusco one or something..it's just painted black..i'll look into it, and if i get a chance i'll jack my car up and take some comparison photo's..

jnr 13b
14th October 2005, 06:15 PM
hmmmm
I dont' really think so.
It make out of steels and has the same bush set up as my S Series.

here is another question
does it matter if my shock does not have any travel?

well that is the guy from pedders said. Shock need to travel.
plus may be with harder bush might help.

and also upper trailing arm will help if you know what you are doing?

well i'm getting whiteline Adjustable trailing arm.
and may be pan hard rod would go in it too.

then i'll have to get someone to adjust it for me.

crazy86
14th October 2005, 08:09 PM
Roberto x, thanks for that dude, i thought something like that would happen, but wasnt sure.


Jnr 13b


He said your shocks dont have enough travel?

I assume your car is lowered.
How much?
Do you have short stroke shocks?

If your car is lowered with normal size shocks, then the shock travel is limited to the last part of the stroke. This isn't good, as the shock doesnt have the travel it was designed to use, and is often hitting its limit. Best fix is to buy short stroke shocks.

As far as the adjustable trailing arms go, make them exactly the same length as the stock arms to start with (measure it accurately). Mabey add a few mm to the top arms to start with. Then take it to a professional shop to be set up.

Easiest way to put the panhard rod on, is to leave it off the car, drop the car onto its wheels, drive it straight back and foreward (no turning at all!!) and then adjust the rod so it is the length required to fit it on.

Monster
15th October 2005, 02:00 AM
For heaps of Whiteline pics for AE86 suspension:

http://www.pdm-racing.com/products/toyota_corner.html

Shiny traction brackets fitted:

http://www.ae86drivingclub.com.au/dcimages/4/8/4/3/79842.jpg

***AND***


I've never seen the first method you have mentioned there on a sprinter but I think that is a very good idea. The upper trailing arms on a sprinter are quite short! However it is a bit more extreme (IMHO) as it is a chassis modification, you can't just tack on extra mounts (safely) where you please without appropriate engineering ;D[/b]

Check these out:

http://www.ae86drivingclub.com.au/dcimages/4/8/4/3/79843.jpg

crazy86
15th October 2005, 10:47 AM
Gee, Whiteline certainly have stepped up their catalogue for the 86 since i last looked. Looks nice.

jnr 13b
15th October 2005, 06:18 PM
Originally posted by CRAZY86@Oct 14 2005, 07:09 PM
Roberto x, thanks for that dude, i thought something like that would happen, but wasnt sure.


Jnr 13b


He said your shocks dont have enough travel?

I assume your car is lowered.
How much?
Do you have short stroke shocks?

If your car is lowered with normal size shocks, then the shock travel is limited to the last part of the stroke. This isn't good, as the shock doesnt have the travel it was designed to use, and is often hitting its limit. Best fix is to buy short stroke shocks.

As far as the adjustable trailing arms go, make them exactly the same length as the stock arms to start with (measure it accurately). Mabey add a few mm to the top arms to start with. Then take it to a professional shop to be set up.

Easiest way to put the panhard rod on, is to leave it off the car, drop the car onto its wheels, drive it straight back and foreward (no turning at all!!) and then adjust the rod so it is the length required to fit it on.
ok the springs is only about 1 1/2inch lower then standard.
the shock is a Oil tanabe Short stroke shock.

well i'm getting upper adjustable arms and change the bush to the lower arm and put a T3 pan hard rod on.

crazy86
do you know anywhere is sydney I can that my car to?
I need it done by satureday as the IDA pratice day is on.

thank you for all the info

crazy86
15th October 2005, 09:00 PM
Where abouts do you live dude? Your up Newcastle way arent you?

I used to know a suspension guy that set up race cars in Castle hill, but that was about 10 years ago. Other than that, you could go to the Whiteline workshop in Minto, or their distributors in Gladesville (cant remember what they are called. RPM?). Dont know how much they charge though. If you ring Whiteline, they will probably have a list of reccomended workshops in your area.

mumblezzz
16th October 2005, 01:38 AM
I'm assuming the old diff was an open wheeler? and the T diff is LSD. Probably just because its spinning 2 its now tramping. My hachi would do it when it was stock but after changing the shocks it stopped. What bushes are you using? Stock rubber crap? try changing the bushes first before f***ing with anythign else. My mates KE70 had shocking axle tramp before but with new nolathane in the rear it stopped completely. Makes for great burnouts!

jnr 13b
16th October 2005, 04:32 AM
old diff is a s series with lock centre.

mumblezzz
when you change the shock
what kind of shock?(hard sorfter)

Crazy86
I'm in sydney liverpool

But it sound like i should change my bush first.

cheer.
I'll let you guys know how is running when it done.

crazy86
16th October 2005, 09:00 PM
Yeah, Money wise, i would start with good Bushes, and make sure your shocks are right, then go from there. Bushes are a pretty inexpensive change compared to everything else.

jnr 13b
16th October 2005, 09:06 PM
ok i got some nolathane bush to day for the lower trailing arm.
just for the guys who can't find other bush apart from whiteline(over $100)

the same in Nolathane iis $64 or less if you know where to get it from, it'll be cheaper.

it not on in the nolathane's book. but the part number is "46057"

I'll keep you guys up date

jnr 13b
18th October 2005, 07:38 PM
ok guys
pretty sure the problem is fix.

I have replace upper trailing arms to whiteline adjustable. replace lower trailing arm bush to Nolathane bush. and pan hard rod to T3.

I have not adjust anything and the tramp has seen to be gone.

launghing it at 4000rpm and wheel spin all the way to 8000rpm.
very little tramp right at the start. But i have not try on the spot burn out yet.

to sum it all up.
if i just replace all the bushes i get it would have fit my problem.

thank to Crazy86 and all the other guys who has reply to this post.


PS the part number i post on the the nolathane bush for the trailing arm is not 100% prefect. the centre pin is too long for the AE86. i had to grind it down a about 5-8mm shorter.

cheer

crazy86
18th October 2005, 07:57 PM
Good to hear dude, See you on the 22nd http://www.ae86drivingclub.com.au/forums/emoticons/wink.gif http://www.ae86drivingclub.com.au/forums/emoticons/cool.gif

jnr 13b
19th October 2005, 04:09 PM
yeah see you them.
look out for a little asian guy driving a red 20v Hack roku.

he can't drive for shit http://www.ae86drivingclub.com.au/forums/emoticons/smile.gif

hahahaha. he only know how to give his car shit.

yeah that's me.
TUAN