driveline / diff problem

neb · 08-03-2005, 11:43 AM

This has been annoying me for a while now so I'm hoping I can get some advice. If you don't know my car its an ebII 6cyl wagon, it was converted from manual to auto approx 6 months ago. When it was first done it was fine. But from about 3 months ago the driveline has gotten 'clunky'.

The problem is.. in almost any gear if i let off the accelerator the car will jerk back and forward really bad, i have to either accelerate or put the clutch in or change to a lower gear to stop it from jerking. This seems to be slowly getting worse. It also seems to clunk into gears a bit when i change gears.

I did have this checked out about a month ago.. and I was told its the diff and basically I could get the diff rebuilt but it would probably start doing this again after not very long.

What do you guys think? Am I doomed to have a car that jerks badly whenever I let off the accelerator. I know I have been in and driven other manual fords and they definately don't do this.. maybe its because its a wagon?

Ben.

InitialD · 08-03-2005, 11:45 AM

Ben, do you mean that when your doing say 80k's and you back off the accelerator, and the car will kinda "smack" back and then "smacks" forwards if you try to accelerate?

If so YES MY CAR DOES IT NOW!!! thus why i need a new diff

I dunno about it will keep doing it after a new diff? id say replace the diff and it should be all fine

neb · 08-03-2005, 11:51 AM

Yes thats exactly what it does it started off not so bad.. But it seems to be getting worse. My car does it worse at lower speeds.. once i get to say 100ish it doesn't really do it too bad.

The mechanic that checked it out also said when it was auto it kept load on the diff all the time so thats why it didnt do it, but with a manual its always load on and off.. so it causes problems.

edit: i'm pretty sure it is my diff thats stuffed but the thing that worries me is that he said i can get the diff rebuilt but it would just start doing it again after a while.

Bass Crazy · 08-03-2005, 11:52 AM

Id be a little worried if it were drivline slack causing all the jerking. How are your engine/gearbox mounts?

The clunks are caused by slack, but i reckon the diff would have destroyed itself by now if it had enough slack to shake the whole car around.

InitialD · 08-03-2005, 11:52 AM

Yeep, replace the diff.

Whats your current one?

neb · 08-03-2005, 11:54 AM

current diff is a 3.27 (or 3.23 i cant remember) 28 spline single spinner... but it seems to be leaving 2 black lines fairly often lol.

i'll have a look at the engine mounts and gearbox mount but i'm pretty sure they are ok if they're not i'll be ****ed off because they were all replaced only late last year.

also it doesn't feel like it did when the engine mounts went.. definately feels like diff.. or driveshaft.. uni joints something like that.

ned · 08-03-2005, 11:55 AM

I agree with checking you engine mounts too, I had a 'similar' problem and found that both my engine mounts were mangled.

InitialD · 08-03-2005, 12:00 PM

Well my car does this, engine mounts are fine aswell, as are my lower trailing arms. But it still smacks about land its all loose inside the diff aswell when you turn the wheels.

neb · 08-03-2005, 12:07 PM

I'm about to go on lunch break so I'll check my engine mounts. But when somethings stuffed it means it must be time to upgrade it hey... hmm get it rebuilt with LSD and hope it doesn't stuff up again

stockstandard · 08-03-2005, 12:11 PM

I have the same problem. My diff has done somewhere around 270,000k's and is a 3.08 ss so I am not going to be to upset about loosing it. I never had the problem when it was an auto so I guess the auto must be a little more forgiving.

Thanatos · 08-03-2005, 12:32 PM

You will find that this is a VERY common problem with e-series manuals.

And it MAY not necessarily be your diff, lumpy cam, etc can all have a bearing on it as well.

For example, my car has the same problem, and my diff is probably only 10,000kms old.

You will also find that some ratios do it more than others as well. (can't remember for sure, but i THINK the shorter the ratio, the more it does it)

The clunking is not normal, so there is obviously something wrong there, but the jerking back and forth could be caused by a number of things, and is almost impossible to eliminate completely.

T_Terror · 08-03-2005, 01:24 PM

Ditto. I got it too.
I replaced the engine mounts and it got better. Then it started coming back as my diff started wearing.

I find it hard to accept that it is the diff because if so, then its a problem that has persisted to the current model Falcons. An example, my mums XR6T which does it worse than my ol EA!

neb · 08-03-2005, 01:36 PM

engine mounts are fine.

well what the mechanic said is that its the diff. i can get it rebuild but its a bit of a waste because it is just going to come back. he said it was because of the manual and the cam and theres not really much i can do but select my gears better. which i can do to drive it with minimal jerking.. its just mainly in stop start city kind of traffic it can get really annoying. i was hoping there was a fix to it because people that get in my car think its ****ed lol.

stockstandard · 08-03-2005, 03:19 PM

That is similar to what I was told. It is a combination of things but it comes down to engine tuning (well a combination of modified engine + manual + old diff). I am looking for a fix as well because the car kind of "rocks" back and forward when cruising at 60 in 4th, so depending on how bad it is I sometimes drop it back to 3rd. As soon as the rpm > 2000 everything is fine.

I am still hoping it is the diff though.

dansedgli · 08-03-2005, 03:32 PM

Auto conversions for all!!

galapogos01 · 08-03-2005, 03:38 PM

dont warn trailing arm bushes cause symptoms like this?

Sox · 08-03-2005, 03:57 PM

This sort of problem can be helped by taking the slack out of all the suspension components, that is, fitting urethane bushes.

It's also not helped by tall gearing.

Rick.

neb · 08-03-2005, 04:02 PM

Thanks Sox I might have to look into that.. it would just be the rear suspension that would have to be done right?

Thanatos · 08-03-2005, 04:02 PM

Quote:

Originally Posted by Sox

It's also not helped by tall gearing.

Rick.

So it's tall gearing?? I knew the gearing made a difference, i just couldn't remember which was worse! lmao

neb · 08-03-2005, 04:08 PM

3.23/3.27 whatever it is i have isn't tall gearing is it.. fairly average. do you think upgrading to 3.45 or even 3.7 would make much of a difference? by that i mean much of a difference to the jerking problem not performance wise.

neb · 08-03-2005, 04:13 PM

also if the rear suspension is tightened up/firmer.. is this likely to put the stress back on the engine mounts. because when i used to have lowering blocks in instead of custom leaf springs i kept breaking engine mounts.

Sox · 08-03-2005, 04:28 PM

3.27 isn't tall, but it's tallish.
3.45 will help, and 3.7 will help further.

Taking the slack out of the rear end won't hurt anything, though it may make it ride a little harsher.

When you had lowering blocks things would have been worse than they are now.

How many leaves do you have, and are they all the same thickness?

Rick.

neb · 08-03-2005, 04:35 PM

I'm pretty sure it had one extra leaf added and its lowered to superlow height. They're all the same thickness. I'm pretty sure the leaf springs are fine they were done at your favourite automotive company after all :-p

Well i think i might get the diff rebuilt with lsd and maybe 3.7 diff gears, and urethane bushes in the rear.. should hopefully fix my problem.

Sundeep · 08-03-2005, 05:07 PM

I had the same problem in my old EA when I was using a CFI pump with the MPI setup, the power would kind of come on and off and cause it to jerk back and forth like violently styles.

So yeah, my point is it could be caused by a number of things, but you should probably do the diff first if you know it's fubar.

Sundeep

neb · 08-03-2005, 05:52 PM

actually that makes a bit of sense.. with the cam my engine idles pretty lumpy.. which could cause the revs trying to go up and down a bit while its in gear? so a chip or aftermarket computer would probably help get rid of the problem as well

SileNceR · 08-03-2005, 09:27 PM

My driveshaft unis are ****ed i can clank it around (and it clank/clicks when you accellerate/decellerate, I assume this is the driveshaft?)

I checked my engine mounts... and both were obliterated (as in, only 1/2 there)...

and now my harmonic balancer has gone... lol

what'll it think of next... stupid ea.

neb · 08-03-2005, 11:12 PM

lol bad luck dont worry everything that can possibly break is breaking on my car lately.. so you're not alone

SileNceR · 10-03-2005, 10:28 PM

wow my harmonic balancer is ok (maybe) but one of my timing chain guides may be cracked... bah

theres a bit of metal hanging out of my rear uni and I can move it about 1cm lol... tis ****ed..

Bass Crazy · 11-03-2005, 08:14 AM

Quote:

Originally Posted by neb

actually that makes a bit of sense.. with the cam my engine idles pretty lumpy.. which could cause the revs trying to go up and down a bit while its in gear? so a chip or aftermarket computer would probably help get rid of the problem as well

Try bumping up the base idle another 100-200rpm. It helped my car stop jerking and low speeds while rolling in gear, probably wont do much for high speeds tho.

neb · 11-03-2005, 10:34 AM

thanks bass i'll try that since its something easy to do. i think i'm just starting to get used to it.. when i'm slowing down and down gearing sometimes i can tell if its about to jerk and push the clutch in or whatever to prevent it. they only time it really annoys me now is in busy stop/start traffic at low speeds (below 60).

at the moment it idles around 900-1000ish rpm.. if it bump it up to 1100-1200 is that too high for it to be idling?