Knock noise comming from drive train HELP..

guyph_01 · Post by **guyph_01** » Tue Jul 14, 2009 7:56 pm

Hi guys,

I've been driving me car for about 2 weeks now and the noise is getting worst.

I hear a big knock noise that seems to come from around the rear diff area/ shaft. maybe gearbox.

Heres what happens:
Basically when i push the car in 1st or 2nd and let go off the acc pedal i hear the knock.

Hard to explain. It does it when its still in gear. IF i press the clutch and let go off the acc pedal no noise.
It has to be in gear so that it produces that sudden acceleration and deceleration. Only when i take my foot off the pedal it gives that big knock.

When pushed and foot is taken off the accelerator it then does a big knock, knock, small knock... (in sound LOL)

From what i can hear its like screws are not tight enough.
I was wandering if any of you guys had a prob like that before and point me to what could it be.

I know its hard to tell but any help/advice would help:)

thx
Guy

GOD · Post by **GOD** » Tue Jul 14, 2009 8:41 pm

Sounds a bit like a noise my car makes. I'm saving for a gearbox rebuild.

All I can suggest is checking basic stuff like oil levels and all the bolts on the diff, tailshaft, centre bearing and gearbox mounts. Tailshaft uni joints can also wear out, but I'd expect them to behave the same regardless of clutching.

Is it any different in 4WD?

Dane.

AlpineRaven · Post by **AlpineRaven** » Tue Jul 14, 2009 8:42 pm

What gearbox is it? How many kms and do you know if its original gearbox for that car?

Does the knocking get worse when you're driving downhill but not accelerating but in gear?

Does it happen any speed or specific gears?

Cheers
AP

AlpineRaven · Post by **AlpineRaven** » Tue Jul 14, 2009 8:44 pm

GOD wrote:Sounds a bit like a noise my car makes. I'm saving for a gearbox rebuild.

All I can suggest is checking basic stuff like oil levels and all the bolts on the diff, tailshaft, centre bearing and gearbox mounts. Tailshaft uni joints can also wear out, but I'd expect them to behave the same regardless of clutching.

Is it any different in 4WD?

Dane.

Yeah I agree... i would be looking at the uni joints as well and rear diff & mounts, bolts etc etc... Another thing is to change the gearbox oil & rear diff oil to see if there is sound difference (don't do both at once, do it different times)
Cheers
AP

AndrewT · Post by **AndrewT** » Tue Jul 14, 2009 9:47 pm

I beleive he's using original 5spd part time box with an adaptor plate to EJ22.

I second GOD's suggestions on checking all mounts. It sounds like driveline backlash. There's always abit of a jolt thru eveyrthing in the situation you've described and all the mounts work together to absorb it, one buggered one exposes it as a clunk.

Also check the engine stay-rod.

Eliminate all these little things before you even consider things like gearbox, quite often it's something smaller than large, and really it's more likely too.
Also eliminate all these before spending all your dosh on oils. Lack of oil, or old crappy oil will usually cause a whine and slowly build up over time, I havn't experienced it causing a clunk before.

phillatdarwin · Post by **phillatdarwin** » Tue Jul 14, 2009 10:57 pm

sounds like a uni joints

guyph_01 · Post by **guyph_01** » Wed Jul 15, 2009 12:57 am

hi guys,

whats the engine stay rod?
What the uni joint? is that the rear cv shaft?

The sound seems not to come from the internal of gears in the gearbox or the diff. but more like bolts holding them.
I'll have a better look at all of them first and keep you guys posted.

Also while on the subject of gearbox noise, my 3rd gear always crunch when i move it fat from 2nd to 3rd... I think syncros or something. What would you guys use in the box as additive with fresh oil. The brand name etc would be helpfull.
the oil one i know of is a white Nulon additive but not sure if there are better stuff.

Your experience would help

thx

GOD · Post by **GOD** » Wed Jul 15, 2009 1:54 am

The engine stay rod is the brace from the firewall to the back of the engine. It's a good suggestion actually, as that's one of the things I still haven't done to finish my car - could be part of my problem.

Uni joints are the joints in the tailshaft (that's the one that runs front to back down the centre of the car).

As for oil additives, I've always struggled to believe that they can do much. Yes, there are better quality oils, but if synchros are buggered, they stay buggered until they're replaced. Some additives I've looked at claim to "renew worn components", which is just bollocks.

Dane.

Post by **TOONGA** » Wed Jul 15, 2009 9:49 am

Sounds like a rear bearing has given way and the rear cv joint is dancing around in whats left an easy fix if you do it quickly

TOONGA

guyph_01 · Post by **guyph_01** » Wed Jul 15, 2009 12:31 pm

i dont have a engine stay rod in my car. There is still the part on the firewall but theres none on the gearbox or engine. To what can i connect it?

What could happen worst to the rear bearings if i keep on driving.
Do you need to press them out or do they come out like on the gen 1 liberty?

thx

AndrewT · Post by **AndrewT** » Wed Jul 15, 2009 2:47 pm

heh....Matt's car nearly caught fire....
showthread.php?t=7296&

Jack the rear of your car up and spin the rear wheels by hand, u should be able to tell if the bearings are buggered.

AlpineRaven · Post by **AlpineRaven** » Wed Jul 15, 2009 3:27 pm

if the bearings are buggered its not ideal to keep driving because if you do, the grease can be dried up, once they do they'll get hot and weld up inside the bearing housing. Hence seized bearing and can be harder to push it out, i've seen it happen, ended up getting another hub..
To get them out, a slide hammer will do.
Cheers
AP

Battlewagon · Post by **Battlewagon** » Wed Jul 15, 2009 8:25 pm

There's supposed to be a bracket bolted on to the top of your bellhousing, I don't know if it will still fit with your mods.

GOD · Post by **GOD** » Wed Jul 15, 2009 8:53 pm

That bracket is on EA engines and EJ gearboxes, so if you use an EA gearbox with an EJ engine, a bit of fabrication is required. I think some people have used the little lifting eye on the back of EJ engines - there are pics around here somewhere.

Dane.

guyph_01 · Post by **guyph_01** » Wed Jul 15, 2009 10:42 pm

yeah like GOD says you need to fabricate something. I tried to look for the pics but cant seem to find them. Would anyone know when to find them?

AndrewT · Post by **AndrewT** » Wed Jul 15, 2009 11:58 pm

Here I found a couple of pics of a "prototype" which wasn't finished yet. A guy by the name of maxxair posted them up back in January.

GOD · Post by **GOD** » Thu Jul 16, 2009 12:00 am

Just dug these out of my big folder of Subaru pics:

I think it's Subarino's car.

Andrew - does Wackybug have a stay rod? Got any pics?

AndrewT · Post by **AndrewT** » Thu Jul 16, 2009 10:32 am

nah never got around to making one for WackyBug. I should if I actually continue with that thing. When we hit a treestump once and stopped dead, the engine nearly kept going! Busted both the engine mounts.

Yeah I beleive those photos are Subarino's. Although he was having huge issues with it constantly breaking.....but I think that problem only started happening after he fitted the supercharger. Not sure if it was ever resolved.

Post by **TOONGA** » Thu Jul 16, 2009 4:52 pm

heres what the hub looks like in exploded view off the car

if you have the gregorys manual thats where this picture comes from

the ring nut is a pure prick to remove there is a special tool available but I think they cost more than a wheel bearing kit

I once made one out of a 3/4 socket and some tool steel but that was before I left to live in Singapore and before all my tools dissapeared

good luck if you do it

if you need the gregorys manual tell me and i will upload it to your prefered download server

TOONGA

AndrewT · Post by **AndrewT** » Thu Jul 16, 2009 5:03 pm

I got that ring off my car on both sides fairly easily by tapping it around with a large size pin punch.

Have you managed to confirm where the knocking is actually coming form yet?