s9ott

My 3dr Sierra has a loud knocking/vibration noise from the T5 gearbox when lifting off the accelerator when in gear.
There is no noise when I’m accelerating or if I dump the clutch or even free wheeling out of gear.
When driving the car it sounded like it was coming from behind the box, maybe the prop shaft or diff, so I’ve up rated the diff mount and replaced the prop shaft Rubber Donut and centre bearing, and it’s still making the same noise.
I’ve just put the car on jacks and ran the car to try and find where the noise is coming from, I’m sure its coming from inside the gearbox.
Anyone have any ideas what might be wrong as I’ve just pulled the box out and not sure what to do with it.
Any help please

botters

iTrader: (2)

best bet send it to a reputable gearbox repairer and get it checked allthough it will cost to be checked even if they dont find owt it will be worth it for peice of mind allthough it does sound like possibly a worn gearbox mount allthough these normally give noise on acceleration and decceleration

s9ott

Think that is the best way to go, going to drop it off and get all the bearings replaced and anything else that looks bust in the gear box.
If it does not sort out the noise will try uprated gear box mount.
Will update the thread once the box is back in and road tested.

s9ott

Well got the Gear Box rebuilt and up rated the Gear Box mount, and it’s still making the same f**king noise.
Took the Box off again and changed out the release bearing again, but used the rounded edge type for Twin plate clutches, and also used Burtonspower’s release bearing extension, but it’s still making the same noise.
Going to try a hydraulic clutch setup next and do away with the clutch bearing release arm, not going to hold my breath.
Anyone had this problem?

botters

iTrader: (2)

have you checked the engine mounts?

2001ode

iTrader: (1)

Hi,
Check turbo damper seting.

Claude

tabetha

Turn the stereo up.
tabetha

AndyPen

iTrader: (24)

Very good point - amazing how this noise transmits like it is the box!!

Danny.

iTrader: (2)

Are you sure it's not the exhaust knocking? I have to adjust mine as it can make contact on the anti roll bar, gearbox and even diff in not positioned correctly..

s9ott

All mounts and bushes on the car are new up rated ones, but because I have the competition type engine mounts I have a feeling that they might just be to stiff.
I’m just in denial as they cost over 300 quid for the 2.
But think I will need to put standard ones on just to see what happens.
Cheers

s9ott

The Damper is up rated too and all looks ok.

s9ott

Think you got it, just one problem don't have one in the car yet

D16PJM

its not the propshaft dounut?, had that on mine when lifting of the accelerator.

i should of read it a bit better as you have already done the prop.

davecosworth

sounds like diff mount my one used to bang around when lifting off to fitted msd one and noise stopped

s9ott

I’ve had the car on axel stands and been under checking everything while mate was running the car.
I'm convinced it’s coming from in the gear box or even in the bell Housing.
That’s why I’m thinking of going for the hydraulic clutch set up, plus I keep having problems with the plastic clutch ratchet on the pedal with using a twin plate clutch.

So next step will be:
1. Try standard engine mounts
2. Hydraulic clutch set up
3. Run it till something breaks then I’ll know what was wrong

s9ott

When I had the car on axel stands running, I had my hands all over the diff, plus I’ve up rated the diff mount too.

martynhomer01

iTrader: (1)

what about the spigott bearing when you take the box off. its the bearing that sits on the centre of the flywheel and the gearbox shaft goes into. i had a standard sierra once that had these symptoms, and the bearing was shot. it causes the input saft on the gearbox to spin off balance when decelerating. have a look and see what it is like.

Grayson

Some Merkurs with T5s have the same issue. Here is a good discussion of the issue, though the solution is still yet to be determined:

http://www.turboford.net/cgi-bin/ult...c;f=2;t=040828

I'm running a polyurethane gearbox mount, and I'd like to swap in a factory (Mustang in my case) rubber mount to see if that solves the problem. Many other parts have been swapped out, as discussed in the linked thread.

s9ott

Was new one put in on the rebuild, but last time i put the box back in, I hand my finger in bearing making sure all the roller bearings were still ok.
But is there any difference on 2wd and 4wd spigott bearing, I know the clutch center spindle bit are different.
I'm sure it’s the right one but you got me thinking again

martynhomer01

iTrader: (1)

i wouldnt know if they are different or not i am afraid matey.
check not only for the play in the bearing, but any damage from taking the box in and out. i know that was what caused mine to go years ago, becaus ei had taken the box out and damaged it then. for the sake of only probably a few quid, may be worth putting new in again.

good luck mate

m3cosworth

any resolution yet scot?
got a similar problem that at about 3000 rpms it vibrates/grinds when i take my foot of the gas.
just had a new recon gearbox, prop changed,new clutch, balanced the flywheel! and its still doing it

s9ott

Not had the time to take the box out yet hope to do it this weekend.
Did your car just start making the noise without changing anything?

I’m going to change the following on mine next
1. Spigot bearing AGAIN
2. Fit central push Hydraulic clutch kit
3. Take off twin plate clutch check for signs of vibration damage
4. Try standard engine mounts

Some things I change on the car before it started to make the noise
1. Full engine balanced
2. Lightened flywheel
3. Forged Pistons
4. Twin plate super clutch
5. Spigot bearing
6. Full poly bush kit
7. Competition engine mounts

What I’ve done so far to try and fix the noise
1. Up rated the diff mount
2. Up rated Gear box mount
3. Gear box rebuilt
4. Replaced the prop shaft Rubber Donut and centre bearing
5. Modified the clutch release arm and bell housing
6. New clutch release arm
7. New Clutch release bearing flat type for standard clutch
8. New Clutch release bearing rounded edge for up rated clutch
9. Burtonpower clutch release bearing spacer
10. Car on axel stands and drive it to try and find where it’s coming from, sure it’s in the gear box or bell housing still.

luke_rs1800

Hi. I’m digging this very old post up from the past!! Did you ever get to the bottom of this ? I have the exact same problem and I cannot find what is causing it to save my life. Hope your still on here and respond! Thanks

s9ott

I’ve not touched the car in years, so probably will still have the issue.

i did bin the clutch release arm and upgraded to a hydraulic system, but never had chance to try it out.
the other thing I was going to try, was standard engine mounts 🤔

hope you can fix our issue soon, as I’m planning on putting car back on road next summer🤞
Cheers
scotty

luke_rs1800

Thanks for the reply mate. Did you check out the spigot bearing was it damaged at all ? As that Is all I can think of with mine. I have standard mounts. Also had my box checked etc and is all ok. But mine definatly sounds like it’s coming from that area too and only when I let off in say 4th gear around 2500rpm. Driving me mad

s9ott

The spigot bearing was ok, so still 🤔

luke_rs1800

Changed my spigot bearing and gearbox mount. And still got the bloody noise!!!!!! Driving me mad

Adam-M

Does your prop have the proper spacers between the prop and the floor to keep it parallel?

Bjorn_H

I have the same noise and im pretty sure that is the sound from a worn pinion bearing.

luke_rs1800

I have a 1 piece custom made prop in mine as it’s in a fiesta. But it is a complete Sierra floor pan and running gear. It doesn’t sound like it’s coming from the rear but from the gearbox / engine Bay Area. However I can’t actually find anything untoward. Also I know the car my diff came from and that made no noise at all. Very very frustrating and very annoying

Bjorn_H

Any update on this? I have rebuild my diff and change all the wheel bearing and still have the noise. I have not checked my gearbox yet.