Told This Was Normal... Not Happy Ford.

[seduced]

I have other threads on this, but I really need people to read and reply to this one.

Took my car in this morning as it suffers an audible booming/vibration from the rear under heavy torque at 20-40km/h in any gear. Secondly, the rear makes a booming/rattly/diff noise under hard acceleration through the first 3 gears. It has to be under full throttle torque to hear it. (I got a different service guy this time... the last guy who was fantastic was promoted to BMW service....) Tailshaft/diff has been replaced recently to try and fix the problem.

The guy from the workshop wasn't sure about it. He then drove two other XR6Ts and said they had the same problem, therefore its all normal.

I'm not buying that. Has anyone here noticed any sort of noise/vibration when under full throttle acceleration? Would you say a WOT run to 100km/h is dead smooth I.e no sounds/vibrations from the driveline at all?

I have to try and convince them now that it can't be normal...

[davidald]

Miine, and my previous BA had a tunnel noise from the rear under acceleration. I fixed it by changing tyres.

[bambis]

Does it do it all the time after a certain speed? or just when accelerating hard? my BA doesnt do this.. Maybe your rear wheels are not balanced correctly? Maybe u are getting some axle tramp while under WOT? whats the tread like on your tires?

[turbo.vixen]

I had a vibration at 80km/h and it turned out to be the tail shaft needed balancing, ford found it and fixed it

[seduced]

hmmm. It does it under any torque at 20-40km/h. No axle tramp (although it will quite badly if I drop the clutch... something I avoid like the plague). Wheels balanced by ford. The tyres are coming up for replacement. They are falken 452s. The drivers side rear has severe wear on the inside edge, the passenger side looks fine. I pointed this out to the Ford guy, said this might be a clue. He said its out of alignment, but didnt check why it was so severe, just kind of ignored it really.

It also has this crazy drone at anything over 100. It sounds like diff whine, very similar to the drone the old diff had. Showed him this aswell, but when they rang and said "its all normal" I said the drone at 100 is NOT normal and I need to know why its happening. He said they will look at it tomorrow.

In any case, I've got new tyres on order and will have them on by the weekend. I need to rule them out completely before Ford will take it seriously.

The sound I mentioned can be felt through the rear seat. Its a shuddering boomy noise. As its at such a low speed, tyres seem unlikely. Even the Ford guy agreed with this. If tyres and Ford cant fix it, I will be taking it to someone who can. I dont care if I have to pay, its driving me mad.

[tmac450]

This is why Ford looses customers. How is saying all of the cars do it a soloution to the problem. So if all the doors fell of the XR's, Ford wouldn't fix it because they all do it!

Again, wake up Ford!

[Shark]

What springs are you running?

Is your car sitting on the bump stops?

Springs sagged to the max?

IF so, it can cause MAJOR shuddering accelerating in most circumstances.

On boost its alot worse.

Can also cause VERY bad axel tramp etc.

[seduced]

Std prings in the rear. The fronts were replaced only a month ago due to sagging/bowing. The rear does sit lower than other XRs, so I bet this is the problem... Theres about 10mm clearance to the bump stops (whats normal here??) Car suffers horrendous axle tramp anytime the wheels spin. And the shuddering is only there when accelerating hard. I reckon you've nailed it!

NOW IF ONLY I CAN GET FORD TO REPLACE THE REAR SPRINGS....... THIS WILL BE ITNERESTING.

Update: The diff whine at 100km/h plus was tested. The driver couldn't hear anything apparently. So get this- I get a call: "it probably only does it when its warmed up - just bring it back in next time your hear it.." I said "of course it does it when its warmed up, I told the mechanic that... " he says "yep, well bring it in when you hear it again..."...

I told him to just forget it for now. Its getting new tyres tomorrow, I'll bring it back in after that.

[seduced]

Shark : How did you know? Have you had a similar experience? Did new springs fix the problem? I OWE YOU BIG TIME IF THIS IS THE FIX!!!!!

[Shark]

Hey mate.

My old man had this problem recently, and we knew this was the cause.

(owns a worked BA xr6t)

Basically the rear end was sitting on the bump stops due to the rear springs sagging SO MUCH. They were absolutely f*cked.. but the fronts are still alright.

With 5-10mm clearance, there mayaswell not be any at all.

From a standstill, taking off fast, when the rears spin the rear end generally sags. If there isn't enough bumpstop clearence it'll hit the bump stops and start bouncing.

Do this enough and it can destroy a rearend very quickly (or atleast stress it the f*ck out).

When driving normally, accelerating normally or on boost, it's exactly the same thing.

No clearance means the rear end is riding on the bump stops. Boost it, rear end sinks, and it hits again and again and again causing mass shuddering as you're accelerating.

I noticed that accelerating smoothly didnt do this as it didnt cause the rear end to push down as hard I guess.

I'm betting that you are having the exact same problem in regards to the shuddering when taking off, and accelerating.

To fix this, all you need to do is change the rear springs. This will make it sit higher, and it wont hit the bump stops everytime you dump it or accelerate hard.

MAKE SURE YOU TELL THE DEALER TO LOOK AT THE BUMPSTOPS AND EXPLAIN HOW THIS CAN HAPPEN.

Hope this does the job man

Cheers,

Paul