M12 GTO 3R gearbox / clutch knocking noise ? anyone know ?

[nigelw]

The gearbox seems to make a low but quite quiet cyclical knocking noise a bit like a tooth off a gear . The noise gets a bit louder when the oil is hot , but disappears when the clutch is pressed ... before i rip everything out ( big job ) I wonder if anyone has come across this before ? thanks for any help

Nigel

[doug_porsche]

Does the knock stay consistent with engine rpm, or vary by gear selected?

If it stays consistent with engine rpm then maybe clutch/throw out bearing?

[nigelw]

it doesnt seem to make any noise whilst driving , just when stationary , at tickover , until the clutch is pressed , then it stops ...

[TuxMan]

I had this at the start of the year , turned out to be a damaged 5th gear cog :-( engine out and rebuilt with a 2nd hand mainshaft as Ford are no longer producing them :-(

[nigelw]

Cheers ! do I remember correctly that its worth cutting a section out of the chassis and making it removeable to take the box out ? ..my car has always suffered from stiff synchros ( I've never driven another one ) so might do that at the same time . So was your symptons like mine ???

Nigel

[jamie g]

does the noise stop as you apply a little pressure to the clutch pedal or does it have to be to the floor?

[nigelw]

the usual amount for the clutch to " clear " ..which makes me suspect something on the gearbox ....I suppose I'm just asking if there is a history of this sort of thing , and one person has kindly said that they had a problem with 5 th .. just wondered if its quite widespread on the 6 speed box ( which mine is ) ..thanks Nigel

[TuxMan]

5th gear is weak on the 6 speed box . Jetstream Motorsport are working on a replacement shaft that will be stronger !!

[nigelw]

thanks everyone ! just need to summon up the enthusiasm to pull the box out !

[Blu3R]

TuxMan said:

5th gear is weak on the 6 speed box . Jetstream Motorsport are working on a replacement shaft that will be stronger !!

Hi Simon, any news regarding this upgrade? My box is still apart as you know and I'm considering delaying the rebuild if Jetstream will have the replacement available soon.

[TuxMan]

It's being worked on as we speak !!!!

[nigelw]

Does the car have a dual mass flywheel ? What symptoms does this show ? Could this cause this knocking ? Thanks Nigel

[TuxMan]

No solid steel flywheel .

[sundance002]

TuxMan said:

5th gear is weak on the 6 speed box . Jetstream Motorsport are working on a replacement shaft that will be stronger !!

Hi Simon , It's not just the shaft That needs strengthening, after we re welded and pinned 5th gear to The shaft, it's then broke
3 teeth off the 5th gear cog. That May of been due to we used the old shaft and gears, it's possible That my gear was worn or damaged,
From before. We repeated the process using one of the last new shafts, and so far so good, but Then I'm reluctant to stamp on the loud pedal in 5th.
If the gears and shaft were made from a stronger material then Maybe at last we will have a solution.

Edited by sundance002 on Thursday 15th December 05:06

[TuxMan]

Hi Craig , all new gears are being made along with the splined shaft !!
It's being professionally built so should be good enough for the job ! Unfortunately with Ford no longer producing the shafts we have no choice but to push forward with the project although Jetstream are concerned about developing a product in customer cars but we have no choice !!!