What could this noise be?

LeffeBrune · Post by **LeffeBrune** » Mon May 16, 2016 9:44 pm

I had a new 5 speed gearbox put into my S1 4.2 OTS together with a new propshaft. Also had new tires mounted. Drove it over 1000 km already. All fine except one thing.

On sharp right turns, at fairly low speed, but under load, there is a loud noise, like a tock, tock bang, and you feel something is hitting something. Difficult to locate precisely but it feels as if it is under the armrest or slightly further to the rear. Only occurred under load in second (and once in third) gear at fairly sharp concerns at very moderate speed. Did not happen in long corners at higher speed or when turning not under load. And so far only in right turns not in left turns.

Any ideas welcome.

Thanks.

Georg

PeterCrespin · Post by **PeterCrespin** » Mon May 16, 2016 10:54 pm

Ideas? Get the fitter to do the job correctly unless he worked for free.

Adjust the engine and gearbox on their mounts to give more clearance to the gearbox case (or propshaft?) on the affected (left?) side. Next time don't give him a case of Leffe until AFTER the job is good, not while he is working... :-)

abowie · Post by **abowie** » Tue May 17, 2016 4:30 am

PeterCrespin wrote:Ideas? Get the fitter to do the job correctly unless he worked for free.

Good advice.

We had a problem with a propshaft recently just hitting against the inside of the tunnel in similar circumstances.

The guy who rebuilt it had put worm drive clamps on the rubber boot and one was hitting against the tunnel.

chrisfell · Post by **chrisfell** » Tue May 17, 2016 7:29 am

Check the bush and spigot on the gearbox mount. After umpteen thousand miles of constantly being bathed in warm oil mine had disinterated. The noise was the spigot hammering against the gearbox mounting plate, only on RH turns, only under acceleration. The top engine mount was also out of adjustment leading to the symptoms you've described.

Before I discoverd this I had the prop out, halfshafts dismantled, exhaust re-hung......

I'd check the gearbox mount next. If there is no bush in the hole where the spigot pokes through, then the spring rubber will almost certainly need to be replaced. I hope replacing yours will be easier than mine was..........

A PO, (a former business that once claimed to be the world's largest retailers of E-Types) had mounted the plate with new bolts. Not set screws, but bolts. The shank of the bolts has stripped the threads of the captive nuts. In addition they had drilled new holes in the floor with more fixtures to try and keep the plate from comng loose. And they had elongated the screw holes in the plate "to provide a margin for fitting".

LeffeBrune · Post by **LeffeBrune** » Tue May 17, 2016 7:55 am

Thanks guys. I would go back to the guy who installed it but it's a 500 km drive :( . Going forward, I will keep the Leffe for myself :-).

Georg

ralphr1780 · Post by **ralphr1780** » Tue May 17, 2016 11:28 am

Georg,
Due to the handbrake positioning, the transmission tunnel is narrower on the handbrake side. So most probably upon right turns, the propshaft is hitting the tunnel along this section. Few parameters involved as mentioned by other fellows. Didn't the garage take the car for a test ride before delivering it back to you?

LeffeBrune · Post by **LeffeBrune** » Tue May 17, 2016 5:15 pm

Thanks Ralph. The garage did take it to a test ride but, to be fair, this only occurs in certain situations (hard right turn, low speed, acceleration). I did not notice it on the way from the garage to the highway (although I did do a couple of hard right turns). So it is possible that this simply did not occur on their test drive. Another possibility is that something went loose after the first 150 km on the autobahn. Not an excuse but an explanation.

Anyway, I found a specialist garage nearby (Paul Soret in Hoeilaart) and have an appointment for Saturday. Should know more after that.

kingzetts · Post by **kingzetts** » Tue May 17, 2016 7:12 pm

I had exactly this problem with the T5 box in my car. It was due to the bolt/nut heads on the front propshaft UJ hitting an internal stiffener rib inside the transmission tunnel when the engine/box were twisted on their mounts under the conditions listed. Some appropriate adjustments to the bodywork to create additional clearance solved the problem. One of the side effects of putting components into situations not designed for them......

ralphr1780 · Post by **ralphr1780** » Wed May 18, 2016 1:38 pm

Georg, but most important: your first impressions about the 5 speed and the MX5 seats?

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What could this noise be?

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