Lotus Elan

Metallic rattle

PostPost by: Terrydales » Tue Feb 12, 2019 3:24 pm

This rattle could come from the vacuum non return valve and be associated with a failure of the servo.
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PostPost by: andyhay » Sat Feb 23, 2019 9:49 am

Hi all

Quick update. I took the car around to a generous and knowledgeable club members workshop today and put the car on a hoist. We concluded the noise is probably coming from the gearbox which is a concern.
Further investigation required prior to anything drastic like pulling out the gearbox.


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PostPost by: miked » Sat Feb 23, 2019 10:49 am

I have chased several gearbox noises on a plus 2. Not that it is different than an Elan.
The tunnel and bellhousing making a sound box that can fox the exact ID.
Worst was the needle roller between the first motion shaft and main shaft broken up in the cage. Found in many gearboxes i have bought for parts. Engine out twice for this one. Sounded like bell housing. Also shitty copy thrust bearing (doing the rounds) spinning on carrier on one car. Then i had a noise on a mates car which was the input shaft bearing shield adrift and tinkling.
Re: detent springs, i have shimmed these many times for a more positive snick. I personally can't see how these could make noise. Whilst the spring compress and weaken, I can't see it possible to squash so much. I have lots of them and measure for the longest if building a box. They only differ by about 20 thou at most. Others may disagree. Al will know as he has done lots. :D
As a point of fact, even new springs from TTR don't measure up to the spec in the manual. They are shorter. I have shimmed those with little alloy slugs punched out with a leather punch.
If/when you bite the bullet and pull the engine there are a few suggestions to look at. I will usually enter a box if i have gone to the trouble of taking the engine out. Especially after the needle roller business and second engine out time. I even changed a clutch plate on that occasion after suggestions it was the plate springs. It was not.

Cheers Mike
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PostPost by: prezoom » Sat Feb 23, 2019 4:51 pm

Have done the shimming of the dent springs, and stretching the springs as well. Stretching seems to work just as well and takes less time. Slipped a small screwdriver between the coils and bent the spring sideways over the screwdriver blade. Alternating the bending motion keeps the spring straight, while working from one end to the other.
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Lotus is a life sentence with no parole
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PostPost by: StressCraxx » Sat Feb 23, 2019 5:08 pm

If the oil level is very low, the gearbox will be very noisy with the engine idling.

Before you pull the engine and gearbox, first try checking the oil level by removing the square plug on the side of the case. Stick your finger in the opening and feel for a level. Fill if required and drive it to see how it sounds.

There is no cure for Lotus, only treatment.
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PostPost by: Harvey » Tue Mar 12, 2019 4:58 pm

My drive train noise is the same as Richard J's noise, only louder. I can't attach video because the one minute recording must be too large. It occurs on overrun in all gears but is most prominent in 4th from about 4,000 down to 3,000 rpm. It cannot be duplicated on jack stands only when car is on the road. Depressing the clutch will silence the noise.

I've been chasing this noise for a couple years with multiple engine/gearbox out/in exercises. I've replaced almost everything in the drive train except the diff. All ball bearings in the gearbox have been replaced. The noise issues from forward of the gear change lever. Fitting stronger springs on top of the gearbox made no difference. I've even scrapped the original clutch slave cylinder and release arm lash up to T/O bearing in favor of a concentric hydraulic clutch release bearing from Tilton but, again, no difference. Clutch friction disk and pressure plate are new.

A local shop which does gearbox work believes that noise is coming from excessive end float to either gearbox shafts or gears and is preparing to strip down the box. I will report back after I get box back in car and can say that the noise is gone and let the forum know what was done to get rid of this annoying chatter on overrun.

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