Rattling in my shift linkage

[garyeanderson]

This sounds like gear sizzle. First before you do anything more put some weight near the shift knob. some stick on wheel weights or fishing lead sinkers, a couple of oz. each. Take the Plus2 for a ride and see if it goes away. if so find a way to make your mod acceptable and please don't fix whats not broke.

[jimj]

You shouldn`t need to remove the seats to remove the console. Try driving with the console and gaiter off and stick a tube in your ear while your passenger moves the other end around the likely sources of the sound.
Jim

[Sea Ranch]

Thanks, gentlemen.

(I have the newer style interior and the console is overlapped by the rear seat section - a fiberglass box that holds both seat and back - so it has to be unsrewed from back and the inner seatbelts unbolted in order to lift it up - at least - so the console can slip up, forward and free. Removing front seat(s) makes this easier.)

I have driven with the console (and gaiter) out. The inner boot is impossible to remove as the metal plate around it is attached behind/under the dash, so that's not going to happen. But you can push the inner boot aside from the plastic dome/cap and slip in a listening tube, for sure. Good idea.

As for the sound, this is my first Lotus but based on my general experience with manual transmissions (including four other Brit cars), if this noise is coming from the gear cluster, then the transmission needs to be pulled and rebuilt. It is not normal/healthy gear noise. If that's the case, so be it. I'll pull the motor/box this winter; always lots of things to catch up on when you have the motor and box out (like water pump, re-sealing the abundant oil leaks, dealing with sticky clutch, etc.

Having said that, the tranmission shifts BEAUTIFULLY. Each gear, click, click. No synchro problems, no tendancy to want to pop out of gear, no buzzing in the shift lever, everything works as it should (once the clutch is warmed up enough that it will allow shifting into gear at a stop) (it always releases nicely for shifting while under way). There is no change in the noise when I push the shift lever in any direction while moving. I can't seem to do anything to affect/control the noise, except to get the car up to speed (and as I mentioned, once the noise starts, it continues or is exacerbated by slipping the clutch and/or selecting neutral).

I am still wanting to investigate the possiblity of this being related to the speedo drive. Another question came up: what is the oil level in the box? If it were near-dry, perhaps this noise? Will jack it up and pull the level inspection/add plug to check.

Randy

[Sea Ranch]

Next step:

Put the car up on blocks again and inspected the speedometer drive. All external parts are there, well connected and snug.

Pulled the gearbox level check/fill plug and the oil is well below the bottom of the hole. I wrapped my finger around and down into the box and - it's hard to say but - it "feels" like the level is down at least an inch.

How low does the gear oil level have to go before you start hearing noise??!!!

Will pull the diff plug and check that as well.

Any recommendations on gearbox and diff oil? Thanks,

Randy

[stugilmour]

Randy, I use Redline MTL in mine, and also in my BMW. Really improved shifting in the BMW. No direct point of comparo in my MT75 as used it from initial installation. Although both the BMW & Ford MT75 call for this type of fluid, I believe others here have recommended MTL for the Lotus boxes in past threads with good results. Although you may not be using the car much in winter, MTL is very good in the Great White North to minimize notchy shifting when cold.

http://www.redlineoil.com/product.aspx?pid=45&pcid=7

[Sea Ranch]

Great. Good for our old-school boxes, I hope. Web info seems to say so. Hoping a full-to-the filler plug box will not rattle so much (if that's where the rattling's coming from).

Thanks, Stu.

[Sea Ranch]

Next and perhaps final update on this little saga . . .

Checked out Red Line Oil, as suggested by Stu, and filled in the request info form on their website as their car-specific info on Lotus Plus 2 was a little thin. The company's rep wrote back within 24 hours and gave me the info you see below: recommendations for gearbox and diff oil for our Lotuses. Very helpful.

I drained my box yesterday, replaced with suggested Red Line 75W90ns, topped up to the fill/check hole, and took the car out for a 10 minute drive.

The shifting improved markedly. Always had shifted nicely but a little heavy (too much effort). Now it shifts lighter and the synchros are even better. BUT the noise/rattling etc. was still there

Went back home, put the interior back into place. Today took the car to work, transmission was still noisy. Then I took one of the shop/tech teachers out for a boot after school to get his opinion. And lo . . . the gearbox refused to be noisy (beyond the typical gear whine expected). Dropped him off, did more driving, still none of the harsh rattling I've had all along.

Working hypothesis: gearbox oil level was too low. I don't believe it was any of the gear pairs that was noisy. Something else was loose and the extra oil volume has taken care of it. Could have been the speedo drive. The tail/extension houses the speedo drive and it appears to run in an oil bath which flows over from the box. If the box oil level is too low, perhas the oil cannot migrate over to the extension and thus the speedo drive runs low on oil and makes lots of noise. The noise I had could be heard once the car got up to ~40 mph and at that speed the noise was present whether the clutch was in or out, and even when you slipped into neutral and coasted.

Anyway, I now recommend checking the gearbox oil level, and using a good quality oil like Red Line's sythetics. See the conversation string below for why I chose the product I did.

Crossin' my fingers . . . Randy


On Jun 22, 2011, at 10:13 AM, Dave at Red Line Oil wrote:

Randy,
Thank you for contacting Red Line Oil, in your Lotus transmission the 75W90NS would be recommended and the 75W90 in the differential. Hopefully topping up the transmission will help though other issues may exist.
Regards, Dave
Red Line Oil

On Jun 22, 2011, at 10:24 AM, Randy Skinner wrote:

Thanks so much for your speedy reply.
A friend with a similar Lotus Elan +2 is using MTL in his gearbox, which he chose - I believe - because he uses it in his modern BMW. The 75W90NS you're recommending for my gearbox would be more suitable than the MTL, then?

On Jun 22, 2011, at 1:59 PM, Dave at Red Line Oil wrote:

Randy,
MTL certainly could be used in your transmission where an 80W gear oil was originally called for; the MTL would be about 30% lower viscosity at low temperatures than the original, similar viscosity at operating temperature. The 75W90NS would be very close to the viscosity of the 80W gear oil at low to moderate temperatures, a little higher viscosity at operating temperature and a good choice where you were complaining of noise from the transmission, the reason I suggested it; better suited to your particular transmission where noise reduction was the primary concern.
Regards, Dave
Red Line Oil

[Robbie693]

Hi Randy,

Glad it appears you have sorted the noise.

Can I ask, have you noticed any increase or the start of any leaks with the Redline? I ask because I recall a few people have mentioned this happening with the MTL, presumably because of the lower viscosity, which has put me off changing to it as my box leaks a bit as it is...

Cheers

Robbie

[Sea Ranch]

Interesting question, Robbie.

Of course I have only just installed the Red Line on Thursday, but I'll keep my eye on it and report back here on this thread. Having said that, my car is a terrific leak-er and so much comes from the motor and is blown backward that when it comes to the gearbox, it's hard to tell where it's coming from. But when I pulled the drain plug, I noted there was a drip forming on the bottom of it so presumably the box has been leaking.

I'll keep you posted

Randy

ps. LOVE the work on your site; I wish you much success!

[stugilmour]

Next and perhaps final update on this little saga . . .


On Jun 22, 2011, at 10:24 AM, Randy Skinner wrote:

Thanks so much for your speedy reply.
A friend with a similar Lotus Elan +2 is using MTL in his gearbox, which he chose - I believe - because he uses it in his modern BMW. The 75W90NS you're recommending for my gearbox would be more suitable than the MTL, then?

On Jun 22, 2011, at 1:59 PM, Dave at Red Line Oil wrote:

Randy,
MTL certainly could be used in your transmission where an 80W gear oil was originally called for; the MTL would be about 30% lower viscosity at low temperatures than the original, similar viscosity at operating temperature. The 75W90NS would be very close to the viscosity of the 80W gear oil at low to moderate temperatures, a little higher viscosity at operating temperature and a good choice where you were complaining of noise from the transmission, the reason I suggested it; better suited to your particular transmission where noise reduction was the primary concern.
Regards, Dave
Red Line Oil[/i]

Thanks for the info Randy.

For both my 1987 BMW M6 and the replacement ~ 90's MT75 box in the Lotus Plus 2, important to note both these more modern manual transmissions call for different oil than the stock Lotus four or five speeds in their original applications. The manufacturers call up fluid more akin to ATF. The M6 is a different box than the E28 five series or E24 six series, and has its own unique fluid spec. That said, lots of guys on the BMW forums use MTL with great success in all ranges of BMW transmissions. The Ford MT75 calls for a specific Ford fluid that I assumed would be difficult to find here, although I admit I didn't look to hard. Looking at some fluid properties info on-line, I figured Redline MTL was a good readily available substitute here in NA, and has worked well in this applications for me.

Others here reported good results for MTL in the stock Lotus boxes, but I have no first hand experience Good to see this confirmed by Redline, along with the alternative recommended for an older box. Can't hurt to go with their recommendation!

[Sea Ranch]

No, thank YOU for the info, Stu!

Going out shortly in the car for further "tests" ( )

But who would've thunk that gearbox oils were so differentiated and product-specific. There's the viscosity, the "friction modifiers", the synchro rings and their need for some "traction", certain metals and corrosion issues, etc.

Well, no one said owning and operating a classic car wasn't at base a learning experience!

Thanks again for the tip (and impressive also that the company is so responsive, no?)

Enjoy the weekend . . .

Randy

[Robbie693]

ps. LOVE the work on your site; I wish you much success!

Thanks Randy, that's very kind.

I'll be interested to see how you get on with the leaks.

Cheers

Robbie

[Craig Elliott]

Randy, some slightly left-field things that may be worth checking on this...

1: Have you checked that your starter motor hasn't come loose? (Give the symptoms you've noted I'd be surprised if it was but they are very good at trying to escape so probably worth checking).
2: The other thing that might be worth trying is to undo the speedo cable and seeing if the noise changes/goes away. Even though the angle drive might be firmly attached, the cable or the internal gearing might be on the way out. That said you'd probably also have spotted the speedometer bouncing around/not reading properly if this was the problem.

From your description it sounds as though the problem is more related to road speed rather than engine revs - is this right?

C

[Sea Ranch]

I'll be interested to see how you get on with the leaks.

So far, so good, Robbie. I see no leak or drip accumulating yet. Drove it throughout the weekend.

[Sea Ranch]

1: Have you checked that your starter motor hasn't come loose? (Give the symptoms you've noted I'd be surprised if it was but they are very good at trying to escape so probably worth checking).
2: The other thing that might be worth trying is to undo the speedo cable and seeing if the noise changes/goes away. Even though the angle drive might be firmly attached, the cable or the internal gearing might be on the way out. That said you'd probably also have spotted the speedometer bouncing around/not reading properly if this was the problem.

From your description it sounds as though the problem is more related to road speed rather than engine revs - is this right?

Funny you should mention the starter. I'd installed a new remote starter solenoid a couple weeks ago and this morning it locked up in the "on" position: when I started the car the secondary/high current side stayed closed, causing the starter to continue spinning full speed. By the time I popped the bonnet and figured out what was going on, then popped the boot, threw out the flooring and disconnected the battery (thank goodness for quick-disconnect terminals), I had smoked the starter, literally! More details on my other thread! elan-f15/anyone-try-rebuild-lucas-remote-solenoid-t22978.html

I was under the car last week inspecting the starter and it's firmly in place.

As for speedo cable and drive, this is a good observation. Although the speedometer needle looks good, I will consider your idea next time I'm under there.

After a weekend of driving, the gearbox continues to be quite free of the abnormal noise and I'm pretty pleased. And it would seem to be the result of topping up the box to full level and/or using a superior quality gear oil (Red Line 75W90NS).

And yes, the problem was road speed related. Once I hit an indicated 50 mph, the noise appeared, and remained even when slipped into neutral and/or slipped the clutch in. Once I had slowed down substantially, or was at a stop, there was no noise.

But currently, that sound has - thankfully - abated.

Randy