lotus 5 speed lube

[gjz30075]

Chris, I hope that's not my problem. An omen perhaps: when I first got the box, I was going through the gears
with the box on the floor and reverse always ended up locking the whole box up. I had to remove the reverse
light switch and whack the rod to move the selector back to neutral. Per my machinist/diagnostic guy, the
reverse fork was jamming against the case. He relieved a bit of the case and all is well now (maybe).

Davidb, this lube was also recommended to me by my machinist guy. This will be 'plan B'.

Mark, the stick is in good shape. good and solid plastic ball (had another made, just in case), good bellows.

Thanks!

[Esprit2]

I don't have a 5-spd Elan, so pardon me if I'm intruding. But I do have two Eclats, and the Elite-Eclat 5-spd is basically the Elan's Lotus-Maxi gearbox with a longer tailshaft & housing. One of the things I like best about my two Lotus-Maxi 5-spds is the shift quality. If you're having trouble getting yours into/ out of some gears, or if the shift action feels bad, then I'd suggest that it's not the gearbox design as much as how yours is set-up/ adjusted. Unfortunately, 'fixing' that may require removing the gearbox from the car and opening it up.

Without re-visiting the whole 20W50 motor oil Vs gear oil debate, I'll just say I use gear oil.

Redline 75W90 is intended for use in hypoid final drives, specifically those with clutch-type limited slip. It contains a slip agent additive that allows a clutch-pack to slip a little when it engages, softening the otherwise harsh kick felt when it engages. The 'kick' may be acceptable for drag racers, but it's not desireable for road racers that go around corners. If the slip agent doesn't eliminate the kick, it at least softens it.

A manual transmission's synchros require an opposite affect... they need to grip better in order to give a quicker, graunch-less shift. So 75W90NS is for synchro transmissions and deletes the Slip additive. The NS suffix means 'No Slip'... or expanded to a complete thought, 'NO SLIP additive is included'. Of the two Redline 75W90 gear oils, the 75W90NS is the one to use in a synchro gearbox.

The Redline MT gear oils (MTL & MT90) take that a step further, including a friction modifier additive that 'promotes' synchro grip/ friction bite. It's the opposite of the Slip agent in 75W90, it's specifically formulated to improve synchro friction/ grip, and it works. Well, in my experience, MT90 works well, but I'm not pleased with MTL.

MTL is the right, lighter viscosity per spec, but I prefer how the Elite-Eclat gearbox works with MT90. The synchros seem to work better, giving smooth, 'right now' shifts. Yes, the heavier viscosity might have a negative impact on fuel economy, but I don't drive a Lotus for best economy.

My Esprit S2 has the Citroen 5-spd. I wanted to improve the quick-shifting for autocross, so I switched from a regular gear oil (? I don't recall which) to Redline MTL. The shift action immediately went in the toilet. Shifts were slow, needed more force, and often resulted in some grinding. And it was a 'right now' transformation. It went from not bad but not great before the oil change, to plain crap after. I barely got out of the driveway before I knew something wasn't right. I bought another gear oil without a plan, just anything to get rid of the MTL. By luck of the draw, it ended up being Valvoline Synthetic Gear Oil, 75W90 (meets both GL4 & GL5). Another immediate transformation, with the gearbox reverting to shifting smoothly. It was fine for a while, but I eventually resumed my quest for quicker shifting and gave Redline MT90 a try. The shifts weren't any smoother, but they could be made much faster. It's what I was looking for in the first place. I've stayed with MT90 since then, and it's my default first choice for manual transmissions.

The Valvoline Synchromesh that Davidb mentioned sounds like it would be similar in concept to MT90. I'm curious. I'm just now putting the transmission back into my Europa S2, and I just may have to give 'Synchromesh" a try. If it's easier to find over-the-counter than MT90, that could be a good alternative for the daily driver Europa.

GM used to (still does ??) sell a friction modifier additive for synchromesh transmissions. I don't recall it's name or part number, but I do recall autocrossers raving about it. Just throwing one more thought on the pile.

Post by: pharriso ? Mon Sep 11, 2017 1:00PM, Phil Harrison wrote:
> While that is generally true, one has to remember that the 5-speed
> internals came from the BL Maxi & were designed to run in engine oil.

Yes, where the same gear sets had to cope with less power in an un-inspiring vehicle that wasn't driven by a nutzo boy-racer as often as a Lotus is. Motor oil may have been adequate there. I presume the same gears would need a little more help surviving in an Elan or Plus 2, and they were definitelly over-worked behind the 2.0 liter 907 in the Elite-Eclat.

Regards,
Tim Engel

[rgh0]

I would not use motor oil in a gear box anymore than I would use gear box oil in an engine.
I would not use a standard GL5 75w/80 or 75W/90 gear oil either in the gearboxes. Safe that for the diff
cheers
Rohan

While that is generally true, one has to remember that the 5-speed internals came from the BL Maxi & were designed to run in engine oil.

The attached article may be of use if you do not have it already.

Elan_Lotus-Maxi_5-Speed_Rebuilding-Upgrading-Fitting.pdf

Yes but engine oil was always a compromise between the transmission lube and engine lube needs in the maxi application. in the 5 speed plus 2 you dont have to make that compromise and Lotus dont recommend it.

cheers
Rohan

[Davidb]

Esprit2 --NO! Good for a gear box not good for a transaxle where the diff shares the oil with the gearbox. At least that is my understanding.

[mbell]

Seems Redline also now do MT-85...

Out of interest, have you checked that the clutch isn't dragging when the pedal is fully depressed? (The +2 has a travel limiter for the pedal...)

[Esprit2]

Esprit2 --NO! Good for a gear box not good for a transaxle where the diff shares the oil with the gearbox. At least that is my understanding.

Davidb,
Not a problem. The typical front-engine/ rear-drive, live-axle layout (ie, Mustang) uses an extreme offset hypoid gear arrangement in order to lower the driveshaft and minimize it's tunnel's intrusion into the cabin. The pinion input axis is almost down to the point of being tangent with the bottom of the crown wheel. In that common, 'maximized-hypoid' case, the mesh is more like that of a worm gear, and there's an extreme amount of sliding friction. A gear oil with Extreme Pressure/ Anti-Wear/ Anti-Friction capability is critically important. That is the hypoid application that requires a GL-5, hypoid-specific gear oil, and it's NOT the hypoid condition that exists in most transaxles... definitely not in the ones used in the Lotus Europa & Esprit.

Most transaxles, including the Citroen & Renault units used by Lotus, have the input/ primary shaft vertically offset in order to pass over the differential housing, and the secondary shaft below it, centered on, or only minimally offset from the Crown Wheel's centerline. True, 'ANY' offset from on-center is technically 'hypoid' by definition, but functionally, the ~half inch or less of offset used in these transaxles is so minimal that the CWP's mesh is more like that of a spiral bevel gear than a hypoid. More rolling mesh than sliding mesh. GL-5 is not required by hypoid design, but Lotus still recommended it quite often.

Lotus has a history of choosing transaxles from small, lesser powered, grocery-getter cars, and putting them into sports cars with more power and berzerker owners. The need for a GL-5 gear oil has more to do with more Exstreme-Pressure and Anti-Wear additives protecting ALL the over-loaded gears (both helical and minimally hypoid) from loads greater than they were designed to handle; but it's not driven by a hypoid 'need'.

The Redline 75W90NS (and MTL/ MT90) may be rated as GL-4, but it's a muscular, modern, full synthetic, top of the range GL-4 that provides better protection to the 'minimally offset' hypoid CWP than the gear oils that were available back when the gearbox was designed. In the Esprit world, all the 'on steroids' gear oils Lotus specifically approved are no longer available... haven't been for almost two decades. Redline MT90 has become the gear oil of choice, and has proven it can protect the Renault UN1 5-spd behind the Esprit V8's 350 hp twin-turbo 918. I'm not too worried about it being able to protect the Europa's transaxle behind the 1.5 liter, 80 Hp Renault 4-cylinder. Really, the 'hypoid concern' doesn't apply to these 'Lotus' transaxles... don't sweat it.

But all that has little to do with making a Lotus-Maxi 5-spd shift better... sorry about the wordy diversion.

Regards,
Tim Engel

[Esprit2]

Out of interest, have you checked that the clutch isn't dragging when the pedal is fully depressed? (The +2 has a travel limiter for the pedal...)

Right on point. Any clutch drag will make shifting difficult to impossible without grinding.

Regards,
Tim Engel

[gjz30075]

Interesting perspective, Tim. Thanks.

The clutch engages/disengages about 4" from the floor, right about at the 'over center' feel of the pressure
plate. However, I noticed the master's fluid never goes clear and is very black, despite of the amount of
fluid I pushed through it. It could need a rebuild, hence, not fully functional 100% of the time.

[Esprit2]

I noticed the master's fluid never goes clear and is very black

"Black" is the master cylinder's seals dissolving. It does need a rebuild.

Regards,
Tim Engel.

[The Veg]

Tim, I enjoyed the tangent- always good to learn stuff! And yes, MT90 was great in my former Esprit's Citroen box too.