Differential removal

[Ianashdown57]

I have the engine and transmission out of my S1, the engine for rebuilding and the transmission for cleaning, replacing gaskets and seals etc. I also want to give the underside a gentle pressure wash while all the drivetrain is removed, as it is quite oily underneath, and detail the engine bay while the engine is out.

I'd also like to take the Differential out of the car as it is also quite oily, maybe from oil finding its way back from the engine but maybe leaking from the Diff itself. It needs to be cleaned, seals, bearings and gaskets etc replaced and generally check out the condition of the crown wheel and pinion. I've heard horror stories about removing the Differential.

So the question is, how difficult is it really to remove the Diff with the body still on the chassis? Are there any special tips? Is it possible to remove the nose piece and leave the aluminum casting attached to the chassis? How are the driveshafts removed? How easy is it to replace the rubber bushings on the torque rods?

Lastly, as there is no more EP 80 or 90 oil to be found what is the preferred Diff oil? For that matter what is the preferred oil for the transmission?

Many thanks,

Ian

[Galwaylotus]

That oil is there to protect the steel frame from corroding. It's a safety feature!!

[Paul Chapman]

I believe that Comma can still supply EP80-90, could one of these be suitable ?

http://www.commaoil.com/productsguide/index/6/29

[richardcox_lotus]

Although I've never done it, I am assured that it will only come out from the passenger side of the car....,

[john.p.clegg]

It's a bugger of a job,I was under there for nearly an hour struggling,went for a tea break and when I came back it nearly fell out on my feet....

John

[ricarbo]

Looking on the internet, Castrol still list EP80W.
I don't know much, other than to think you should be very careful in your selection, for both diff and gearbox, as modern oils are meant for modern cars. For example, many modern gearbox oils are to GL5 specification, which apparently ruins brass parts, The synchroniser rings in the gearbox are bronze, I believe, so a GL5 oil sounds like a disaster to me. I think I would speak to a couple of oil makers technical departments, before making a choice. I don't know the answers. Maybe the answers are in the archives.
regards
Richard

[tonyr27]

The Opie Oils website has a classic section which should list suitable oils. I guess then you need to find them locally,

TonyR

[rgh0]

Yes the diff only comes out the left side. It takes a lot of juggling but once you get it at the right angle it just drops out. If the chassis tray underneath has been jacked on and bent you may need to bend it back down to get the diff out!

I consider the Redline oils the best you can get if more expensive than most due to the polyol ester synthetic base stock they use.
Redline MTL 75W/80 GL-4 gear oil for the gearbox
Redline 75w/90 GL-5 gear oil for the diff

cheers
Rohan

[prezoom]

Check with your local Chevron station. RPM Dello has an 80/90w gear oil.

Rob Walker
26-4889

[billwill]

The removal procedure is in the Workshop Manual, I think.

I know I've done it once before. You get it out complete, nose and alloy carrier together.

The chassis needs to be quite high off the ground; higher than you would normally need for getting underneath.

I don't recall if it is sufficient to just lower the left rear subframe or if it is best to completely remove it out of the way. in either case you will need spring compressors for the rear suspension.

You need a socket set with long extension bars underneath and a mole wrench or helper on top for the hanging bolts.

It needs a lot of jiggling about after you have removed the propshaft bolts ant the hanging bolts, but then as John said suddenly you find the magic fit and it pops out and falls on you. Be aware that it weighs about 19 Kg.



If you don't like getting oily and if your car is still roadworthy, you might want to consider visiting a steam cleaning workshop before tackling the job.

[stugilmour]

Yes the diff only comes out the left side. It takes a lot of juggling but once you get it at the right angle it just drops out. If the chassis tray underneath has been jacked on and bent you may need to bend it back down to get the diff out!

I consider the Redline oils the best you can get if more expensive than most due to the polyol ester synthetic base stock they use.
Redline MTL 75W/80 GL-4 gear oil for the gearbox
Redline 75w/90 GL-5 gear oil for the diff

cheers
Rohan

Agree with Rohan's recommendation regarding Red Line products. They are commonly available (at least here in NA) and about $15 per quart.

Rohan, just to clarify. The available MT and MTL grades may have changed. Lotus originally recommended 80 EP (Extreme Pressure). On the Red Line site, here are the MT & MTL grades available. These are all GL-4 lubricants and compatible with the 'yellow metals' used in the synchronizers.

MT-90 75W90 GL-4 Gear Oil - This is the one used in my Esprit transaxle.
MT-85 75W85 GL-4 Gear Oil -
MTL 70W80 GL-4 Gear Oil - I think this is the grade Rohan is recommending. It is the only one called 'MTL'

Note the Red Line application guide actually recommends Red Line 75W90 NS GL-5 Gear Oil for the Elan transmission. I personally would not recommend this for your gearbox as it might have too high an additive concentration for the yellow metals. Many folks have used the GL-4 MTL for years with no adverse effects, so why risk an issue? I expect the Red Line recommendation is probably based on the 'EP' in the original Lotus specification. My two bits is oil technologies have moved on sufficiently that the GL-4 with synthetic base stock is fine.

Rohan's recommendation of Red Line 75W90 GL-5 gear oil for the diff is consistent with their Application Guide, and great stuff as well.

======

Bill, pretty sure I did the diff without having to use a spring compressor on my Plus 2 (Spyder frame). Might have to add a bit of weight to the boot for this to work on the Elan? With the car solidly supported in front of the rear wheel well and the half shaft disconnected, place a floor jack under the left side hub carrier. Take the weight, unbolt the wishbone at the outboard attachments, and slowly lower the hub thru the outboard wishbone mounts. Spring remains completely confined, so no safety issues. Get the wishbone and half shaft / CV's / Rotoflexes out of the way. and remove diff. I think I left the spring and hub carrier in place and just hanging on the top shock / strut bolt. Hold your mouth right and the diff pops out. (easier with Spyder frame, but still tight) Only have to disconnect on the right side; no need to drop the hub carrier. Installation is reverse of removal.

The clearance is very tight but doable. When I removed my original rusted frame, we eventually cut the frame to remove the diff. As mentioned above, the clearance was screwed up due to 40 years of jacking the car up on the frame.

HTH

[paddy]

A further comment on removal: if you have the strengthening brace installed (not standard on S1 but one might have been fitted) you need to remove that also from the diff before it will come out.

Paddy

[rgh0]

It looks like Redline have added a third MT grade since I last bought it.
They used to just have MT-90 and the MTL which was quoted as a 75W/80 ( at least that is what I had written down in my list of fluids and lubricants I did not actually look at the bottle in the garage to check)

They have added one in between at MT-85 and lowered the cold "W" viscosity specification for all those Canadians in the MTL to 70W/80. I recall reading it quoted as 70W or 75W in some of the literature ( may have been on the back of the bottle) so potentially its no real change

I would certainly still stick with the MTL for the transmission.

cheers
Rohan.

[stugilmour]

...They have added one in between at MT-85 and lowered the cold "W" viscosity specification for all those Canadians in the MTL to 70W/80. ...

cheers
Rohan.

Thanks for clarifying Rohan. With the MTL viscosity change I am not sure what I have in my BMW right now, but I certainly recall a huge improvement in cold weather shifting after putting the MTL in. We routinely get to about 10 degrees C in August here, and anticipating snow tonight!

I would certainly still stick with the MTL for the transmission.

I recently had some confusion with the available grades, and have actually installed the wrong stuff in the Esprit. Consulted with a Red Line technical representative by email and going to change it out. They have also added an Esprit transaxle recommendation to their application guide this week based on my inquiry (although the vehicle was already in the database). They are very responsive, and really know their products.

I haven't contacted Red Line regarding their existing recommendation for the Elan gearbox though (75W90 NS GL-5 Gear Oil ). Kind of interesting that this is also their recommendation for other cars using a similar Ford gearbox (Cortina, Lotus Seven, etc.). Any thoughts? I know from previous posts you are pretty familiar with lubricant technology. Although I am a Petroleum Engineer, my career focused on upstream production rather than downstream refining and blending. I have removed the stock gearbox anyway in favor of a Ford MT75 which uses the MTL, so not directly effected..

Cheers!

Stu

[rgh0]

Hi Stu

Don't know why Redline don't recommend MTL of the ford gear box. It is a classic manual transmission and everything about it says use MTL including the original 80EP specification. The current GL-4 oils are better in all respects than the EP oils of the 60's. You certainly don't need a Gl-5 gear oil in it from a gear design perspective. GL-5 oils are designed for sliding contact gears such a hypoid or worm gears Gl-4 oils are designed for rolling contact gears such as straight cut (spur) or helical gears.

I found this on the Redline MTL web site page which is why I believe It used to be quoted as a 75W/80 before they introduced the MTL 85 (75W/85 grade).
"Satisifies the gear oil viscosity requirements of 70W, 75W, 80W, and motor oil viscosities of SAE 30, 10W30, and 5W30"

Their recommendation of 75w/90 NS GL-5 gear oil for the ford 4 speed is a mystery from a couple of view points. The 90 viscosity is higher than the original 80 specification and there are no gear sets in the transmission that require a GL-5 oil. The 75W/90 NS Gl-5 gear oil sounds ideal for cars with a single transmission containing both the gear box which is typically helical and a diff which is often a hypoid gear set. In these transmissions it is a compromise to balance what's required by the syncros the helical gears and the diff and this appears designed to achieve that compromise.

cheers
Rohan

PS I run MT90 is my Citroen gear box S1 Esprit as the diff is a spiral bevel not hypoid and thus also does not require a Gl-5 oil and MT90 GL-4 is a better compromise I feel for this specific transmission