Unexpected CV boot surprise !

[simonbuk]

I have taken out the o/f driveshaft. The end nearest the hub was as expected, full of grey/black grease and everything looked ok.
When I took the other end off it was more like oil, runny to the effect that it could be poured out ? I thought it would be the same grey CV boot grease in it.
There was also a white disc inside the boot, presumably to try and keep the oil in place ?
Anybody else had/seen this ?

Sorry, forgot to take a photo, cleaned it out and inspected it before packing with grease and putting back together.

[RonR]

You're not alone Simon, I had the same a few years ago.

My guess is: If the grease has been in there for 30-odd years being mashed between tripod and housing the long-chain molecules will break into shorter chains, sort-of like a liquidiser does with smoothies. Add in some unknown (to me) chemical deterioration and you have liquid grease.

Oh, and the white disk is there to stop the tripods from damaging the boot.

[dapinky]

Bear in mind that the tripode uses a different grease than the CV joint - you should not use 'standard' CV grease in a tripode unit.

https://www.merlinmotorsport.co.uk/p/gk ... Qn0TzCiqM-

https://www.merlinmotorsport.co.uk/p/gk ... kn-ms9u024

There are cheaper CV greses around than GKN, but Tripoid grease isn't so prevalent.

I can't tell you that it won't work - but it will be a bit like using mineral gear oil in an engine designed for synthetic oil.

[simonbuk]

Damn - cleaned and refilled one side

I watched Toby's Restoration series on YouTube but he didn't mention any difference !

[Giniw]

Hi, I just worked on my CV shafts.
The first time (10 years ago) was because of worn boots, and indeed it was a very soft grease, more or less running out of the inner joint. I can't remember the wheel side.
Like you I thought it was just an old grease.

I needed to do it again (this time... vibration :/) and by miracle it was the left side that was worn, so I bought a new driveshaft from SJS.

My outer joints were still good, so I kept the new outer joint and decided to install the new left tulip on my shaft, and to keep the rest in a box for the future.
Also, I already had bought new CV boots, so I thought I would replace the 30+ years old new-old stock boot anyway.

And guess what? The grease from the new inner joint was also extremely soft, not very far from liquid.
So, I stopped the rebuild and got back to the computer to check what was really suitable on a tripod.

The Granville Toby is talking about (and I had bought a can) is https://www.granvilleoil.com/techData/p ... ta?ptdID=8, a NLGI 2 MoS2 grease and seem to be suitable for the outside (with the big bearing balls)

However the tripod grease apparently needs to have a lower NLGI consistency because of its needles bearings inside the rollers. NLGI 1 is apparently about right. But as it's heavily loaded, it also needs to have some EP features (EP=Extreme Pressure).
=> a NLGI 1 EP Lithium grease would apparently be a good choice (sometimes labelled EP1 — EP2 is a NLGI 2, etc)

So, I bought 1 kg of Lithium-calcium EP 1 grease (11.40€ + 15.84€ for the fast shipping).
It looks about right, slightly thicker than the new (but 30 years old) original, but much much closer than the NLGI2 Granville.

I would be curious to see what the merlinmotorsport looks like and what it is made of.

[dapinky]

Well, Simon - I don't think you have done anything that loads of other people (not just on Elans) have done over the last 40 odd years that these joints have been used.

In the past, I have used CV grease - and it works - but I have no idea of the long term effects of using it. As GiniW says, it is all about the solids and viscosities to get into the needle bearings. I have to say in my defence, that I have only used it through naivety, and not just because i thought I knew better. and wouldn't do it now - except in an absolute emergency to get home - any oil/grease is better than no grease!).

It has been reported many times over the years that the inner joint appears to use a thick oil, not a grease (but I don't know at what viscosity an oil becomes a grease anyway - if there is any correlation).
Anyway, recent research by me (when I found the replacement GKN tripodes) lead me to the specific stuff.

I actually intended to get a tube of grease whilst at Castle Combe on Saturday but forgot - so at the moment I can't tell you what it says on the tin. I would love to find a suitable alternative in a tin not a tube, so my investigation will continue.

[dapinky]

Now I'm getting more confused......

Having looked on various websites for the exact specs of the GKN products, I can't find them (unsurprisingly, really, but I'm sure the info is out there somewhere in a 'safety sheet' or whatever).

The 'basic' specs are listed on Raceparts website - but they are identical to the GKN CV grease....... although the 2 are clearly different - so it is easy to say that we need a NLGI grade 1, without MS - but to find one is proving harder.

The thing is, anything I get will work to start with, but only the OE spec will be (almost) certain to last over 100K miles, and it seems a bit pointless buying something "almost" right, when GKN still sell the stuff they designed to work with these exact joints.

As such, to quote RonR's words from another thread "I know what's going in my joints when I repack them."

[Simon_P]

The outer joint has a grease designed for higher temperatures and higher pressure point contact, the inner joint has some sliding friction.

Grease is just oil suspended in soap. If it sits for a while the oil separates, just use it and it will go back to being grease, it is lower viscosity than normal grease.
I never understand why people "service" CV joints unless the gaiter has split - servicing is taking the good stuff out and adding the wrong quantity of something else and a bit of dirt for no aparant benefit.

The white plastic disc is to stop the tripod coming out of the tulip when the driveshaft is being handled.

[Simon_P]

Oh and Simon I saw your bearings on faceplant - they look like after market bearings as there only appears to be one oil hole.

[simonbuk]

Oh and Simon I saw your bearings on faceplant - they look like after market bearings as there only appears to be one oil hole.

Oh interesting thanks ! Maybe somebody changed them then when the head gasket blew ? Maybe some damage had already been done and they were trying to fix it ?

[simonbuk]

Oh and Simon I saw your bearings on faceplant - they look like after market bearings as there only appears to be one oil hole.

And thanks again as it reminded me of something i was meant to do - my second hand engine i bought and got rebuilt, was going to check the shells in that as i remember you saying they were no longer available.
The originals in that were indeed a two-holed version, the new ones that have been installed have only one hole.

I guess i have to run with it if nothing else is availble ? Can you make/drill another hole to be on the safe side or are you tempting fate with a bit more damage ?

[Simon_P]

As the aftermarket bearings haven't lasted long you need to find out why, or it'll just happen again. Measure everything and clean everything.
The workshop manual is thorough - follow it to the letter.

Use Plastiguage to check the clearance of your new bearings. don't rotate the crank.
Polish the crank
Very carefully drill/grind the hole in the correct position.
Thinking about it I'd drill from the back face so that any slips or distortion are more recoverable (I haven't done this job)
Measure and Plastiguage again.

[dapinky]

another thought on the 'work' for the shells (and I fully agree with everything that Simon P says) - the extra oil holes are pretty well guaranteed to be contributory to your other issues - the Lotus version of the basic Isuzu engine has the extra oilways to allow oilspray to the underside of the pistons - to help keep them cool. Isuzu used Cast pistons, whilst Lotus wanted forged ones and the cooling properties of the two are not identical. This may well have made the whole lot just a tad hotter than the gasket liked.

As for machining them, I would be tempted to check the angle of the oilway in the crank, and get the shell drilled to match (I can't remember if it is a 'straight' hole or drilled at an angle to the face).

If they are angled, it could be awkward to do with a hand drill - it will need setting in a vice and using a pillar drill - and the correct bit for the material. As always, start with a 3mm bit and then expand it in stages, cooling it with suitable coolant as you go.

Maybe I'm over-reacting, but any damage to the surface will translate to uneven rotation in some way or other, even if not noticeable. Do not be tempted to use a centre-punch to start the hole/position the bit as it may deform the shell.

If in doubt, let a local engine building shop or machinist do the job - it is not going to take them long, and it will be done properly. If it were me, I'd do a trial assembly with plastiguage to start with, get the sizing correct, and only after that would I drill the holes just in case my drilling causes any deformity (and to avoid taking time to do something which may or may not be the correct size).

Be aware that the Lotus crank has been hardened at the time of production (again, forged metal, not cast - unless it's from an NA engine!), so if it has been machined, it needs to be hardened again for use.

[simonbuk]

Just to be clear we are talking about two different engines here. The one that has been dismantled is not going to be used - not for the time being anyway. This was the engine that in it's history had a head gasket replacement. I know nothing of it's history - it's kaput.

[dapinky]

I appreciate that it isn't the one you are using, but the information is still valid! At some point, it will need to be rebuilt (or scrapped, which is a bit of an expensive waste of parts) by you or someone else. Back in the day when I could buy a good Elan engine, ready to fit with 80K miles for £300, these things never got thought about..... I could even buy a new crankshaft (with correct bearings) for about a hundred quid brand new from the factory - but those days are long gone, and many S/H engines are in need of 'proper' machining.

I have all the parts in stock for a complete rebuild of my old engine - except for a new oil pump, which I have been looking for for 15 years - and will get round to it one day. I may or may not need the new crank and/or oversize pistons, but I have them if I do..... and if not, they will stay in the loft for the next one.

[simonbuk]

I totally agree, it's all very useful information and needs to be somewhere in case somebody searches for that type of information.
It's just that i'm getting more information on what to do with an engine that I'm not going to be using, than the one I am - in a thread about CV boots !

Can a moderator clean this thread up a bit ?

If I start a new thread about my rebuilt engine then perhaps some responses here could get copied over to it ? That way it will all be contained within a suitable thread - and anything I decide to do will be detailed and can be followed ?

[TorqueHorse]

Sorry to keep tagging on to the engine part of this conversation (hopefully it'll get organized better going forward), but also of note is that I think the images posted on FB were of Big End Shells, aka Con Rod bearings. While the main bearings need two holes, I don't think the Big End Shells need two (nor 1 even, if there isn't a oilway up the conrod shaft, right?).

[simonbuk]

While the main bearings need two holes, I don't think the Big End Shells need two (nor 1 even, if there isn't a oilway up the conrod shaft, right?).

It's the other way round isn't it ?!

[TorqueHorse]

Nah, that's why I was bringing attention to it so that you didn't get confused by what the other guys were saying. Everything they said was correct, it's just that its applicable for the main bearings, not the conrods/ big end shells.
Check page 315 of the service manual pdf

Screenshot_2-6-2025_142218_.jpeg

That's for the conrod. And my conrods don't have oilway holes in them, and it doesn't look like yours did either, so plain bearings *could* be fine for that application, if you can find any.

Then check page 320 of the pdf

Screenshot_2-6-2025_142440_.jpeg

That's for the main bearings. You can see the extra hole is for the oil jet. That's what folks were talking about.

[simonbuk]

Ah ok - and yes - it confused me !!

I'll study this later and go back and look at my engine again.