4x4 splinelube

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barry badger
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4x4 splinelube

Post by barry badger » Sat Apr 22, 2017 7:39 pm

i've been trying to replace the clutch on my 4x4 estate now since last july. i've replaced the bottom ball joints,n/s rack boot,rear main oil seal,n/s rack knuckle,starter motor and numerous other parts along the way. The gearbox has had new bearings and seals fitted and 3rd & 4th gear ratios changed to bring them closer to the longer 5th i fitted a few years ago. the gearbox is back in along with a new luk clutch. So far so good, but now to the stumbling block - how to lubricate the spline drive to the transfer box?
My splines are perfect due to the fact that the two shafts have been replaced at some time in its life and whoever fitted them damaged the o/s gearbox seal housing so that oil has been leaking onto the splines keeping them nice and wet ( and the floor too).
What i have come up with is 56mm id shims ( 3 shims totalling 1.3mm ) that fit between the gearbox and transfer box which along with silicone sealant will seal the splines from the atmosphere.
I initially decided to grease the splines and began researching the best grease, after hours of poring over grease specs i settled on millers hi moly 20.
The problem now is after much research into why splines wear i've realised that there is only one location dowel between the gearbox and transfer box and so no guarantee that the shafts are central with each other even if only by a few thou. Alignment problems are a major cause of premature wear.
I have devised an oil lubrication system for the splines which will require the seal carrier to be removed and drilled and tapped to take oil level and filler pipes. Oil will work better if there is a slight alignment problem, But given the rate of progress i'll be lucky if i get it back on the road before july 2018 if i go ahead with this idea.
So basically, am i over thinking this? will the splines have a satisfactory life with a modern grease and being sealed from the elements.
As far as i can see the splines were never sealed from the factory . What would the factory have lubed the splines with originally? What mileage/age were the splines typically failing at?
I only do about 4,000 miles a year so they will last several years whatever i do but i like the idea that even if i chose to do 40,000 a year my splines are not going to be a worry.
What do i do?
1993 tzd estate, on sorn
1992 tzd estate, slowly being raided for parts
1992 txd estate, "doom blue" on the road
1991 4x4 estate, on the road

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Re: 4x4 splinelube

Post by assembled » Mon Apr 24, 2017 6:14 pm

Hi, thanks for starting this. I have also looked into that as I already own three spline sets: completely broken, partially broken and one like-new.
I did not actually bought anything or tried anything, so don't take this as a fact or experience.

Keyword here is anti-fretting agent / grease.

For example:
MOLYKOTE® G-407 ANTI-FRETTING GREASE Website, technical PDF. Meant for brake caliper pins, but I don't see why it would not work for splines in BX. In this sense, other caliper guide pin greases meant for metal-metal applications, not for metal-plastic.

SKF LGAF 3E
Easier removal of general industrial components in a wide range of applications such as nuts, bolts, flanges, studs, bearings, guide pins, couplings, jack screws, lathe centres, push rods, and spline shafts
In general, it seems that molybdenum (moly) pastes are most suitable for this application. As I understand, they are designed to work long after oil has evaporated leaving a dry film. See here (marketing material, but can give an idea):
Loctite Shaft Repair Service Manual
Lubricate and protect sliding spline assemblies from unecessary fretting and wear.
Wear will occur where there is friction and movement in the spline coupling
Contamination between shaft and socket
1992 TZD Turbo berline, aircon, ABS
1991 TZD Turbo berline
1989 GTi 4x4 berline, ABS

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barry badger
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Re: 4x4 splinelube

Post by barry badger » Mon Apr 24, 2017 11:11 pm

My original choice of grease was a molykote one , can't remember the number ,but i couldn't find it for sale in this country in single tins.

Were the worn spline sets you have from your own car?
If so were they rusted on removal or just worn?

I've got an engineer coming to look at this later in the week, so i'll see what he makes of it.

The one concern with oil lubrication is whether the oil will stay on the splines and not migrate through the gearbox or transfer box oil seals as they are facing the wrong way.
1993 tzd estate, on sorn
1992 tzd estate, slowly being raided for parts
1992 txd estate, "doom blue" on the road
1991 4x4 estate, on the road

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Re: 4x4 splinelube

Post by Kaapelimies » Tue Apr 25, 2017 3:09 pm

Splines on the original axles of my 4x4 were worn, no sign of rust, not a single spot so I don't buy the theory on rusting. Why I dismantled, was because the gearbox seized up (it did keep awful noise on first gear so it must have blown teeths from a sprocket). Luckily found a donor from a Pug 405 with 370 000 km but splines were like a virgins.. well, tight and perfect anyway ;) . So probably repaired at some point. Put together with the famous Anylube I had on hand, I think dark grey MoS2 by Anybrand. It's pretty all-purpose for nuts and bolts also when put back together.
BX 4x4 estate, several BX Van's and some more normal estates in Finland.

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Re: 4x4 splinelube

Post by assembled » Tue Apr 25, 2017 10:58 pm

barry badger wrote:My original choice of grease was a molykote one , can't remember the number ,but i couldn't find it for sale in this country in single tins.

Were the worn spline sets you have from your own car?
If so were they rusted on removal or just worn?

I've got an engineer coming to look at this later in the week, so i'll see what he makes of it.

The one concern with oil lubrication is whether the oil will stay on the splines and not migrate through the gearbox or transfer box oil seals as they are facing the wrong way.

I bough a 4x4 BX with broken splines, a replacement with worn and another replacement from Peugeot 405 with perfect.
There are two wear factors: atmospheric (dust and water -> rust) and fretting. Later happens due to misalignment and shaft in transfer box having axial clearance. it is held in a gap between other components and if not properly adjusted, will be loose. There is a 4x4 repaid bulletin with specified axial movement tolerances. Also, rust and dust helps vibrating shafts to brake more efficient.

Both broken and partially worn sets had rust on them where surfaces were not contacting something to brush the rust away. No rust on the perfect set, AFAIR.

Regarding seals, I am not sure if there is a seal inside female shaft to stop oil going on to left driveshaft that passes inside. Anyway, proper fix should be sealing both sides: gearbox/transfer box interface and inside of female shaft. Also adding some good quality anti fretting agent to reduce damage. Gearbox shaft seal that faces transfer box could be substituted with two-lip seal to keep oils from migrating. Different topic, but I think it might be a good idea to replace all seals with two-sided ones to both keep oil going out and dirt from coming in. But again, I am not an expert on this.
1992 TZD Turbo berline, aircon, ABS
1991 TZD Turbo berline
1989 GTi 4x4 berline, ABS

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Re: 4x4 splinelube

Post by barry badger » Sun May 21, 2017 7:21 pm

I'm still in a quandry about what lubrication to use, I've removed the seal carrier and drilled two oil channels in it, one at 12 oclock and one at 8 oclock. I've tapped them to 4mm and fitted two pressure nipples from a model aero engine each with a length of injector leak off pipe attached. I've filed a channel in the gearbox casing so that the lower pipe passes out just behind the differential.
So the plan is to put lsd 80w90 oil in the top pipe until it runs out of the lower pipe and then plug them both or grease the splines with mos2 grease, fit the transfer box then add oil in the top pipe to make the grease thinner so that it flows better.
Incidentally there is a company called atd performance that does new stronger shafts for the bx, they look much more substantial but out of my price range at the moment at 2,520 euros.
1993 tzd estate, on sorn
1992 tzd estate, slowly being raided for parts
1992 txd estate, "doom blue" on the road
1991 4x4 estate, on the road

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Re: 4x4 splinelube

Post by Way2go » Sun May 21, 2017 11:49 pm

Probably worth posting a request to Philhod and Brian King into the following thread to ressurect how far their solution progressed! :?

https://www.bxclub.co.uk/forum/viewtopi ... ne#p240235
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Re: 4x4 splinelube

Post by assembled » Tue May 23, 2017 10:52 pm

I don't think I follow what you did to your box. Could you possibly post some pictures or a drawing? This topic is especially important to folks with still running 4x4 BXs.
1992 TZD Turbo berline, aircon, ABS
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1989 GTi 4x4 berline, ABS

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barry badger
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Re: 4x4 splinelube

Post by barry badger » Mon Jun 12, 2017 10:24 pm

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1993 tzd estate, on sorn
1992 tzd estate, slowly being raided for parts
1992 txd estate, "doom blue" on the road
1991 4x4 estate, on the road

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barry badger
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Re: 4x4 splinelube

Post by barry badger » Mon Jun 12, 2017 10:58 pm

Sorry for the first picture being repeated a few times ,don't know how to correct it.
A few pictures of my lubrication mod to the splines,
showing the top fill pipe which extends out of the gap between the two units up by the distributor and then looped down and left open to allow it to breathe
the lower level pipe so that the splines fill up to about halfway , which extends out through an 8mm hole made in the rear of the final drive flange, (plugged with the small grey cap).
the two small oil channels are just visible in the seal carrier adjacent to each pipe
two shims on the transfer box totalling 1.3mm, this will probably be different for each car, i used a selection of shims and plastigauge to arrive at that thckness,
when it was assembled i sealed the shims with elring dirko, this seemed to be the best sealer, i have a spare gearbox and transfer box and trial assembled them with shims and different sealers.
i filled the splines with lsd 80w90, they took a grand total of 4ccs of oil. i can check the spline oil level quickly and easily and also check on the colour of the oil to spot any potential problems.
the car is now fully assembled and passed its mot test last friday the problem now is the water pump has developed a slight leak,but not to worry as the cambelt is on my to do list anyway. will tax it tomorrow and put some miles on it first.
1993 tzd estate, on sorn
1992 tzd estate, slowly being raided for parts
1992 txd estate, "doom blue" on the road
1991 4x4 estate, on the road

assembled
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Posts: 79
Joined: Thu Jan 05, 2012 2:21 pm
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1989 Citroen BX GTi 4x4

Re: 4x4 splinelube

Post by assembled » Tue Jun 13, 2017 5:41 pm

Thanks for writing this up so nicely!
1992 TZD Turbo berline, aircon, ABS
1991 TZD Turbo berline
1989 GTi 4x4 berline, ABS