BTR Diff - Breather Cleaning

[ChimpOnGas]

Hi all,

Can someone confirm the hex size of the BTR diff breather?



Has anyone serviced their breather with the diff in situ?

I hope to reach up with the correct size ratchet ring spanner to wind the breather out, I can then properly clean it off the car before re-fitting.

I realise access is a right PITA, so I'd be interested to hear from anyone who's done this job.

Thanks, Dave.

[bobfather]

I've often thought of doing what Marcos did. Under the carpet on the rear shelf they fitted a hatch in the GRP. If ever I need to get my diff out again I'd seriously consider doing a mod like that to gain better access to the top mount

[jojackson4]

bobfather said:

I've often thought of doing what Marcos did. Under the carpet on the rear shelf they fitted a hatch in the GRP. If ever I need to get my diff out again I'd seriously consider doing a mod like that to gain better access to the top mount

I have some boat hatches what I bought but are too big
I think I’m going to use 1 for that very same job as I am pulling the diff this winter

[Classic Chim]

ChimpOnGas said:

Hi all,

Can someone confirm the hex size of the BTR diff breather?



Has anyone serviced their breather with the diff in situ?

I hope to reach up with the correct size ratchet ring spanner to wind the breather out, I can then properly clean it off the car before re-fitting.

I realise access is a right PITA, so I'd be interested to hear from anyone who's done this job.

Thanks, Dave.

That’s my Dif,,, glad the pics come to some use.
Sorry I can’t help as I never thought to check.
Funnily enough I met up with a mate last night who was a down hill mountain bike rider and a massive motorbike fan who’s a big online racer too.
Never been in a Tvr and on wet roads I gave him a 0-60 but more like 90 mph test drive. This very Diff did a great gob of keeping both rear wheels firmly planted ( or was it my tyre’s) on the road.
I’ve not accelerated like that since Shaky 6 months ago but the noises coming out my mates mouth were amusing as hell.
Says it’s faster than his mates Impreza ( I know) and he was super impressed with the cars grip. This little Diff is a safety feature
I happened to notice at York at least two Cerbs had knackered LSD in their Diffs just going by the wheel spin that is.

[ChimpOnGas]

Can anyone help with my original questions?

[Classic Chim]

Based on the other bolt sizes around it you could take a good guess.

[ChimpOnGas]

Classic Chim said:

Based on the other bolt sizes around it you could take a good guess.

I guess so Alan

Thanks for the loan of your photo mate, royalties in the post

Has anyone has cleaned their BTR diff breather with the diff in place?

[Classic Chim]

Ask a silly question and all that. I’m assuming that’s a vent to air with a loosely fitting cap on it, not sure how it would block up and I’d likely just use a rag doused in petrol and soak the general area failing pulling it out.

[ChimpOnGas]

Classic Chim said:

Ask a silly question and all that. I’m assuming that’s a vent to air with a loosely fitting cap on it, not sure how it would block up and I’d likely just use a rag doused in petrol and soak the general area failing pulling it out.

Oil vapors/mist can condense & congeal in the thing causing over pressurisation of the diff, a partially blocked breather can cause seal leaks. The one thing you don't want is a leaky diff, because the one thing that will kill your diff in short order is a lack of oil.

Of course if you catch it in time you can save significant expense, your diff will definitely thank you for occasional breather servicing, my breather hasn't been touched for 21 years and the chassis has seen regular Waxoyl treatments too, that stuff gets everywhere and could easily have covered my diff breather.

My pinion seal isn't leaking as such, more sweating around the pinion seal, if I wipe my finger over that area it comes back damp with a hypoid gear oil smelling residue, so that's diff oil for sure. If I can get access and wind the breather out I'll douse it in carb cleaner and blow it through with my air line, as I see it after not being touched for 21 years it's just good maintenance.

I'll have a go at it tomorrow

[Classic Chim]

Dif oils not very nice brand fire new let alone after it’s been squeezed through the gears for years on end. Any leak would be undesirable.

My long haul jaunts and road trips this summer have been curtailed cos of that Dif.
But as soon as it was fitted I was glad I’d done it. Fab feeling to have it all tight and the LSD working propery, bodes well for the future.
I thought I had a bit of noise from it recently but a decent blast and engine revs had warned and splashed the oil to good effect it seems.

For the first time in 6 years I turned the stereo up to a volume that cancelled out the engine after putting the Rainsport 3 tyre’s to 20/22 psi earlier had a slightly profound experience, I’m not one to exaggerate or anything but foook me on a 50 mph country A road I burbled along in the dark with the music blaring and cancelling any noise whatsoever and the car felt so good.
Without all those sound pointers I’ve used for every single mile in the past I drove the Tiv like a modern car with no audible sounds to go on, just a distant vibration from the engine and a constant note that I could vaguely pick out, Latin horns and drums punching through the speakers at a high and exciting tempo, suspension and brakes working in this weird mechanical silence, it’s like half my ability to feel the car had completely disappeared and only feel is left to sense things, trusting the engines ok without me constsntly and lovingly listening* to it,,,, Use the gears and can’t here the clunk of it hitting home, run a few white lines and cats eyes and as I can’t here the rattling it’s actually rather serene and very comfortable.
I don’t think I’ve ever really trusted it to drive without my ears peeled for mechanical change that spells bad news and I enjoy the engine nots so much who really needs music.
But today driving with The Mambo blaring out by a great Conga player and his band I found a bit more from my Tvr, shut the noise out and rely on feel alone, thay are really rather better cars than given credit for,,,, the volume was at 36 of 50 so everything’s relative :Biglaugh:

[ChimpOnGas]

Ok, so just to close this off... the breather is a right PITA to get to, so much so.... I gave up

I simply topped up and it took 300ml, the capacity of a BTR diff is 1.6 litres so it had leaked 20% of it's capacity since I'd last changed the oil, yesterday evening I looked back through my records to find that was five years ago, June 2012 to be precise

Recently I noticed one of my upper mount bolt holes has lost it's thread into the diff, the diff is sill very firmly mounted with no movement so it's not an urgent job but it will need a Helicoil at some point. As fitting the Helicoil is a diff out job the breather can be cleaned then, obviously it'll get a oil change at that point too.

Essentially, as it stands, my diff is leaking 5ml a month or 60ml a year, even leaving it as is I figured I'm in no danger as long as I do an annual check and top up. As I was under the car I also took the opportunity to top up the gearbox which took 500ml so that was 20% down too, both diff and gearbox clearly needed topping up but I see this all as just normal regular maintenance rather than anything to worry about.

However, what I did notice that definitively needs more urgent attention is the fact my two rear Rainsport 2s are on the limit, looks like I'll be moving to Ransport 3s sooner that I'd thought .

[phazed]

You could have use my two post lift Dave.

[ChimpOnGas]

phazed said:

You could have use my two post lift Dave.

That's very kind Peter.

Taking the diff out looks like a nasty ol job to me, I was looking at your 'hole saw bolt access through the rear bulkhead' method, which looks like the best idea to me, sadly that means taking my gas tanks out which while do-able does add time and complication

I'll keep your offer in mind though mate, much appreciated

BTW, I cleared my lockup the other day and finally found that CG lock, typical

[phazed]

The method through the rear bulkhead was purely for tightening the bracket to the back of the diff. Very necessary as the bolts need to be tightened to about 30ftlb.

You can access the mounting bolt at the rear of the differential with long extensions through both wheel arches as the mounting bolt runs from side to side. Much easier with two people.

Yes, it is a bit of a pain Alun changed his diff at my place earlier this year but very doable.

[ChimpOnGas]

Many thanks Peter, how long do you think it would take?

Is it something that could be done in a day?

[Sardonicus]

Dave you need to up your service interval unless you like replacing/rebuilding final drive unit 5 years is plain mad even road miles only

[ChimpOnGas]

Sardonicus said:

Dave you need to up your service interval unless you like replacing/rebuilding final drive unit 5 years is plain mad even road miles only

I've now gone back through my records in more detail Simon, the June 2012 date was when I had to weld a wheel nut on the drain plug to get the damn thing out, TBH at that point I don't think the diff oil had ever been changed since the car was built in 1996 so that 2012 change was it's first.

I'm not too stressed about this because while TVR specified a 12,000 mile diff oil change interval, I bet most TVR dealers ignored this and many still charged you for the change without ever doing it, most Chimaera diffs seem to last well and most will have done lots more miles than mine on the same oil. A leaky diff is more of a concern to me than the age of the oil, I was pleased to catch it in time and while 20% down is not inconsiderable and it definitely needed topping up I wasn't too worried as these things work by splash so as long as the crown-wheel is in a decent bath of oil there's really no risk of it running dry if it's a bit low. I would say though if you're making that oil work at higher temps, a track day for instance, a completely full diff is essential as more oil helps keep temps within tolerance.

The father of a good friend of mine is the DANA CEO for South America and he assured me BTR were selling their diffs as 'filled for life' in the 90's, these days most modern diffs are 'sealed for life' and have you playing hunt the drain/fill plugs that may be well covered up or not even in existence all, I don't doubt the BTR will easily run the same oil for 50,000 miles or with no issues whatsoever, the 12,000 mile change interval TVR applies was massive overkill and just there to help their dealers improve their servicing profits.

With transmissions it's not like there's a combustion process element to factor as with engine oil, and anyway checking my records in more detail I can see I did a second diff oil change in 2015, so that's...

• Fresh oil from the factory in late 1996

• An aborted attempt to change it when I first bought and serviced the car for the first time in may 2009, (couldn't shift the diff plug for love nor money)

• Returned to the job in 2012 with a Mig and welded a wheel nut to the plug (so my diff got it's first change to my knowledge 5 years ago)

• Changed it again in 2015, easy job now with my new drain plug

• Topped it off yesterday with 300ml so its actually leaking 150ml a year, some of this seems to be coming from the drain plug itself indicating I need to anneal the copper washer

In the last 8.5 years since I've owned the car it's been serviced way more thoroughly by myself that it ever was in it's first 13 years of life before it came into my possession even though it came with a full Kerriges & Offord TVR service history. When I first bought the car apparently Offord TVR had just serviced it, not trusting the quality of their work and attention to detail I went right through it in my first week of ownership and found 12 clear faults, I also discovered many service items had simply been missed or more likely ignored.

A full 8.5 years on and many happy miles later the car performs, drives, handles and stops way way better than it did when I bought it with just 30,000 miles on the clock, TBH I'm in no doubt it drives way way better than when it was brand new. I'll admit just keeping up with servicing and regular maintenance keeps me busy, the modification and improvements I've added to make the car way better than when it left the TVR factory in 1996 being in addition to that.

Going through my records also prompted me to look at tyres which was interesting ...

• When I bought the car in May 2009 it had virtually new Goodyear Eagles on it

• By May 2013 they needed replacing, so I fitted a set of Uniroyal Rainsport 2s

• This morning I bought a pair of nice new Rainsport 3s to replace my worn out rear Rainsport 2s I'd fitted back in in 2013

So rear tyres seem to last me between 3.5 to 4 years and roughly 21k mls a pair, that's not bad if you ask me. Interestingly in May 2013 Camskill charged me £165.78 including carriage for a pair of 225/55/16 Rainsport 2s, fast forward to October 23rd 2017 and Camskill charged me just £147.60 including carriage for a pair of the newer design 225/55/16 Rainsport 3s. That shows us in more or less 3.5 years my tyres are actually getting cheaper

My relationship with this car is a journey, a constant battle against the inevitable deterioration of parts while at the same time trying to make it better than it ever was when brand new, but I guess that's simply the definition of any fully engaged TVR relationship

[Classic Chim]

ChimpOnGas said:

Many thanks Peter, how long do you think it would take?

Is it something that could be done in a day?

Yes.

I assume you want to take back plate off to re seal so add another 40 mins for that but it’s not as bad as you might imagine with good tools a ramp and gearbox jack taking the weight,, oh and Peter’s experience which is invaluable and saves a lot of faffing.

[ChimpOnGas]

Classic Chim said:

ChimpOnGas said:

Many thanks Peter, how long do you think it would take?

Is it something that could be done in a day?

Yes.

I assume you want to take back plate off to re seal so add another 40 mins for that but it’s not as bad as you might imagine with good tools a ramp and gearbox jack taking the weight,, oh and Peter’s experience which is invaluable and saves a lot of faffing.

Cheers mate, there's a helicoil and new bushes to add to the list too on mine, but hopefully a day would still do it?

[phazed]

The bush at the top rear is a right pita!

Simon did mine while I faffed on other, (easier) bits......................