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Gearbox Oil


Alan C
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Hi Everyone

 

My GT6 has been running with a big saloon J-Type overdrive equipped gearbox for the last 25 years. It's still has excellent gear selection and the overdrive operates without hesitation. The only slight niggle has been that it has an audible whine at speed. I have changed the oil regularly, partly because the overdrive likes to leak all over the exhaust.

Now I realise that ultimately I will have to remove the gearbox and have both problems fixed as part of a rebuild but that's still a long way off.

Can anyone recommend a heavier oil or additive that would reduce the whine in the interim. Just being a bit lazy for once.

 

Cheers

 

Alan

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Alan.

 

I'm happy to be quoted differently, but I think you will find:

 

1. any additive added is likely to have a negative effect on the efficiency of the overdrive as it's dependent upon correct pressure within the unit.

 

2. a thicker oil will also have a similar effect.

 

Personally, I would stick with the EP90 hypoid and set a date for sorting the units out.

 

If it eases the pain, I will be doing exactly the same over the winter !!

 

Regards.

 

Richard.

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I am sure Pete will know, but I would have thought that going up to say, an EP140 from an EP90 would not be advisable due to the greater viscosity, and may have adverse consequences for the overdrive in particular, which is a precision bit of kit. My J type dribbles on to my exhaust too, but I regard the resulting aroma as all part of the character!

 

Steve C

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the OD is actually spec to run on engine oil , used in other marques gearboxes , the Triumph inadequate box needed EP90  to survive.

 

the big saloon box is far more substantial, , far from an easy fit in a small chassis car

  have you got this box or just the J type  OD ( which was used on later 3 and single rail gearboxes ) and a 3 rail . ??

 

 

     addatives of any form can play havoc with old designed synchromesh 

 

           i would promote ...    stick to whats specified

 

Pete

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Pete

 

I have the box and overdrive from a saloon fitted. I fitted it in the late 80's in lieu of upgrading the engine. Although it's a snug fit it only requires a very minimal amount of surgery on the chassis rails. I've no regrets and no worries about it not coping with the 2.5l tuned six pot the car now has.

 

Alan

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Have a Mk1 Vitesse with a three rail box with j type overdrive, oil leak on mine was from speedo drive. This was on to exhaust pipe, must be a Triumph design feature, cured by new O ring and seal for the speedo drive. Bit fiddly but done without removing gearbox just by removing gearbox cover.

 

Regards

 

Paul

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  • 2 weeks later...

Good morning, I'm a bit confused here, I seem to remember reading on the forum some years ago and possibly the Moss catalogue, that EP90, I.e. an extreme pressure oil as recommended by Triumph, was actually the wrong oil. I've used Penrite 40, recommended by them for O/Ds with no problems. And added bonus is no smell. Can anyone clarify this, please?

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Derek.

 

I'd be very surprised if manufacturers quoted incorrect oil for mechanical applications. 

 

Having driven thousands of miles in various Triumphs I have owned over the years, the oil quoted is the oil used and have never experienced a problem. 

 

Conversely and out of interest, my Alpine uses 20/50 mineral oil for the engine + g/box and OD; in fact this point is specifically highlighted in the Rootes WSM. As such I have never used EP90 in the Alpine g/box and OD.

 

Personally, I would use the EP90 as specified by Triumph for the very reasons that were first identified as the start of this thread.

 

Just my opinion.

 

Regards.

 

Richard.    

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A perennial issue.

 

I believe laycock specified a non-ep oil for the overdrive. Triumph however specified EP stuff.

 

Difficult to say the manufacturer specified the wrong oil? They designed and built the cars after all, including the gearbox. But there will  always be the debate. If you are happy with a engine oil, that is fine. If not, use EP oil. So no clarification possible.

 

And it appears there is no real evidence that either is better! (the smell bit does appeal though)

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In a Triumph, the gearbox and overdrive share the same oil.

 

The "correct" oil for a Triumph gearbox is EP90 (GL4)

 

The "correct" manufacturer specified oil for the laycock overdrive is a normal oil.

 

A triumph gearbox will wear out if you use a normal oil.

 

The overdrive wont wear out if you use EP90, but it might be slightly slower to engage.

 

If EP90 was going to cause a problem with the overdrive, the Laycock would not have supplied them for Triumph to use, as the failure rate would have damaged their reputation.

 

My choice is to preserve the gearbox - good replacement parts are getting difficult to source - and live with a slightly slower overdrive engagement.

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Its all down to tooth loading and stress within the box

I was brought up with Rootes units Being a Commer Aprentice, and even in the Pb van the box works with engine oil, they are a different kettle of fish,as said the OD is designed to work on engine oil, it does work with EP oils the Triumph box is derived from before the Standard 8 and put behind a 2ltr with minimal upgrades, it needs an EP oil to survive the pressures involved

And with gear teeth well exceeding thier designed life span you need all the help to presersve them.

Pete

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Thankyou for all your comments re the EP90, very interesting indeed. I have a small job to do on the overdrive, the filter gasket has a small weepage, and I'll take the opportunity to change the oil and give EP90 a go. Apart from the GL4 spec, are there any brands preferred? 

I see the club shop has Millers...

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Thesedays I would use an 80/90 multigrade. Not sure it was around in the 60's, but easily available now. I have been using it in all my Triumph gearboxes (and diffs) for best part of 25 years now. Always comma brand, cheap and cheerful but has always been fine.

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Echo Clive, its easier to buy a 80/90over the counter than straight 90, which is sold by your club shop.

 

more important the GL4 spec is tolerant of bronze in hot pressured loaded conditions

more modern GL5 is less and can disolve degrade bronze fittings ( there, s loads of data about some gl5 being ok these days its all in the addatives small print) cant see its worth the risk.

so this can affect thrust washers on layshaft and on diff planets, baulk rings, and 2nd 3rd gear bushes

(Later boxes had steel mix 3rd 4th bushes)

 

pete

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one knackered overdive thankfully slipping and noises and failure to enage  only started few miles from hone on way back from triumfest  

looking at what came out i think the clutch in it has gone 

20151010_163418%255B1%255D.jpg

 

getting it out this time a lot easier with a lift , rather than axle stands and ramps  

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Clive/Pete and all, further to the oil spec thread, I was in our local Wilkos today and they keep Comma EP80/90 GL4, £3:50 a litre, so I grabbed a couple. Comma have a technical department and I fired off an email to see what they have to say. I was impressed with the speed and enthusiasm of the response. They reckon while GL4 will do perfectly well, GL5 is actually nearer to original service spec.

I'll listen to what you guys have said though and go with the GL4, as always I'm in danger of thinking myself into a corner. Many thanks to all for your thoughts!

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There's seems to have  been loads of opinions on this over the years but for me, Pete and Clive's assessments of the subject have convincingly concluded  the debate = EP gear oil not engine oil.

 

EP's sulphurous aroma does have some strange attraction but I rather went off it many years ago.As a teenager feeling rather pleased with myself changing the clutch on my dad's 105e Anglia I thought I would remove the gearbox without draining it.After removing the propshaft  rear mounting etc I was  looking up , guiding   the gearbox down and rearwards when 1 1/2 pints of EP  90 poured out of the tailshaft over my head ,face and shoulders.A humbling experience.I was convinced I could still it smell for many weeks afterwards.

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  • 4 months later...

Feedback from this thread.

The gearbox was filled with Comma oil and I have to say after a couple of road-tests I'm pleased with the results, quiet running, nice smooth gear changes and the overdrive behaving itself superbly. A good result!

Thanks for your help, Clive, Pete and all... again!

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