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Oils

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supercass
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Oils

Postby supercass » 05 Feb 2015 20:38

Just a quick question. Am proposing to drain and replace the oil from my gearbox and back axle. What is the best oil to use for the back axle and what is the best way to get all the gearbox out of (what I would refer to as) the 5th gear extension. supercass

darrellw
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Postby darrellw » 05 Feb 2015 21:54

The center plate, which connects the gear case to the rear extension, has a good sized opening at the bottom, so there shouldn't be any fluid left in the rear of the transmission.

I just took mine apart, there was maybe a quarter cup of fluid left in the whole transmission, it seems to drain pretty well.

If you are really concerned, I would just do another fluid change in a month or two.

Darrell Walker
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Stag76
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Postby Stag76 » 06 Feb 2015 04:19

There's a stud partially hidden by the rear mounting that drains a small chamber under the pump. It's designed to catch any bits of metal etc. If you remove it with the engine running in neutral it will empty it.

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TR Tony
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Postby TR Tony » 06 Feb 2015 09:57

Castrol Syntrax comes well recommended for the back axle. And if you want to stick with Castrol you can use Syntrans in the gearbox.

Tony
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<font size="1">1981 TR7 FHC Cavalry Blue
1980 TR7V8 DHC Jaguar Regency Red - sadly sold!
1977 TR8 FHC EFI Factory development car Inca Yellow</font id="size1">

Hasbeen
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Postby Hasbeen » 06 Feb 2015 12:42

I filled my box with Penrite manual transmission fluid about a year or so ago. It was slightly more noisy immediately after putting it in, but that disappeared in about 50 Km. It does give great gear changing.

When I bought the car I used Penrite EP 80 & STP in the diff. That was 14 years & 70,000Km ago. Yes I know I'm slack & should have changed it, but I hate pulling the back cover off an oil tight diff, & sucking the oil out of a diff is worse than leaving it there, it just stirs up the muck on the bottom. Besides my magic STP will keep it fine.

Now sit down folks, & I'll tell you a tail.

When I bought my Lotus 20, it was close to the Bathurst easter meeting. While checking everything we magnafluxed the crown wheels & pinions of the Hewland transaxle, & found cracks in the root of 2 teeth of the high ratio crown wheel. I could not get one from the UK in time for Bathurst, & nothing was going to make me miss Bathurst with my new, [to me] open wheeler, so we stuck it together & crossed our fingers it would hold together.

As it was a crash box, with the diff in there, I added STP as usual. DON"T EVER USE STP IN A SYNCHRO BOX, IT DESTROYS THE SYNCHROS BY ELIMINATING THE FRICTION THEY REQUIRE.

I got through Bathurst, & changed to the low ratio crown wheel & pinion. Out the back of the shed was a damp area, with very long grass, 4 Ft or so, fenced off from the rest. It was my dump, & I threw the old crown wheel & pinion out into that grass.

9 months later, with the next Bathurst easter approaching, a very good mate rang me. He had raced an MG A when I was racing my Morgan, & then we both moved to Lotus 20s at the same time. We often helped each other out loaning bits. He wanted to know if I had a spare high ratio diff available. His was shot, & without one he could not go to Bathurst.

I told him of the one in my soggy long grass, but thought it would be rusted away by now. He was desperate. He came over on Saturday, & took well over an hour to find both bits, half buried out there.

To our amazement there was no rust anywhere. The STP had totally protected that metal all that time.

To prove how we are often overcautious with parts, he did Bathurst & another meeting on that diff, & it was still going strong.

So, if you want to stop your car rusting, forget that that wax oil & other stuff, just smear it with a mixture of EP80 gear oil, & STP. Not only will it not rust, it will probably look so dreadful, you could forget insurance, no one will pinch it, I'll bet.

Hasbeen

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Postby FI Spyder » 06 Feb 2015 14:33

I too put in a little STP (after Hasbeen's recommendation) in the diff and it seemed to quiet it down a little. I had drained it when I had the back axle out to pull the gas tank for resealing. Easy to do as you just turn it upside down and it drains out the fill hole. You need a pump otherwise unless you want to pull the rear plate because it's leaking there anyways (mine wasn't). I used a Pennzoil hypoid oil for diff's.

When I separated my spare trans (which had ATF in it) it was clean as a whistle. The high detergent of the ATF makes it a good flush. Particular sycro's require particular oils so the slipperiness of the oil matches the required drag of the syncros. That's why some oils work in some transmissions and not in others. Ours are known to work best with Pennzoil Sycromesh Transmission Oil (not their synthetic stuff) or the GM version which is the same thing with different packaging. While ubiquitous over here, apparently harder to find overseas. There is an oil that was specifically designed for the LT77 in conjunction with Rover, a search should find the post.

When I first picked up my Spider in California to drive it home, it was in the high 80's/90's and it shifted great. By the time I hit Blaine, Washington I had to stay overnight as US Customs was closed and I had to present to get the papers to bring it into Canada. The next morning was the first cool day (day 4) and it was raining (spitting). I experienced the second gear crunch that I didn't know about that went away when the oil warmed up. After double clutching for a summer or two and reading the recommendation here I got around to changing the (original?) oil to Pennzoil Synthetic (Synthetic is better right?) Wrong. While it was better it wasn't great. The following year I switched it out to the Sycromesh and it was good. It is "notchy" into second when cold (as the LT77 is known for) but no double clutching needed. I know BMW owners prefer the Red Line Synthetic but because an oil works in one transmission that doesn't mean it will work in another.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT
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supercass
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Postby supercass » 06 Feb 2015 14:51

Thanks everyone for the info. TRTony, I presume it is Castrol Syntrax 75w 90 for the back axle, but is it Castrol Syntrans 75w 90 for the gearbox or the extended drain version Castrol Syntrans 75w 80 long life? Regards, supercass

dursleyman
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Postby dursleyman » 06 Feb 2015 16:50

Supercass, have a go with the search function on gearbox oils. There are pages and pages of suggestions and recommendations.
I have got Pennzoil Synchromesh in mine and highly recommend it.

Russ

1981 TR7 Sprint DHC
Dursley
UK

http://tr7russ.blogspot.co.uk/

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Postby TR Tony » 07 Feb 2015 15:04

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by supercass</i>

Thanks everyone for the info. TRTony, I presume it is Castrol Syntrax 75w 90 for the back axle, but is it Castrol Syntrans 75w 90 for the gearbox or the extended drain version Castrol Syntrans 75w 80 long life? Regards, supercass
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
I think it's the same stuff - some advertisers are using misleading description to suggest there is a "long life" version when in fact Castrol just state that the various qualities of the oil should give extended drain periods anyway! i don't suppose many of us do the sort of mileage that would require frequent changes anyway [:)]

It's the 75W90 GL4 oil, easily available on a well known auction site.

As has been mentioned, it's a huge topic with many varying recommendations. I understand the late Ken Tomlinson, who built the boxes for the TR7/8 rally cars, would only use Motul Gear oil. Motul Gear 300 is suitable in but seems to be slightly more expensive than the Castrol.

Tony
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<font size="1">1981 TR7 FHC Cavalry Blue
1980 TR7V8 DHC Jaguar Regency Red - sadly sold!
1977 TR8 FHC EFI Factory development car Inca Yellow</font id="size1">

john 215
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Postby john 215 » 08 Feb 2015 06:30

Hi,

I run MTF 94 oil in my DHC, it was used in PG1 Rover front wheel drive gearbox's and a lot of BMW gearbox's including Mini [;)] Land Rover also issued a technical bulletin suggesting the use of it in there R380 gearboxes which as you know is the upgraded and updated LT77 box rather than ATF.

http://www.texacobaltic.eu/en/products/cars/mtf-94.html


Cheers John

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