Gearbox oil for Spitfire 1500??? GL4 only?

[ryan2022]

Hi folks,

I've got my parents Spit up on stands in the garage this week. I'm just going over it, and doing some mechanical work for a fathers day effort for my Dad.

I was wondering about doing the gear oil in it, as some of the shifts are getting a bit notchy.

I've got some NAPA (valvoline) GL5 fluid on the shelf, which would work, however, it calls for a GL1-GL4 fluid.

Do the new gear oils contain sulphur. I know its hard on the yellow metals.

My other option is Amsoil GL4, but I'm not sure if this old girl will like the synthetic. I may be able to find some other GL4 at the local tractor supply store.

any thoughts?

thanks,

Ryan

 

[crw]

If the shifts are getting notchy, you might need to do a clutch master cylinder rebuild. This is not expensive or difficult. I had to do it to a Spitfire that I owned over 20 years ago. Unlike my BMW, with the Spit you don't need to get on the ground to access the clutch MC.

 

[mechtech2]

You may not have a synchro first gear in that tranny - my '66 didn't.
GL4 is not void of sulfur, it has about 1/3 of the GL5 amount.
And most Gl5s are buffered to stop this corrosion. Many Gl5s say GL4-Gl5 on the bottle.
But get a modern manual trans lube. Redline MT90 or Amsoil MTG would be my choice.
Yes, you probably have to order it, but you will only do this once, and they are superb fluids.

 

[expat]

I agree with the above posts; Check the clutch is releasing properly AND use a transmission lube like MT90, it works wonders!
DO NOT use GL5 in the Differential! it will (over time) dissolve the thrust washers.
But you proberbly noticed that the Diff has no facility to drain!
many owners Drill and add a drain plug. there was a Flat location at the bottom where previous models HAD a Drain plug located.

1500's (with the original transmissions fitted) all had syncro on all forward gears.

 

[ryan2022]

Thanks guys.

seeing how its the parents ride, I'm going to shell out for some new GL4.

Yes the MC's are both easily accessible. I know the brake MC will need TLC soon.

thanks, wish me luck under there.

Ryan

 

[expat]

You may consider switching Brake/Clutch fluid to DOT5, if only because of the location of the master cyl's. If fluid leaks, conventional fluid will eat away the paint on the engine fire wall.
Be careful where/ and what Brand parts you buy, I now only use genuine Girling hydraulic parts.
If your supplier cannot tell you what brand (Victoria British) don't buy from them. There is a lot of garbage out there!
........
I was able to buy Pennzoil Syncro (which is Yellow Metal friendly) at my local parts store. REALLY, it did improve my gear shift and Overdrive operation.
At a pinch, some people use 30w engine oil in that tranmission and cliam good results!

 

[ryan2022]

Expat, good to know.

Yes the synchromesh fluids are excellent. I thought it would be too thin seeing how it calls for a gear lube.

I may check again. Maybe it went down to an SAE 50 gear oil, which is a good bit lighter than an SAE 90.

yes they are fussy cars. Fun as heck though.

 

[widman]

I assume you mean the transmission? Normally differentials have no bronze and can take the GL-5, But not the synchronizers in the trans.
GL-4 has 50% of the Sulfur/Phos additive. Corrosion is not the issue. Corrosion was fixed 15 years ago with buffering. Synchronizers is the issue.

I would not use most of the syncromesh fluids out there as most are too thin for transmissions that asked for 80 or 90 wt.

Read through this before you buy anything. GL-4 vs GL-5

 

[expat]

"I assume you mean the transmission? Normally differentials have no bronze and can take the GL-5, But not the synchronizers in the trans."

No, This Diff uses yellow metal thrust washers, they are known NOT to stand up with GL5.

The syncros pose less of a problem, but none the less, I would not use GL5
Many people have switched to MT lube in these transmissions.
You may want to Google Spitfire MT90 or Spitfire Pennzoil syncro.
I have used it for 10 years with very good results.

 

[widman]

Then you are on the right track for staying away from the GL5 and anything that says GL4/GL5.

The viscosity thing would depend a lot on ambient temperatures.
Quote:

I may check again. Maybe it went down to an SAE 50 gear oil, which is a good bit lighter than an SAE 90.


Actually:
A SAE 50 is 16.3 cSt to 21.9
A SAE 90 is 13.5 cSt to 18.5

Two different SAE scales. SAE 50 can be thicker than SAE 90.

J300
J306

Since there is a lot of overlap (16.3 to 18.5), in general terms, you will find them basically identical in viscosity, depending on the brand.

 

[edhackett]

Ryan,

This works in old Alfa Romeo transmissions calling for GL1 with no problems. It should work just fine in the Spitfire too. It does not use a S-P based EP additive package.

https://cglapps.chevron.com/msdspds/PDSDetailPage.aspx?docDataId=76979&docFormat=PDF

Ed

 

[widman]

That link doesn't do anything. but there is no reason to drop down to GL-1. A good Diesel SAE 50 will give you GL-4 performance.

 

[ryan2022]

Hmm, I didnt know that about the SAE grades 50 and 90 being different. Good to know.

So whats the concensus, will a deisel sae 50 work the same? Lots of EP adds. And it'd be inexpensive.

 

[widman]

Volvo recommends the SAE 50 Diesel for transmissions in it's big trucks. I usually go one step further with a SAE 50 that meets CAT's TO-4 spec for clutches and discs. For just the Differential, the SAE 50 Diesel will be fine.

(Note, this is why motor oil works well in the combined engine/trans/dif of the Austin Mini's)

 

[ryan2022]

Thanks for the replies guys.

I didnt want to second guess myself later on, so I went with the Amsoil GL4 MTL. should do the trick nicely.

 

[mechtech2]

ryan - So you got the lighter synchromesh version of the Amsoil?
The MTF?

 

[ryan2022]

No, I grabbed the 75w90 GL4 stuff.

they had the synchromesh as well, but its a bit thin. I've used it in applications calling for Honda fluids or GM synchromesh and its excellent.

Just didnt want to chance the thinner stuff on the Spit.

 

[mechtech2]

Good choice. Age and initial English/loose clearances indicate the thicker version.

 

[ryan2022]

thanks.

Im hoping it'll improve the shift between 2nd and 3rd, and the smoothness in general.

Knowing the mechanic my folks use, the old fluid is probably like tar. If there is any in there.