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Spitfire & GT6 Forum

Differential Questions

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Roy Avatar
Roy roy o
Marietta, GA, USA   USA
Don't insulate the rear . It does get pretty hot(can't hold hand on it after a long run) & doesn't carry much oil .

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grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
In reply to # 1505585 by Roy Don't insulate the rear . It does get pretty hot(can't hold hand on it after a long run) & doesn't carry much oil .

+1 to that! If the noise bothers you, add sound insulation inside the car to the rear floor sections & underneath the tank. Never do anything which will make the diff oil overheat any quicker than it already does!

Canley Classics used to sell rear diff casings made in light alloy, with external fins, to help to lower the oil temperature.

CraigL Avatar
CraigL Gold Member Craig Larsen
Santa Clara, CA, USA   USA
Thanks for the opinions - will try other ways to reduce whine!

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hearditallbefore Avatar
Portsmouth, Hampshire, UK   GBR
Check it has oil in it, any oil, there often isn't.

Use a heavier grade oil.

Yea I know, 'the factory said' … well back in the day when I drove these things as proper daily drivers, putting heavier grade oil in a noisy diff was a common practice.
You can get EP diff oil up to 140SAE

http://www.millersoils.co.uk/products/classic-gear-oil-ep-140-gl4/169



Swatting the yellow jackets away from the Triumph apple of truth…

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
I tend to agree with Andy.

A car salesmans trick back in the day was heavy oil with some oats.

However I would not recomend this. The diff should not whine so that you can hear is at 70.

Do you by chance have urethane diff mounts?

hearditallbefore Avatar
Portsmouth, Hampshire, UK   GBR
Hey! I never put oats in any diff!

OK, grease once in a clunker I was selling. winking smiley



Swatting the yellow jackets away from the Triumph apple of truth…

grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
If you do choose to use 140 grade oil, fill the diff in summer - the stuff is like treacle in the winter!

Adding oats to the oil to reduce noise is a relatively expensive solution - where I come from, sawdust was the additive of choice - it's much cheaper! smiling smiley



Edited 2 time(s). Last edit at 2018-01-03 04:47 AM by grumpicus.

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clshore Carter Shore
Beverly Hills, FL, USA   USA
I would use cheap remote wired microphone to investigate.
Use plastic ties or duct tape to temporarily secure the mic down below,
route the wire into the cockpit, and headphones to monitor the sound.
The whining sound could be anything from the diff to the tire treads.

Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
In reply to # 1505705 by clshore The whining sound could be anything from the diff to the tire treads.

Last spring I was thinking the sound of a worn front wheel bearing might actually a whine comming from my diff.

Checking the easy things first, paid off.

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Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
The classic was sawdust in the crankcase.

Makes worn gears feel like new. (At least until the 30 day warranty expired.)

grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
In reply to # 1505770 by Tonyfixit
In reply to # 1505705 by clshore The whining sound could be anything from the diff to the tire treads.

Last spring I was thinking the sound of a worn front wheel bearing might actually a whine comming from my diff.

Checking the easy things first, paid off.

Good advice - it's when the whining noise gets so bad that you almost expect the diff to come up through the floor & land between the seats you know exactly what the noise is!

colodad Avatar
colodad Silver Member Calvin Williams
Grand Junction, CO, USA   USA
diff gear oil that is safe for brass, "yellow metals".

colodad Avatar
colodad Silver Member Calvin Williams
Grand Junction, CO, USA   USA
UTube has videos showing how to check the ratio.

'Triumph Spitfire Diff ratio, the faster 1 Wheel Way.' Published on Oct 28, 2017.
Turn the wheel and count the drive shaft revolutions, 3.89:1 you will see 19.5 turns of the wheel as DL turns 10, multiply by 2 because one wheel is not turning.

'Triumph Spitfire 3.89:1 diff ratio using wheel rotation to drive line.' Published on Oct 4, 2017 with both wheels off the ground.

scardini1 Avatar
scardini1 Gold Member Jim Moscardini
Great Mills, MD, USA   USA
1968 Triumph GT6 "Rocinante"
2003 Jaguar XKR "Kitty"
I used the Ed China, "ratchet strap technique" to swapped diffs a couple of years ago. I've got to admit that it really shortened the time to remove the diff. However, when I tried to install the new diff, the spring added some kind of load to the diff that made aligning the front diff mounts a true PITA. I think the extra few bolts involved with removing the spring is time well spent. I'll be replacing my spring this winter and I'll want to see if I can do it by leaving the shocks connected and just moving the vertical link out of the way. That would eliminate the need to re-bleed the brakes and re-connect the parking brake. If the technique works, then it would be applicable to a diff swap as well - allowing the diff to re-installed without the spring's interference. If necessary, the ratchet strap could be used to help support the vertical links once the axles are disconnected.

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