L.S.D. as per 390 SE

[drak ula]

hello all, ok i know the original 390se cars of 1984 had limited slip diffs and as my car is a 1984 car with 390se motor (albeit with carb rather than efi) it should be roughly the same power and weight as a 390se even though it started life as a 350i, i reckon it would benefit from the same lsd as the 390se had.
first of all anyone know what ratio the 390se diff was?
i understand various jag's had lsds that will fit but don't want one with a ratio that is way off.
secondly do the tvr/jag diffs have a tag on them stating the ratio the way ford diffs do? if not is there another way to tell the ratio other than opening it and counting teeth?
lastly (bit optimistic i know) any one got a good lsd of the correct 390se ratio that will fit for fair money?

[mk1fan]

The diff should have a tag on it with the ratio. There will be a seperate tag denoting it is an LSD. Prescilla still had her tags fitted when Gary and Paul were doing the back end jobs. I haven't checked for tags on Wendy but there's clearly some form of LSDness going on. So check for the tags first.

There was a complete Jag back end on evilbay last week. Claimed to be an LSD and stated the dif ratio in the ad. It was £400 but did have 'offers'. £400 seemed fair to me if mechanically sound.

[TVRleigh_BBWR]

Ratio should be 1:3.54 and should have a powerloc tab if its a LSD.

ETA correction should be 1:3.54 not 3.4

Edited by TVRleigh_BBWR on Tuesday 27th September 19:28

[drak ula]

thanks guys that is exactly what i needed to know, leigh is that the one you have on your racer?

[TVRleigh_BBWR]

drak ula said:

thanks guys that is exactly what i needed to know, leigh is that the one you have on your racer?

Yes and on the 400SE, I would like to find an ultra rare 1:4 or higher as that would give better acceleration, but a lower top speed, but I cant see me doing more than 140MPH on any UK track, so the current 170 Limit is too much for the racer really.

your want the lower one thou for the road, some people even use a 1:3 or lower, not for top end but for low rev cruising at 70MPH.

The 1:3.54 though is the most common version that is LSD most of the other sizes are not LSD.

Edited by TVRleigh_BBWR on Tuesday 27th September 19:28

[Number 7]

Just to add to what Leigh has said, I think that the LSD was only an option on the early 350i models, whereas it was standard on the S2 / A frame cars. Ratio either way should be 3.54:1. If its a PowrLok, there should be a tag with PL on the case. Ratios: a couple of my reference books quote the 400se, 390se and 350sx as having a 3.31 diff as standard, with other options available. At least 1 car (the white 1985 390se owned by the late Russ Wood) had a Torsen diff - totally different to the plate versions in the Salisbury 4HU. Don't forget also that the 390se had 225 x 50 x 15 tyres.

[TVRleigh_BBWR]

Number 7 said:

Just to add to what Leigh has said, I think that the LSD was only an option on the early 350i models, whereas it was standard on the S2 / A frame cars. Ratio either way should be 3.54:1. If its a PowrLok, there should be a tag with PL on the case. Ratios: a couple of my reference books quote the 400se, 390se and 350sx as having a 3.31 diff as standard, with other options available. At least 1 car (the white 1985 390se owned by the late Russ Wood) had a Torsen diff - totally different to the plate versions in the Salisbury 4HU. Don't forget also that the 390se had 225 x 50 x 15 tyres.

N7 is totally correct its 3.54 not 3.4 should have looked it up instead of relaying on memory.

[drak ula]

thanks guys, paul what is a torsen diff?

[anonymous-user]

1984 390 SE would have been a Torsen.

[Number 7]

No idea how it works, but it is gear-based, rather than having clutch packs like the Salisbury.

[Number 7]

TVRMs said:

1984 390 SE would have been a Torsen.

Didn't realise that they were more widely used (relatively speaking) John, as I'd only ever heard of Russ's car having one. Interesting to know.

[anonymous-user]

Number 7 said:

TVRMs said:

1984 390 SE would have been a Torsen.

Didn't realise that they were more widely used (relatively speaking) John, as I'd only ever heard of Russ's car having one. Interesting to know.

Hi Paul,
Our first 390SE (1984/5) was Torsen, standard, not an option.

http://www.learnengineering.org/2014/11/Torsen-Dif...

Helpful?

Edited by anonymous-user on Tuesday 27th September 20:43

[Number 7]

Thanks John - I'll read that later. Wonder why they changed - cost / availability?

[anonymous-user]

Cost and availability is a reasonable shout. Good old Salisbury has served TVR well and is a better lsd than the hydra-track used in the later cars.

[drak ula]

i had heard of torsen diff and knew it was in the 84/85 390se because it is mentioned in the 'fastlane' mag feature i have for the car (beautiful black one with red interior) just didn't know how it worked or what the difference was between that and any other kind of lsd.

Edited by drak ula on Tuesday 27th September 22:24

[drak ula]

VERY helpful!!! i want one of THEM!!!! lovely explanation with great graphics and simply and elegantly explained. thanks, even i sort of understood it ;-)

TVRMs said:

Hi Paul,
Our first 390SE (1984/5) was Torsen, standard, not an option.

http://www.learnengineering.org/2014/11/Torsen-Dif...

Helpful?

Edited by TVRMs on Tuesday 27th September 20:43