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LSD and Ratio's
Graham G - 26/9/02 at 08:37 PM

As a complete newbie, wot does a LSD look like and how can I tell if it is working or not. Also wot is the best ratio to use with a 2.0l pinto ???

Noodle - 27/9/02 at 05:47 AM

The simplest way to determine if a vehicles fitted with an LSD is to raise the driven axle off the ground and turn one of the wheels. If the opposite wheel turns in the same direction, it's an LSD. A counter-rotating wheel proves otherwise.

Neil.

Graham G - 28/9/02 at 12:57 PM

Hey u r right !!

Thanks for that.

Graham

James - 30/9/02 at 10:53 AM

Graham G wrote:

quote:
Also wot is the best ratio to use with a 2.0l pinto ???


It depends what you're aiming for and whether you're planning to keep the donor's speedo etc.
You can raise your acceleration (at the cost of top speed) by fitting a lower ratio diff (ie. 3.62:1 as opposed to the more common 3.92:1). But bear in mind any changes in ratio will affect the speedo by that same percentage.
Saying that though, you could decrease* wheel/tyre diameter to compensate.

What is it you're attempting to achieve?

HTH,

James

*I think I've got that the right way round?

Graham G - 30/9/02 at 06:57 PM

I'm aiming for acceleration. I can't see the point in having cars capable of 150mph! I've checked the diff. and the tag has rusted away but by turning and counting I reckon its 3.62 (ish !!!).

James - 1/10/02 at 11:38 AM

What are you planning to do about the speedo? Bear in mind the difference between 3.9 and 3.62 is about 8%.
It's only an issue if you're planning to re-use the donor's speedo I guess.

Cheers,

James

James - 1/10/02 at 12:32 PM

What are you planning to do about the speedo? Bear in mind the difference between 3.9 and 3.62 is about 8%.
It's only an issue if you're planning to re-use the donor's speedo I guess.

Cheers,

James

Graham G - 2/10/02 at 08:19 PM

I don't have a donor yet. A pinto came up for sale and when I got there he also had a diff. The guy said it was LSD so I had it away, willing to take the risk that it was an ordinary unit. Hence my first post. It is a LSD so like u say I have the added problem of matching a speedo to it.

I'm really only planning my build yet and getting a few bits together. I've left it a bit late throu - my new MK chassis came today !!!!!!!

interestedparty - 2/10/02 at 08:46 PM

quote:
It is a LSD so like u say I have the added problem of matching a speedo to it.


Unless you are planning to use the speedo from your donor car, then you are going to have a matching problem anyway, regardless of which diff you use. If you are using an aftermarket speedo then tell the supplier the diff ratio and the tyre size and hopefully they will supply the correct speedo. Some speedos can be set by the customer.
If you want to use the original Sierra instruments then your best bet would be to obtain an instrument cluster from the model of Sierra that supplied the diff.

John

James - 3/10/02 at 01:43 PM

Or reduce(?) your tyre diameter by 8% to compensate.
Presumably speedos that are sold (by the likes of Raldes etc. etc.) are calibratable otherwise life's gonna be very hard!

I was thinking of using the donor speedo (to get me through SVA) and the tyre trick will do until I get some nice clocks!

Cheers,

James

David Jenkins - 3/10/02 at 01:46 PM

Try this link

http://www.fernblatt.com/longhurst/tyre_bible.html

Tells you how to select a tyre profile to match your new bigger wheels (plus lots of good stuff as well.)

David