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best diff choice
Matysiak - 24/3/10 at 08:55 AM

Hi All,

I need to replace my diff on my 1700 kent Locost. It is a fairly highly spec engine, running a 244 cam, race head etc. The car is running a standard type 9 five speed.

The current diff is a 3.89 and is whining more than i would like. I have a choice of a 3.7 LS diff or a 4.55 standard diff, both from an alfa junior.

My feeling is since the car is mainly a track day toy, i should go for the 4.55. The gearing calc shows a top speed of 120 MPH, which is about as fast as i want to go in a Locost.

Or, should i be going for the LS diff?

tul214 - 24/3/10 at 09:20 AM

Buy both and swap the 4.55CWP onto the LSD

jimgiblett - 24/3/10 at 11:06 AM

I didnt realise that they did a 3.7 LSD on the junior. There were two different sizes of drive shaft which may mean that the CWP swap may not be practical.

The Alfa LSD was on the 2.0 Bertones and Spiders and a 4.5 IIRC. These are tough units (I hope so as I will be putting c.300hp through mine) and can be picked up for between £150 and £300.

Cheers

Jim


quote:
Originally posted by Matysiak
Hi All,

I need to replace my diff on my 1700 kent Locost. It is a fairly highly spec engine, running a 244 cam, race head etc. The car is running a standard type 9 five speed.

The current diff is a 3.89 and is whining more than i would like. I have a choice of a 3.7 LS diff or a 4.55 standard diff, both from an alfa junior.

My feeling is since the car is mainly a track day toy, i should go for the 4.55. The gearing calc shows a top speed of 120 MPH, which is about as fast as i want to go in a Locost.

Or, should i be going for the LS diff?


[Edited on 24/3/10 by jimgiblett]

Matysiak - 24/3/10 at 11:41 AM

Budget won't allow me to buy both, so i need to choose one.

jimgiblett - 24/3/10 at 05:05 PM

With a gearing calc of 120 top speed with a 4.55 that sounds ideal with the kent.

What size wheels. eg. 205-60-13s give a reasonable increase in top speed compared to 185-60-13s

- Jim

britishtrident - 24/3/10 at 07:50 PM

If you put a 4.445 in the first gear will be too short to any use, and you might find 2nd a little on the long side to substitute for first.

I don't know what your rev limit is but I would expect a 3.77 would give you 115 in 4th which would be close to top speed, 5th would purely be a cruising gear.