engine and drivetrain What type of limited slip diff?

[SBriggs]

It seems like a LSD is a useful upgrade and I have read a few threads about the merits of the 3.64 versus the 3.91 ratio, with a few other options thrown in. I have a '73 Tii US spec with a rebuilt engine. It has 10:1 pistons, 292 Schrick cam, aluminium flywheel, fully balanced bottom end, original size wheels and tyres, original 4-speed gearbox and easy access to 98 octaine fuel.

I assume I have the original ratio. What ratio would you recommend? Aardvarc have both 3.64 and 3.91 that are being offered with modifications so they are a simple bolt on. I seem to remember reading good things about Aardvarc. Ultimately, I would like to add a 5-speed transmission but I think the transport costs to Europe would be too high, maybe next winter.

[whitmontross]

I currently run a 5 speed transmission and 3.91 LSD and love the set up.

[jdirecto]

If your keeping it 4 speed then I say 3.64. I also have a 5 spd o/d with 3.90 and it runs pretty well.

Joey

[Guest Anonymous]

Have had three combo on the same car: 4 speed/3.64, 5-speed/3.64 and 5-speed/3.91 lsd, and much prefer the 5-speed/3.91 lsd.

________________________

Roger

'72 Malaga

RBenson685@aol.com

[dubois]

It all depends what kind of driving and how much horsepower you have. I am assuming with that type of cam and the 10:1 CR, you probably are pulling about 140-150. If you do a lot of in-town and hill climbing, I would do 3.90, or planning to track it on a short track..

But you also have enough horsepower to pull that 3.64, if you do some highway driving, you love the 3.64, easy cruising at 100mph. with a 5 spd overdrive. You will give up a bit on the lower end and taking off you will rev higher, but will get to 60 mph in second gear, and a top speed of 125+ which is nice.

Right now I am running 3.64 with a 5 speed overdrive and I love it.

[josh72ooh2]

Nice answer dubois.

it would be nice if the other responses elaborated as to why they like their ratios.

How's the highway driving with a 5speed and 3.90?

If i understand ratios correctly...

It seems that the 3.64 is good for the highway,

3.90 is good for off the line and quick acceleration.

i have a 3.90 lsd in the garage that i hope to install someday...

and my driving is mixed highway/ around town... daily driver stuff.

-Josh

[74tiiGolf]

How's the highway driving with a 5speed and 3.90?

If i understand ratios correctly...

It seems that the 3.64 is good for the highway,

3.90 is good for off the line and quick acceleration.

-Josh

Josh, you're totally right about the ratios. When I was in college, I had both the 4-speed 3.64 and the 5-speed 3.64. I used to drive 3 hrs home on occasion and the 4-speed was tough on the freeway. Doing 63mph in the slow lane at 3500 RPM and it was pretty loud. The 5-speed was fantastic for the freeway and I didn't feel like I lost that much in acceleration. I now have the 5-speed with a 3.91 LSD and, while it is GREAT fun around town, on the freeway I do miss my 3.64.

I have a (mostly) stock tii. If you think you're gonna be putting out 15-20% more power than stock AND you want to hear your stereo on the freeway blasts, I think a 3.64 LSD would make you happy. I know if my car had a little more power, I wouldn't hesitate. HTH

Matthew