Helstrm

Although I scrapped the turbo conversion for now I am still installing a full turbo suspension with Koni's on all 4 corners. Since I am doing that I will need to drill the spindle for the speedometer.

Now for the million dollar question. I have access to an 86 951 trans. If I install that trans will it screw with my performance since I am sure the ratios are different. Second question... Can I use the late speedometer and mount it in place of the early one in my gauge cluster? The benefit of this is that later down the road I will revisit the turbo conversion or a supercharger and this would eliminate several high dollar changes.

special tool

Don't put that in there if you are using the NA engine.
I use a 944S LSD in my 924S

If you want to retain the low gears with a plan to have some power - use an S2 box in the car. My S2 box is fine with 500++ HP.

Helstrm

Thanks, I will stay with what I have for now. I read somewhere that the trans in the 87 924s pulls better in 5th anyway.

Porsche-O-Phile

Yep. The 951 gearing will be too tall to make for an enjoyable experience.

Helstrm

And yet again my $18 membership just paid for itself.. I love it when this place saves me work..

Scootin159

I have an '86 951 (non-LSD) transmission in my N/A right now, and I can say that it's a little too tall, but it's hardly 'bad'. I won't argue that there are better choices out there...but if it were somebody's only option, it's not that bad a setup.

Actually for around town it's kinda nice to be able to take 2nd gear all the way to 60mph. 5th gear on the 951 transmission is actually SHORTER than it was in my N/A transmission ('87 N/A non-LSD), but hardly noticeable (maybe 100rpms at 75mph?)

-- as a disclaimer, I do have 'slightly' shorter tires, so I am gaining a little bit of help in the gear ratio department from them.

special tool

Scootin - that is a little confusing. Yes, 5th is shorter, but when you factor in the final drive (ring and pinion), the turbo 5th is MUCH taller.

Helstrm

So while I have access to a few more parts should i convert to the 951 external oil cooler? Seems like that would be a good idea....

Scootin159

If you don't have LSD don't bother with it (not needed and is just prone to cause leaks), but if you have LSD it might be benefitial.

Scootin159

I remember when I got my 951 transmission I made a little excel sheet that calculated the final drive in all 5 gears (gear * final drive). I thought when I did that 5th was just slightly lower in the 951 and all the other gears were just slightly higher, bringing everything closer together.

I could be wrong though, I'll be sure to check when I get home.

Helstrm

I should have been a little more descriptive. I meant the external engine oil cooler not the trans cooler.

Jakerx

well the external oil cooler for the 951 and the 944 n/a from mocal are different setups. i would recommend one either way.

Oddjob

944 R/P = 3.889, 5th = 0.730, final drive = 2.84

944T R/P = 3.375, 5th = 0.829, final drive = 2.80

So the Turbo gearing in 5th is taller, but just a hair. At 6500 rpm It works out to be only about a 2 mph theoretical difference (170 for the Turbo, 168 for a 944 n/a).

Helstrm

I have an external Oil cooler and housing from a 941 that I can bolt up instead of the internal cooler from the stock NA.