I will try to post pictures tomorrow (Wednesday). I don't think that I'm going to have time today.

 

Awesome Thanks!

 

I have the Andial R&P.

I would suggest either increasing HP or changing the R&P, but not both. I did both and you run out of gear very quickly. Also if you cruise on the freeway changing the R&P will increase your RPM and noise and can get annoying over time. If you are doing track work and are trying to optimize for a specific track you should be looking at gears in any event.

 

what about just changing 3rd and 4th gear sets?

the problem I see is that 4th is useless as it's too close to the other 'overdrive gear' to 3rd. for the money, wouldn't it make more sense to buy a new 3rd gearset... more like 1.00:1 ratio... and push the original 3rd into the 4th position? I think you spin about 600 rpm higher at 75 that way instead of the original 4th. NBD

it seems to me an 8:39 (4.875:1) buys nothing. quickness... maybe, but still the same 'fall off boost thing' happens between 2nd and 3rd, and you run out of gears sooner.

 

Would you mind providing some pics and part numbers for your Andial 8.39? I have a unit sitting on my bench for which I am trying to verify its origin and application.

Thanks![/QUOTE]

 

Here' s a shot of the data on the ring gear.

 

Tom -

Thanks a million that was exactly what I was looking for. It looks like I have the same unit (at least per the part number... 930.302.111.01). Do you have any idea what the other numbers represent? The only difference in the numbers on my unit and yours is that where yours pinion has 2/1007/13 mine has 2/1007/09 and where your ing gear has 2/1010/24, mine has 2/1010/07.

If anyone knows the significance of these numbers I would be HUGELY appreciative.

Regards,

 

A postscript. The 8:39 R&P rocks. It is just right for a Turbo that you're going to drive around. Might not be right for a track car, but I haven't looked at that situation closely.

The combination of SC cams, post 86 exhaust and Euro muffler, K27-7200 and the 8:39 makes for a great combination in an early Turbo 3.0.

I am still looking for advice on the right advance curve and timing settings for the ignition distributor. What are people using for a CO setting at idle on a stock fuel unit with the other mods I've made? I've got it a 3.1%, but I feel that it's running on the rich side.

 

R & P .. 935's run either a 8:37 or an 8:41 with a titanium spool..I have never broken one... 700-825HP depending on the dial... my GT1R car makes over 600HP and runs a flipped 1976 short bellhousing turbo 4 speed with a 9:38 and I have broken one of those...I don't think strength of any of the ring and pinions is a concern . I have broken numerous Quiaffe LTDs in my GT1R car...Quaiffe always replaced them for free and were great to deal with..but I ended up going with a Guard GT LTD and no problems... the gears for a 935 or 930 are basically the same...racing sets are lightened but the real differnce is in the 1-2 nd and 3-4th slider, dog teeth . Real 935 sliders are very expensive and is better than a standard 930 peice...though I run the 930 sliders in one of my 935's with no problem and no real noticable difference in shifting . When using a turbo 4 speed for street and strip this is where the problem begins..basically we set our box up like there is no first gear...75-85mph 1st gear..usually an IX or 18:33 ..and then gear the car from there..but unless you are driving a short track it may be difficult to find a usable set up for street and track. If it is a short track then you can keep your stock 1st and spend about 600 a gear set for 2,3,4th . But if you are in there you may as well put in new sliders , syncros etc..but if your parts are in good ondition you may be able to re use them...then you could re gear your car for less than 2k if you do it yourself.
If you are going to switch to a 5 speed use a G50/50 .

 

Thought I would try one more time to see if anyone can decode the numbers on these parts.

Thanks!

 

Sorry, I never learned what the numbers mean.

 

Brent 930,
I agree that in today's world the four-speed rock crusher tranny isn't a good track box. But, in its day it was the best. Reliable and strong, it would bring you home after 3, 4, 6, 12,or 24 hours. It wasn't the fastest shifting box in the world, partially due to Porsche's insistence on running synchros in their racing boxes. Made it easier on the driver to shift, but wasn't as quick as a pure heel-toe match the revs and cram it in box. However, the wicked torque of the 93X series racers more than made up for the few milli-seconds extra you were taking to shift. I actually enjoy the four-speed. Around town you can leave it in second or third and just drive it. First I only use to get it rolling, and fourth I use very rarely unless of course I'm on the highway. Once you learn your box's idiosynchrosies, its really a pretty smooth beast. Obviously, the G50 was a great evolutionary improvement over the old 930 tranny, but after almost 21-years of continuous service I love that old four-speed.