930 ratios

[Steve C]

Hi

Not sure about the typo, I received the information from a Porsche wrecker. Im nearly sold on going for the 4 speed 930 box. The are about $4500 down here, a G50 would be nice but they run about $9000. The 930 ratios are not ideal but Im not racing for sheep stations so I will take strenght over ideal ratios.

Does anyone know the shift pattern on the 4 speed 930 box as in where is reverse?

Steve

[GS guy]

930 - Ultimate strength. According to the V8-914 guys, the perfect ratios for a V8 car.

Did an interesting comparo - plotted both the 914 and WRX ratios on my Excel spreadsheet gear ratio calculator. Since I'm coupling the WRX motor to the 914 trans, I'm interested to see how the two trannies compare ratio-wise, and in particular interested to know how well the combo "loads" the turbo to make boost.
Turns out, first gears are all but identical. All the other ratios progressively drift slightly wider apart as you go up through the gears. The 914 ratios provide a slightly closer ratio gear spacing than the WRX, to the tune of about a 200RPM difference between 5th gears @ 70mph (with my 255/45-17 rear tire size). Overall, the 914 box just looks like a slightly closer ratio WRX trans. It should work well behind the WRX powerplant! I'm only planning to tune the motor to around 250hp or so, which should be adequate since the whole vehicle should weigh in ~ 1400lbs.

Steve, I haven't read any info regarding any "undesirable" aspects of the 930 shift pattern (unlike the 901/914), so I'm guessing it's a standard H. Don't know about reverse location. Plotting the 930 ratios, darned if they (the 2/3/4 gears) don't nearly fall right on top of the 3/4/5 ratios of the WRX trans, with only a very slight taller ratio on the 930 4th compared to the WRX 5th. The 930 1st is a near dead split between the WRX 1st & 2nd. Interesting..
Jeff

[Steve C]

Hi

Thats interesting about the ratios, if you want a quick gear calculator go here http://home.earthlink.net/~jalby/gears.htm and some inbtersting stuff about the 930 box http://www.mechtech-ms.com/html/sswinter.html

Im just thinking if I can modify a stock bug shifter the work the 930 box.

Steve

[Steve C]

Hi

Found some G50 ratios

1st: 3.5
2nd: 2.05
3rd: 1.4
4th: 1.074
5th: .861 > 1987 & .868 1988 >
R&P: 3.44

Steve

[Bruce2]

Originally Posted by Steve C

Im nearly sold on going for the 4 speed 930 box.

You are about to make a huge mistake. Go back up and look at the gear ratios.
1st in the 930 'box is almost the same as a stock VW 2nd gear.
2nd in the P 'box is almost the same as stock VW 3rd, and
3rd is exactly the same as stock VW 4th.
The R&P is also very close to stock.
Short of a large displacement V8 or a big boost turbo'd 6cyl, nothing you can put in your car will work with that gearing.

[Steve C]

Hi Bruce

Thanks for your input. I just don’t know what else to use, I’m told the 915 box is still fragile and the G50 is very expensive. I'm going to price some ratio gear sets for the 930 box I might loctated one for a good price with an LSD or I might just save a bit more and go G50. I've heard some good reports about Renault UN1 transmissions, but they seem to be a bit hard to find.


Steve

[71superbug]

steve. its anthony from AVD,

9000 for a g50?


when i rang chellingworth porsche over here in perth (new porsche dealer). they gave me a number of a guy in perth that sells the boxes..and i got told 5000 for a used g50 5 speed.


also, i looked into the renault boxes as that is probably the one i will use
for my 13bt conversion. the UN1 is not bad..but go the UN5. apparently a stronger box. guys over here in perth use them a fair bit for offroad racing. diff is not LS but is a solid chunk of billet. gears are about twice the size of a 6 rib 2L kombi box's. they are quite low geared though. 4.?? is what the final drive is.

but they would work fairly well. UN5 is stronger than UN1, 5 speed, but not as strong as a G50. but when looking into them. i spoke to a guy over here in perth thatbuilds off road racing boxes..and he told me the guy he gets them from imports the boxes..is over in nsw i think. not sure. but said he sells them for about $2000 used. which is why i decided to go the UN5 over the G50 or built 6 rib.

hope some of this helps you with your decision. U2U me or something andi will try get the contact details for the g50 and UN5 places that i got referred to.

Anthony

[Steve C]

Hi Anthony

I was quoted $9000 for LSD G50 by a wrecker over your way, different guy maybe, I bought a G50 from Peformance 9 in Melbourne, its a low milage 1988 Japanese box that was in a running car over here, I have been assured that its in good nick with no noises and shifts well. No one in the east deals with the reno boxes so that came to a dead end.

Steve

[71superbug]

it was definately a guy in the east that imports them all and sells them to diff places...


and you probably called swann porsche parts didnt you?


they are quite expensive for everything. i was referred to this other guy by chellingworth porsche.


anyway, tell me how the g50 goes...it would be no good for my turbo rotary application anyway. cos the gearing is too high. rotas need to be able to rev freely and quickly to make their power. i am following your project looks to be good. should be some big steps taken in my project pretty soon. should be buying a motor and all the other main aprts to start assembling finally. will be running the stockl ssp box for a while though....just hope it doesnt break


Anthony