since v8's don't use 1st, and second is not interchangeable.

what is the latest thinking on the best gears for 3,4,5 ??

stock is ok - but @ 3000-3500 rpms at @ 65 mph - really sucks the gas : ((

jim

I can't help you on 3, 4, 5 but I can mention that 2nd is kinda interchangeable...
914.6 (GA) 2nd is a bit taller.
IIRC there are some other 2nd's that are even a bit taller than GA.
Yes - you have to change the whole mainshaft, but if you're changing 3, 4, 5 you have the stack apart anyway...

replace 5th with new gear,. move 5th to 4th, 4th to 3rd, toss the 3rd gear out keep 2nd and 1st as stock. 1 st can be used when creeping around a parking lot, it still has a use.

so esentially you will have 1, 2 4, 5 and new top gear

I have a GA set in the shop. It's F/S ( 400bucks, OBO) in very nice shape.....that means you can just slap it in with no repairs.

I have a gear set that I'm about to toss up for sale which is the sought after top gear

Is it H or Z (or is that HZ?)? or are they both worth about the same?

what kind fo ratio will that give for top gear? or what rpm will the motor be at with stock tires at freeway speed (say 70 mph or so?)

I am looking for a better gearing for my Buick powered 914

thanks

http://forums.pelicanparts.com/porsche-911...calculator.html

aaron's chart
http://www.914world.com/bbs2/index.php?aut...ach&id=1795

Jim,
When I rebuilt my 901 at DR. Evils So. clinic I had purchased an H gear for the rebuild and my intention was to move the gears around as suggested earlier. Mike talked me out of it...anyway just installed the H. Very happy with the results. 70mph with my 16 245 wheels dropped 700 rpm from stock 5th gear--great for freeway cruising.

The PO of my car re-geared my trannny. Not sure what gears he used but at 3200rpm the cr does 85mph with 245/45/16 on the rear

I did the same as Mark. I ust replaced my 5th with an "h" gear. I unfortunately haven't had the opportunity to use mine. Motor is still out for a couple months. I'll report on it when I actually get to use it

Jeez! $400 for a GA set? I wish I could get that much for them, I have had a few.

There are a few options, all depend on money.

1) Put an H in 5th and call it a day. Easy, fairly inexpensive (compared to other options).

2) 904 main shaft and any 2nd gear set you want to dick with (min $1800 for the shaft alone. Chris Foley may make you one for less, but then you still need to buy the gears for about $400 a set).

3) Find the correct sporto tranz and use the r/p out of it as it is a shorter one that will drop RPM in all gears. I have an incorrect one (wont work as a direct fit in a 901), and I think I know how I can make it work using a 912 intermediate plate to bring the pinon into the diff a little more (PM me if you want to be a guinea pig).

The rest is a colossal waste of time. You will not do better than a flipped H in 5th in a stock transmission.

The gears that Mark was talking about are probably a Z gear which is a stock 5th in a /6 box. The $400 GA set is a stock 2nd in a /6 box and not that rare, IMHO.

It's not a bad price for a mainshaft and a gear, if you need a mainshaft.

I think most of us would call that 'taller' but no matter...


stock /6 top is ZA (/4 is ZD)

Another but not immediate option is that Guard Transmission is finally making 901 gears. Tell Matt what you want and when demand reaches cost to supply, it can happen. The advantage of this approach is that you can finally have a 'flipped H' ratio with the correct helix.

When I said /6 I meant 911/6. So, a 911 901 box. Geez, Rich, busting my balls much? You see how coherent you are at 0320

In the midst of a 215 v8 conversion and those sound like the gears I will need. Tried my best to find a way to attend Dr. Evil's upcoming clinic in Denver but just can't make it happen. I'm hoping that the DVD that will be available shortly will be enough to guide me through the process. What do you need $$$ to part with those gear(s)?

here: Charlie White's Gear Page is a chart of all the ratios for all the boxes.

H is nominally a 3rd gear that can be flipped (drive gear becomes driven gear) so 19:32 becomes 32:19. H is actually the shortest 3rd which means it becomes the tallest top when flipped - unless you want to get into the 2nd (E, F, and G-series) gears. But those are really rare (motorsports) items since interchangeable 2nds means a 904 mainshaft (bring $$$).

You could consider flipping a first gearset but the tallest of those (D) is 16:35 which would be 35:16 flipped and REALLY tall - like Diesel territory... (if the stock /4 ZD top is ~.7 a flipped D would be .45...)

H really is about as good as it gets in a 901 box... You can look around for a GB set but it'd be quite the coup to snag one...

so is teh H gear simply teh third gear turned backwards? i heard that a 911 style tranny was the source of the gear needed, can teh 914 tranny third gear be turned backwards in place of fifth, will that result in the correct fifth to lower rpms for a larger motor?


thnaks

Have a look at the link I posted - all the answers are there.

H is _a_ 3rd gear turned backwards. It is not from any 914 (4 or 6). So yes - it will have come from a 911/912/Motorsports bin.

A 914 3rd gear (4 or 6) flipped won't gain you much - they're at the 'tall' end of the available 3rd gears and are pretty close to 1:1. In fact, a flipped 914/4 3rd is actually shorter than the stock 5th - so that's the wrong direction...

Thanks that is the info I need. i guess I need to find a used 911 / 912 tranny now to get the gear. That is a four speed tranny right? any particular year models to look for to find the H gear?

This will have to be your research project - I can't be doing your homework for you...

Find or buy a copy of PET/ETKA. It has all the part numbers and all of the applications for all of the production cars.

'H' could have been a 4-speed or 5-speed transmission gear. It might have been a 'special order' or Porsche Motorsports gear. (I just don't know, and I have no reason to research it.) Now that you know what you're looking for, search here. This topic has come up before, including sources for vintage parts.