924Board.org

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

It is known that the "Audi" gearboxes in our 924s are almost identical to today's Audi A4 and perhaps also A6 models.

i've personaly seen an 2002 Audi A4 gearbox and it would fit a 924 NA(small diameter input shaft)

now...there are high end A4s and A6s that do high cruising speeds like 140Km/h @ 2800 RPM.
These are mainly diesel powered cars but i think the gearboxes are the same...maybe just a bit more beefed up compared to the ones on regular gas cars.

The problem i'm trying to solve now is that if i want to do 140 on the highway i'm forced to run at 4000+ RPM. That ruins mileage and makes for a noisy ride in the 924.

My ideea is to take the 5th gear pinion and syncro from the A4/A6 gearbox and put it into the 931 audi gearbox.
The result would be a fast 931...but with a high speed cruising capability and i'm quite sure higher top speed.

Does anybody have the possibility to check/try/investigate this ?
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RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Interesting idea Morghen, can understand your reasoning. Can`t offer any help though, know bugger all about interchangeability on the manual boxes and nothing whatsoever about A4 or A6 boxes. Wouldn`t mind seeing a pic of one if you can post it.

Is the 944 or 951 tranny that has the tall 5th gear, that racers especially don` want. Might be worthwhile going through the ratio charts. Also what is your (Euro) final drive ratio? Is there lower ratio ring/pinion sets that may change over from other trannys. Sure it will affect all gears a little but be most noticeable in top. Will give a broader spread between all gears that may or may not be an improvement, particularly between 1 & 2.

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

i will try to get some pics of the A4 and 924 gearbox side by side.

i have no ideea about the final drive ratio...however i'm not happy with the current 944NA gearbox...this gearbox sucks big time.
For city driving you have to revup to 3000-3500 just to keep up with diesel trafic. i dont like noisy revvy driving in the city....i want taller gears for the city driving and not only.
Also...for cruising and driving outside the city...yea its fast like a rocket but top speed is only about 220-230 and the much wanted 140 is only after 4000RPM....that is too noisy for long journeys.
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9XX Girl! · Posted: Thu Jul 01, 2010 5:23 am Post subject:

Ideola had a gearing calculator spread sheet on his website but i can't seem to get it to download http://garage.ideola.com/downloads.html

mine will do 90mph (145km/h) in 5th @ 3500 and still pull more. This is with an increased rear wheel diameter of 662mm instead of the stock 614mm.
Ok bigger rear wheels make all the gears taller but i would like to think there would be enough toque in a 924 N/A to make it work morghen let alone a 931. In theory, with my tyre sizes it should reach 148mph (237km/h) at red line,,,,, but as being caught speeding over 100mph in the UK results in a ban from driving, i cannot afford to test it.
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

145 at 3500 ?

what gearbox is that....snailshell or ?

the diameter on my wheels is 627mm
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9XX Girl! · Posted: Thu Jul 01, 2010 6:14 am Post subject:

zimm · Joined: 18 Oct 2006 Posts: 62 Location: Hereford, UK.

90ish mph @ ~4000rpm on stock tyres sounds about right for both my NA's, my 944, and my 932

what transaxle is in yours morghen ?

click below for spreadsheet

http://garage.ideola.com/downloads/PorscheTrans1.xls
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6 bikes, 9 cars, 1 van.... the more you have the less they work.

9XX Girl! · Posted: Thu Jul 01, 2010 6:48 am Post subject:

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

i use an early 944 NA gearbox....but its too short for the 931.
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9XX Girl! · Posted: Thu Jul 01, 2010 7:11 am Post subject:

Ok i can get it on Internet Explorer and Safari but not Firefox

So... if i type my tyre size into cells B5 C5 D5 on Dans spread sheet. (255/50/16), 3500 rpm gives me 90.94mph (145.504km/h). Cell F52
5500 rpm is 168.88 mph

ouch... i want to go there....
So how do i workout what gearbox i have?????
_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Paula, most likely your problem is related to the cache in your Firefox browser. If you had an aborted download attempt from a previous session, the incomplete file will be in your cache. You can force your browser to fetch a new copy by shift-clicking the reload button. There's nothing magical or special going on on that download page that would prevent Firefox or any other browser from getting to the file, so it has to be a local browser issue.

And for the record, I can't take credit for the spreadsheet. Applebit put it together.
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erstwhile owner of just about every 924 variant ever made

9XX Girl! · Posted: Thu Jul 01, 2010 8:11 am Post subject:

Thanks Dan & triple thanks Applebit

all that work in Excel given away for free

_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

So...a guy who opened both the A4 box and the 924 box said they are different inside and you could not use the 5th gear from one to another.

but...he swears that the 6 speed A4 1.8Turbo gearbox fits the 924/944
He said he can get me one of those 6 speed gearboxes to look at and if i want it i can buy one.

that would be great...6 speed on a 924

1900 RPM at 62mph and @100mph at 3000RPM
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rat · Posted: Sun Jul 11, 2010 8:28 pm Post subject:

I'd love a 6 speed with that taller top in all my cars. I'm an old man at heart despite my real age.. Just need a tweed cap.

Just the case of time and money..

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

well i've looked for a 6 speed before...from a 968..but the best price i could get was 1700 euro + shipping.
I think a 6 speed from an A4 would be much cheaper and easy to find.
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