G50/50 - G50/01/02 ??

[Paul Thompson 'Hooligan']

Hi all -

I am looking to possibly fit a Porsche trans shortly and have no prior knowledge of such units.

I have read several things, including that the G50/50 is the unit to use, but is rare and is more suited to high speed endurance type events.

Now, on speaking to another chap whom I hold in high regard on all things Porsche, he suggested a G50 '01' or '02' unit, but to install new selected ratios and stainless race synchro's (all available from Porsche racing specialists) and have all shot peened to relieve stress. Whilst not absolutely bomb proof (what is?) - he said it is very good value, about £3.5K - £4.5K and more suited to intended use. (car is 2150lb GTD with 560ish BHP / 540ft/lb max 6200rpm - trackdays with 30 min sessions + sprints / hillclimbs)... He did also say that shifts are 'slow' though ? and should never be 'forced' as that is what destroys the units - fair comment I guess?

Any additional opinions, comments from the community would be much appreciated.

Thanks

(I also still like the idea of the ZFQ or possibly DG500...££ ££)

 

[Russ Noble]

Paul,

From research that I have done I would not be comfortable using a G50/0x with 540 tq in competition driving.

The G50/52 is more plentiful than the G50/50. Exactly the same box but with a longer mount which can be shortened or swapped out.

IMHO first gear in the G50 trans is too low to be useful in competition, even regeared. So, since you then effectively have a 4 speed box, why not seriously consider the 930 which is stronger and cheaper? And has a better first and about the same top.

If you're worried about slow shifting and are going to regear anyway, it is not a lot dearer to convert to dog box for the slickest shifting you can get. Check out Albins. There is a link to them in this thread which should give you quite a bit of background too. http://www.gt40s.com/forum/gt40-tech-powertrain-transaxles/16212-porsche-g50-info.html

Cheers,

 

[Paul Thompson 'Hooligan']

Thanks Russ -

lots of reading for me now....!

 

[JohnC]

Paul, you should speak with Roger Brown - he's now with California Motor Sports, and they have a new website: California Motorsports - Porsche transaxles, gears, differentials, parts and service with all their contact information.

Roger is very good about corresponding by email if you don't care to run up a transatlantic telephone bill.

They're currently building a G50/52 for me with a longer 2.62 1st gear and a 3.44 final which should result in a much more usable 1st & 2nd, and at 70 mph, in 5th I'll only be turning around 2500 RPM. My goal was to have useable ratios for a street driven car.

Best,

John

 

[Peter Delaney]

Paul & Russ, a quick word of warning on Albins. In order to hopefully avoid any libel actions, I'll just state the facts :

- Stock old '87 G50 sent to Albins for a rebuild (anything wrong - fix it, new synchros, higher ratio 5th gear set).

- After some weeks of chasing, got the box back & stupidly installed it in straight the car - no 2nd gear selectable (should have checked before re-installing it) & a huge whine in the new 5th gear set.

- Removed box & sent it back to Albins :
- Oops, terribly sorry, but we put the 2nd gear synchro ring 1/3 of a turn out & somehow never got around to testing it - will fix & return

- Noisy 5th gear ? : We've only had 1 in 100 with that problem - unfortunately, we have no others in stock & won't be doing another run for some months. But when we have a set, we'll send one up to you.

- Reinstalled box, put up with the 5th gear whine, hugely unimpressed with the rest of it :
- Chronically slow shifting 1st to 2nd & 3rd to 2nd (specially when cold)
(I think a g'box oil heater is preferable to a cooler for this one) !!
- Bucket loads of lash - totally ignored in the rebuild
- 2-3mm of free end-play in the LHS drive flange => clunking as the
suspension works & the friction in the drive shaft splines shove the
drive shaft in & out - again, ignored in the rebuild

- Replacement 5th gear set arrives months & months later - having totally lost faith in Albins, I finally found a local guy who specialises in Porsche boxes & will he do another rebuild & try the new 5th gear set at the end of June.

So as you can see, I am not too happy (but then, I have refined the art of g'box R&R - a skill that probably will come in handy in the future) !!

Kind Regards,

Peter D.

 

[Paul Thompson 'Hooligan']

again.... thanks guys........all useful info...

 

[Paul Thompson 'Hooligan']

again.... thanks guys........all useful info...

 

[Frank Catt]

Paul, why not consider the new ZFQ, Porsche gears in a ZF size and look caseing.

 

[Paul Thompson 'Hooligan']

It's on the shortlist and I'll be having a look at any possible installation issues next Monday...

So is a Hewland DG500.....

 

[Russ Noble]

Paul, DG500? DG300, LG500?

DG300 too weak, constant source of agro in F5000's.

LG500, 4 speed, plenty strong and LG600 5speed version. All dog boxes. Best box is the LG600 Mk2. With all these boxes watch for corrosion of the magnesium cases. Rot from the inside out, I believe. Do a search on here on LG600. I'm sure Richard Timte had some info. Pretty expensive though. But way cool, also homologated original fitment. Used by Paul Hawkins in AMGT2.

Bang for buck dogbox? 930 with dog gears. Secondhand 930LSD rebuilder approx USD2000 Albins dog gear kit, your choice of ratios , selector forks etc approx AUD6000. Then put it all together.

I know Peter Delaney had trouble with Albins but in your case any dog box is going to be noisy. Put it together yourself or get your local trusted specialist to do it.

Cheers

 

[Jac Mac]

Paul, why not consider the new ZFQ, Porsche gears in a ZF size and look caseing.

So is the ZFQ, to put it simply, a ZF style housing redesigned to accomodate porsche gears? I have not read any reference to this in the ZFQ thread.

Jac Mac