Broken G50s

[Stage7]

Hello,

I'm trying to decide what to do with my G50 considering my power goals (greater than 700hp, and 600tq). Since the Ultima's probably have the longest history w/modded G50s running higher than originally intended power, along with being lighter than intended weight, I was hoping to get an informal poll of broken G50s.

If you've broken your G50, can you post:

1) Your power levels, and engine mods.

2) The g50 mods (was it rebuilt-what options, etc).

3) What exactly broke.

4) What were you doing when it broke?

5) What version g50 was it? (g50/50, g50/20, 5spd, 6spd, etc)

[738 driver]

This isn't really the type of answer you were looking for but IMO its how you drive or your level of mechanical sympathy combined with the units previous history, that contribute to failures.

There are some owners who like to leave their car in top gear at 30-40 mph, floor their several hundred HP and ft/lbs and expect their box to live a long and trouble free life! The gearbox is just a torque multiplier and should be used as such. If you dont like the clutch and gearstick, fit an auto box. Also not fully knowing the units past life does not assist, if its already had 120'000 miles of Porker abuse before being resprayed and sold on for Ult use, it might not be in the best health to handle a big capacity upgrade !!

Edited by 738 driver on Monday 31st May 21:09

[Steve_D]

738 driver said:

......IMO its how you drive or how much mechanical sympathy combined with the units previous history that contributes to many failures........

Agree with this principle but in support of the OPs question I am not aware of many Ultima owners who have reported lunching their 'box.

Jeff puts 1003HP through his. I believe it may be the later G96(?) and may have had some internal upgrades but all a deal away from some of the exotic 'boxes around.

Steve

[DHGTR]

Have to agree with Steve.
I've been hanging around here for 6/7 years now and off the top of my head, can't remember an owner reporting the gearbox dying.

Dave

[andygtt]

If you want to run that level of torque and use it a lot you will need the big diff version of the G50 (G50/50 or G50/52 or the GT2/3's) and it will need to be fully reconditioned (i.e. not a 120k miler)... Remember though that the Ultima is light, so with a little mechanical sypathy its very reliable

[Stage7]

Thanks for the replies so far. They are helpful as most of the info/recommendations have minimal real world experience behind them. The Ultima community has the longest running real world experience running the g50s in various builds/power levels/duties.

I'm building a FF GTM which will be ~2400lbs completed.

I have a g50/20 6spd that had 28k original miles prior to being rebuilt w/steel synchros, forks,and Kaz lsd, etc.

My motor is a LS based 468ci with 750+hp,and over 600lbs of torque. However it will be street driven (legal speeds,lol) 99% of the time. With 1 to 3 trips a year to either a hpde day, or drag strip w/street tires.

If I decide keep the g50, I'll add a billet side plate to help ring/pinion deflection, but otherwise just enjoy it sensibly.

Please keep the replies coming. I appreciate it!

[738 driver]

468 is a good sized LS donkey.............tall deck LSx block ?

[Stage7]

738 driver said:

468 is a good sized LS donkey.............tall deck LSx block ?

ERL Superdeck block (standard height deck). Longer sleeves to accomodate a 4.250" stroke with a 4.185 bore. The piston was custom designed by HKE Racing(Erik Koenig). They also of course built the whole long block. I was going to put it in my C6, but the gtm came along.

[738 driver]

Very nice, great all round project.

[Stage7]

Thank you. I've always loved the Ultima as well. Incredible automobile. It really raised the bar.

[ezakimak]

DHGTR said:

Have to agree with Steve.
I've been hanging around here for 6/7 years now and off the top of my head, can't remember an owner reporting the gearbox dying.

Dave

ill second that, i can only remember a 930 turbo box (i think?) where the flywheel/clutch let go taking out the case and chassis rail.

there was also one of the 996 versions of the porsche box that had some issues, might have been a synchro cant remember.

other than that i cant remember of any other failures being reported.

[Gulf LS3]

Steve_D said:

738 driver said:

......IMO its how you drive or how much mechanical sympathy combined with the units previous history that contributes to many failures........

Agree with this principle but in support of the OPs question I am not aware of many Ultima owners who have reported lunching their 'box.

Jeff puts 1003HP through his. I believe it may be the later G96(?) and may have had some internal upgrades but all a deal away from some of the exotic 'boxes around.

Steve

Ive seen 3 damaged boxes.... one was apperently completely destroyed by a 700bhp sbc!!

The other was destroyed by a less powerful engine but it appeared the crown wheel had not seen a great deal of oil.

I have a broken G50 at the workshop at the moment but we have not checked inside as yet.

[ezakimak]

may be of interest

http://www.racetechmag.com/articles/article.php?id...