An interesting G50 transaxle approach

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Bill Bayard

For those builders thinking if using a G50 there's one currently for sale on ebay that you should check out. The seller has machined the front of the bellhousing completely off, shortening it by quite a bit(3"+). It is mated to a Chevy small block, uses a standard Chevy starter/flywheel, and the Porsche clutch disc. This approach would very likely allow the fitment of a Porsche 6spd in a GT40, if somebody was so inclined. Another option(maybe), since G50/50s & G50/52s are becoming as rare as rocking horse poop. Even regular old G50s are nowhere near as common as they were just a few years ago. Second hand Porsche 6spds aren't prohibitively expensive either.

Disclaimer: I ain't guaranteein' nothin'! /ubbthreads/images/graemlins/wink.gif

Just a thought.

eBay Item #Z8048612146QQ

BTW, this gearbox has an LSD, and could be fit to a SBF very easily(see disclaimer above! /ubbthreads/images/graemlins/wink.gif ). Current bid is only $1000.



Bill
 
R

Davey

Hi, I too saw the Chevy / G50 transaxle. I emailed the guy "Hank" just helpful and he put me in touch with another chap who's doing a SBF to a G50, in Canada. I am planning to go this way too.
I have some photo's of the 2nd guys attempt, haven't worked out how to post them yet...
Any opion on using a G50-20 transaxle...??
Regards Dave
 
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Russ Noble

GT40s Supporter
Lifetime Supporter
[ QUOTE ]
Any opion on using a G50-20 transaxle...??

[/ QUOTE ]

If you do a search on here you will find quite a bit of info. Also references to them being prone to failure. At one stage I was considering a 6 speed G50.First gear is too low for me but the remaining 5 give quite reasonable ratios and a more desirable effective dogleg first (second). But the perceived weakness of them put me off. I believe the trans weighs about the same as the five speed and some of that is achieved by lighter castings. I decided against the five speed also because I couldn't get a high enough first gear for that either, so that would have wound up being an effective four speed with (I think) a dogleg top gear. It was better to go with the 930 four speed because I can get the right first gear for it and it is also heaps stronger. 235mm crown wheel as opposed to G50/5x 215 and G50/0x 190. Be interesting to know the comparative gear shaft spacings on these boxes and which r&p the 6 speeds use. Maybe Eric can chime in here.

/ubbthreads/images/graemlins/twocents.gif

Regards
 
E

"Be interesting to know the comparative gear shaft spacings on these boxes"
I'm curious what it is you are talking about, I can go measure whatever.
Rekab, I'm the one you have been talking to. I'm sure the pics are already on here but that was a long time ago.
As for strength and weight, the g50-20 uses the 190mm ring gear, same as any normal g50 so I suspect it is just as strong. Compare it to an Audi ring and pinion and it dwarfs the thing. From talking to powerhaus, the 5 and 6spd share the same bellhousing, diff and center section. There is so little extra parts for the 6spd I wouldnt imagine the weight difference is more than 15lbs, all they did was add 2" to the shafts, added the gears and lengthened the last housing.
 
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Russ Noble

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Eric,

I think it is generally accepted that one of the factors that governs the strength of a gearbox is the shaft centre distance. In this case the distance between the pinion shaft and the input shaft. Since posting I have done some further reading and it would appear the measurement for the G50 is 85mm, the earlier 915 was 76mm. I don't know what a 930 is, but I have one here and I will measure and post when I get around to stripping it. I suspect it will be 85mm also. Not that the actual gearbox is the weak point, it is the ring and pinion and the 930 wins hands down here. 235mm equals 9" same as T44. Wonder what the shaft centre distance is on the T44?

Whilst some trans have other inherent weaknesses like puny input shafts, these can always be beefed up but you are still limited by the basic design ie r&p diameter and shaft centre distance. So comparing these is a good way to get a basic comparison between makes or models. /ubbthreads/images/graemlins/twocents.gif

Regards
 
R

Russ Noble

GT40s Supporter
Lifetime Supporter
Hey jack, not wishing to have you inundated with the smoking chequebooks again but for the sake of adding information to this thread could you post the shaft centre distance for those T44's you're building /ubbthreads/images/graemlins/smirk.gif /ubbthreads/images/graemlins/beerchug.gif

Thanks
 
E

I messed up my back and cant lift the tranny to pop the cover off and get an exact measurement but measuring the tail housing, it measures approx 85-90mm. I am 99% sure the later 5 and 6 spd used the exact same cases so I guess the 85mm is right.
 
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Russ Noble

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Thanks Eric,
I think the problem with the later 6 speeds is that none of them come out with the 210mm r&p but I could be wrong. Anyone know for sure whether the turbo 6 speeds had the 210mm r&p? Can anyone check if the part # is the same?

Regards
 
D

dale

A friend of mine purchased this g50. it is done right and is nice piece of work, it will be going in a valkyrie
 
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BruceA

Useless bit of Information Post

I just measured the crownwheel of the Renault Un1-13 (21 Turbo) and the 369 gearboxes and they are both 190mm. Difference is the 21T CW is 8mm thicker than the 369 box. (3.44 and 3.89 FD)
The shaft centres are 76mm.

Of course you always wanted to know these things.
 
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Russ Noble

GT40s Supporter
Lifetime Supporter
Hi RamboLambo.

The more comparative data that can be compiled as a reference the better so that anyone can base more informed decisions on transaxle basics.
The difference in thickness of the crown wheel is not a strength issue . In the same housing, the thicker ring gear accomodates the smaller diameter of the pinion with less teeth. ie lower geared (higher numerical ratio)

BTW jack (now shown on here as jac mac) has just informed me that the T44/toploader shaft distance is 3.18' or approx 81mm As a comparison he also mentions that the T10 and Richmond 5/6 speed (not transaxles) are 3.25" and 3.5" respectively.

Still haven't pulled the back off to measure my 930!

Regards,

Russ
 
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Russ Noble

GT40s Supporter
Lifetime Supporter
Russ Noble said:
Eric,

I think it is generally accepted that one of the factors that governs the strength of a gearbox is the shaft centre distance. In this case the distance between the pinion shaft and the input shaft. Since posting I have done some further reading and it would appear the measurement for the G50 is 85mm, the earlier 915 was 76mm. I don't know what a 930 is, but I have one here and I will measure and post when I get around to stripping it. I suspect it will be 85mm also. Not that the actual gearbox is the weak point, it is the ring and pinion and the 930 wins hands down here. 235mm equals 9" same as T44. Wonder what the shaft centre distance is on the T44?

Whilst some trans have other inherent weaknesses like puny input shafts, these can always be beefed up but you are still limited by the basic design ie r&p diameter and shaft centre distance. So comparing these is a good way to get a basic comparison between makes or models. /ubbthreads/images/graemlins/twocents.gif

Regards
Click to expand...

Well I've just got round to starting to strip my 930. Shaft centres are 76mm same as 915 and UN1-13. I think that's just scarpered any ideas I might have had about only spraying the r&p. I think the gearsets might also be worth doing oil feeds now. Wow that's a surprise! With the G50 listed at 85mm it must be the r&p that makes the 930 reputedly the stronger trans. My good mate Lims G50/52 should arrive from the States in a month or so. Will confirm G50/5x measurements when it arrives. Interesting.........

Got to go out to the workshop and have a cleanup before spreading any more 930 parts all over the floor!

Wish me luck!
 
M

Mark Worthington

How did I miss this thread earlier? There's some good tech in here. I can measure one of the Audi 01E boxes down in my basement this weekend. How exactly do you measure the ring gear? Is it the distance across from the outside of the teeth?
 
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Russ Noble

GT40s Supporter
Lifetime Supporter
Mark.

Yep you got it! O/D of the teeth. Can you do the shaft spacing too? Good to add all this info.

Cheers
 
J

jmracecar

That is true except for the turbo. The 993 Turbo 6-speed G64/51 has the 215mm (210? 215?) diam ring gear. If you convert one to a 2wd version by hacking off the stub at the other end of the pinion gear, use the 2wd end cover, and put in steel syncros, the result is close to a G50/54.

For all the rest of the 993 6-speeds, you are correct, they have the 190mm ring gear. That goes for the G50/20 and /21, as well as the C4 version G64/20 & /21. Conversion of those to 2wd is the same as the turbo, but you still have the small ring gear and bellhousing (in the diff section).

Russ Noble said:
Thanks Eric,
I think the problem with the later 6 speeds is that none of them come out with the 210mm r&p but I could be wrong. Anyone know for sure whether the turbo 6 speeds had the 210mm r&p? Can anyone check if the part # is the same?

Regards
Click to expand...
 
R

Russ Noble

GT40s Supporter
Lifetime Supporter
jmracecar said:
That is true except for the turbo. The 993 Turbo 6-speed G64/51 has the 215mm (210? 215?) diam ring gear. If you convert one to a 2wd version by hacking off the stub at the other end of the pinion gear, use the 2wd end cover, and put in steel syncros, the result is close to a G50/54.

For all the rest of the 993 6-speeds, you are correct, they have the 190mm ring gear. That goes for the G50/20 and /21, as well as the C4 version G64/20 & /21. Conversion of those to 2wd is the same as the turbo, but you still have the small ring gear and bellhousing (in the diff section).
Click to expand...

Good info Joel. We're slowly getting the jigsaw together.

So it would appear the 6 speed G50/54 and a chopped G64/51 would be as good as a G50/5x strengthwise. I'm sure accomodating the extra length in a GT40 is not as insuperable as many people seem to think, since it's all out the back.

Maybe a slight mod to the bottom of the rear clip. You probably wouldn't notice it unless you got down on your hands and knees!

To all you guys who've GOT to have a 6 speed, you now know which one to get.

Thanks Joel
 
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