Anyone change out only the R&P (930)?

[David]

Has anyone changed out just their R&P on a 930 tranny? If so, could it be done through the side cover?

PS, I'm not so sure about the new search system.

[David]

I guess the pinion shaft is one of the main shafts in the gearbox so would it need to be completely disassebled to change the pinion?

If so I guess I'm springing for a tranny rebuild. Mo $$$.

[David]

I called Pro Technik here in Houston. They said they would change the R&P and any syncros that need it for $1000 labor plus parts. There goes another grand but at least it's something I can take off my to do list.

[David]

The tranny is out (and clean ) and the $1000 is only for labor. Andial has the R&P for $1495, so I'll have them buy it from Andial and resell it to me.

They said they would probably have it together and apart 3 or 4 times to set the R&P. They figured about 10 hours.

[rw7810]

David - Whoa nellie......classic Pelicanite fever. Didn't this all start with i'm just going to do an oil change I wonder what the worst case of this fever is ever recorded. Might make for a good thread.

[dd74]

Not to defer from 125's question, but has anyone ever swapped a 5-speed transmission into a 930? I'm just a-wonderin'...

[john walker's workshop]

i've never seen a shim stack come with a new R+P. you're on your own setting them up. book time is actually about 10 hours and the installer should have the factory setup tools and a good supply of all the shims in various thicknesses. that's just the setup time on the R+P, not to rebuild the trans too.

[beepbeep]

Originally posted by dd74
Not to defer from 125's question, but has anyone ever swapped a 5-speed transmission into a 930? I'm just a-wonderin'...

Oh, you must be first person ever to contemplate something like that


Just kidding. There have been both 915 and G50 installations from begginning of time. G50 is good but requires coilovers and lot's of rebuildning. 915 is a quick hack that often breaks under 930 torque.

[Rob 930]

David,

With these costs, you might consider changing gears instead. It depends on what your goal is. But if you're buying a new R&P and going through the labor of getting to it (which means you'll be "rebuilding" the gearbox anyway), and then paying for 10 hours of labor just to have the R&P set up, that will buy you a bunch of new gears. If you change gears, you get to leave the 9:38 R&P in there, which is a good thing, because it's bulletprooof. The 8:39 and other short R&Ps aren't as strong. Each custom gear costs about $750 new, as I recall, but you can find some good used ones for less. And you may not need to change all four; it depends on what you're trying to accomplish. The "breakeven" will be at three new gears. That's approximately the cost of the R&P and labor to change the R&P. But if you spring for a fourth gear as well, you have the benefit of setting each one right where you want it, plus you can keep your 9:38. Just might be another option...

[David]

Rob, this had been suggested by another shop. The cost was close to $4000. The shop in Houston said the 8:39 would not be as forgiving as the 9:38 if there are any problems. If I just change gears, I would change all four.

Hummm... In a couple of hours my cost has gone from $1500 to $2500 to maybe $4000. I'm starting to wonder if I should have sold the 930 and bought a Carrera and a race car. Oh well you live once.

rw7810 (Bob), I'm pretty sure I've lost my mind at this point. My initial budget for this project was pretty high but now it's reaching ludicrous.

What the he!!, anyone have a G50/52 laying around?

[David]

Still thinking about this one. How difficult is it to change gears? Would changing gears require special tools (I work at a machine shop so I can make most tools) and do any shims need to be adjusted?

Wayne, how's that transmission book coming?

[drsimonwong]

I figured if each individual upgrade doesn't exceed the original overall budget for the entire car rebuild than I'm up......oh, hang on that's not right......:-)

[Rob 930]

David,

I'm not sure what that shop meant by "forgiving" when referring to the 8:39. Do you know?

Gear changes are a snap on the 930. It's the easiest transmission to work on (easier than the 901, 915, G50, etc.). The gears are all swappable -- none are tied to the mainshaft as with the 901 and 915. It's perhaps the best transmission choice for the DIY guy who wants to change gears or do other maintenance (except the R&P!). I bet, with the transmission on the bench, the whole stack could be changed in an hour. Maybe less.

You could change all four gears of course, but it may not be necessary. What are your goals for the car ? (I know you and I have talked about this, but I forgot.) With as much power as you'll be producing, I question the sanity of lowering 1st gear very much (as would happen with the 8:39). It will just be a lesson in wheelspin.

It could be that you could "center" your gearing around the stock 2nd gear, which I did. With stock 4 speed gearing in a track car, I disliked the too-short first gear, the gap between gears, and the excessively high 4th gear that I'd never be able to use. So I made a close-ratio "active" 4 speed, where first gear is a very tall racing gear. I raised 1st and lowered 3rd and 4th to optimize for the track. Probably not what you want. But there are other options.

I've heard of people leaving 1st alone, lowering second and third, and putting their 3rd gear in the 4th gear position. That would make a frightfully quick car up to redline, but maximum speed would be limited to something like 135, if I recall. But you'd only need two new gears. The more gears you buy, of course, the more precisely you can meet your goals.

If you want the best of all worlds, then the G50 5 speed is the way to go. But figure on $8k to do that. The four speed is a compromise. You'll never get it to have perfect gearing for all occasions.


rw7810 (Bob),

If we're going to have a contest for over-the-top-Pelicanite-cost-overrun fever, please allow me to throw my hat in the ring. I took my engine out to fix a slipping clutch 5 years ago. Now, 660 miles later, I have run it with four different clutches, four different turbos, three different exhaust systems, and countless other mods, or re-mods, or re-re-re-mods. And it's still not running since I took it apart two years ago. The cost? I'm afraid to add up the receipts. Or to have my wife add them up...

[David]

The shop in Houston said the 8:39 was a bit harder to line up than the 9:38 and they said there would be some gear whine.

My main objective for the gearing is to go about 75-80 mph at 7000rpm in 2nd gear (for autocross) and top out about 170 in forth gear (because I don't see a need to go faster than that). I have thought of gearing a little higher than 170 in 4th for fuel economy.

[john walker's workshop]

why would a properly set up R+P whine? aftermarket gear sets (1-4) might whine due to the bevel angle, but not a R+P. it won't last long if it does.

[patkeefe]

put really small tires on the car

[David]

Originally posted by john walker's workshop
why would a properly set up R+P whine? aftermarket gear sets (1-4) might whine due to the bevel angle, but not a R+P. it won't last long if it does.

John, do you see any reason not to go with a new R&P. I've checked the gear ratios and I don't see a much better set of ratios than just changing the R&P.

[David]

I've done some reading on Rennlist and they mention strength of the 8:39 as an issue, since the pinion only has 8 teeth compared to 9. Since I'll be over 500hp this may be a valid concern. My current thought is to change 2 thru 4th gears to close up the spacing. I would like a little shorter 1st gear but some folks think too short a 1st gear will rev out too fast with high hp. I also wouldn't mind not buying all 4 gears.

Any comments on a DIY'r changing the gears, not the R&P?

Here's a chart with the three options laid out. The new gears option is for shorter 2 - 4th. Shifting is at 7000.

[Cory M]

The Jerry Woods trans class is coming up in December. I went last year and really learned a lot, I recommend going if you can (before you do your trans). You get to disassemble and reassemble all of the trannys in question (930,915, G50, 901) and really see what the differences are between them, you also discuss performance and durability mods. You can ask as many questions as you want and get expert advice, you can even take pictures. MAYBE you could talk them into your trans as the 930 model for the class. Check it out if you can.

From the website:

http://www.911handbook.com/

Transmission Class
# COST: $400.00
# December 12 - 13, 2005

We hope to have some classes again later this year. Please check back in with us for future dates. If you would like to register for any of these classes please email Bruce or write to him at:

Bruce Anderson
BookWorks
1485 Yukon Drive
Sunnyvale, CA 94087

Phone: (408) 737-0122
Fax: (408) 733-3694

[Rob 930]

David,

As my earlier posts suggest, I think changing gears (as opposed to the R&P) is a better idea from the standpoint of 1) keeping the stronger, stock R&P, 2) being able to select exactly the ratios you want -- which allows you to close the huge gaps between gears (that aren't improved by the R&P change) and 3) shifting the work in the direction that allows you to handle better by yourself. I think your gear selections look good from the chart you showed. I don't have any experience with the usability of a shorter first gear other that I'd be very concerned that it would be hard to keep the wheels from spinning. In fact, with as much power as you have, you may still have that problem in second gear if you're autcrosssing it.

To address the issue of a shorter first gear in autocross, you might talk to some successful drivers of G50-equipped cars. One who posts on Rennlist is Jeff91C2T. If you can reach him, let me know and I'll put you in touch. He's been very successful with his stock G50 gears, though his engine is quite stock.

The transmission DIY question is a good one. The act of simply changing the gears is easy -- especially on a 930. I see the bigger issue being that of properly scrutinizing the rest of the gear box for worn out parts (bearings, operating sleeves and such) and various activities that require special tools. Changing the dog teeth, for example, on 930 gears (if you need to do it), is a bit of a trick. But you're obvious pretty far up the scale of DIYers, with your project, so I'm sure you wouldn't have any problem learning the ropes. It just becomes another conquest...