The Sportomatic transaxles had a 7:27 R&P gear in them. Will they fit in a 5 speed 914 transaxle? Seems like it would make a great daily highway driver with better fuel economy. Has anybody tried or know if it fits or will bolt in to the 914 transaxle?

Ralph

74 2.0

QUOTE (Rog914 @ Jun 4 2005, 06:37 PM)

The Sportomatic transaxles had a 7:27 R&P gear in them. Will they fit in a 5 speed 914 transaxle? Seems like it would make a great daily highway driver with better fuel economy. Has anybody tried or know if it fits or will bolt in to the 914 transaxle? Ralph 74 2.0

i think this was answered on the PP 911 board.....

gut instinct says the 905 sporto stuff is incompatable

I believe the 901 & 905 used the same parts. I know the gears, syncros and shifting sleeves are the same. If you have a chance to get the 7:27 pick it up and compare it to the 901.

Ken

To my knowledge, the sporto is based on the 901

QUOTE (0396 @ Jun 5 2005, 10:29 AM)

To my knowledge, the sporto is based on the 901

the 905 is based on the 901;
the 925 is based on the 915 ...

but AFAIK no 925 ever had a 7:27 R&P.

don't forget that Sportos were 4-speeds. donno right offhand if there a difference between the 4-speed and 5-speed output shaft, but i know the mainshafts are different...

925 IS 7:27

KEN

QUOTE (KenH @ Jun 5 2005, 10:41 PM)

925 IS 7:27

you are correct; i see that 8:27 was also available as well.

so does it fit?

I would say yes, based on the fact all the other parts are interchangable, but I have not tried it.
If you get it from an existing transmission try and get all the Pinon shaft shims and the shims under the bearings on the differential. The new ring & pinion gear will have to be "fitted" to the 901 case. Spare shims will help in setting the Pinon depth and backlash. If you need any more assiatance just ask.

Ken

So where does a guy find a dead Sporto box?

And if you found one what is a Sporto R&P worth?....

How does this compare to the "H" gear change in terms of a final drive?

How would that effect the first through forth gear set?

Too many questions...

it effectively makes ALL gears slightly taller.....

H gear makes your 5th gear taller.
if you like your 1-4 ratios, just go H gear,
if you want to make 1-5 "taller" buy a 7:27 r/p

Does this mean that there are 8:27 R&P sets available for the 915?

QUOTE

you are correct; i see that 8:27 was also available as well.

for a 901, you would need a 905 sporto....


for a 915 you would need a 925 sporto correct?

I am fortunate in having found a sporto box some years ago. I have not disassembled it to try anything, but I may get a chance to compare part #'s.

One caution about changing the final drive to lower RPM's is that lugging the engine is the foremost cause of overheating heads. The opinion of many people is that 2.0 head cracks are found mostly in the south due to traffic congestion lowering speeds so that the engine is lugging a lot of the time, and in addition to higher ambient temperatures will cause overheating.

good point but - both rick and ewdsyar have v8's
not a good idea for 4cyl or 6cyl porsche motors

QUOTE (rick 918-S @ Jun 6 2005, 08:22 AM)

So where does a guy find a dead Sporto box? And if you found one what is a Sporto R&P worth?.... How does this compare to the "H" gear change in terms of a final drive? How would that effect the first through forth gear set? Too many questions...

"How"?, you ask. Simple! You grovel at the feet of The Cap'n, begging him to sell you one. Same way you get an "H" gear ..................... The Cap'n

QUOTE (Cap'n Krusty @ Jun 6 2005, 12:05 PM)

You grovel at the feet of The Cap'n, begging him to sell you one.

"How much?" he says in simple supplication

For the tranny or for the "H" gear? Well, they're the same price ....$200. The Cap'n

QUOTE (Cap'n Krusty @ Jun 6 2005, 12:34 PM)

For the tranny or for the "H" gear? Well, they're the same price ....$200. The Cap'n

thats a deal! i though H's went for ~300

Ahhhhhhhhhhhh Mark, I think the Cap'n was pretty specific in stating both "Grovel" and "Beg" in his post. There was "nothing" about simple supplication.

You may begin Grovelling and begging now.

How about

Oh high and mighty Cap'n! Sultan of Santa Maria. King of Krust! Tyrant of transmissions and gatherer of gears!

Although I have falsely titled myself to be the buster of clouds (a title which presumes elevate me to the stars) I come to thee penitently, to prostrate myself prone-ly to pitch for purchasing of some parts.



Please, please, please be persuaded to ponder parting with....

A HERRING!

No, a sport-o-matic. Specifically a 7:27 R&P for a 901

pretty good

Wowie, what a deal. I'd have to do some math before figuring out if I'd want a 7:27 R&P, as I already have the H gear.

(calculate calculate)

Whoo, 2000 RPM at 70 mph in the highest gear.. imagine the gas mileage! Might have to go to an A maindashaft tho.. Hmm, I have a couple of those...

You'd have to clutch it and blip the throttle every 50 miles or so to get the carbon out but hey... with gas at $23.68 a gallon, might be good!

Aren't the Pinion and the 2nd gear attached to the same shaft in 901s?

So I'd have to hope a sporto 2nd gear (1st?) gear is the same ratio?

QUOTE (bondo @ Jun 6 2005, 04:29 PM)

Whoo, 2000 RPM at 70 mph in the highest gear.. imagine the gas mileage! Might have to go to an A maindashaft tho.. Hmm, I have a couple of those...

Uhh... your heads HATE YOU.. or they would.

These cars rev like they do for a reason, if they didn't, they'd melt.

You get about 1/2 more miles out of a motor run between 3500-4500 than you do a motor run from 2500-3500... or so..

I owned 3-4 cars before I figgered out how to drive them... under 3 grand til warm, and then hwy shifting at 4000... I will stay in 4th until 75 or thereabouts. That's being easy on it.. low revs are tough on it.. lug-lug-lug..



M

QUOTE (Cloudbuster @ Jun 6 2005, 05:05 PM)

Aren't the Pinion and the 2nd gear attached to the same shaft in 901s?

no.

2nd gear (1st in 4-speeds...) is fixed to the MAINSHAFT.
nothing is fixed to the pinion shaft.

QUOTE (redshift @ Jun 6 2005, 05:13 PM)

... your heads HATE YOU.. or they would....

it was pretty clear in the context of this thread that it's the V8 guys (with watercooled heads...) who are interested in dropping the rev range.

BEEATCHIN! I have that ring and pinion. So what will it drop your RPM, say at 70?

Oh yeah...

The R&P is the weakest link... uhh... more leverage ain't going to be good.

I am stupid sleepy.. stupid.


M

Here's some whacky math

If you do the flipped 3rd & 5th, plus the 'S' 4th, then apply a 7:27 R&P, you get ratios for 3 - 5 that are close to stock.

BUT, you get a much higher 1st and 2nd, with a closer delta between 2nd and 3rd.

This seems like a long way around to get what a stock 914/6 box delivers.

(Hard to see, sorry)
Black = stock (blue for 1st and 2nd)
Blue = flipped 3rd & 5th, plus the 'S' 4th. 7:31 R&P
Green = flipped 3rd & 5th, plus the 'S' 4th. 7:27 R&P

Buy the whole transmission. The clutch was electrically actuated and normally shifted without gringing, you may find good dog teeth and sliders that can be used during a rebuild.

Ken

QUOTE (KenH @ Jun 6 2005, 06:34 PM)

Buy the whole transmission. The clutch was electrically actuated...

sorta...

the vacuum servo was electrically actuated. the vacuum servo - if properly adjusted - operated the clutch...

still a good idea to buy the whole thing, because you're never going to find a good R&P cheaper, and the remaining parts (stuff like the mainshaft...) are bound to be worth something to someone some day.

donno if John is throwing in the vacuum servo clutch parts, but if you've got the room to store 'em, i would...

QUOTE (ArtechnikA @ Jun 6 2005, 02:38 PM)

donno if John is throwing in the vacuum servo clutch parts, but if you've got the room to store 'em, i would...

John's NOT offering the whole tranny. After some thought, the thing needs to come aopart for inspection, and the freight's gonna be relatively prohibitive for a whole gearbox which is of little value to someone without sporto experience. Unfortunately, I have that experience ................. The Cap'n

QUOTE (Cap'n Krusty @ Jun 6 2005, 04:32 PM)

QUOTE (ArtechnikA @ Jun 6 2005, 02:38 PM) donno if John is throwing in the vacuum servo clutch parts, but if you've got the room to store 'em, i would... John's NOT offering the whole tranny. After some thought, the thing needs to come aopart for inspection, and the freight's gonna be relatively prohibitive for a whole gearbox which is of little value to someone without sporto experience. Unfortunately, I have that experience ................. The Cap'n

Yup, I'm thinking for my V8 conversion. The firebird I took the LT1 out of had a 6 speed trans, and in 6th it was About 2200-2300 RPM on the highway. If it can do that pushing a firebird, I bet 2k RPM in a 914 would work fine. Now I just needto figure out if I want to pay $200 for it, if it's even still available. Hey cap'n, has that puppy been claimed yet? No freight needed for me!

You're second in line, Royce .................... The Cap'n

You're second in line, Royce .................... The Cap'n

QUOTE (Cap'n Krusty @ Jun 6 2005, 06:25 PM)

You're second in line, Royce .................... The Cap'n

I'll step out of the line now... unless it comes with a mainshaft somewhere between A and F. (A would be too low, F too high... and that's all I have)

ahh... a GA mainshaft?

i have a 4 spd mainshaft which has a first gear stuck on it

QUOTE (Aaron Cox @ Jun 6 2005, 10:24 PM)

ahh... a GA mainshaft? i have a 4 spd mainshaft which has a first gear stuck on it

That's what I have too. It has an A where 2nd would be for a 914. Too low for a V8 tho, even with the sporto R&P. A GA mainshaft is from a 914-6, and still has 2nd gear as part of it. A GA is actually higher than the F that a 914-4 comes with. I'd need something like a C, CA, or D mainshaft.. not sure those even exist. I'd best just leave well enough along and stick with what I was doing (standard re-ratioed 901).

yeah, you need a 904 main, and weld on your magical gear for 2nd.

could you go

C, HA/HB, Q, ZA, H?

tallest gears available - stock 5th becomes 4th.... H becomes 5th?

still a 5 speed

QUOTE (Aaron Cox @ Jun 6 2005, 11:36 PM)

yeah, you need a 904 main, and weld on your magical gear for 2nd. could you go C, HA/HB, Q, ZA, H? tallest gears available - stock 5th becomes 4th.... H becomes 5th? still a 5 speed

I've never seen anything but an A that fits where 1st goes in a 5 speed (splines are different). I know they must exist, but that is big money territory. Besides, the cantilevered gear setup isn't strong enough for a V8.

I think I'll be happy with a 4 speed. This engine was originally mated to a 6 speed.. It was annoying to drive, because the torque range is huge. I could probably get by with a 3 speed!