915 differences?

[GaryR]

Just read a post that listed some of the differences between the 915's in earlier cars shown here - (thanks Pete Z.)
915/06 = 1974 7:31 with FIVE forward speeds
915/16 = 1974 7:31 with FOUR forward speeds
915/40 = 1975 8:31 with FIVE forward speeds
915/43 = 1975 (Euro) 7:31 with FIVE forward speeds
915/45 = 1975 8:31 with FOUR forward speeds
915/48 = 1975 (Euro) 7:31 with FOUR forward speeds

How about later 915's? Was the 7:31 R&P standard in any of the SC's or Carerras? Was the gearing any different in a Euro vs. a US car?

[Peter Zimmermann]

Hi Gary,
All later 915s ('77 911S - 1986 Carrera) had the 8:31 R&P and five forward speeds.

915/61 = '77S - '79SC Worldwide trans
915/62 = '80 - '83SC RoW
915/63 = '80 - '83SC USA
(Minor ratio difference between the /61 and /63 in 2nd speed, and between the /62 and /63 in 2nd and 5th speeds. The /61 and /62 actually use the same 2nd speed).
915/67 = '84 Carrera RoW
915/68 = '84 Carrera USA
915/69 = '84 M 491 RoW
915/70 = '84 M 491 USA
915/72 = '85/86 Carrera RoW
915/73 = '85/86 Carrera USA
(Minor ratio differences; /67, /69, and /72 used a different 2nd, 4th and 5th than the /68, /70 and /73. 915/67, /69, and /72 had oil coolers, the USA models did not).

[Bill Verburg]

Originally Posted by GaryR

Just read a post that listed some of the differences between the 915's in earlier cars shown here - (thanks Pete Z.)
915/06 = 1974 7:31 with FIVE forward speeds
915/16 = 1974 7:31 with FOUR forward speeds
915/40 = 1975 8:31 with FIVE forward speeds
915/43 = 1975 (Euro) 7:31 with FIVE forward speeds
915/45 = 1975 8:31 with FOUR forward speeds
915/48 = 1975 (Euro) 7:31 with FOUR forward speeds

How about later 915's? Was the 8:31 R&P standard in any of the SC's or Carerras? Was the gearing any different in a Euro vs. a US car?

8:31 was std from MY75 up
here are a bunch of 915s , from '72 -'86, If it's not here I have it.

[GaryR]

Thanks Pete and Bill, exactly what I wanted to see!

[Joe Bob]

Early 915 have a different case differential side cover and alloy which is less desireable.

[zioo]

Where can parts be sourced for a 915/16 1974 Base 911 Transmission? For example bearings and synchros and gears. Zioo

[Matt Monson]

Our host has a very good assortment of service parts for the 915.

[daniel911T]

I have been wondering if a 915 support bar (the bar with the tranny mounts) will bolt up to a 901 tranny? I would really like to have replaceable mounts.

Thanks!
Dan

[onboost]

Originally Posted by daniel911T

I have been wondering if a 915 support bar (the bar with the tranny mounts) will bolt up to a 901 tranny? I would really like to have replaceable mounts.

Thanks!
Dan

Dan, if I recall correctly, I don't think the 915 bar will work for you on the 901.
The 901 box and that of the 930 actually use a similar "support bar".. both with non-replaceable rubber mounts.

I too ran into the same issue with my 930. My mounts were very worn and I was just not happy with the thought of using them with the loads my car could generate.

I went with the mod/fix offered by Wevo and have been very pleased.

Check them out @
Welcome to Windrush Evolutions - WEVO - Porsche Products

Paul

[RWebb]

to use the 915 cross bar support on a typ 901/911 trans., you will need to make an adapter plate to match the mounting holes

you can then easily & cheaply replace mounts until the sun goes out

make the thickness of the plate so that the 901 shift shaft lines up at the level on the Z axis as the 915 did

I posted details on it before; dunno how hard it will be for you to search

[onboost]

Originally Posted by RWebb

to use the 915 cross bar support on a typ 901/911 trans., you will need to make an adapter plate to match the mounting holes

you can then easily & cheaply replace mounts until the sun goes out

make the thickness of the plate so that the 901 shift shaft lines up at the level on the Z axis as the 915 did

I posted details on it before; dunno how hard it will be for you to search

I knew someone had another fix.. couldn't remember what or who! Great post.

P-

[daniel911T]

I incline toward the solution that allows use of factory mounts. However, when manufacturing adapters and paying other people to cut metal the price can get pretty high pretty quick. The WEVO solution may ultimately be cheaper.

That said, I think it's time to start looking for a 915 support bar.

Thanks, and I'll be looking for your thread on the subject,

Dan

[daniel911T]

Randy,
I think I found your old thread:

http://forums.pelicanparts.com/porsche-911-technical-forum/286513-type-911-using-915-support-bracket-mounting-adapter.html

However, I'm still left with a question. How thick is your adapter plate? (What's the Z dimension?)

Thanks!
Dan

[RWebb]

Great - glad you could find it

unfortunately I don't recall the thickness - BUT it was for a typ 911 trans. and a 1973.5 body, so you'd need to have measured for your car anyway.

I did not need to mill that piece of steel down any - I just used a commonly available thickness, cut it to size; added threads & had it powder coated.

start with 1/2 inch and see if that is about right - the coupler will obviate the need for an exact match (and I don't have my shaft exactly in the center... anyway)

[Porsche84]

Gary

I e-mailed you my Excel file on 915 trans gears and other info. I have two 86 trans here waiting for you to choose one. I'll pack in one of Matt's LSDs and ship for free end of January (on Dan's truck returning from Sebring). You know you want it!

[Porsche84]

Oops, my bad, an old post.

[mikedsilva]

Very old post, but probably better than starting a new one, as there is some good info up top.

Question; are the gears from a '74 mag case 915 interchangeable with a mid 80's 916/73?
Pretty sure 1st is not, as the shaft design is different, but what about the remaining?

[mikedsilva]

One thing I did notice, was that the teeth on the later box 2nd gear, look 'pointier' than the older box 2nd gear. I took some photos and when looking closely, it actually seems that the 2nd gear teeth from the later box, have a bevelled edge.. wondering if this was an improvement to the later boxters to increase strength or perhaps reduce noise?
(yes, the gears are on different shafts.. ie, later model gear is on older shaft and vice versa)

[Porsche84]

Mikedsilva

IMHO, the gears are all interchangeable in 915 from 72 to 86. Yes, the input shaft changed but it it could be used in a later box, but I wouldn't. There were also improvements with dog teeth and sliders that should be considered if you are using early parts, but the gears are all interchangeable as sets. The pictures above are reversed. The input shaft with the sleeve touching 2nd gear is the later improved design, the photo below shows why they changed

[mikedsilva]

Originally Posted by Porsche84

Mikedsilva

IMHO, the gears are all interchangeable in 915 from 72 to 86. Yes, the input shaft changed but it it could be used in a later box, but I wouldn't. There were also improvements with dog teeth and sliders that should be considered if you are using early parts, but the gears are all interchangeable as sets. The pictures above are reversed. The input shaft with the sleeve touching 2nd gear is the later improved design, the photo below shows why they changed

Thanks for the info.
Just doing a bit of searching and it seems that the 5th gear was a tad taller in the older transmissions too. That might come in handy.