915 transaxle casing part#?

[blue72s]

Hello

What is the part# of the 915 transaxle magnesium casing (outer seal type of input shaft, introduced in very late '73) ? Were all casing from late '73 until '76 the same?

thanks

[wevoid]

Blue72s,

No there were significant casting variations in the 73 to 76 period.
I think the number you are looking for is 915/02 on the underside, lowest portion of the casing, facing the ground.
Add some context to your question, I may be able to help further.

Regards

Hayden

[blue72s]

Originally posted by wevoid
Add some context to your question, I may be able to help further.

OK, first of all, I only need to know what is the part # of the bellhousing case (mag), not including gear housing, and it has to be the later input shaft seal where you can change the seal from the outside unlike the stupid 72 ones.

I looked at PET CD... only two came up: 915-301-901-03 and 915-301-901-04. I guess the 03 is mag (-76) and the 04 is ally (77-)? That's it?

915/02 you mentioned isn't on PET, but is this the 72 one where the seal can only be changed from the inside?

Let me know.
thanks again

[wevoid]

The numbers on the casting for the final drive
I checked a '72, 915.301.101.0R '76,915.301.101.1R and '77,915.301.101.7R(Aluminum) case.I have loaned a 73 final drive to a customer, I could call him if you really need to know the casting number but I suspect it is .0R

I dont know how you would order the part # you are asking about. If I had to guess, I would say that both the 1972 and 1973 style parts are both machined from the same casting. In fact I would say the '72 version was NLA once the 73 version was introduced (thankfully).
The '76 casting, the .1R version, logically the next version after .0R was reconfigured as a casting and has the extra boss feature for the bolt on guide tube. I would have assumed this was introduced in 1974 and went through the last of the mag housings - except that it does not allow for the provision of another .?R for when the speedo sensor feature was added....curious

915/02 is listed in PET for 1973 and with the separate press-in guide tube of 1973 (but no number listed), once again I think this was due to total removal of the original 915/02 once the supply of inside out version was exhausted.

Not sure I can add anything beyond that, but I am willing to read off numbers or ID features from the wide range of housings I have on hand.

Regards

Hayden

[blue72s]

Originally posted by wevoid
the .1R version, logically the next version after .0R was reconfigured as a casting and has the extra boss feature for the bolt on guide tube.

Excellent info! I actually need that boss feature, so .1R is the one.

The two bolt holes in the boss feature, are they size 6mm and on a 55mm PCD?

Regards
p.s. what are the variations of speedo sensor?

[wevoid]

The mount holes for the Guide tube on the 915 are on a 56mm PCD, but they are 6mm screws.

The 74 /75 915 casing had a cable drive speedo tht required feaures on the front cover casting.
The 76 casings had the electronic speedo, that requires a cast feature, with a machined finish, to mount the electronic sensor on the side (RHS) of the final drive. A 74/75 final drive housing has no provision for the sensor.
Machining for the mounting of the clutch cable was also different, along with some other cast features, one of which was redundent on the 915, although used for the clutch cable on the 1976 912E, that had a 915 deritive transmission...

Regards

Hayden

[blue72s]

Are you saying that the speedometer instrument gauge (in dashboard) in pre-75 cars were mechanical, and in post-76 cars were electronic?

Did both type of intruments share the same face appearance?

I guess the electronic one is more accurate and reliable?

[wevoid]

Correct, early cars were mechanical, cable driven gauges. I am sure there are subtle differences in face appearence, but I'm not the person who can tell you that.

Reliability?, electronic probably, more flexible in range too. Less parts in the electronic version, it was the future when it was introduced, I suspect it's less costly too.

Hayden

[blue72s]

thanks for clarification.

Just curious.... were there any variations of the gear housing between 72 and 76?

[wevoid]

There are a couple of very minor feature changes in the magnesium 915 maincases, but none that prevent complete interchange ability. Once again '72 is .0R, by '76 it was .1R
Early cases (.0R) had a boss for an oil return on the LHS , slightly above and immediately behind the filler plug.

Regards

Hayden

[blue72s]

Originally posted by wevoid
There are a couple of very minor feature changes in the magnesium 915 maincases, but none that prevent complete interchange ability. Once again '72 is .0R, by '76 it was .1R
Early cases (.0R) had a boss for an oil return on the LHS , slightly above and immediately behind the filler plug.

I guess the oil return is for oil cooler?
Why was the boss phased out when .1R was introduced?

thanks

[wevoid]

Actually, I was assuming that the boss feature was for an oil return. Probably not a good idea to assume as such.
Some of the early 915 production components were developed from the 916 style transmission for the 914-6 cylinder GT race cars.
The boss, which looks similar to the feature for the oil filler, might also have been an alternate filler, should the oil level have needed to be higher? As the FIA regs in the early 70's allowed very little lattitiude for modifications to parts like the transmission housings, Porsche might have added features as homologated safeguards for potential requirements.
I am not sure.
I think my asumption for the .1R version might be a little more accurate;
Once the additional boss was truly deemed redundent, it was an expensive feature to add to the repeat sets of tooling - hence the removal.

Hayden

[blue72s]

Originally posted by wevoid
As the FIA regs in the early 70's allowed very little lattitiude for modifications to parts like the transmission housings, Porsche might have added features as homologated safeguards for potential requirements.
I am not sure.
I think my asumption for the .1R version might be a little more accurate;
Once the additional boss was truly deemed redundent, it was an expensive feature to add to the repeat sets of tooling - hence the removal.

I understand what you mean.


Then, I'll keep my original gear housing (.0R) and look for a 74/75 final drive housing .1R (mechanical speedo).

You've been a great help.
All the best!