915 Transaxel Questions

[fredmo1947]

I've got a 1976 911S with a 1978 3.0L engine. I expect the 915 5 speed transaxel is original equipment. Two questions from a new Porsche owner.
1) Shifting through the gears is smooth both up and down. However, if stopped and shifting from second to first, it is often difficult to get the trans into first. It feels as if it is partially in first and with just slight pressure when shifting from first to second it "pops" out of first with a noticeable thump. It does not do this all the time ,but often enough that I have taken to down shifting into first while rolling to a stop. The car shifts smoothly into first from second during deceleration. Does a downshift from second to first during deceleration and while the car is rolling harm the transaxel?
2) Having learned the hard way regarding the proper method of checking the engine oil level in a 911, I am wondering if there are any nuances regarding the proper method for checking the 915 transaxel oil level? Normally, I would remove the check plug, stick a finger into the transaxel and "feel" for oil. If low I would add oil until it started to leak out the fill. Is this the procedure for the 915 and what is the recommended oil?
Thanks Fred

[Rouxzy]

Fred,
I had the same issues with my 915 in my '77. After 30 some odd years shift bushings and motor/tranny mounts wear out. I replaced all the shifting bushings and replaced the motor and tranny mounts which corrected all my shifting problems.
From what I have been told the way that you are checking the tranny fluid is correct.
Tom

[Christien]

Every 915 I've driven (which isn't that many, maybe 10 or so) have all downshifted poorly from 2nd to 1st, and that's probably the single-most read complaint about 915s here on Pelican.

[Peter Zimmermann]

Originally Posted by fredmo1947

1) Shifting through the gears is smooth both up and down. However, if stopped and shifting from second to first, it is often difficult to get the trans into first. It feels as if it is partially in first and with just slight pressure when shifting from first to second it "pops" out of first with a noticeable thump. It does not do this all the time ,but often enough that I have taken to down shifting into first while rolling to a stop. The car shifts smoothly into first from second during deceleration. Does a downshift from second to first during deceleration and while the car is rolling harm the transaxel?

Every time that you downshift from 2nd to 1st at a slow roll (but before stopping) it will extend the life of your 1st gear synchro by many thousands of miles. You have discovered a "key" to finding 915 happiness.

Difficulty shifting into 1st with the car at rest can be caused by a number of problems (linkage issues, new or flipped synchros installed using the old slider, etc.), but the one most common is that the synchro has worn to the point where, when engaged by the slider, it can no longer brake the gear to a perfect stop. Also, the relationship between the synchro ring and slider become strained. Many drivers force their transmission at this point; unfortunately the next thing that happens in the wear cycle is gear crunching combined with broken dog teeth, then a failed synchro that requires repair.

[fredmo1947]

Thanks Gentlemen for the comments and suggestions. Any recommendations regarding the gear oil?

[edbaus]

Wow. Very good coments from Peter. I did not know that about 915 nirvana being found in the downshift roll. Good stuff. Interesting that the flipped syncros came up. I thought I was the only one who did that on my race trans.

I had always found that if I have trouble with getting the car in first, I would pull it back into second and then up to first. I suppose I am letting the second gear syncros slow the assembly enough for the first gear syncros to do the job.

Issues with the slider are often overlooked by the rebuilder.

Swepco 201 is my gear oil of choice. It is like magic honey.

Ed

[tcar]

FWIW, my mechanic said "never, never downshift a 915 to 1st while the car is moving".

[Peter Zimmermann]

Originally Posted by tcar

FWIW, my mechanic said "never, never downshift a 915 to 1st while the car is moving".

Hah! He has his priorities in his wallet, not yours. But I guess that there's a possibility that he just doesn't know...

Regarding gear oil, my recommendation is Kendall Three-Star Dino 80W/90...

[fredmo1947]

My instincts tell me shifting a transmission that is sync'ed smoothly into first from second at a roll is not a bad thing. If it were difficult to make that shift or if the dreaded grinding of gears were occurring, I would not do it. However for me the alternative has been shifting into first from second at a stop and occasionally having difficulty getting first gear fully engaged. When beginning to accelerate and disengaging the clutch in this situation the shift lever "pops" out of first with a thump.
Since there are conflicting opinions regarding the second to first shift protocols, perhaps others would like to weigh in on the subject so we can benefit from wider base of experience.

[911st]

I double clutch from second to first or come to a stop first.

I also do not shift into reverse until I first put the trans in 5th.

[ossiblue]

I do what both Peter and Ed do, either shift during a slow roll or first move toward second (don't have to totally engage) and shift into first--the latter when sitting for extended periods at a signal, for example. Both ways provides a smooth shift on a 73 915 trans of unknown mileage. Also use Swepco 201.

[fredmo1947]

Bump..any other second to first gear shifting comments?

[otto in norway]

Hi there!
I had the same issue with my 915 trans last fall. But this winter, I replaced the syncro rings for 1. and 2. gear.
It now downshifts into 1. like a dream. And also, the 2. gear is swifter to engage.

The labor for doing this, is surprisingly easy, once you get out the engine/trans.
And it's the only "real fix" IMHO.