Unknown transmission

[Briana]

So I was under the impression that I had the original transmission to my car. Since it's a 70 S it should have a 911/01 transmission. I know where the serial & type numbers are located on this type of transmission since I have one of these from a parts car.

The transmission in question does not have a type number. All it has on the bottom is the number HA25063. Does anyone know what these means or what type of transmission this may be.

[Briana]

Here are some casting numbers off of the transmission.

901.301.301.2R is located on the selector rod case

911.301.311.OR is located near the transmission flange

914.301.101.80 is on the side of the transmission

[Briana]

Any feedback would be appreciated. Well almost any.

Anyone?

[Grady Clay]

Brian,

It looks like someone fitted a 914 transmission into your ’70 911S at some point. What size clutch does it have – 215 mm push type or 225 pull type? Judging from the clutch release arm it looks to me to be the earlier 911 215 mm (same as 914) push type.

Clearly it has the 911 nose casting, the 108 mm CV flanges and the 911 external hex drain and fill plugs (914 were internal hex).

The HA25063 S/N on the main casting is a ‘74 914-4 (Type 914/12.)
The 914/12 gearing is:
1st = 11:34 A
2nd = 18:34 F
3rd = 23:29 N
4th = 27:25 V
5th = 31:22 ZD
R&P = 7:31
The differential is the updated “Simplified” version.

Another clue is the transmission breather is on the non-starter side on a 914 and on the starter side on a 911.

Your ’70 911S probably came with a Type 911/01 5-speed.
1st = 11:34 A
2nd = 18:32 GA
3rd = 23:28 O
4th = 27:25 V
5th = 29:22 ZA
R&P = 7:31
The differential was the un-updated “Simplified” version.

I will speculate that the differential had the typical catastrophic failure common to the un-updated version and some or all of the internals were changed to 914/12. The only way to tell is to partially dissemble the transmission and inspect the gears. The 911 came with higher quality gears with matching serial numbers and were date-stamped.

The disappointing part I see is the smaller clutch from a 2.0 911.

EDIT: There appears to be some really good creative engineering here; in true Pelican tradition. The side cover appears to be a late ’69 only magnesium part. Two of the side cover studs were slightly longer to accommodate the 914 clutch cable pulley bracket. Even those got changed. Obviously the R&P was set correctly when the ring gear was repositioned to the other side from 914 configuration.

I can see the situation where a PO had a total transmission failure and also needed a clutch. A modified 914 transmission and a 215 mm clutch would be an economic and suitable repair for the street. I’ll be interested to see what gears are in there.

Depending on your use, you might start a search for several donor ’70-’71 type 911 transmissions. These are remarkably easy to rebuild and you can change gear ratios to your heart’s content.

The 2.2 225 mm clutch and related parts should be new wear parts (bearings, disc, pressure plate, flywheel, hardware, cable, etc.) and good used otherwise (ring gear, guide tube, etc.) If you intend to do this, there are some subtle but VERY important differences.


Best,
Grady

[john walker's workshop]

it has a push style release arm on it, so it will also have the 69 and earlier flywheel and clutch assembly on the engine. notice the notches on the end. they would face the other way on a pull style 70/71 trans.

[silverc4s]

I was very interested to read your response, Grady. When restoring MY 1970 S, which I purchased from the brother in law of the original owner, it was represented as totally original.
When we opened the transmission (a 911/01) it was full of VW gears, from a 914 I guess. The original 7:31 was there, pretty badly worn.
Bottom line; I had to replace EVERY internal part in that transmission!!! It was not a good day...

There I learned that the VW gears are the same dimensions but lesser quality that the Porsche 901 gears..the hard way. The original box worked, but sounded at all times like a box of rocks.

[Grady Clay]

Here is a good link for the “simplified” differential problem ’68-’71.
broken transmission, any ideas?


Bill, the 914/VW gears are VW-Porsche 914-4 only, not any other VW. The 914-6 used the 911/Porsche gears and castings. The VW gears were just fine just not as finely manufactured, certainly not a box of rocks. That noise is usually a failed 4-point ball bearing or a totaled pinion gear.

A serious problem in any transmission is that when there is a failure, hardened steel parts get circulated through perfectly good gears and bearings. Any time there is an apparent failure, STOP. I use several large Alnico magnets inside my race transmissions to catch any steel slivers.

Best,
Grady

[silverc4s]

Grady, thanks for the added info.
I am sure the noises and feel were a combination of things. the car was original, but well used and very worn out when I bought it. I had a 69 T targa with a really nice 901 box at the time, so the difference may have been over dramatized.

[Briana]

Grady,

Is there any reason I shouldn't use this on my car with a "new" 2.2S built to factory specs? According to the PO this transmission had $1500 worth of work done including clutch,syncros,gasket set and some other stuff. I can verify the clutch and pressure plate are new.

[Joe Bob]

914 transaxles are regularly used for flat and V6 as well as v8 conversion that handle over 300hp. Pretty good for box of rocks.

[silverc4s]

Yikes!!
Sorry Mike, No intention to dis your tranny on my part, I just got stuck with some really worn out stuff in that deal. Still stings a bit when i think about it...;-)))

[Plavan]

Briana,
I have a 1970 transmission case if you are interested. That is if you want a 911 901 case. It does not have the nose cone, or stub axles (which you should not need). I also have ALL the gears (1st-5th) that should of been in your original 911 S. I know you spent a ton already. This would make it original again if that is important to you.
I used a 914 trans case in my race car so I could fit a Guard Transmission 80% LSD in it. They do not make one for the aluminum 901 transmissions. I gathered up a 1969 side cover from John Walker (Thanks, John), burglarized some stub axles and the nose cone from the 1970 901 tranny I have.

[Joe Bob]

No dis taken....sounds like a hack put in used parts and did so...badly...if you see what NEW 914 trans parts go for....they are only available thru the finer parts houses....

[Grady Clay]

Brian,

What you have will work just fine. The clutch parts will hold up and are sufficiently inexpensive so you can replace them periodically.

The partial transmission that Chad has sounds like the making of a future original for you. It will take some time (many months) to collect all the necessary pieces at bargain prices.

Chad, is that ’70 transmission still reasonably assembled? If so, may I disassemble and get images of it somewhere in the middle of things?

Best,
Grady

[Plavan]

Grady,
It's disassembled. I pulled all the gears out with the intermediate plate. The diff is still in there along with the side cover. What areas were you trying to get a picture of? I can probably take some pictures.

[Grady Clay]

Chad,

I’m trying to gather stuff for Wayne’s alleged transmission book here. I figure that if I get a start somewhere, it might inspire him to oversee the project. To do justice to this subject will take the efforts of many, many contributors. The beauty of doing much of it on the Pelican 911 Forum is that every little detail will get critically reviewed.

Every year transmission had subtle differences and I want to take note of each. I want to document the spacers. I want to measure the length spread of the inner races of the free gears. With care, I can measure to 0.0005 mm. In ’69 there is the change from aluminum to magnesium. There is also a change in the casting in ’71. There are slight differences between the mag ’69 and the mag ’70 main castings. And much more.

If you send the necessary parts and everything very clean, I’ll reassemble it for use – for free. Did you measure or save the paper gaskets/shims between the intermediate plate and the main casting? That is a good starting point for seeing where the R&P has been running.

Is there a Pelican in the Denver area who wants to go into his 901/911?

Best,
Grady

[Plavan]

Grady,
The I think the paper gaskets are still on there.... The only problem is that I do not have a nose cone or stub axels.
This might be a good way for Briana to have a original 911/01 tranny built up for free from Grady

[jpnovak]

Grady, I have a 912/16 that will be a donor for a 911/01 rebuild. The 911/01 reubild will swap with the worn box on my 71 targa. Then that box will be rebuilt and possibly sold to fund this whole advanture. Both boxes are outside the garage waiting for my schedule to clear from house restoration/repair. I am doing the final trim paint now.

If there are any pictures you want/need please let me know. If you want to inspect the boxes, let me know. I could arrange some method to get them from TX to CO.

Please tell what method you use to measure to 500nm resolution!!!

[Grady Clay]

Jamie,

That sounds like a very useful project.

You get them to Denver in nice clean condition. I’ll partially dissemble and inspect for free. Of course I’ll photo and post the process. I’ll reassemble for shipment but not for use. You get them back to TX. I’ll lead you through the process that I just did, go over the diagnosis and plan, and lead you through the repair and reassembly. Did I miss anything?

BTW, there is a DE at Pueblo this weekend. Are you or any locals coming? Might be free transport.

When handling or shipping transmissions the shift rod and input shaft need to be protected. They are relatively easy to get bent or damaged. I’ll post some ideas.

Save me from searching. What is a type 912/16? Do you mean type 902/16? What did it come out of? Most type 912 have 12 cylinders and came in various 917s.

Best,
Grady

[Grady Clay]

OK, let’s make a plan.

Brian’s 914/911 transmission is a direct fit into a ’69 911 or 912. I think it should be inspected, a few new seals & gaskets added, not scavenged for parts, and be available for someone to use.

Chad’s partial 911 transmission can be rebuilt, updated, and completed to be an original for Brian’s ’70 911S. It is probably going to need the following:
Axle flanges – good used including bolts and washers.
Nose casting – good used.
Simplified differential update – good used, new roll pin.
A set of new seals and gaskets.
Clutch release arm pivot update – new part.
Two new 4-point ball bearings for the intermediate plate - expensive.
Some syncros, sliding sleeves, and gear dogs, including updates - expensive.


My procedure would be to:
1) Visually inspect everything before starting – there is no sense to beat a dead horse.
2) Reinstall the gear cluster/intermediate plate with new shim gaskets and inspect the R&P contact pattern and measure the backlash.
3) Measure the differential bearing preload.
4) Disassemble the shafts; clean and inspect the bearings, gears, syncro parts, etc.
5) Inspect for bent input shaft and shift rod.
6) Check for proper bearing and seal fit in the castings.
7) Inspect for cracks in the castings.
8) Ascertain if anyone has been inside prior – if I can tell, I up my level of inspection.
9) Form a more detailed plan for repair and assembly. Note that no money has been spent thus far – only shipping and my (free) labor.

I would expect to at least find the 1st and 2nd gear dogs, sliding sleeves, and syncros in need of replacement. If the transmission has been shifted with the clutch dragging or not disengaging; more dogs, sleeves and syncros may be damaged. The 4-point bearings are a weak point in the transmission and should be replaced with new. Clearly it gets new seals, gaskets, and lock tabs.

Clearly it should have the updated differential parts. Those are common to every 914 and are not wear parts.

It is not uncommon to find many of the studs loose in the magnesium castings. Those should be HeliCoiled as a proper repair.

The clutch release bearing guide tube should have a drain grove ground in it and the “Dam Seal” installed. The clutch release arm pivot should be replaced or updated. I like to grind a little more case clearance in the “free play” direction of the arm. The differential side cover ring for the clutch cable Bowden tube needs to be inspected. If not in great condition, we need to find a repair or replacement.

Install new plastic bushings in the accelerator bell-crank. Replace ground strap with new. Lap the faces of the axle flanges, check for proper threads, and inspect the seal surfaces. Get new inboard CV bolts and Schnorr washers.

All of the steel hardware that contacts the magnesium castings should be new or re-plated. This prevents galvanic contact corrosion. Finally this will inspire me to find a source for a small quantity of Tectyl preservative for the magnesium castings.

I’ll see if I can get some of the local shops to let me use their parts cleaners, etc. I have everything else. I would like to go very slowly and photo document everything. I want to get as much Forum participation as possible. If others want to work in parallel offering their images, that would be great. Perhaps the moderators will give it a “sticky” for the duration.


Brian, you need to decide if you want to go this route. This is not an insignificant expense although you will recover when selling the 914/911 into a ’69 911 or 912. The costs are going to be shipping, transmission parts, a complete 2.2 clutch, and no doubt other that hasn’t been thought of.

Chad, you need to get together with Brian and discuss your transmission parts. Can you post some images? What is the S/N and Type?

Best,
Grady