901 let go with a bang!

project911 · 05:46 PM

Hi all,

A little history... My tranny has had 1st and 2nd gear shifting issues since I purchased the vehicle two years ago. I learned to live with them after changing out the coupler bushings and was able to drive without crunching it (still happened once in a while). No other real issues with the car, other than oil leaks, and exhaust leaks.

I began driving the car daily this summer and have logged <10,000 since it was purchased.

Coming home one day I was in 5th gear doing around 65mph when I heared a bang! The shifter went into neutral and I immediately took my my feet off all the pedals. I steered over to the shoulder and sat there with the engine still running. I put the clutch in, then release it, ok no problems there. I put the cluth in again and proceeded to shift through a few of the gears, ok still good. Then I tried first and let out the clutch ever so slowly, clutch should be grabbing by now, uh oh. I try another gear and another but no luck. I rev the car a bit with the trans in neutral and i hear a rattling noice. I shut the engine off and call AAA to take me to squires autowerkes in bellevue.

We put the car on a lift and do a visual inspection, then we try turning the tires both ways. Interesting I thought the other tire should move the opposite direction due to the open diff, huh. We decide to start the car and it fires up no problem, no noises. He tries the same things I did on the side of the road. At this point we drain the trans fluid, can you say metallic! I decide to take the car home to do the repairs myself and thank squire for his help and he gives me some ideas for things to check, no charge!

I get the car home and it sits for a few weeks before I can get to it. I dropped the engine tonight without incident and this is what I find.

I'm not sure what this is, maybe someone can enlighten it me if its a problem, or just another leak.

EDIT: It was an old unrelated dried leak.

Obviously big problem, I have cracked 901 case right along the top "spine" near the bellhousing, and another crack where the input shaft cover goes on.

Anyone have a 901 for sale?

I'll post more as I uncover the source of the problem. Stay tuned.

Grady Clay · 11-01-2005, 04:43 PM

Aah, the "Simplified" Differential I'll bet.

I wonder what got the nose piece. Sorry to see that. Please take some good images for all to see. See if you can find the two tits off the axle flange stretch bolta among the carnage.

What kind of stretch bolts do you have in your err, .. transmission?

Best,
Grady

Want to be · 11-01-2005, 04:44 PM

Yes, PM'd ya!

My mechanic has 1800 number, trans waiting for a happy new car.

Owner swapped out due to type of racing class.

jpc

Grady Clay · 11-01-2005, 05:38 PM

Remember, you need a 5-speed from a ’70-’71 only. It is a type 911 not type 901 although many parts are similar.

Best,
Grady

john walker's workshop · 11-01-2005, 05:51 PM

i have many good used differentials to choose from. maybe a 71 case too.

Joe Bob · Joe Bob's Garage

I've blown more than a few transmissions....not fun. Most of my 901 trans problems involved first and reverse....

project911 · 11-01-2005, 06:48 PM

Update.

It seems the input shaft sheared off, and when I move the trans around all sorts of goodies rattle around inside.

Someth'n wrong here:

Also the bolt that holds down the shift fork was loose.

Now I need to wait until tomorrow so I can get the air compressor to remove the cv drive flange bolt to gain access to the diff and the first gear bolt to get the gear stack out.

John, I'm local, once I see what is salvagable I will give you a call or I may just go with a complete tranny.

Thanks for the offer Want to be, I'll let you know if go that route.

Bobboloo · Bobboloo's Garage

Some JB Weld and some duct tape and she'll be good as new.

Seriously though, sorry, it looks like you did choose the correct screen name however.

Grady Clay · 11-01-2005, 07:19 PM

Yes, that is a “Simplified” differential failure. The tits ware off the ends of the stretch bolts. The differential shaft slides out of the differential housing while driving. The inertia of the car cuts the transmission apart, including the input shaft and more. Usually not much is salvageable. Check here.

Sorry to see that preventable failure.

Best,
Grady

project911 · 05:37 PM

Quote:

Originally posted by Bobboloo
Some JB Weld and some duct tape and she'll be good as new.

What a great idea! Anyone have the chapter from the factory service manual on the proper procedure?

Seriously though, thanks for the replies and insight. I'm excited for tomorrow its like opening a christmas present. I can't wait to see all the goodies inside. I was planning to do a rebuild/replacement on the tranny sometime in the future anyway, now it's just a bit more expensive, but fun nonetheless.

I was reading the 901 rebuild tutorial from here: http://home.san.rr.com/pb914/rebuild/ and it says that if you engage the 1st/Reverse, 2nd/3rd, and 4th/5th shift forks that you can remove the 30mm nut without an impact wrench. I can't seem to get the 4th/5th to go into the intermediate plate, I wonder if it's hosed from the breakage.

project911 · 11-01-2005, 07:37 PM

Grady, I just found you threads on the simplified differential upgrade last week. Unfourtunately it is to late for me. Let this be a lesson to all you procrastinators out there. If I had known I would have dropped it sooner, and taken care of business.

Also since I'm here I'd like to thank you for the wealth of knowledge that you share on this forum, I speak for all of us when I say it is very much appreciated. That goes for John Walker and Warren as well, and anyone I missed. To you guys.

project911 · 11-01-2005, 09:40 PM

Last pic of the night.

And one of the car.

D@vid · D@vid's Garage

Great car you've got there, hope you'll have it back on the road soon.

D@vid.

project911 · 06:44 PM

This is what it looked like when I pulled the diff.

This is where the case cracked along the top of the the spine.

project911 · 06:47 PM

Gear stack side of the input shaft.

Half of the diff shaft.

The infamous nipples.

Center section of input shaft that the differential hit.

Stupid bolts.

project911 · 05-08-2006, 09:23 PM

I'll add captions later. Let this be a lesson to me and others who procrastinate changing out their "simplified differential" bolts.

project911 · 06:58 PM

Cracked pinion tooth.

Saturated drain plug.

Input shaft, notice the section the diff whacked out.

Empty 70 911 case.

Intermediate plate input shaft bearing.

Input shaft guide, notice the stretched hole and the piece of magnesium broke off the case.

All the components on the input shaft (plus 3rd gear).

Intermediate plate, bearings look good.

All the components on the pinion shaft (minus 3rd gear).

project911 · 05:41 PM

Nose cover, reverse, and throw out bearing arm.

Shifters

1st dogteeth.

1st slider.

2nd dogteeth.

2nd slider (note the chipped tooth on the 3rd slider side).

3rd dogteeth.

3rd slider.

5th dogteeth.

5th slider.

project911 · 05:41 PM

4th dogteeth, the bits are rubber from the hammer I used to get the gears off the input shaft.

4th slider.

project911 · 05-14-2006, 07:04 PM

I am amazed at how easy it is to work on these things, this is the first transmission I have done myself, and I'm enjoying every minute of it!

I'm thinking I should have any parts I plan on reusing (4th/5th slider, etc.) checked for cracks prior to installation, who knows what parts the shockwave impacted at this point.