GregBBRD

I don't agree.

I think different people have different abilities.

blown 87

They also have different levels of, well lets just call it mechanical perfection, and that takes a lot of patience and dedication to doing a job to the highest standard that it can be done.

Many think they have done a great job, while others look at what they have done and go WTF?

I see it at every car gathering I go to, that many are very proud of the work they have done and I wonder how they got so far away from home in that car.

dr bob

I --probably-- could, with about a 90% confidence level. But I drive far enough from home that getting stranded would be more than a casual inconvenience. Risk of damage to the car being towed home. Have to rent a car while I fixed it the first time, then again when I fixed it the second and maybe third time. It would cost me $1k in parts pieces and logistics to do it myself, for the sake of this discussion. For another $1k, I could completely eliminate the 10% risk, the next $1k of inconvenience, and the next 10% of risk on my second attempt. Odds get better every time I would do it, right? But by the end of the second attempt, be it good or bad, I'd be even at best, and only then assuming no value to my time doing the rebuild.

Mark A is less than an hour away, Greg B the same. Reality is that a $2k trans rebuild is about the same cost to me as the time to R&R the thing and bring it to either of them. Assuming I don't consider the work as therapy time, that is. I'd rather let Greg do it. I've seen his work, and know that it would be done to a standard that would shame Hans and Fritz, the two guys that tag-teamed building my car originally.


I'm **** about servicing stuff like the transmission, and I drive the car gently. No reason to believe that the trans won't last longer than I do. Greg will retire and Mark's wife will force him to stay home and play there before the trans on my car is due to crap out.

danglerb

The more you know, the more you know that you don't know.
When I knew nothing I was ready for everything.
I want a 928 that I can drive like a Porsche every day, and that takes me rebuilding an AT off the table.

Landseer

Yet, you seem comfortable with rather extensive engine work?

Or have you been just disassembling them and screening the parts, passing them to Greg or others for actual building?

Black Sea RD

Fully agree with Greg and Greg.

Some just don't have the innate mechanical acumen and/or patience to do complicated mechanical work well. Then there is the experience of someone who has been doing it for years and knows all the little secrets that make a job perfect rather than just acceptable.

Having done so much with my own 928s, I know where I need to draw the line. Rebuilding transmissions and motors is where that line is for me.

Seems the OP has gotten answers and made his decision. Another successful Rennlist discussion!

Happy Holidays to all,

dr bob

I'm quite comfortable doing darn near anything on the car, and would do the AT in a pinch. But there are some things that are a lot more big-picture economical to have done by somebody with demonstrated expertise. I have expertise in electrical stuff and have no reservations about diving into anything that has wires running to it. I can test and analyze components and systems with equipment that I own. I've had more than a few engiines apart and together, to the point where I'm not at all intimidated by things that are held together by bolts. When building an engine for instance, I can test and measure all the parts as they are assembled. I can roll the crank as eash bearing and rod are connected, after carefully fitting each piston and ring set. The auto trans isn't quite the same. You have no good way to know that you've done everything right until you get it in the car and connect it, fill it, and start the engine. The first 'test' is done while filling it with the engine running. The work is initially tested with a couple hundred pounds-feet of torque applied, and mistakes result in trash running through the hydraulics, scoring pistons and bores and generally creating mayhem.

I preach to my clients that they should hire me for my very specialized expertise in what I do. I ask them why they would risk the short and long term survivability of their power plants when, for just a few hundred $k, they could have a completely automatic thermal island. Something that will avoid $millions in instant damage during unit commissioning, and $millions more in longer-term thermal stress damage. I feel the same way about the auto trans. If there's a known-best go-to person for this stuff, why would I risk my $80k car? (in 1989 dollars, it's more now in today's pygmy dollars). Penalty for failure is too high.

Landseer

That makes sense in a lot of respects.

For me, the equation is different and I read the risk differently.

Here I see a firesale, 2500-max bank repo.
I would buy install and test the $400 trans + begin the teardown and repair of the original.
Depending on the performance of the trans (and the rest of the car), I would decide whether or not to complete the rebuild or just wrap the parts in a box.
But honestly, I'd have to have a very bright, clean workspace, ultrasonic cleaner and lots of clean containers for parts.


Really nothing to loose. Only way to loose is to invest 3 to 5K in a cattaneo or other pro trans for installation in this car, which is very likely a complete mechanical and electrical and exhaust basketcase.

Worst case, my approach, I'm out 2500 + 400 and I'd have to get crackin at parting it out.

soupcan

I wouldn't agree with that, every transmission I have ever rebuilt (30+) I was 100% confident was going to work because I had checked every clearance and air tested every seal in each sub-assembly before final assembly. All clutches have travel checks and all seals have an orifice feeding them.

Biggest mistakes made are not properly testing the transmission pressures before removal and once the unit is removed not taking pre-disassembly measuments of each component.

Fluid pressure readings, end-play and checking travel go along way in helping you determine what the problem really is.

danglerb

I do feel pretty confident about rebuilding the engine and the manual transmission. Plenty of good documentation, and I can ask Greg questions and occasionally have him check what I have done.

So far all my engine work is disassemble, clean, and inspect. First engine build I am hoping for very soon.

I think its important to make some distinctions about "rebuilding". Required ability varies depending on how far apart the thing is disassembled, and who fixes the subsections. If I disassemble to the short block, send out the heads, and reassemble with new water pump and tensioner parts, that is a MUCH more basic task than tearing the engine all the way down and actually measuring everything and fitting new non stock size parts after machine work.

Landseer

One thing is for certain.
There are a LOT of parts inside one of these 4 speed boxes.
I still look at the seal kit and wonder where they all go.

Podguy

It took me about a week to learn the details. Steve was a big help. I found once I got the assembly right it was pretty much a piece of cake. Of course I have not installed the transmission. Someone want to take a risk and test out my first rebuild.

Take the pump apart and inspect it carefully. Mine was making a scraping sound and was scared.

I found a Mercedes kit. It had most everything except differential seals. I had a hard time sourcing them. I finally found a double seal that was a couple millimeters thick. Porsche wanted over $100 dollars to special order the seals. 928 International did not have them. I still would like to find a source on these critical seals.

The next time I could do one in about 4 to 5 hours once it was clean, drained and on the bench.

Good Luck

smyth1

got the car back to the shop but didn't get the chance to pull the trans.had to fight with a 4.3 vortec in one of the company vans that died.if you think the engineering on a 928 is bad,try working on a chevy van.everything has to be done from inside under the dash.at least the older ones give you some room.could barly even touch the plugs.

GregBBRD

This seems like the information that gives people a false hope, to me.

I've done many and I spend more time than that, on the valve body.

You could hold a gun to my head and I couldn't do the transmission, without the valve body, in that amount of time. I'd just have you shoot me, right up front.

Tom928

I'm heading down the path of rebuilding my old 4-speed auto.
I was quoted $3750 and $4200 for professional rebuilding. With the value of our cars as low as they are, it's almost un-justifiable for the early 16v cars.
I know used units are available, but you still should have some things done. TC bearings and bolts, front pump seals etc. If I can learn to rebuild it, I can keep my car running if parts are available.

I've rebuilt 2 of the 4-speed valve bodies. The first was from the old trans just to see if I could do it and practice. The second was pulled from a running trans due to hard shifting. When I opened it up, it was black inside. Dirt and grit accumulated in the passages and bores so bad the valves were hard to move in teh bores. After cleaning, replacing springs and a couple screens it shifts much smoother. It really wasn't that difficult and parts were available. The WSM, Jim M's CD set and information I collected on the 722 trans (from a MB website), made it doable. No special tools (maybe a magnet for the *****), big and small screwdriver, metal pans, lint free wipes and clean ATF.

I have all the parts to the old trans but the sun gear and one of the clutch housings are damaged so I need those parts. Both parts new are $$$, so I'm looking for some good used parts.
I'm interested in any 4 or 3 speed (I have both) A/T rebuilding anyone has done and has information to share. I though about documenting the valve body rebuilding, but didn't think many would be interested.