Imo000

There are no cheaper Benz boxes Dan.

I can tell you are new to this and excited but all this has been discussed in details over the years. Spend some more time reading and you will find the answers.

My suggestion is to just drive the car as is for a year and THEN decide what needs to be fixed or changed.

skpyle

What he said...

foxint

Hi Guys,

Yes, I am new…but it is a topic with far too much interesting stuff to just stop….

if anyone knows of the equivalent auto box from the Benz barrel, I am sure it will help those who are not so keen to go down the manual road – or who want to save a few bob….

A Benz box has got to be cheaper than one bought from a Porsche dealer, (it is a Benz box after all) …I have not got a lot of money, so I do not want to waste too much…ha-ha.

It is a long project, as all Classic Car Projects. Just need to keep the excitement going.

By the way the car is in Sydney for a few months getting the basics done….1st job is the timing belt and the sunroof. I want it to be watertight.

Surely there has got to be an answer…. if nothing else it is a good centralise resource for those who like auto boxes.

Thanks again, and please excuse my naivety.

Dan

FredR

Dan,

You came to the list asking for advice, you have been given some very good input and yet you do not seem to want to grasp that a stock MB box cannot be used on the 928 transaxle.

This reminds me of a rather amusing story about the rabbit who went to the butchers and asked for some carrots. The butcher politely told the rabbit he was a butcher and did not sell carrots. The following day the rabbit went back to the shop and asked for some carrots and again but somewhat irately the butcher told him "we do not sell effing carrots". On the third day the rabbit went back to the butchers and asked for some lettuce. The butcher by now was totally pissed off and told the rabbit "we do not sell lettuce" to whit the rabbit duly replied "OK so can I have some carrots?". At that point the butcher grabbed the rabbit by his throat, chopped his head off with his cleever, skinned the carcass and put the meat up for sale in his counter.

In life you have to be careful just how many times you ask for carrots in a butcher's shop!

hacker-pschorr

Comparing new for new, there is nothing inexpensive about Mercedes parts, even when compared to Porsche.

Then modifying a Porsche is not a very good idea.

As others pointed out, it's 2017 and these cars are 30-40 years old. This topic has been asked over & over & over with many threads stating the exact same responses as this thread.

There is no inexpensive way to increase the performance of a 16V automatic 928. Except maybe nitrous but that's inexpensive only initially, the bottle fills get rather expensive.


I'm upgrading the stock auto box in my 87 to a unit from 89. Different gear ratios and shorter R&P, when this goes in I'll also be installing a smaller torque converter to increase the stall speed. The torque converter in question will be from an early 928 (like yours).

foxint

Hi Guys,

My apologies. My enthusiasm has obvious put some off.

But in the post on this very forum: “Did Mercedes manufacture the complete 928 automatic transmissions”, it stated that the Porsche box was in fact a Benz. Brain Long in his book Porsche 928 said the Porsche box was sourced from Mercedes. In this post, it was confirmed that there was a Mercedes casting mark on the box.

I was just asking for additional information that was not in the post, “Did Mercedes manufacture the complete 928 automatic transmissions”.

I am sorry if my lack of knowledge and my inquiries has put some off. I meant no offense. I agree, the cars are old and sometimes the information is hard to find. It makes it more important to share information. I thought the forum was a reasonable place to ask.

If someone has the information and would like to share, I would be most grateful, but if not then I will have to make my investigations over another conduit.

Thank you for your time.

Dan

The Forgotten On

I'll try to make this clearer for everyone reading this thread.

The only thing the Porsche boxes share with the rest of Mercedes line sharing their 722.X designation are the internals.

The case/housing and rear diff are all custom per Porsche for the 928.

So you cannot swap in a standard Mercedes box.

You can however use later Mercedes parts such as superceded brake bands, seal kits ( there are a few hidden o-ring exclusive to the 928 btw), and piston and spring kits for 3 and 4 speed automatics to liven up the shifting.

The Mercedes sourced bits are cheaper than getting them from Porsche and much more readily available.

James Bailey

Many of the internal parts are shared with MB transmission but with different specifications like torque convertor stall speeds. But the housing/ case is quite different even though it has MB cast on it it is Porsche 928 specific. You can find cheap rebuild parts made to "fit" in a Mercedes box but they tend to be very poor qualty Chinese parts.
You do realize that doing the T belt on your car is quite easy and not critical since it is not a valve bender.....less than a days work. Why the workshop would need it for months is rather troubling.

foxint

Sir

Thank you for clarifying this.

For me I have always understood that the transaxle was not Benz. I apologise if the guys on the forum have assumed I was asking about the “complete” transmission from torque converter to final drive.

If there is anyone still willing to share some information, it may be beneficial to all who want to rebuild their boxes, as it is now confirmed that at least the internals are from Benz and cheaper. I am sure we all want to cut down on the parts spend.

Perhaps the more experienced may like to share their knowledge to list the appropriate Benz boxes as they compare to the Porsche autos??

I am still learning and would very much like to have a resource to either up-date my 3-speed to 4-speed or rebuild it. There is a post about up-grading to 4-speed, but it does lack some specifics.

Just to confirm what I have found on this forum, it would appear (and I am more than happy for those with more experience to correct me) ….

The Benz boxes to look at are the 722.3XX and the 722.4XX – for the 4-speed only. I am not sure (and please if you know add to this resource) that the 722.3 were 6-bolt Large pan and the 722.4 are the 6-bolt Small pan. As my car is not here, I have no idea what I have, but I am sure someone knows.

Thank you

Dan

Wisconsin Joe

Naivety is one thing.

Ignoring what you are being told is another.
The trans was made by M/B to Porsche's design specs. While there are shared internal parts, it is different from every other M/B trans out there.

What makes you think you can get a new trans from a Porsche dealer, at any cost?

There were a couple that popped up a couple months ago. They're gone.
Greg Brown found some "New Old Stock" a couple years ago.
That's about it.

And what makes you think a "Benz Box" is going to be cheap(er)?

Getting into a 928 is not cheap. In any way, shape or form.
Paying a shop to do the work is the wrong way to go if you are looking to save money.
Put that money into tools and learn to do the work yourself.

Last, but not least, the sunroof will never be "watertight'.

There's no real seal. There is a gutter that goes around the inside. There are 4 drains (one in each corner).

Imo000

Your mechanic should know.

Instead of asking people to educate you why not just do it yourself and keep reading for a few weeks.

Lizard928

As someone who has put in 4speeds, and rebuilt numerous boxes, I think you should fit a 722.6 instead. Please take lots of pictures. I want to see how you get it to fit!

foxint

Guys

Thanks for encouragement. I do plan to do a lot of the work. But timing is not on myside. My garage is gone after the neighbour over the back fence let his BIG digger roll down the hill into the garage. He is an old bloke and the insurance is not paying. Saying the building was not adequately described on the policy. We are in the country, so people tend to have these things and our block is below the neighbours. He has no money.

Luckily the wife keeps the old golf at the front and the 928 was at the side. I have only had it for a month or so and almost had the garage sorted for the move…. Now we have tools and things like the lawn mower in the house. The spare room is now the garage.

It has been an interesting adventure the gearbox…. ha-ha. I will have to investigate the 722.6 – thank you. I suppose I am trying to keep my mind busy, rather than being too sad about the future of the garage. What do they say idle hands are the work of the devil….

Totally agree about the work. But since the car had bugger all detailed history and the owner’s manual may as well have not existed. I took it to Sydney (as there are no mechanics willing to work or whom I would trust). We are trying to get it watertight, stop the battery from running down (yes, I have a trickle charger) and the timing belt. The rest I “hope” can wait.

Sorry I did not share my distress about the garage, did not think it was relevant…But there you go….

I have found some interesting things about the gearbox, form here and the www…I get so close then no

Thanks again.

Dan

Alan

The 5 speed manual is the Holy Grail IMO - however to be clear there is no Porsche 6 speed option, for that you'd need a transplant from something else altogether....

Alan

Marti

Drawing a line under the 4 speed discussion or swap out activity I started to give some thought to whether it would be possible to swap the box to a modern transaxle auto unit from another car with 5 or 6 speed.

For some people the holy grail is a manual box but for others an auto is preferable.

I personally would like a modern auto box in 928 to provide closer ratios and a quicker more responsive change.