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The added centering spring on the selector shaft (did not "happen" until 1983), centering the gearshift lever towards 4th and 5th, when in neutral. Most people do not like this and Porsche was forced to change this in 1985. The idea behind having the gearshifter "center" is so that you know exactly where you are at (when you get "lost" mentally about what gear you are in.) You can let go, simply allow the gearshifter to "center", and either push forward or backwards. As I said, "centering" in 4th and 5th was a very poor idea by Porsche....no one ever seemed to get "lost" in 4th and 5th.....and didn't like having to "overcome" the extra spring to get into 2nd and 3rd, witout "snagging" 1st and reverse. Almost everyone likes and picks our custom centering spring option that centers the gearshift in 2nd and 3rd [like a late ('85-'95) transmission does.]
57,000 miles and all new synchros, but the head gaskets are fine, because the car was used easy and well maintained. The choices you make are really interesting.....
I hope they didn't talk you into "increasing" the percentage of the limited slip, by separating the friction discs, too! This really sucks for an early car with "limited" horsepower. Turns the early cars into complete dogs through the corners (with the increased drag of the increased friction of the limited slip.) Also makes a transmission oil cooler almost a requirement....the extra heat generated is significant.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Good eye -added spring is correct. I added it after driving the original design that flopped from side to side. This was a haunting sensation from years ago when I owned 914's and totally detested the dead feeling of the gearshift lever / linkage. I like this solution. It is a well engineered example of Porsche evolution.
Good eye -added spring is correct. I added it after driving the original design that flopped from side to side. This was a haunting sensation from years ago when I owned 914's and totally detested the dead feeling of the gearshift lever / linkage. I like this solution. It is a well engineered example of Porsche evolution.
I'm not too sure of it being a "well engineered example of Porsche evolution" since it only lasted for two years before pressure from drivers who hated it made Porsche change the design.
The "extra" spring pressure required to move the gearshifter over to the 2nd and 3rd gear plane made the "feel" of moving too far to the right into the 1st and reverse too vague...and common.
Destruction of reverse gears and first gear synchos (and brake bands) became commonplace.
....not even close to their best engineering, but certainly an "evolution"!
Once you've actually driven this "transmission" a few miles....and you think about it....."centering" in the 2nd and 3rd plane is a huge improvement.
Hello RJTW,
Thanks for your kind words. Regarding the front spring swap, it is too early to say. It won't be until a week or so after it is settled on the ground. This is an experiment, I've set my blue stripe springs and perches aside for archiving to stay with the car. Three parts were changed, all from a '84 (the threaded ring, the lower perch and the brown stripe springs). I can send you part no.s if you want them. These replacement springs are not much stiffer 252 lb / ft vs. the blues at 246 lb / ft. The big difference is the free height -the 'new' ones are 1 inch lower (365mm-340mm). The wire diameter of the new springs is slightly thinner at 14.8mm vs. 14.5mm on these new experimental springs. (Above data compliments of Rob Edwards)
My '78 is a late production and already had the yellow springs that are substantially stiffer than early (green) springs. Mine are double yellow stripes at 171 lb ft vs early 78s that were a gooshy 119 lb. ft.
My goal in doing all this is to lower the front of the car, ever so slightly from the stock ride height. One half inch lower is an enormous number in this world. Goal is to creep back up on the front original height while being able to control all four corners. I love fully adjustable suspensions and 928's are a dream!
How it all comes together in terms of balance? Who knows..... I will be more than happy to keep you informed. Stay tuned!
The "extra" spring pressure required to move the gearshifter over to the 2nd and 3rd gear plane made the "feel" of moving too far to the right into the 1st and reverse too vague...and common.
Destruction of reverse gears and first gear synchos (and brake bands) became commonplace.
....not even close to their best engineering, but certainly an "evolution"!
Once you've actually driven this "transmission" a few miles....and you think about it....."centering" in the 2nd and 3rd plane is a huge improvement.
What aftermarket spring set is available to get that centering effect? I am too late for this because the drivetrain is already up there and no intention to lower it again. But just in case I have to do it all over again...
What aftermarket spring set is available to get that centering effect? I am too late for this because the drivetrain is already up there and no intention to lower it again. But just in case I have to do it all over again...
Just one spring that replaces the spring that Paul had added (closest to you, in the picture) which forces the shifter towards 4th and 5th gears.
On the pre-1983 transmissions, there is no spring present in that position. Just add in the proper spring.
California Motorsports Inc. finished the rebuild on the transaxle and LSD unit. Quiz: besides the safety wire on the shift forks, what is the one item that is not stock on this gearbox?
I was hesitant to bring it up, because you don't seem to want any input from the experts that do this stuff every day of their lives, but there is one other obvious thing that isn't stock....and it really needs to be changed.
That "roll pin" which is at the top of the picture on the center shifting rod is incorrectly installed and will fail...very quickly....and the extremely hard pieces that break off of the roll pin will fall into the gears, doing major damage. That roll pin is the "anchor" for the large "lockout spring" that provides the spring pressure for 1st and reverse. The split in that roll pin must face 180 degrees from where it is, in your picture. The way that the roll pin is currently installed forces the large lockout spring to put all of it's pressure on the two open "splits" of the roll pin, instead of on the backside of the roll pin (opposite of the split), where Porsche always installed it. The large lockout spring will put pressure on the "split", which will "flex" the sides of the roll pin, which will quickly fracture the sides of the roll pin. The chunks will fall directly down, into the gear sets.
And BTW....the roll pins in 2nd/3rd shift fork and 4th and 5th shift fork also appear to be incorrectly installed (although it is tough to tell in your picture....4th and 5th shift fork certainly looks like the roll pin splits are facing down.) The splits must face "up", so that the pressure from the shift rod is trying to compress the entire body of the roll pin. If the splits face down, the sides of the splits are (as above), being flexed from the sides of the roll pins. The roll pins will quickly compress and fracture, when installed, in this manner.
Common rookie mistake. Simple to repair, now. Very expensive to repair once the chunks fall though the gears.
We are about done with the donor harness from 928 Int'l. If anyone out there in early OB 928 land has an olive green body harness that is brittle or broken. Then this is your day. FCFS If you need it, I will ship it to you. You just need to pay for packaging and postage.
The harness repair technique is detailed above in this thread. If interested send me a PM
We are about done with the donor harness from 928 Int'l. If anyone out there in early OB 928 land has an olive green body harness that is brittle or broken. Then this is your day. FCFS If you need it, I will ship it to you. You just need to pay for packaging and postage.
The harness repair technique is detailed above in this thread. If interested send me a PM
I can't check out my car now but I might be interested. You mentioned olive green harness. Are there different colours?
If you go back to the very start of this thread you will recall that we were going to pay particular attention in restoring the rear suspension on the 928. Before installing the transaxle we took some time out this morning to put the newly rebuild transaxle on a pedestal. Literally. And to take a moment to acknowledge the beautiful design of this gearbox. What an extremely beautiful design that combines dense gearsets and the limited slip differential -all thoughtfully packaged into the stunning cast aluminum case. Ditto the rear crossmember. Transaxle came in at 135 lbs. dry. Bravo to the powertrain engineers at Porsche from 1972-75.
I am new to the the 928 community and want to contribute with something new and share what I have been working on. I have not been able to source a set of factory correct fuel lines for my '78. This is intended to provide an alternative to those that want the factory look and OEM quality in their early OB 928 restoration(s). Over the past two months, I worked with a long time provider in the Porsche community (PartsKlassic) to develop a specific set of lines unique to the early 928s. PartsKlassic is a Cohline distributor and they are highly knowledgeable in application and use of these OEM quality components and tooling in the fabrication of fuel lines. They are a long time provider of fuel lines to the 911 and 930 Turbo community. After receiving the lines, I did some finishing work on the fittings and sourced the black closed cell foam insulation. If anyone is interested in learning more about this alternative I would be happy to provide full details and pricing to this 928 community.
02-05-2019, 09:50 PM
