5speed manual transaxle interchange 1980US

[aluminum]

Hello : Happy May all
Re " Interchange and Quality " of 5speed manual Transmissions
1980 928 US ( my Car ) Then moving up >
Anyone who might Know > steer me in the right direction ?
(1) Do All 928 5 Speed Transmissions fit / Interchange ? ( example 1985 fits 1980 )
(2)What are the changes in the transmissions ? that are useful / Better
Read this on the Net : Re 1985 >
Gearbox synchromesh changed to Borg Warner design and shorter gear lever, improving driveability on manual transmission cars.
(3) 1985 is that a much better Transmission then the 1980 US 928 ?
(4) 1992 has : "Stronger manual gearbox with differential driven oil pump and front mounted oil cooler" well that interchange with the early type ?
Perhaps with a complete unit ?
I Have noted the early Type of 5 Spd's often need to be completely Stopped to engage 1st Gear as if the First Gear synchromesh. are weak ( well the 3 I drove )
Thanks in advance the Manuals do not address these issues

[Landseer]

All can fit.
There was a configuration during 1980, where EuroS will accept later transmissions with less trouble.

Technically 1980 non-euroS has a different TT shaft rear pinchbolt location.

Axle flanges on transmissions may need to be swapped too, minor.

[Barbapapa]

The 85 and later have the 'good' syncros and other improvements. That's a major step, otherwise there are little improvements over the years. An 85-86 box can be had for a reasonable price, later ones start to get rarer and more $. There's an 85 box for sale on rennlist now for 1500 (username BC). It's unlikely to find a 92 or later for less than twice that.

Your car *should* have the later length torque tube and crossmember already. They effectively moved the trans forward so the TT is shorter and the crossmember mouting tabs extend forward.

[aluminum]

Thanks everyone > Hummm " ALL CAN FIT ! " interesting Info I shall continue to research .
Just to compare my 1990 Porsche ( 964 ) 911 C4 Tran's has "syncros" even in reverse and to shift into Low or Reverse at 5 MPH for example is very easy.
ON THE EARLY TYPE'S:
IS it common that Getting Low Gear engaged on a 1980 US 928 5 Spd requires most often that your 100% Stopped ? in order to get a no grind engagement ? or just a sign of worn Syncro ?
Are the 1978 / to 1983 the same Tran's ? or perhaps 78 through 84
GEAR RATIOS :
do the 928's have a wide Ratio and a Close Ratio 5 Spd Available
If so What Years have what Ratio's ? OR are they on a Special Order Basis perhaps ?

Humm let me guess ? the Euro's have a Close Ratio Available for only $2,000 more when ordered new ha ha

[Barbapapa]

They added reverse syncros at some point, 85s have them.

Not being able to get into first when stopped implies your dual disc clutch is dragging and needs adjustment. If you adjust it you may like your trans after all.

The ratios are all very good on the early boxes and all similar IIRC. By 85 they start having varied gearing with tall US final drives and closer gears for the GT. There are charts out there somewhere. 928 Specialists has some tech info on their site, probably 928 Intl too.

I'm starting to wonder if your 80 has the later TT/crossmember or not. You might need to verify it yourself if you're going to get a new box.

[Landseer]

They say you can use the earlier TT and put another notch in the shaft.

Here's how to tell easily. The G28-03 box is the early setup. It has nuts on studs around the back cover.

The G28-05 box, which was used worldwide in 1981 model year, was introduced in 1980 on EuroS only. It has bolts around the rear cover.

You don't have gear swap options to speak of that matter.

I have a G28-05 from a 1980 Euro S --- that I installed last fall, direct fit, into my 1984 US and researched this pretty well before, btw.

All the gear ratios and parts change nuances (trans & clutch )are covered in the workshop manuals.

The first gear and second gear synchros and dogteeth apparently take a beating on these cars and most are crunchy, new perfect clutch or not. Especially when transmission is cold.

Regarding 1st gear: There is little reason to downshift to first when moving anyway.

[aluminum]

Thanks Guy's :
Yes no reason to shift to Low when moving > But trying to describe the symptoms.
The Car Go's into Low Gear fine when stopped however I just noted that if your moving just a bit she want's to grind as if it was almost as if it's a non syncro low trans ( Now that can't be )
You Know I was thinking the Clutch Adj also Hummm > It feels just fine and It is Smooth in Action . However I have barely Driven the Car and am waiting on parts to finish it to drive more.
I Understand to adjust the Clutch requires a strict procedure ( that I don't know yet ) But that's another tread .
"The ratios are all very good on the early boxes and all similar IIRC"
Yes I was thinking the ratios where good also I noted that the few Miles I drove it so far . Was wondering what's out their however as I seem to somehow run into parts and parts cars over time and wondered what's out their Overall .
Sounds like to me the 85 Trans is a Nice one except for the Ratios perhaps.
Landseer : RE: Here's how to tell easily. The G28-03 box is the early setup. It has nuts on studs around the back cover. ( Thank You )
Now that's what i want to know also I well check it tomorrow I bet I have that one .
Thanks everyone I well reevaluate after I get it going again

[Landseer]

Pull the numbers off the bottom of the unit.
That information, compared against the chart, will decode it further.

For adjustment, all I'm doing is levering the adjustment "T"s back full.
Seems to work on both 84 cars well, must then self adjust forward.
They have the same basic setup as yours.

Bleeding is a PITA. Only way I've succeeded is burping the air bubble into the passenger compartment after conventional bleeding yeilds no more improvement. This is accomplished by removing the clutch actuation rod (simple) then removing the piston snap ring while holding piston in the cylinder, then by hand inching the piston out. It gives up a belch of air, then you jam it back in place before letting much fluid into the car and reassemble.

Easier to do with seat out and still requires contortionism.

[Barbapapa]

Originally Posted by aluminum

Sounds like to me the 85 Trans is a Nice one except for the Ratios perhaps.

There's no concensus that any ratio is 'better'. Some like the tall US 2.20 gearing for highway cruising. I like to have 5th gear be maxxed out by 170mph at 7500 rpms but that's just me. IMO the early ratios are perfect for a race car and allow 5th to actually be used. Now I have an 87 2.20 box and can't use 5th at all, I don't care about highway driving.

[aluminum]

Thank again :
all good info : the 2.20 final sounds good to me as I drive Long Distance . a lot now as I think about it.
Bleeding Info is good .My Master Cylinder has 2 DIFFERENT Size Rubber Seals from the Reservoir to the main body of the Cylinder and some fool installed them backward ( small seal in Large hole ) so the brake fluid leaked out . Then they wrapped Teflon Tape around the Smaller Leaking Seal to try to stop the leak . I removed the tape and reversed the Seals Cleaned everything and Voila no more leak. Point being Air got into the system and the sat and sat. Strange when I look up the seals under parts and in manual I do not see 2 sizes but only 1 size for both seals ? . Wonder what master Cylinder I have ?
I see no Numbers on my first look under the Transaxel ? Don't know where to find them Looked along the bottom front and rear > cleaned off with wire wheel but no numbers .
Rear Inspection Cover ( Drain Plug at Bottom ) fits over Studs with Nuts retaining Cover on the Studs > So sounds like the early type
Build Date is 8/79 on Vin 1980 model year on Pink slip > Car ia a US Model

[Landseer]

Right!