>Has anyone done a 5 speed conversion on an Alpine?
I have tried to follow this thread on this mailing list with very little success. There are people out there who have the recipe, but Macy's is apparently not telling Gimballs. I the interest of public disclosure, I will summarize what I have learned, and add some conjecture. Until we can pry some info out of someone more knowledgeable, we'll just have to pool our ignorance.
The guys down under apparently adapt early Toyota 5 speed T-50s with cast iron gear cases and aluminum bell housings with good success. This trans has a decent set of gear ratios, including a 5th gear that approximates the Laycock OD at about .80. This trans was used in the Corolla and Celica in the late 70s, and later changed to an aluminum gearcase. The problem is that the shift lever was moved about 5" back on the later trans by using linkage that is internal in the top of the trans. Adapting one of the '82-85? trans. from a Celica would require cutting a new hole, or using a serpentine shift lever. BTW, Toyota went to a FWD for their Celicas and Corollas in about 1986.
I have been measuring transmissions off and on for the last 5 years, and I looked at one of the cast iron T-50s once. It was quite narrow like the Alpine's and I got the impression I that it would fit in the Alpine's trans tunnel, and that the shifter would come out where the Alpine's does. I am trying to find an early T-50 in my area, but so far no success. Apparently they are much valued for swaps, upgrades, and maybe racing.
I recently posted a message from a Healey mailing list where a guy adapted a Supra 5 spd. trans in a Healey. He said they used the Healey clutch cover and yoke, but had to use a Toyota clutch plate. This figures, since it would have splines to match the input shaft. You would have to make sure the Toyota clutch plate fit the Alpine pressure plate face and the flywheel. The Toyota transmissions I have seen have a very small dia. spigot on the end of the input shaft (about 1/2" dia). It would seem you could adapt them to virtually any engine just by getting a thick-walled oillite bushing with an OD that fits the crankshaft hole and an ID that fits the spigot.
On the output side, it should be a simple matter to mig weld the front end of a Toyota drive shaft to an Alpine drive shaft. Just make sure you have it balanced and use new U joints.
So now we get to the interesting part: splicing the bell housings. I once thought this was done only by alchemists, but apparently it's a common rodder's trick. If the Alpine's clutch yoke and throwout bearing are used, I would assume that as much of the Alpine's bell housing as possible would be included in the final product. But the bell housing would have to be the correct height so the input shaft would just fit into the spigot hole in the Alpine's crankshaft. After measuring (at least twice), both bell housings are cut (only once), and then heilarced together to form a solid unit. Matching the pieces would be an issue, as would the opening to accommodate the clutch yoke. Of course, it would be critical to maintain a parallel plane for the front and rear faces of the bell housing, as well as the correct rotation of the trans. This looks like a job for a machinist with "real" tools, and not me with my metal cutting blade on the skillsaw. I don't know if you can cut aluminum with a plasma cutter (Macys? Gimballs? can you tell us?), but that would be a slick way to section the bell housings.
After that, it's a matter of adapting the Alpine's trans cross member for new mounts, hooking up the clutch linkage from the slave cylinder, lining everything up and bolting it all together. Have I left anything out ? (OK, you have to fill the trans with oil).
There are probably other 5-speeds out there that could be used. The Ford Ranger 2wd PU trans (both early Toyo-Kugu and later with aluminum case & integrated bell housing) look like a match. I'm not sure about the ratios, but they have 5th OD.
Keep in mind, none of these transmissions are that much stronger than the Alpine's, so 150 HP fire breathing hipo engines are probably not a match (bad news Jarrid). Below are some measurements I took on a S III trans tunnel. I am pretty sure you can get a trans that fits without re-arranging these dimensions. The critical part is the "saddle" that sits just behind the ashtray, and just ahead of the junction of the X- brace. It is a structural member, and modifying it, or the X-brace would be dicy.
My 2c. Let the games begin.
Rex Funk
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Viewed from top: (Crude is not the word for ASCII drawings. . sorry if this gets trashed)
| firewall
|<------------------24"----------------------->|
____
| firewall to saddle
/
|
/
| ____------------------------------------/
\ /___/
\ -------\/----/ | |
\ 4.5" / | 5.5" 8" tapered 9"
14" <Inside dimensions
/--------/\---\ |__|
of Tunnel
/ <---7"---->\ /\ \--------____________________
/ \ Saddle
\
X- brace
\
\ ____
|
|
Measure your Alpine's transmission, and try to get as close to it as possible. The critical dimensions are: (based on All syschro, non OD trans. Recheck your own trans)
-Distance from the front of the bell housing to the centerline of the shifer lever My Alpine's is 22 1/4". . . short by modern standards -Height of shifter lever base (to fit raised cover, or hump, on Alpine tunnel) Alpine's is relatively high off centerline of trans (plan on adapting lever). -Width of the gear case at various sections (to fit the tunnel). Alpine gearcase is 7" wide, narrow compared to many other trans. The last 4" of the trans must be narrow enough to fit into the 5.5" wide "saddle" part of the tunnel -Overall length (to fit in front of the X-member) Alpine's is 32 1/2", shorter than many (like Nissan 300 ZX (at) 35")
Q: Why all these long transmissions with "far back" shift levers?
A: Modified driver positions due to laid back and longer windshields. Really screws things up for us more vertical-windscreen LBC guys.