Some 4x4 enthusiasts were discussing an engine swap that would use an aluminum bellhousing that had a 1.00" section removed and the rear face then welded back on and trued up on a milling machine. A jig was to be used to keep the alignment of the front and rear faces in the proper relationship.
My question regards the feasability of welding something like this. Can an aluminum bellhousing welded like this be considered safe and strong enough to use in a vehicle?
I am pretty sure parts like this are cast, machined and then heat treated when they are produced by the original manufacturer. I guess I'm concerned that major welding on this unit is not a good idea.
I don't doubt the strength, but I'd sure as hell question the ability to end up with the pilot bearing in the crank concentric with the main bearing in the trans. One that is not is likely to be the cause of premature clutch failures, as well as bearing failures. Even if a fixture locates the two halves properly, I can't imagine that the welding process would leave them where they were desired. I would worry about that more than the strength, especially if the welding is in the hands of a good weldor. Is this a case of re-machining the bore of the bell housing , too?
It could be done, and accurately, but would take a bit of skill. The welding be be easiest if the bell housing was relatively new so it didn't have a decode of oil saturated into the porous surface of the casting.
The jig that aligned the 2 surfaces would be critically important. The welding would take some time as it couldn't be done too fast without cracks forming around the weld area.
I though these adpater bell housings were already available off the shelf for a few $100.
My son's mustang needed a different bell housing, and the only one we could find in the salvage yard was severely cracked. I welded it up and then had to re-machine clearance for the ring gear. Worried about just this problem, I bolted the bellhousing to the engine, and then slid the tranny on where I could feel the fit into the pilot bearing, I got lucky, it was perfect. My "plan B" would have been to pin the tranny where it needed to be and redrill and tap new hold down bolts. (This idea wouldn't work on GM products - the bell housing and tranny are one piece)
The car ran with this real well, till he blew up his Crate engine. Right now the engine is in pieces in the shop waiting for funds. ( Me thinks this is a good thing - maybe the kid won't blow the next one so soon) In the mean time, the kid drives my old minivan.
Not for this application. What I'm trying to do is mate up a Toyota Supra Turbo 7M-GTE motor with an R series transmission in a Toyota pickup truck. The Turbo Supras also used R series trannys but they had a longer inputshaft (+30mm) than the R series truck trannys (same diameter and spline though). The Supra tranny is undesirable for 4x4 trucks because it has a higher first gear and you can't change that gear without changing the input shaft to a truck input, which would then be too short. The truck trannys will bolt right up to a Supra bellhousing but the input shaft will be 30mm too short. A pilot bearing adapter that moved the pilot bearing 30mm out to the input shaft seems like it would interfere with the clutch disk hub.
The most desirable R series truck transmission has a 4.31 to 1 first gear and the Supra tranny has a 3.21 to 1 first gear.
The 5 sp. transmission used in a 1996 or later Tacoma is also an R series and it will also bolt right up to the Supra bellhousing, but, it has a different tail housing (for mounting the transfer case). A company called Marlin Crawler makes an excellent adapter to mate the correct tranfer case to this transmission for $349, but (yes another but) the first gear ratio in the Tacoma trans is 3.89 to 1, which is better than the Supra ratio and not as good as the earlier transmission with the
4.31 ratio. There is no gearset available to change the ratio in the Tacoma trans to a lower ratio as Toyota changed the helical cut on the gears in 1996.
It would be possible to have a longer custom input shaft made, but these inputs also have and integral bearing race and a gear; they are not just a simple shaft, so a "one off" job might be prohibitively expensive (although I'd welcome input on that).
The easy answer looks to be a stock Supra bellhousing and clutch, Tacoma transmission, a $349 transfercase adapter and live with the 3.89 first gear. My only worry is that the Supra motor, while it has good low end torque, displaces only 3.0 liters and probably could benefit from a lower first gear in this application. I guess it works well enough in the Tacoma behind the 3.4 V6, but heck I want to do better than stock :-)
Ron Millen had to splice parts from two bellhousings to mate up a 4.5 l V8 to a Toyota 6 speed manual tranny for his IS300 project. The trick his guys used to make sure everything would line up is they machined steps in the mating parts so they had to go together right.
Aluminum bellhousings are normally used as cast with no post-heat treatment. So welding one shouldn't make it weaker. They're normally thick enough to have sufficient strength without such treatment.
As others have said, welding, if done properly, will be OK. The real problem is getting everything parallel and concentric. When I put a buick V6 into my '52 jeep the store bought adapter was not concentric. There was enough slop in the tranny input shaft to slip in but it rubbed on the nose piece. I had to fix the adapter. But the bell housing also needed work so I put it on my mill and machined the face and changed the bore. You would probably be wise to do this. Make a fixture to align the bell housing for welding and then check in a mill. If it's out the use the setup to bore and mill it. Then, because the bore is bigger, make a ring to press in that brings it back to original size. Or weld in the bore and machine that out. I'd make the ring. And make it so when the bell housing is bolted to the tranny it is trapped and cannot work it's way out. ERS
|It would be possible to have a longer custom input shaft made, but these |inputs also have and integral bearing race and a gear; they are not just |a simple shaft, so a "one off" job might be prohibitively expensive |(although I'd welcome input on that).
The Supra transmission input shaft won't fit the Tacoma transmission ? Rex in Fort Worth
The Supra shaft has an integral gear that has a different helical cut in it than the gears in the Tacoma transmission. You can't change the counter gear either because it is part of the counter shaft.
A custom Bellhousing could be done, but it requires high skill. I know I could do it, but I would have trouble finding more than 2 other people I know who could do it.
On Mon, 09 Feb 2004 19:44:39 GMT, Ernie Leimkuhler wrote:
|In article , F. |Hayek wrote: | |> In article , |> Ernie Leimkuhler wrote: |> > |> > I though these adpater bell housings were already available off the |> > shelf for a few $100. |> |> Not for this application. What I'm trying to do is mate up a Toyota |> Supra Turbo 7M-GTE motor with an R series transmission in a Toyota |> pickup truck. The Turbo Supras also used R series trannys but they had a |> longer inputshaft (+30mm) than the R series truck trannys (same diameter |> and spline though). The Supra tranny is undesirable for 4x4 trucks |> because it has a higher first gear and you can't change that gear |> without changing the input shaft to a truck input, which would then be |> too short. The truck trannys will bolt right up to a Supra bellhousing |> but the input shaft will be 30mm too short. A pilot bearing adapter that |> moved the pilot bearing 30mm out to the input shaft seems like it would |> interfere with the clutch disk hub. |> |> The most desirable R series truck transmission has a 4.31 to 1 first |> gear and the Supra tranny has a 3.21 to 1 first gear. |> |> The 5 sp. transmission used in a 1996 or later Tacoma is also an R |> series and it will also bolt right up to the Supra bellhousing, but, it |> has a different tail housing (for mounting the transfer case). A company |> called Marlin Crawler makes an excellent adapter to mate the correct |> tranfer case to this transmission for $349, but (yes another but) the |> first gear ratio in the Tacoma trans is 3.89 to 1, which is better than |> the Supra ratio and not as good as the earlier transmission with the |> 4.31 ratio. There is no gearset available to change the ratio in the |> Tacoma trans to a lower ratio as Toyota changed the helical cut on the |> gears in 1996. |> |> It would be possible to have a longer custom input shaft made, but these |> inputs also have and integral bearing race and a gear; they are not just |> a simple shaft, so a "one off" job might be prohibitively expensive |> (although I'd welcome input on that). |> |> The easy answer looks to be a stock Supra bellhousing and clutch, Tacoma |> transmission, a $349 transfercase adapter and live with the 3.89 first |> gear. My only worry is that the Supra motor, while it has good low end |> torque, displaces only 3.0 liters and probably could benefit from a |> lower first gear in this application. I guess it works well enough in |> the Tacoma behind the 3.4 V6, but heck I want to do better than stock :-) |> |> Fred | |Believe it or not I get it. | |A custom Bellhousing could be done, but it requires high skill. |I know I could do it, but I would have trouble finding more than 2 |other people I know who could do it.
These guys can do it:
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Craig Taylor is the nicest and most knowledgable guy you will meet on performance drivetrains. Located in the DFW area, but ships all over the world Rex in Fort Worth
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