Real Fiero Tech

Friend sent me a link to a guy doing a 6 speed swap into a Grand Am. Read thru the Thread and look at the pictures the guy posted about the swap. He used a part from Archee that is a flywheel spacer to get the input shaft and clutch disk to mate. From what I see and take on this issue is--The 1.5 inch or so adapter plate puts the input shaft to far out to mate with the clutch disk. So brilliant had a flywheel spacer made to put between the clutch set/flywheel to bring the clutch to the input shaft. Then the clutch set/spacer are all held on by longer bolts. This doesn't make since to me and maybe I am seeing it the wrong way. Does the spacer have something to do with making up the differance cause of the type of clutch/flywheel that the G6 some with stock? I know the guy that did the 6 speed/3800 didn't have to use a spacer of any sort with his setup. Here is the link to the built and pictures.


http://www.grandamgt.com/forum/showthread.php?t=73212

The F40 was designed to use a thick dual mass flywheel. This makes just about every aspect of the bellhousing area deeper than the Getrag/Isuzu.

Here are distances from the bellhousing face for the Isuzu and the F40:
Dist to end of input shaft: 5/16 vs. 1 1/8
Dist to full input shaft spline: 9/16 vs. 1 1/2
Dist to fully seated TO bearing: 2 3/8 vs. 3 3/16
Depth of bellhousing at bearing boss: 2 7/16 vs. 3 1/2

To install the F40 in a non-stock application requires moving the clutch splines about 15/16" further into the tranny. Thr guy in the 3800 thread used an un-cut Fbody flywheel to accomplish this. The kit for the SBC was designed to reuse the existing flywheel/adapter and uses a spacer to make up the difference.

F40:




Isuzu:

If I were doing a 6 speed swap, I'd use a flexplate for the starter drive, a small diameter "cookie" to get the right depth in the bellhousing and a piece of 3/8" or 1/2" steel plate drilled for the crank flange and clutch mounting patterns for the clutch friction surface.

For my F40 install w/ SBC, I will use the fact that SBC crank flange already protrudes about 11/16" (and why adapter plates could not previously be much less than 5/8") to get the clutch closer to the tranny splines.

An adapter plate in the 1/8 to 3/16" will gain 13/16" to 7/8" of additional clearance between the frame rails that could be used for a multitude of things.

Makes since now--So instead of having a custom flywheel made or find one that is already the right thickness, a spacer was used for the job? I guess that makes since to a certain point. Wouldn't using a thinner adapter plate for the engine/trans fix the issue with needing a spacer for the flywheel?

MstangsBware wrote:Makes since now--So instead of having a custom flywheel made or find one that is already the right thickness, a spacer was used for the job? I guess that makes since to a certain point. Wouldn't using a thinner adapter plate for the engine/trans fix the issue with needing a spacer for the flywheel?

For the SBC, yes a thinner adapter plate will lessen the issue. However, the kit was designed to reuse the current pieces and parts, so a spacer of some kind is the only way. Since the 153 tooth flywheel will not fit within the tranny, then the spacer must be on the flywheel side.

To run a thinner adapter, requires going to a smaller diameter flywheel (like the Z-style) because the 153 tooth SBC one will not fit within the tranny bellhousing. So with the thinner adapter plate, a new flywheel and starter combo will also be needed... adding to the cost for a retrofit, but would provide a more compact, and possibly less expensive package for someone installing the SBC & F40 for the first time.

The LSx RWD blocks crank flange does not stick out as far as the SBC, so the thinner adapter will not get you as much for those installs

Everything else does not take an adapter, so thicker flywheel, deep dished flywheel or some spacer are about the only options.

You can't do a thin adapter plate for SBC to FWD very easily.

A BOP to Chevy adpater plate can be very thin because those patterns share dowel and some bolt locations. There's room around the remaining bolts to put nuts on them.

For Chevy to FWD, no locations are shared and everything is packed in tightly. That means that the adapter plate has to locate the dowels AND have the threads for the transmission bellhousing bolts. 1/8" wouldn't cut it.

The 1/8" plate will pose some challanges, but going to steel helps these issues.

The 2 upper most tranny bolts will hit the SBC bellhousing flange slightly. With the steel plate you could weld studs to the plate for these, or press in wheel studs from the back side and clearance the SBC flange to clear the studs.

The center bolts on both sides will not hit anything on the SBC. For the diff side dowel pin, drill the hole in the plate for the dowel pin, then weld on a plate w/nut welded on its back side (or another wheel stud). For the other center hole could use a stud or welded nut to the back side.

Bottom hole by the diff also is clear on the back side, so stud/welded nut.

The bottom hole by the oil fileter assy for the 2nd dowel pin has some interferance to the SBC, but could be cleranced to clear the plate/stud combo for this.

Another alternative would be to rotate the tranny relative to the engine (bring the diff up). This will eliminate some of the interferance issues with the tranny bolts to the SBC block. It also would lessen the halfshaft angle with the engine mounted as low as possible in the chassis. There is room for a small amount of rotation until the tripod hits the starter pad, but if you wanted more you could clearance the starter pad that is no longer used.

If next reason why it can't work is the stiffness between the engine/tranny, the G6 has the extra bolts on the bottom so the adapter will go down to use them (and to stiffen up the starter area - stud mounted), and two stabilization rods will come from the SBC motor mount pads on the block and attach to the bottom 2 bolts on the tranny (like GM has been doing on their 4x4 stuff for years).

N* "Cookie" which should help a bit in seeing it -



Backside installed ( sort of w/o the bolts and what not. )



Hope that helps.

--Allen

so V8Archie uses a 30 lb flywheel and then you can add on the extra weight of the spacer?