04 Marauder: Terminator Swap Flexplate and Converter

[MTBSully]

Not sure if this forum is still very active but I could use some help with an upcoming build! I'm going to be swapping a built terminator engine into a low mile 2004 Marauder. I'm working to gather the parts now but one area i'm struggling is the transmission.

• I've heard the factory torque converter is around a 2800 stall on the 2004s. Is this a solid choice for a street car? No major plans for drag racing or anything. The car already has 4.10 gears installed. Keep this or go aftermarket?
• What 8 bolt flexplate should I get? I'm running the terminator factory forged 8 bolt kellog crank so the OEM marauder 6 bolt flexplate wont work. Will a 99-01 Mustang GT 8 bolt flexplate work? I measured the TC in the car and it looks like there is about 10.5" between the mounting studs. Any other suggestions?

If anyone else has done this swap before and has any suggestions, i'm all ears!


Chris

[RocsMerc]

I don't know the exact specifics of which parts are interchangeable, but I can share some knowledge that may put you on the right track. Our factory engines are completely identical to the automatic transmission 03-04 Mustang Mach 1 with the cast crank and 6 bolt flexplate, and the manual Mach 1 has a forged crank with an 8 bolt flexplate. I would suggest starting by researching the manual trans Mach 1 flexplate. There's a chance it may be a direct bolt on fit.

As far as the stall and gears goes, that depends on what your goals are with the car. Are you going to supercharge it?

When I was still naturally asperated, the 4.10 gears were a night and day difference for the better and feels like how the car should have came from the factory, so definitely keep them if you are not going blown. I have no experence with higher stall torque converters while NA, so I can't comment on that.

If you're installing a Terminator blower or any other roots/twin screw style blower, there's no reason to increase the stall. You'll have plenty of low end torque to break the tires loose. I have a Trilogy blower on my car with 4.10 gears and factory stall, and to be honest the gears do feel a bit overkill, but it's such a minor thing that I wouldn't recommend taking on the added expense of changing them out just because. A set of 3.75 gears may pair slightly better with a roots blower, but I guarantee you will be happy regardless.

Now if you are going with a centrifical blower like a Vortech, then you definitely want a high stall and the 4.10 gears. A friend of mine has a Vortech blower with either a 3200k or 3400K stall (don't remember which) and 4.10 gears. It has a completely different feeling driving it, but even with the high stall and gears, it's actually a smoother driving experence. It doesn't break the tires loose as easily or slam you back into your seat as hard, but his car is faster than mine overall. Driving it feels like smooth continuous power. Apparently the high stall and gears compensate nicely for the issues a centrifical blower may have at lower RPM's.

[MTBSully]

I don't know the exact specifics of which parts are interchangeable, but I can share some knowledge that may put you on the right track. Our factory engines are completely identical to the automatic transmission 03-04 Mustang Mach 1 with the cast crank and 6 bolt flexplate, and the manual Mach 1 has a forged crank with an 8 bolt flexplate. I would suggest starting by researching the manual trans Mach 1 flexplate. There's a chance it may be a direct bolt on fit.

As far as the stall and gears goes, that depends on what your goals are with the car. Are you going to supercharge it?

When I was still naturally asperated, the 4.10 gears were a night and day difference for the better and feels like how the car should have came from the factory, so definitely keep them if you are not going blown. I have no experence with higher stall torque converters while NA, so I can't comment on that.

If you're installing a Terminator blower or any other roots/twin screw style blower, there's no reason to increase the stall. You'll have plenty of low end torque to break the tires loose. I have a Trilogy blower on my car with 4.10 gears and factory stall, and to be honest the gears do feel a bit overkill, but it's such a minor thing that I wouldn't recommend taking on the added expense of changing them out just because. A set of 3.75 gears may pair slightly better with a roots blower, but I guarantee you will be happy regardless.

Now if you are going with a centrifical blower like a Vortech, then you definitely want a high stall and the 4.10 gears. A friend of mine has a Vortech blower with either a 3200k or 3400K stall (don't remember which) and 4.10 gears. It has a completely different feeling driving it, but even with the high stall and gears, it's actually a smoother driving experence. It doesn't break the tires loose as easily or slam you back into your seat as hard, but his car is faster than mine overall. Driving it feels like smooth continuous power. Apparently the high stall and gears compensate nicely for the issues a centrifical blower may have at lower RPM's.

Appreciate the input, maybe i'll stay with the stock converter for now. I'm doing a full terminator swap with 2.93 upper and 4lb lower pulley, so it should make close to 450-500 at the tire. Manual mach 1 will use a flywheel instead of a flexplate, so that won't work.

[4Eyedturd]

Good luck, I just recently went thru the 8 bolt flexplate debacle. Called PRW before ordering to find out they don’t make one, ADTR doesn’t either. It’s the Marauders oddball 10 5/8 torque converter bolt pattern. No one has the 99-01 GT one or auto Mach 1 flexplate. I’m getting by with by drilling the flexplate for the marauders pattern.

[fast Ed]

A manual trans car has a flywheel for the clutch to engage with, which is a different thing than an auto trans flex plate other than being a circle. :-)

[MTBSully]

Good luck, I just recently went thru the 8 bolt flexplate debacle. Called PRW before ordering to find out they don’t make one, ADTR doesn’t either. It’s the Marauders oddball 10 5/8 torque converter bolt pattern. No one has the 99-01 GT one or auto Mach 1 flexplate. I’m getting by with by drilling the flexplate for the marauders pattern.

So are you saying the 99-01 GT flexplate would work? The auto mach 1 flexplate wouldnt work anyway since the auto mach 1s came with a 6 bolt non-forged crankshaft.

[FordNut]

I believe Summit has an aftermarket SFI rated flexplate that will work.

[4Eyedturd]

It might work, if you can find it anywhere.