Eyecon pointed out to me that the MSG-5H transmissions are pretty slim pickings down under, and so some alternative transmission choices would be helpful. Also, if you plan on building your car for more power, this is a great option for a stronger factory Transmission.
For starters, one thing that makes this an easy upgrade is that both transmissions share bell pattern, input/output shaft diameters and spline count, and transmission mount locations. This means that from a physical stand-point the transmission bolts right in.
As you can see in these pictures, the MUA-5 (also known as an MSG-5F according to others) is a much larger transmission in both case size, as well as gear size, and it also has much larger and sturdier shift forks.
The biggest difference between the two transmissions that has to be overcome is the shifter. The MUA gearbox shift quadrant box has a longer arm to actuate the internals (I compared mine). It also sits perfectly level, while the factory Impulse MSG mounting surface is actually angled back, and the Impulse quadrant is similarly built on an angle to make it sit level.
This is how the stock Impulse shift quadrant sits without any machine work done. Notice that it is actually angled forward as it sits on the level surface of the MUA.
According to Ludacris2.0: "There is about a 2" gap between the change lever mounting bracket and the trans mount. The manual lever that goes into the trans was also not at the right depth to properly engage all the gears. So I had a machine shop mill the case where the quadrant box bolts up."
This is the mounting surface after it was milled. "They made a cut that took almost nothing from the front and about .375 to .5 from the back. I cannot remember which. This resulted in the manual lever being at a good angle inside the the trans and the quadrant assembly being at an acceptable one externally."
Then finally he stated that There was still a small gap of about .5 inches that was filled with nuts for spacers. Also the internal reverse shift lever was making reverse difficult so it was removed from the truck MUA and left in place on the quadrant box.
Here is said shifter spaced with nuts after machining.
This is the internal reverse shift lever/inhibitor that he had removed.
Finally, he noted the following.
Bolting it into the car was a little more difficult than the original. The dimensions are bigger and it is considerably heavier than the other. I used a 93 pickup 9.5" clutch and flywheel.(There may be sufficient clearance for a 10.25") And also used the 93 pickup slave cylinder. The only other mods where some light dremel work on the slave cylinder mating surface, a small notch on the detent spring plate, and notches on the front two bolt holes of the quadrant box. The shifter bolt pattern was slightly different between the two.
I have driven about 600 miles on the transmission without any major problems. Although shifting is fairly notchy. Cutting out the plate around the manual lever might fix this. Also I used the speedo gear from the original thinking that it would make the speedometer accurate. Its way off, 90mph on the dash reads 70mph on a garmin. The truck speedo gear would probably be more accurate. Revs at 70 are about 3200. And 1st redlines in the 22-25 range.
As far as the shifter pattern being slight different, it is. When you line up the bolt holes of the quadrant with the trans case you can see it. Although it is not much.
In my case I did not have to do any light machining/dremel work to the slave cylinder surface as I used the slave from said trooper. However, I will know more if I have to once I get it mounted. I will also check to see if the Impulse slave cyl. can possible be used without any mods. FWIW, I checked the old 10.25" clutch disc and PP I had laying around from the rodeo and the clearances are fine. (more torque holding capacity).
The speedo gear issue he had is actually not a problem. The early MSG transmissions used a 5 tooth drive gear in the transmission, while most later MSG/MUA boxes had a 6 tooth.
As my math has shown me, and also as Bugle relayed to me in another message, if you retain the 6 tooth drive gear, you simply need to swap out speedometer gears to a 20 tooth unit. Otherwise, you can swap over the 5 tooth drive and 17 tooth driven gear from the stock impulse box and get the same result.
As this picture shows, the trans mount bracket and speedo drive fit perfectly.
This is a side by side of the Impulse Speedo drive and the VSS from the Rodeo that the trans came from. They swap out directly, and according to JLEMOND, you can even simply remove the top portion (plastic) of the VSS and it will function just like the stock impulse speedo drive.
The Stock Impulse is a 17 Tooth gear, while the Rodeo mine came from is a 21 tooth. If I swapped out to the 21 tooth that it came with, my speedo would be off about about 2.5-3mph at 60mph, and read slow (I would only be going 57mph). Since Ludacris went with the 17 tooth gear with the 6 tooth driven gear, he is spinning the speedometer cable much faster, thus throwing off his speedo the way it is.
And just because I like showing off my stuff, this is a 4ZE1 with my frankenstein MUA bolted together.
