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How much HP/TQ can an M20 handle?

12K views 5 replies 4 participants last post by  k-star 
#1 ·
#5 ·
Depends on how well you hookup off the line if that what your going to do with it. The week link is the input shaft. Too much HP and torque and you will twist it off. It can easily handle 500HP if it's in good condition, and your careful with it.

Most people think that the M22 Rockcrusher is the stronger of the Muncie's. Only difference is the M22 had less of an angle (not straight cut) on the gears which reduced end loading on the mid plate. The different gear angle allowed the trans to run a little cooler also, but noisier.

Vince
 
#6 ·
trans

If your M20 is in good shape it will take 500hp during ocasional trips to the track. If you were planning on racing every weekend i would say to invest in a different transmission. One thing you will need to look at is the case where the pin that holds the cluster gear in goes through. This bore in the case needs to be a tight fit with that pin. Once the case gets sloppy here the pin will flex and allow the clearance between the input and the cluster to grow and cause busted teeth.I personally have never seen a muncie with a input twisted off. I have seen the splines twist though. 95% of the muncies that i have rebuilt that were hurt was from broken gears.

The M22 aka rockcrusher, had a few more things going for it then just the gear angle. The gears them selves were made from a different material the the standard M20/M21 transmissions. The gear contact angle also made the gear stronger and added more of a contact area in the pitch diameter of the gear.

Keith
 
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