Hi,

I have a muncie m21 that I believe is about to go out. Some time after accelerating real hard unce I push in the clutch I can feel it "grinding"

My questions are:

1) Is it rebuildable?
2) Is it worth rebuilding?
3) How much should a rebuild cost?
4) Should I just step up to a M22?




Thanks Guys

 

1.) Yes
2.) Yes
3.) No way to answer that. Some parts in the transmission are very costly. A counter gear or instance will cost 600+ new.
4.) Depend on what you want out of the car and how bad yur current trany is.

Your issue sounds more like a clutch issue then a tranny issue. Maybe a release bearing?

Edit: when you push the clutch in nothing in the transmission should be moving. If the car is neutral and not moving then it is possible that the input shaft is turning but if the car is in gear sitting still with the clutch pushed and it is grinding it is not a transmission problem

 

I rebuilt mine about a year ago. There are some re-build kits available. Check the internet. I used the following and was very happy with them:
http://www.thegearbox.org/Muncie.html
I also needed the two sliders and one of the gears. Total cost, around $400. I purchased the following book from Amazon:
How to Build & Modify High-Performance Manual Transmissions
http://www.amazon.com/gp/product/193...ef=oss_product
It was well worth it. The book will help you identify when your Muncie was built. You'll need that to get the right parts. Take A LOT of pictures as you take it apart and take your time. A simple propane tourch is sufficient to heat/expand the reverse gear for removal. The needle bearings are a pain in the ****, but use the grease, take your time.

I have a photobucket account you're welcome to look at. It became a mess after Photobucket changed. All the work I put into putting everything in order for a nice slide show is now out the window. Muncie pictures are spread throughout. Sorry
http://s819.photobucket.com/home/lynnheenan

 

No, it's when the cars is still moving. Yester day after I got on it real hard I engeged the clutch todown shift dropped it into 2nd let off the clutch(going bout 15 mph) and it made a grinding sound then paused breifly, then did it again. I f I dont drive it hard its fine.

I see on ebay a refurbished M21 goes from $1k-$1,300 and the M22 is only $1,500. I was thinking since I like to drive it hard maybe I should just go with the M22.

Thoughts?

 

a m21 is a great tranny they shift good and they are quieter than the m22. the m22 has straighter cut gears so it makes more noise going down the road. thats why it has the nickname "rock crusher" they were put mostley into the big block cars to handle all of the torque.i think it would be better to just rebuild your m21. but it seems like its not going fully into gear when you shift. you might want to try adjusting you linkage arms.

 

Curious, where are you located Ineedspeed?

 

If the clutch is working right tear the trans down and inspect it for problems there real simple to work on I'm in muskegon michigan if your close I can help you out. I've rebuilt saganaw four speeds and a borgwarner four speeds along with a jap 5 speed for my dad. (dropped it into 2nd let off the clutch(going bout 15 mph) and it made a grinding sound then paused breifly, then did it again. I f I dont drive it hard its fine.) Explain what it did in more detail did you stay off the gas or start to excelerate when it started to grind and if i understand what your saying it stopped grinding breifly then made the grinding sound again and then what did it do? are you completely engaged in second gear? The grinding sound is not good your doing damage to the internal parts of the trans. you need to repair it before you distroy it don't drive it hard again until you get it fixed!