My tranny grinds ever so slightly when you put it into 3rd until it has been warmed up for 5 minutes or so, and doesn't do it if I double clutch.

I just read the 5-speed transmission article on howstuffworks.com (good read if you have the time), and had a couple of questions that maybe the more experienced people here can answer.

First off, I'm assuming my grind has to be caused by the synchro going out. As I understand it, all a synchro is made of is some friction material and the color they mate too. Am I correct in assuming that the material has worn causing the dog ear gear deal to grind because it the synchros don't grip well enough to spin it all the way up anymore?

And second, is it really that difficult to rebuild one of these transmissions? I'm sure checking clearances and play values is tedious, but do any of the gears ever really fail if they haven't been subjected to abnormal heat and pressure? I know shift forks can go out, but are tehy that difficult to replace?

I'm just kinda wondering, because I have a feeling that I'm going to be facing tranny failure sometime in the future, and would have to purchase a new tranny just to get me back on the road, but think it would be cool to attempt a rebuild.

Where would one get parts for this kind of thing, and how much do you think it would cost?

Thanks for entertaining a transmission newb.

 

That tranny can still last 20k or more easily unless you're treating it like **** and running it without gear lube.

The rebuild wouldn't be hard, just a shitload of parts. If you don't own a shop, don't consider it though. You need a decent shop press and puller to press the gearsets together.

 

Have you tried some synthetic gear oil? My car used to grind from 1st to second all the time, after I changed it to Mobil One it was fine..

 

Change the fluid, it WILL make a big difference. I've had great luck fixing scratchy syncros with pennzoil syncromesh. Get it at autozone.

 

^ definitly change the oil before you jump to any conclusions, i had a similar problem with two of my fc's and the problem was solved with a nice new tranny lube. the n/a tranny's are pretty solid for stock or near stock cars, i dont think people have had that many issues with them except for when your putting out quite a bit more torque such as a turbo swap and even then some have found the tranny to be just fine. as for replacement gearsets and tranny internals, a mazda tech here in houston told me that the gears rarely ever need to be replaced, i dont know if that helps but its what i heard. im sure someone else knows alot more.

 

I have switched it to Royal Purple, which did make a huge difference, but a little crunch is still there. Some of it could be attributed to it being half empty when I drained it, but I don't know how long it was like that since the clutch had only 2,000 miles on it when I purchased the vehicle.

 

You can get synchomesh as mwpayne suggested. all of the mr2 guys use it and say that it works wonders on their grinding transmissions. I believe they use the GM or ford one though... either way I'm sure its pretty close to the same thing.

 

"it without gear lube."

You said lube, heh heh heh.

 

yeah my tranny on my 91 coupe grinds when its cold. it reminds me of initial d when i shift tho lol. but yeah someone told me to change the fluid in it and im not sure how to do it.... where exactly is the place that i need to drain/refill the fluid? thanks!

 

whens the big meet?

 

First thing to do is remove the fill plug, which is on the driver's side of the transmission, towards the front of the unit, and in about the middle as far as height goes. If you can get that off, you're in good shape

Then you pull the drain plug, which is a big 17 or 22mm guy on the bottom of the tranny, more towards the rear. It is NOT covered by a rubber plug, that's your flywheel access.

After that, it's up to you to find a method to get the fluid in there, it's a pain.

 

I fill it using a scrap hose from a shower head stuck on a funnel.
feed it down past the brake cylinder, then go underneath & stick it in the fill hole.

 

lots of methods...

1. run a hose with a funnel thru the engine bay and stand on a chair and fill.

2. use a supersoaker and a hose

3. go to aaroncake's website and make his homemade pump

4. some cars u can fill from the shifter after taking everything out

2 best fluids for bad synchros mentioned on 240sx boards - gm synchromesh, redline mt90

 

They also sell hand pumps at auto parts stores. They're only like $4 if I remember correctly. It takes a while, but thats what I used. Also, remember to jack the car up evenly at all four corners to ensure proper draining from the tranny.

 

Hmmm, I wish I would've done a little more research on fluids before hand, but the local tuner shop had the Royal Purple gear lube, and it has been working great. Are there any addatives that might help a little more?

 

ok. so do i have to pull the tranny or jack the car up so i can get under it or anything like that? ive never heard fo this so thats why im asking lol.

 

You'll want to jack it up. I did, and just made sure it completely drained then added fluid to spec, dropped the car to make sure I didn't overfill, jacked it up again, and capped it off.

 

1. no need for a chair dont have to run hose to ceiling to work - most common and easiest way to fill.

2. ???? Wierd ?????

3. Works as well

4. WTF - bad advise on a rx - dont work

you will read about three fluids on this board as you employ the search function. Royal purple, MT 90 and normal gear lube as owners manual specs which really works ok as well.