mom'sZ Posted January 24, 2008 Share Posted January 24, 2008 I have a freshly rebuilt 5 speed (early 280z) installed in my car. When you upshift between 2nd and 3rd it grinds. It doesn't do it at first, when the tranny is probably not warmed up. It doesn't seem to do it when downshifting from 4th down to 3rd. If I don't rev the engine very high and I shift very carefully, it doesn't seem to do it. If I try to power shift it, it flat won't engage and horrible grinding ensues. Any ideas about what is wrong? Quote Link to comment Share on other sites More sharing options...
DrEaM Posted January 24, 2008 Share Posted January 24, 2008 did you change the clutch also? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2008 Share Posted January 24, 2008 Sounds like you burned up a synchro already. A quick shift while letting off the gas is not costing you enough time to warrant the damage power shifting causes in my opinion. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted January 24, 2008 Author Share Posted January 24, 2008 DrEaM: no, the clutch is the same one I was previously using with a 4 speed that was in the car Jon: I was hoping you would reply. I guess I need to restate something. By power shifting I just meant shifting at higher RPMs but using the clutch and letting off the gas. I've never tried to do a clutchless shift or not let off the gas. So... you think it sounds like a syncro? That's what I kind of thought to, but I know very little about a manual tranny. Can you tell me a little about what syncros are, what they do, how it works? I have a factory service manual. How hard is it to replace? (obviously the tranny has to come back out and be taken apart) Could I manage it myself or should it go back to the builder? Thanks Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2008 Share Posted January 24, 2008 A synchro is basically a 3/8" long cone shaped brass ring with ridges on the inside and teeth around the edge. It fits onto the tapered nose of a gear cluster, and then the end of that gear cluster has a cone shaped hole that fits onto the top of the next synchro, so the gear clusters and synchros are stacked onto the main shaft. When you shift, the shifter pushes a large round shift ring onto the synchro, which engages it via the teeth around the perimeter. The synchro then pushes onto the front of the gear cluster you want to engage, and then the friction between the two slows the gear cluster so that the shift ring can engage that gear and in that same motion it releases the last gear. That's a simple explanation, but that's pretty much what they are. The brass synchros can crack, but more usually they wear. If this thing is freshly rebuilt you might take it back to the shop that did the work and see if they're willing to do anything for you. If it was done by the PO or something then you'll just have to dive in and fix it. I haven't been into a manual trans in about 15 years and I'm only 33, but they're not hard to get apart and the synchro is pretty easy to replace. I think book time on a whole trans rebuild is 5 hours, if the trans is out of the car. If you have the manual it shouldn't be hard to work through it, although they'll have you checking clearances with feeler gauges and doing a lot of things that your corner transmission shop wouldn't do. If you still have connections to get parts I can tell you that I bought an RPM Superkit rebuild kit and it was $85 at cost + 10%, but the retail was $265, and that was probably 10 years ago (I bought a kit and haven't rebuilt the trans yet). You might be able to buy just the one synchro, but the rebuild kit comes with all the bearings front and rear seal, gasket for the input shaft, etc. If that stuff was all just replaced it would probably make sense to see if you can get just the one synchro. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted January 24, 2008 Author Share Posted January 24, 2008 Thanks Jon, great explaination. I just paid to have it rebuilt, I'm sure the guy would fix it for me, problem is he's in Tenn and I'm in Florida. Shipping is the killer. First question... are all the sychros in the tranny the same? Do I need to replace all the sychros or just one for that gear (are there more then one?) Anybody know anyone who is experienced with zcar trannys that's in the south Florida area? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2008 Share Posted January 24, 2008 There's a synchro between each gear cluster, and the one for 5th is smaller. So I think there's 4 in there, and 3 are the same. You would only be concerned with the 2-3 synchro. Quote Link to comment Share on other sites More sharing options...
Dayz Posted January 24, 2008 Share Posted January 24, 2008 In the mean time, try some other good oil. I remember my tranny grinding while downshifting, switch to Royal Purple $$$ and the grinding stopped. I am far from the best in terms of oil, try a different one is an easy short term fix, at least! Dayz Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted January 24, 2008 Author Share Posted January 24, 2008 OK I just talked to my parts guy and he said the syncronizer consists of a hub, a sleeve and a (usually brass) baulk ring. He said most people refer to the brass baulk ring as a synchro. Then this Baulk ring is what I need? Also can confirm 1st - 4th uses the same part number part. He suggested that I might want to check clutch operation. I had thought of doing this because the more I drive it the more I'm unhappy with how 4th engages, and how downshifting into 1st works. But the system is so simply, how can it be out of adustment? I realize the pedal linkage is adjustable, but the hydralic system is what it is. If it isn't leaking fluid, what else could be wrong? The slave and master are new. PP and disc is less then 5K miles. Any suggestions? Thanks for the help guys. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted January 24, 2008 Share Posted January 24, 2008 What does fresh rebuild mean, all new bearings and syncros? How many miles on this new tranny? Are the shifter bushings new? What gear oil are you using? The 2-3 shift happens between two different shift rods. loose bushings will cause mis-shifting. The first 4 syncros (baulk rings) are the same in the 280 to 280ZX trannies. Unless there is a major problem, only those rings wear. The hub and sleeve are steel. Breaking down the transmission is not too difficult but you will have to remove the countershaft (partially remove the mainshaft), and input shaft to get to this syncro. The seals can be reused. The front cover gasket will need to be replaced. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2008 Share Posted January 24, 2008 The FSM should have info on how to adjust the pedal stop. The other thing that is CRUCIAL is that you have some free play between the clutch pin and the master. 1/8" will do, but if you don't have any free play then the clutch can slowly start to disengage as you're driving. Won't make the shifting worse in my experience, but the clutch might start slipping when you shift. If you have a 280 then there should not be any adjustment at the slave cylinder. So once you get those set, then just pull the rubber boots back and look for fluid leaking on the master and slave, and that's pretty much it as far as I can remember. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted January 24, 2008 Author Share Posted January 24, 2008 Ezzzzzz: fresh rebuild means all new bearings, new synchros and new seals. New tranny has 300 miles on it. Shifter bushings are brand new. Shifter is even brand new. (didn't have one) Gear oil is some kind of synthetic, I think valvoline. Thanks for the advise on doing the job. I have a ZX tranny at home disassembled so I'm sort of familiar with what it looks like inside. (Anybody wanna buy a disassembled ZX 5 speed? can't use it... class rules) Jon: Definitly has some freeplay. Master and slave are (you guessed it) brand new (not even rebuilt... new) steel line new, flexable hose between steel line and slave braided SS also new. No leaks. That's what I'm saying, there really is no adjustment. Thanks for advise guys. I'm still trying to figure out what I'm going to do. I have a spare 5 speed and spare 4 speed. Both are running used condition. Might try the synchro myself, might have a tranny guy friend help (he has a lift) might crate up and send back to orig. rebuilder. Ordered a couple of baulk rings already, seeing about gasket. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2008 Share Posted January 24, 2008 You can use silicone instead of a gasket for the front cover. Quote Link to comment Share on other sites More sharing options...
woldson Posted January 25, 2008 Share Posted January 25, 2008 I used to have a problem with my 82zx, put slick 50 in and the shifting over all got easier and 2nd grind went away. Drove it for 60,000 miles or so. Quote Link to comment Share on other sites More sharing options...
silver280zx Posted January 31, 2008 Share Posted January 31, 2008 I used to have a problem with my 82zx, put slick 50 in and the shifting over all got easier and 2nd grind went away. Drove it for 60,000 miles or so. What is slick 50? I have a second gear grind as well. Quote Link to comment Share on other sites More sharing options...
woldson Posted February 1, 2008 Share Posted February 1, 2008 It is one of the frist suspended silcone engine treatments. I put in highest quality gear lube and one quart of slick 50 to top off. It was the engine treatment not the tranny stuff. Anyhow after I did this 2nd never missed a beat and even in very cold wheather I could shift the car w/o haveing to use both hands when frist started! This was a 82zx, modifed engine with a 150,000 miles and I was younger and gave it hell all the time, never a prob. I saw gas milage and acceration inprovements as well as top end. Iam not saying that is a miracle and if anyone trys it I would like to read there feedback. Since I frist put it in my 86si hatch transaxle with same results, Ive put it in every car I've owned with the same results. On my most recent car, however, it has been energy release, not as impressed. I cant speak for everyone and Ive tried even redline, but I stand by the results in my own experince. Btw you could pick it up at any auto parts store, unless their out of busness. Durealube was great but I heard years ago it contained colrine and ate seals. I recomend at least a quart, due to the slight thinning of the gear oil. My theroy is the syncs are able to catch up faster due to lessening of friction. It is a cheap easy fix if it works for you. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 1, 2008 Share Posted February 1, 2008 Synchros actually need friction to bring the gear clusters to the same speed which is why gear lube is different than motor oil. Not saying the Slick 50 didn't help in your case, just that you're after two different things. My personal choice for trans lube is SWEPCO 201 mixed 50/50 with ATF. There's a bunch of good lubes out there so I don't think there is one right answer. Quote Link to comment Share on other sites More sharing options...
woldson Posted February 2, 2008 Share Posted February 2, 2008 Yea I see how I phased that sorry,,,,,there are many good additives besides slick 50 it is the only one that gave me the best results of the limited ones I've triied. Jmortensen, I guess I need to read up on synchros more or will you enlighten me a bit? I will say this, that additive completey solved both ZX's second gear and one honda! (not saying other additives won't) Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted February 2, 2008 Share Posted February 2, 2008 Avoid Slick 50. I had a similar problem with my '80 5-spd and the problem went away after using Redline MTL. Quote Link to comment Share on other sites More sharing options...
woldson Posted February 2, 2008 Share Posted February 2, 2008 How come:)? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.