BayAreaZT Posted August 5, 2009 Share Posted August 5, 2009 Last week I had the unfortunate experience of having my T5 lock up on me at freeway speeds . First let me say I am very lucky to be sitting here typing this un-injured. Could have been ugly. Back to the transmission. Changed the clutch last month so I put in fresh fluid in the tranny and rear end. Felt normal driving on the street and no weird noises so I decided to take the car to work to break in the clutch. Everything is fine for about 20 miles then after punching it to pass a couple trucks the car felt weird during deceleration. Felt like there was more load than normal and the RPMs dropped faster. Gave it some gas and it accelerated fine but the deceleration got worse so I pulled over to the right lane and tried to get to the shoulder. Before I could get fully on the shoulder it locked up and spun me 180 degrees. I didn't hear any mechanical noise before it locked up and I looked under the car and there was no leaking fluid or damage under the car. Clutch pedal feels normal but the tranny is stuck in gear. I haven't had time to take a close look at the car yet since I've been busy with other things so does anyone have any idea what might have happened? Was it just my tranny's "time"? Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted August 5, 2009 Share Posted August 5, 2009 Throwout bearing? Quote Link to comment Share on other sites More sharing options...
eec564 Posted August 5, 2009 Share Posted August 5, 2009 No, highly doubtful of a throwout bearing. Most likely a transmission bearing seized. Exactly what kind and how much fluid did you put in the transmission and rear end? Quote Link to comment Share on other sites More sharing options...
MAG58 Posted August 6, 2009 Share Posted August 6, 2009 You wouldn't happen to have been in 5th had you? Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted August 6, 2009 Author Share Posted August 6, 2009 Yeah, 5th gear. I used Mobil 1 75W-90. Previously it had Redline MTL or MT-90. I forget which one I used. Filled it until is started coming out of the fill hole. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 6, 2009 Share Posted August 6, 2009 I have heard of transmissions engaging more than one gear at a time, due to a shift fork problem. This locks them up hard. I don't know if it would happen while in motion though. Quote Link to comment Share on other sites More sharing options...
eec564 Posted August 6, 2009 Share Posted August 6, 2009 My bet would be a bearing ate it, causing miss-alignment of the shafts. As the shafts come out of place, things don't work quite right, becoming not at all quite rapidly. The mobil 1 might have been the issue, I don't believe it's rated for GL-4, only GL-5. Fine in a rear end, but does not play nice with out transmissions. The Redline MTL plays perfectly with the brass (bushings, syncros, etc) in our older transmissions. Do you still have the bottle? Double check and post what ratings it has. Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted August 6, 2009 Author Share Posted August 6, 2009 From Mobil 1 website: "Mobil 1 Synthetic Gear Lubricant LS 75W-90 meets the most severe API Service MT-1 and GL-5 EP gear oil service classification." I wish I didn't overlook this detail earlier . Would it degrade the brass that quickly though? I only put about 25 miles on the car since the fluid change. Quote Link to comment Share on other sites More sharing options...
MAG58 Posted August 6, 2009 Share Posted August 6, 2009 Well, this is what prompted my T5 rebuild: On the 5th gear synchro, there is a little metal plate that holds the 3 keys in to keep the tranny from engaging when it's not supposed to. One of the little springs broke and it allowed one of the keys to slide back to hit the metal tab that holds it on (for the 5th gear) this pushed that little plate out until the bearing on the rear of the countershaft chewed it to pieces. The little keys then came out and went where they pleased and the 5th gear slider got to do pretty much what it wanted until my box ate it, though this happend at 10 mph. Scary stuff. Couldn't imagine 60. Quote Link to comment Share on other sites More sharing options...
eec564 Posted August 6, 2009 Share Posted August 6, 2009 Yes, it would happen that quickly. MT-1 and GL-5 use high pressure modifiers to withstand the forces of hypoid gears as found in rear ends and some transfer cases. These modifiers wreak havoc on older transmissions with yellow metals in them (bronze, etc), causing them to fail in VERY short order. All fluids used in Z transmissions MUST meet GL-4 standards, and I perfer ones (for the non-synthetics) that do NOT meet the GL-5 standard as well. That's most likely my superstition, but it keeps me from grabbing the wrong bottle, or getting cheap stuff that's trying to make the best of both worlds, doing neither well. For non-synthetic, I use valvoline in the gallon jug, that's GL-4 only. Hard to find, but works great. Far better is Redline MTL, which is a GL-4 ONLY rated synthetic, not GL-5. Great for tranny, not rear end. At this point, your options are rebuild your tranny, or get a new one. Take it apart and see if you chipped/broke any gears. And just the Redline MTL, it's cheaper than Valvoline Synthetic, and plays nice with Z transmissions. Good luck, keep us posted. -Eric Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted August 7, 2009 Author Share Posted August 7, 2009 Wow...that makes me feel like a jacka**. I had a bad feeling it would come back to bite me when I didn't use Redline like I wanted. The only reason I didn't is because I had to go out of my way to get it and I was pressed for time to get the car back together. I'll post pictures whenever I get to opening up the box. Quote Link to comment Share on other sites More sharing options...
batou Posted August 7, 2009 Share Posted August 7, 2009 (edited) Something like this should be a sticky... I need to go out and check what kinda fluid i stuck in my 4speed. Edit: yep, gonna have to drain my tranny and get something else. Edited August 7, 2009 by batou sh*t Quote Link to comment Share on other sites More sharing options...
dave280zx Posted August 13, 2009 Share Posted August 13, 2009 Argh! I just read this. Twice. The first time, it didn't register. The second time, with my bottle of Valvoline on the coffee table, it all made sense. I wondered why my perfectly fine transmissions busted within 5k miles of use. I though I was just bad luck, but this totally makes sense. Im getting some Redline MTL tomorrow! Ive got my third tranny to put in this weekend. Ghey. Quote Link to comment Share on other sites More sharing options...
eec564 Posted August 13, 2009 Share Posted August 13, 2009 Y'all shouldn't feel that bad. It's real easy to make that mistake the first time, especially with synthetics being advertised as being so good for transmissions, and the weight of the oil being correct. I did it once, and realized within two miles something didn't sound right. Took two changes of oil and a few thousand miles with good stuff in it to get things to settle down. There's still a tiny bit of noise in neutral and reverse, but everything works great now. Be nice if someone who has rebuilt transmissions would chime in here and note which parts of which transmissions are brass or bronze. -Eric Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 13, 2009 Share Posted August 13, 2009 Here is what I am using for the '81 5-speed in my car. http://www.thezstore.com/page/TZS/PROD/PRC15/80-9008 Quote Link to comment Share on other sites More sharing options...
Flexicoker Posted August 13, 2009 Share Posted August 13, 2009 I would recommend using a gear oil that is advertised for manual transmsissions only. The oil requirements for a transmission and differential are quite different. I could feel the difference in shifting the first time I drove after replacing the oil with Redline MTL. Quote Link to comment Share on other sites More sharing options...
eec564 Posted August 13, 2009 Share Posted August 13, 2009 Dave - that's good stuff. Everybody note the GL-4 rating - that's what we need. Flexi - All the fluids we're talking about here are for manual transmissions. No Dexron, Type F, or +4 here. The bad thing is GL-5 (only) rated fluids say for manual transmissions and rear ends on them. They're okay for some newer transmissions without yellowed metals in them, but wreck havoc with ours. Quote Link to comment Share on other sites More sharing options...
dave280zx Posted August 13, 2009 Share Posted August 13, 2009 (edited) So do I throw this used tranny in my car while I have the rare opportunity to work on it this weekend, or throw some MTL in the one I have right now? Its got about 6,000 miles on this stupid GL-5. It shifts like a tractor, whines like jet turbine, and clatters like it got a few marbles in it. I guess my question is: --> Does the GL-5 permanently, unfixably degrade everything in the case, or is it "heal-able" by putting GL-4 in it? If it does degrade certain pieces (the brass ones apparently,) will my bearings be okay, or will I need to replace those as well? I've got the glorious later ratio in right now, despite the whining and "sack of marbles" clattering; the used one is the early ratio that doesn't like California highways. Ive rebuilt one of these before, but I wont have the time or the money for quite a while. Schwarzenegger just jacked up my tuition again, and this Z is my daily driver. Edited August 13, 2009 by dave280zx specifics Quote Link to comment Share on other sites More sharing options...
eec564 Posted August 13, 2009 Share Posted August 13, 2009 I'd say put MTL in and see what happens. Swap it out later if it's not better within a week. How many miles per day/week/whatever do you drive? I know what you mean about the early vs late trannys. My 280ZX is an 82, but has an early tranny in it. Plus the 3.9 R200. 1st is damn near useless, and with the wide torque band of the L6 gears like that aren't needed. 3600 rpm on the freeway isn't that much fun, I need a 3.54 rear, at the very least. -Eric Quote Link to comment Share on other sites More sharing options...
dave280zx Posted August 13, 2009 Share Posted August 13, 2009 Eric, Yeah, I hear that. I just about died and went to heaven when I found out my 2nd Junkyard tranny was a later ratio! Cruising 75 without breaking 3,000 revs is fun. I put about 30 miles a day on it, on average. Weekends are spent on a 160 mile round trip, but thats factored in to the average. I put this tranny in just when the weather was getting warm, so around March? Yeah, sounds right. The Z breaks every March... MTL will go in tomorrow night, and I shall cross my fingers. It should at least give me a few thousand buffer miles while I wait for a good weekend. Unless somebody pops up today and tells me its useless and my tranny is shot. Until then, *hijack over!* Quote Link to comment Share on other sites More sharing options...
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