turbogrill Posted May 15, 2017 Report Share Posted May 15, 2017 Hi After COTA this weekend we destroyed another transmission. Reverse is gone and 3rd is grinding. This is our 2nd transmission in 5 races, they have all been unknown junkyard trannies. How often do you change your transmissions? Car is 280zx. (I suck at shifting and sometimes miss shifts and grind the gears. So maybe it's. User error. ) Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted May 15, 2017 Report Share Posted May 15, 2017 Kinda sounds like user error. Superfastjdmtiteyoshifting is not good for any of these cars. Use good fluids! We change every race. Get a temp gauge and test. If fluid temp is too high, add a cooler or ducting. Quote Link to comment Share on other sites More sharing options...
55mini Posted May 15, 2017 Report Share Posted May 15, 2017 We ran our miata box for three years of racing with no issues other than it getting harder to hold fourth gear near the end. We, as said, changed fluid regularly and used Redline. At rebuild over the winter I replaced all the bearings, syncros and shift forks and it is good as gold now. The drivers are now spoiled with such a good box and want me to do the same with the spare box. The fun of being a wrench. Missing gears and grinding is never good and most likely your cause. Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Andrew D Johnson Posted May 15, 2017 Technical Advisory Committee Report Share Posted May 15, 2017 It sounds like it might be user error. We had one driver that could smoke a trans in one stint by using kung-fu ninja shifts. The rest of the drivers could run years without damaging the transmissions. 2 Quote Link to comment Share on other sites More sharing options...
theamsoilguy Posted May 15, 2017 Report Share Posted May 15, 2017 (edited) Make sure its the right fluid, there is gl-4 which is often required and people use gl-5. gl-5 eats brass syncros when temps get high. So not all 75-90 gear oils are the same. Try to run a cooling duct to your trans or at least make sure there is airflow to it, ie move the overflow bottle out of the way. Most older trans require gl-4 Buy a magnetic drain plug to help pull material out of the fluid. Edited May 17, 2017 by theamsoilguy 2 Quote Link to comment Share on other sites More sharing options...
turbogrill Posted May 15, 2017 Author Report Share Posted May 15, 2017 41 minutes ago, red0 said: It sounds like it might be user error. We had one driver that could smoke a trans in one stint by using kung-fu ninja shifts. The rest of the drivers could run years without damaging the transmissions. I find it hard to do perfect heel toes sometimes when there are 5 car passing each other in a hard braking zone. More practice! 1 Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted May 15, 2017 Report Share Posted May 15, 2017 44 minutes ago, theamsoilguy said: Make sure its the right fluid, there is gl-4 which is often required and people use gl-5. gl-5 eats brass syncros when temps get high. So not all 75-90 gear oils are the same. Try to run a cooling duct to your trans or at least make sure there is airflow to it, ie move the overflow bottle out of the way. Most older trans require gl-4 But a magnetic drain plug to help pull material out of the fluid. This has merit in certain applications, need to research if this is one of those. If so it gets more complicated, gl4 and gl4/5 are 2 different animals,(supposedly reverse compatible) make sure to get gl4 with no mention of 5 Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee Andrew D Johnson Posted May 15, 2017 Technical Advisory Committee Report Share Posted May 15, 2017 57 minutes ago, turbogrill said: I find it hard to do perfect heel toes sometimes when there are 5 car passing each other in a hard braking zone. More practice! Shiiiiiiit, I find just holding my hands at 9 & 3 on the wheel difficult. I too need more practice. 2 Quote Link to comment Share on other sites More sharing options...
Bremsen Posted May 15, 2017 Report Share Posted May 15, 2017 GL-4 only in our Nissan transmission (not sure if its similar the 280zx or not). First transmission went in our very first race, we were pulling partial synchros out with the oil. I suspect we (one of our team members who changed all the fluids) just grabbed whatever at the autobone. After looking, they didn't sell anything GL4. Switched to Redline MTL in the spare and we're still using the same transmission since 2011. 1 Quote Link to comment Share on other sites More sharing options...
skierman64 Posted May 15, 2017 Report Share Posted May 15, 2017 (edited) We've broken one transmission in 5 years of racing (39 races) and it broke because of a retaining clip failure at the output shaft. We always use Redline Synthetic oil in our diff and trans (motor too). I suggest using Red line and slowing down your shifts. Edited May 16, 2017 by skierman64 1 Quote Link to comment Share on other sites More sharing options...
turbogrill Posted May 15, 2017 Author Report Share Posted May 15, 2017 We already use mt90, that is gl4. Seems like there are no excuses this time only driver error. Can't even blame high hp since we are running stockish engine. Quote Link to comment Share on other sites More sharing options...
dogtired Posted May 15, 2017 Report Share Posted May 15, 2017 Hopefully nevah..... Quote Link to comment Share on other sites More sharing options...
Indysupra Posted May 15, 2017 Report Share Posted May 15, 2017 Yep no trans issues in 15k plus track miles. Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted May 16, 2017 Report Share Posted May 16, 2017 6 hours ago, turbogrill said: We already use mt90, that is gl4. Seems like there are no excuses this time only driver error. Can't even blame high hp since we are running stockish engine. If you can't find the right gear due to external stimula, just enter and cruise through the corner in neutral. Find a gear gently on the way out. You may be surprised that you learn that you can have more corner speed if you do this and can decrease breaking into the corner. Once you learn, use the trans and be even faster. Breaking trans and poor breaks can teach you how to go fast accidentally.... Brake, not break.... pretty much everywhere in the above post.... 1 Quote Link to comment Share on other sites More sharing options...
turbogrill Posted May 16, 2017 Author Report Share Posted May 16, 2017 21 minutes ago, wvumtnbkr said: If you can't find the right gear due to external stimula, just enter and cruise through the corner in neutral. Find a gear gently on the way out. You may be surprised that you learn that you can have more corner speed if you do this and can decrease breaking into the corner. Once you learn, use the trans and be even faster. Breaking trans and poor breaks can teach you how to go fast accidentally.... Brake, not break.... pretty much everywhere in the above post.... Good tip! Will try next time. Quote Link to comment Share on other sites More sharing options...
Ogren-Engineering Posted May 16, 2017 Report Share Posted May 16, 2017 WE broke 3- ZX300 trans in 3 years.24hrs each MOL . A couple of guys are not easy on them . Synchro s were the initial soft spot, then bearings, finally 5th gear @ Daytona . Sold wimpy Nissan engine/trans, ready to install BA Chevy with 4 spd. Or 3 spd. 1 Quote Link to comment Share on other sites More sharing options...
Bremsen Posted May 16, 2017 Report Share Posted May 16, 2017 (edited) 16 hours ago, turbogrill said: We already use mt90, that is gl4. Seems like there are no excuses this time only driver error. Can't even blame high hp since we are running stockish engine. But....are you sure no PO put GL5 in? I find it hard to believe your shifting is so bad that you're destroying a transmission that fast. I suspect your issues are years of abuse and possibly the wrong/bad fluid in them at some point in their life. My brother is still learning to H/T and he hasn't destroyed ours yet. I do ask our drivers to be very deliberate with clutch engagement and shifting.....the extra 1/2 second trying to shift fast is definitely not worth the wear/tear when missed. Edited May 16, 2017 by Bremsen Quote Link to comment Share on other sites More sharing options...
turbogrill Posted May 16, 2017 Author Report Share Posted May 16, 2017 1 hour ago, Bremsen said: But....are you sure no PO put GL5 in? I find it hard to believe your shifting is so bad that you're destroying a transmission that fast. I suspect your issues are years of abuse and possibly the wrong/bad fluid in them at some point in their life. My brother is still learning to H/T and he hasn't destroyed ours yet. I do ask our drivers to be very deliberate with clutch engagement and shifting.....the extra 1/2 second trying to shift fast is definitely not worth the wear/tear when missed. Well all of our transmission has been junkyard transmissions, they haven't been great to start with. So maybe they had 40% life left. The rebuild kits are cheap and it's a very simple transmission (they say), but I haven't tried and rebuilding anything yet. There is a Datsun expert that charges $2500 for a rebuild with core, he also sells race transmissions for $4500. On top of that he offered a $7500 transmission to me. His customers are vintage racers, is that what we do? To me it makes more sense to swap tranny once a year with a $150 junkyard one. Takes about 2h. You are so right about the 1/2 second! In fact not having to focus on a advanced shifting might make you focus on the line instead. I think it evens it self out for beginner drivers. 1 Quote Link to comment Share on other sites More sharing options...
skierman64 Posted May 16, 2017 Report Share Posted May 16, 2017 1 hour ago, turbogrill said: Well all of our transmission has been junkyard transmissions, they haven't been great to start with. So maybe they had 40% life left. The rebuild kits are cheap and it's a very simple transmission (they say), but I haven't tried and rebuilding anything yet. There is a Datsun expert that charges $2500 for a rebuild with core, he also sells race transmissions for $4500. On top of that he offered a $7500 transmission to me. His customers are vintage racers, is that what we do? To me it makes more sense to swap tranny once a year with a $150 junkyard one. Takes about 2h. You are so right about the 1/2 second! In fact not having to focus on a advanced shifting might make you focus on the line instead. I think it evens it self out for beginner drivers. Are you doing a proper heel/toe on your downshifts? If not that could certainly increase wear and stress on the trans. Quote Link to comment Share on other sites More sharing options...
turbogrill Posted May 16, 2017 Author Report Share Posted May 16, 2017 23 minutes ago, skierman64 said: Are you doing a proper heel/toe on your downshifts? If not that could certainly increase wear and stress on the trans. I am trying to and that is the problem I can do it in easy turns but I just get brain overload when there to much stuff happening. Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted May 16, 2017 Report Share Posted May 16, 2017 When 1 of our drivers moved, we went from a new trans every race to never having an issue again... 4 Quote Link to comment Share on other sites More sharing options...
skierman64 Posted May 16, 2017 Report Share Posted May 16, 2017 38 minutes ago, turbogrill said: I am trying to and that is the problem I can do it in easy turns but I just get brain overload when there to much stuff happening. I think that may be your problem, why are you shifting mid turn? You should be done downshifting by turn in . Case in point: Quote Link to comment Share on other sites More sharing options...
iampkrfn Posted May 16, 2017 Report Share Posted May 16, 2017 2 hours ago, turbogrill said: I am trying to and that is the problem I can do it in easy turns but I just get brain overload when there to much stuff happening. ....you should try skip-shifting. 1 Quote Link to comment Share on other sites More sharing options...
Evilwheel Posted May 16, 2017 Report Share Posted May 16, 2017 4 hours ago, iampkrfn said: ....you should try skip-shifting. Sure, make it worse for em. 1 Quote Link to comment Share on other sites More sharing options...
iampkrfn Posted May 17, 2017 Report Share Posted May 17, 2017 Less going on, simpler, fewer shifts, how would it be worse? Quote Link to comment Share on other sites More sharing options...
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