It Blowed Up Real Good! (Now With Pictures!)...AGAIN...and again!
11-11-09, 03:06 PM
#76
Maybe you could pull out a dyno sheet and figure out the exact torque that it took to kill the NA unit. Since first and second gears can have wheel spin issues with that much power and third calms down, if you know about how fast you were going you can work backward through the gear ratios and have a pretty good idea of the number.
It would be fun to be able to say, "NA trannys break at 371 ftlbs of torque, give or take a couple"
It would be fun to be able to say, "NA trannys break at 371 ftlbs of torque, give or take a couple"
11-11-09, 06:14 PM
#77
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Wow didn't think it would cost that much to rebuild the transmission. Then again, that amount is probably minuscule compared to the total amount already spent on your car.
11-11-09, 08:56 PM
#78
it usually isn't, the T2 trannies are pretty stout, 5th gear syncro is a definite to replace and probably 2nd as well. the input and output bearings are pricey but only necessary to replace if they whine. most shops recommend replacing the bearings because they can be damaged if you aren't careful during disassembly. the rear output bearing can be a real BITCH to get off sometimes. i've broken many pullers working on that one... the larger sysncros (lower gears) and bearings run about $40-70 each and there's 4 main bearings and 5 syncros.
the most difficult thing about tearing apart T2 trannies is fabricating bearing pullers.
the most difficult thing about tearing apart T2 trannies is fabricating bearing pullers.
11-12-09, 03:38 PM
#79
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11-12-09, 03:51 PM
#80
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Maybe you could pull out a dyno sheet and figure out the exact torque that it took to kill the NA unit. Since first and second gears can have wheel spin issues with that much power and third calms down, if you know about how fast you were going you can work backward through the gear ratios and have a pretty good idea of the number.
It would be fun to be able to say, "NA trannys break at 371 ftlbs of torque, give or take a couple"
It would be fun to be able to say, "NA trannys break at 371 ftlbs of torque, give or take a couple"
A transmission rebuild can be considerably cheaper, but I opted to have all the wear items replaced. If just what is worn out is replaced, it's around $600. I had an NA transmission done like that years ago and it turned out fine (until I shredded the input and cluster shaft gears). With this transmission I opted to have all the syncros replaced, and that ads a considerable cost.
09-07-10, 10:23 AM
#81
We grenaded a newly rebuilt N/A transmission this past weekend. It had about 200 track miles on it. 2 subsequent corners where you top out 3rd gear at 8k rpm and let off, the 2nd corner it blew up. Luckily i had another one but now i will have to figure out what to do about a long term solution. NASA rules basically say if i change any of the forward gear ratios we take points that we don't have to give.
170 RWHP road racing car. First weekend since the car was built.
170 RWHP road racing car. First weekend since the car was built.
09-07-10, 10:30 AM
#82
my rebuilt T2 transmission (3500 miles, had all bearings and synchros replaced by a competent shop) is grinding/clunking under really hard shifts into 3rd. I could be imagining it, but it seems to have gotten a little worse over the past thousand miles or so. Usually it will go into 3rd under this type of driving but I have now chosen to double clutch 3rd for hard shifts. The double clutching eliminates the problem completely. It goes into gear just fine and doesn't make any noise.
I'm not about to get some built T5 or other crap. I'll just keep double clutching the thing. Even if it's a fixable problem, I've spent enough hassle and money on the car, I'll just accept the additional 250 milliseconds of shift time. I have a stock shifter with new shifter bushings. I've considered a Corksport short shifter (just in case a more precise shifter would eliminate the problem) but I am still concerned about rattles. Plus I think faster/harder shifts would only be more abusive on the transmission.
I'm not about to get some built T5 or other crap. I'll just keep double clutching the thing. Even if it's a fixable problem, I've spent enough hassle and money on the car, I'll just accept the additional 250 milliseconds of shift time. I have a stock shifter with new shifter bushings. I've considered a Corksport short shifter (just in case a more precise shifter would eliminate the problem) but I am still concerned about rattles. Plus I think faster/harder shifts would only be more abusive on the transmission.
09-07-10, 12:28 PM
#83
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my rebuilt T2 transmission (3500 miles, had all bearings and synchros replaced by a competent shop) is grinding/clunking under really hard shifts into 3rd. I could be imagining it, but it seems to have gotten a little worse over the past thousand miles or so. Usually it will go into 3rd under this type of driving but I have now chosen to double clutch 3rd for hard shifts. The double clutching eliminates the problem completely. It goes into gear just fine and doesn't make any noise.
I'm not about to get some built T5 or other crap. I'll just keep double clutching the thing. Even if it's a fixable problem, I've spent enough hassle and money on the car, I'll just accept the additional 250 milliseconds of shift time. I have a stock shifter with new shifter bushings. I've considered a Corksport short shifter (just in case a more precise shifter would eliminate the problem) but I am still concerned about rattles. Plus I think faster/harder shifts would only be more abusive on the transmission.
I'm not about to get some built T5 or other crap. I'll just keep double clutching the thing. Even if it's a fixable problem, I've spent enough hassle and money on the car, I'll just accept the additional 250 milliseconds of shift time. I have a stock shifter with new shifter bushings. I've considered a Corksport short shifter (just in case a more precise shifter would eliminate the problem) but I am still concerned about rattles. Plus I think faster/harder shifts would only be more abusive on the transmission.
09-08-10, 09:35 AM
#84
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We grenaded a newly rebuilt N/A transmission this past weekend. It had about 200 track miles on it. 2 subsequent corners where you top out 3rd gear at 8k rpm and let off, the 2nd corner it blew up. Luckily i had another one but now i will have to figure out what to do about a long term solution. NASA rules basically say if i change any of the forward gear ratios we take points that we don't have to give.
170 RWHP road racing car. First weekend since the car was built.
170 RWHP road racing car. First weekend since the car was built.
10-09-10, 11:01 AM
#85
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Yeah, so it happened again....again....uh, again.
Last night I went to the 1/4 mile as it would be the last opportunity to do so for the season and a few other local RX-7 people (Casual John and FC3Sdrift) would be there as well.
I didn't expect much since I long ago reached the limit of my tires, and my new clutch was being overpowered as well (another story). On the first run, I lined up and made my launch at about 6000 RPM. Expecting at least some tire spin, instead I was rewarded with instant wheel hop and before my brain had told my foot to "LET OFF!" there was a BANG! and the car stopped moving under it's own power.
As to not spread oil down the track (too late for that...) I pulled off to the side. It was clearly not a transmission issue as I could hear it whirring, but the car wouldn't go anywhere....Then I saw oil dripping from the differential. Crap. The driver side stub shaft broke. And there must be other damage internally as well because the car wouldn't move under it's own power. You'd think an LSD would at least send power to one wheel even with a broken shaft.
Nothing could be done, so I was towed home on FC3Sdrift's CAA card (Thank you again!!).
I'm going to look my spare diff today and see if I can just swap the stub shaft with the diff still in the car. If so, then yay. If not, then I think I'm out for the season as my shop is full since I just started restoring my '76 Cosmo (see link in signature). Maybe if I can clear some shop space I'll swap the spare diff in...
Last night I went to the 1/4 mile as it would be the last opportunity to do so for the season and a few other local RX-7 people (Casual John and FC3Sdrift) would be there as well.
I didn't expect much since I long ago reached the limit of my tires, and my new clutch was being overpowered as well (another story). On the first run, I lined up and made my launch at about 6000 RPM. Expecting at least some tire spin, instead I was rewarded with instant wheel hop and before my brain had told my foot to "LET OFF!" there was a BANG! and the car stopped moving under it's own power.
As to not spread oil down the track (too late for that...) I pulled off to the side. It was clearly not a transmission issue as I could hear it whirring, but the car wouldn't go anywhere....Then I saw oil dripping from the differential. Crap. The driver side stub shaft broke. And there must be other damage internally as well because the car wouldn't move under it's own power. You'd think an LSD would at least send power to one wheel even with a broken shaft.
Nothing could be done, so I was towed home on FC3Sdrift's CAA card (Thank you again!!).
I'm going to look my spare diff today and see if I can just swap the stub shaft with the diff still in the car. If so, then yay. If not, then I think I'm out for the season as my shop is full since I just started restoring my '76 Cosmo (see link in signature). Maybe if I can clear some shop space I'll swap the spare diff in...
10-09-10, 01:30 PM
#87
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10-09-10, 02:43 PM
#88
As to not spread oil down the track (too late for that...) I pulled off to the side. It was clearly not a transmission issue as I could hear it whirring, but the car wouldn't go anywhere....Then I saw oil dripping from the differential. Crap. The driver side stub shaft broke. And there must be other damage internally as well because the car wouldn't move under it's own power. You'd think an LSD would at least send power to one wheel even with a broken shaft.
Btw, changing from Mobil 1 to Redline MT-90 in my tranny fixed my third gear grinding.
10-10-10, 10:41 AM
#89
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I have not looked at the diff yet because I wanted to spend the day in the shop starting to fill the extra holes (antenna, door handle, etc.) in my Cosmo. It will also be at least a week before there is enough space to bring the RX-7 in, so I'm thinking of just storing it for the winter and fixing it next season.
Yes, that's an NA diff. Actually, a FULLY REBUILT NA diff which was NOT cheap (those clutch packs are super expensive). The plan now is to get a TII diff, have my driveshaft modded to connect to the TII diff, and make hybrid TII-NA half-shafts so I can keep my 4 lug wheels.
Yes, that's an NA diff. Actually, a FULLY REBUILT NA diff which was NOT cheap (those clutch packs are super expensive). The plan now is to get a TII diff, have my driveshaft modded to connect to the TII diff, and make hybrid TII-NA half-shafts so I can keep my 4 lug wheels.
10-10-10, 07:20 PM
#91
That's too bad, Aaron. But there is no sense scrambling to fix it, this late in the season. Parking it for now, and focusing on the Cosmo makes sense. That gives you time to think things through. And if you decide to swap out your tranny, I'll be first in line to take it...I killed the 3rd gear syncho in my car that night. She grinds from 2nd to 3rd all the time now. I'm gonna have to practice double-clutching for now.
10-11-10, 08:34 AM
#92
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Heyy Aaron, I see where you are coming from with the True N/A turbo. But you have already done it, and well, far surpassed the limitations of the components. IMO you have done extremely well but I would def. upgrade to T2 components. You essentially still have a true N/A turbo, just with upgraded parts to handle the torque. This "should" avoid any headaches in the future and will cost you far less. I would not discredit you the N/A turbo status, and i take my hat off to you. Happy thanksgiving btw. take care and drive "fun".
10-11-10, 10:26 AM
#94
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Going to LSD and increasing traction put a lot more stress on the diff. And the glue they laid down (which they almost never do) was the nail in the coffin of wheel hop.
That's too bad, Aaron. But there is no sense scrambling to fix it, this late in the season. Parking it for now, and focusing on the Cosmo makes sense. That gives you time to think things through. And if you decide to swap out your tranny, I'll be first in line to take it...I killed the 3rd gear syncho in my car that night. She grinds from 2nd to 3rd all the time now. I'm gonna have to practice double-clutching for now.
That sucks about your syncro, but it actually would not be too bad to replace. I bet it would be about $600 to replace the bearings and the bad syncro if you remove and reinstall the unit yourself. Winter project?
Probably no pictures until next spring.
10-11-10, 10:55 AM
#95
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Yes, that's an NA diff. Actually, a FULLY REBUILT NA diff which was NOT cheap (those clutch packs are super expensive). The plan now is to get a TII diff, have my driveshaft modded to connect to the TII diff, and make hybrid TII-NA half-shafts so I can keep my 4 lug wheels.
Why modify the driveshaft? Wouldn't it be more cost effective to sell the shaft you have now and find a Turbo2 driveshaft? (Maybe from the donor that you get the differential from, if you haven't already sourced a diff yet?)
10-11-10, 01:08 PM
#96
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i agree, i broke a GSL-SE ring gear with the wheel hop... stock engine and 400+ treadwear tires too
10-11-10, 03:17 PM
#97
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Am I missing something here? You have a Turbo2 Transmission... You're going to get a Turbo2 differential...
Why modify the driveshaft? Wouldn't it be more cost effective to sell the shaft you have now and find a Turbo2 driveshaft? (Maybe from the donor that you get the differential from, if you haven't already sourced a diff yet?)
Why modify the driveshaft? Wouldn't it be more cost effective to sell the shaft you have now and find a Turbo2 driveshaft? (Maybe from the donor that you get the differential from, if you haven't already sourced a diff yet?)
Don't forget about your shed.
10-11-10, 06:14 PM
#99
grats on figuring out that the n/a drivetrain is too weak to sustain those power levels! i'm actually surprised it did this well but i don't know why anyone would beat their head against the wall trailering their car when upgrade parts are readily available for reasonable prices.
i'm guessing you like whips and chains?!
i'm guessing you like whips and chains?!
10-11-10, 07:03 PM
#100
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Am I missing something here? You have a Turbo2 Transmission... You're going to get a Turbo2 differential...
Why modify the driveshaft? Wouldn't it be more cost effective to sell the shaft you have now and find a Turbo2 driveshaft? (Maybe from the donor that you get the differential from, if you haven't already sourced a diff yet?)
Why modify the driveshaft? Wouldn't it be more cost effective to sell the shaft you have now and find a Turbo2 driveshaft? (Maybe from the donor that you get the differential from, if you haven't already sourced a diff yet?)
What I meant to say was to have a TII driveshaft made. I could use a stock shaft, but they have weak and non-replaceable u-joints. The local driveline shop can make me a brand new TII sized shaft that has massive u-joints (they come from some kind of huge Dodge truck) that are easily replaceable. So that's the direction I will go. My TII trans to NA diff shaft (with big u-joints) will be up for sale at some point ($200 is the price).grats on figuring out that the n/a drivetrain is too weak to sustain those power levels! i'm actually surprised it did this well but i don't know why anyone would beat their head against the wall trailering their car when upgrade parts are readily available for reasonable prices.
i'm guessing you like whips and chains?!