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When I looked at my gears, after spending months speed shifting, none of them had ANY wear or tear on them. The broken ones had just snapped.

The only time I have broken a synchro, is while using the clutch.

I don't suspect the speed shifting to be ALL of the problem here, sorry to dissagree. If it was the problem, there would be more wear and tear on the tranny parts, and especially the sycnchros. BUT, they all look real good.

OK, now I have a few questions.

Will the steel rings from NISMO, go into my current tranny? Any idea on what having a machine shop make these things would cost? If the NISMO rings won't fit, where do I go to get steel ones?

I REALLY REALLY don't want to have to convert to an auto tranny, but if this problem still exists 3 months from now, I am going to consider it. That'll be a dark day for me.

Thank's everyone for you help, I am really needing it right now. Also, thank you everyone who has given me advice and input.

Chris Behney
Redline Autosports
 

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Broken doesn't necessarily = wear

Chris,
Just because the sychros don't show any signs of 'wear', doesn't mean they weren't overly stressed. They broke due to speed shifting. Speed shifting is the hardest thing you can do on your transmission. Remember, these are brass sychros, which work quite well, under most situations. When you speed shift, you put extra stress on the sychro to make up for a lack of clutch disengagement.

The force required to do this won't necessarily show up as wear, as you don't have the synchros long enough for wear to occur. You're just pushing the metal beyond it's elastic range, which means the metal has been stressed to the point, that it can no longer absorb any force, and starts to become weaker until it breaks. My advice is to stop speed shifting. A good clutch and lifting the throttle slightly will greatly improve the longevity of your tranny.
You've got to ask yourself a question. Is this car something you want to drive exclusively on the track, or is it used more often on the street? If it's for the track, then go ahead and speed shift, just know that the tranny won't last forever. If you drive it around town, and need the car since you don't have another one, the occasional speed shift is going to be a major pain in the side.

Some advice:
1. Use Synthetic gear oil. This really reduces friction, and helps keep the synchros well lubed. I use Redline 75W90 Gear oil. Works great.

2. Use a good clutch. Something that will hold at high rpm shifts is essential, especially with a 3.1L.

3. Use Stainless Braided hose. I found this to be a weak point in the clutch when you have a high pressure pressure plate. The stock rubber hose swells, creating a loss in transmission of fluid pressure, thus increasing the pedal effort to disengage the clutch. I fixed this by installing a Flexible Teflon hose from Earl's and some fittings. Cost me $25. Much more positive pedal feel and actuation. I highly recommend it.

Later,
Dave
 

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RE: Broken doesn't necessarily = wear

Listen to 240Dave...it's the truth! I have witnessed this in Drag Racing over and over. Along with all the other parts that get broken when a clutch car is drag raced. It is a fact of life..period. Drag Racing breaks parts! The take-over of auto transmissions since the early 70's in drag racing is not because they are faster, they are slower but they are cheaper and they break less parts. For clutch type cars specially designed planetary transmissions are used, and they even break! At $6000 per tranny and they break too. There is NO transmission that will stand speed shifting. Try to get some syncors made, get use to breaking trannies, switch to an auto. or quit speed shifting.

Ken
 

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RE: difference btw power shifing and speedshifting

Chris,
First, there are two types of "speed shifting" as I know it. One is what I have done in the past, which is where you leave your right foot planted ie never lifting, and just jam the clutch in and out REAL fast while jamming the lever into the next gear. Not as abusive as your method, ie no clutch. When you are doing a no clutch situation, ie keeping your foot planted, and just yanking it into the next gear, I would say you are doubling the wear on the parts, even over my now discarded method,(ok still used every blue moon). My method takes the power of the engine and disengages it from the trans, so it keeps reving, i slam in into gear, then let the clutch out, actually, it is a real quick in and out motion for the clutch pedal, anyways, it at least takes the power away, but i am still overcoming the difference in speed btw the gears, ie overriding the syncros. In your case, you are letting the full power of the engine go through while you shift, no wonder you completely break them in 3 months or less. Now I see how you managed a 13.2 at 110. I'd bet good money that you would only run high 13's with normal shifting, ie the same time as me, but with my 3.54 no lsd, etc.. since you weigh so much more.
But I digress from your original questions. When I got my rebuilt tranny, I looked high and low for steel syncros. No luck. The reason I said to check with NISSMO b/c I was fairly sure they didn't offer it anymore, but you never know, I could have gotten bad info. But no, the steels syncros for that tranny will not fit in yours. They only fit in that tranny, so you need to buy that one, if you can find one. Someone told me that some year of the roadsters had a 5 speed that had steel syncros, but you have to switch the front part of the trans so it will bolt to the L6 and I change the tail shaft so it will work, but it was too involved, and the parts were very hard to find,(2-3 different cars to make the trans work). But they had it, and it worked. BUt it only had the .84 overdrive.
I just looked and couldn't find the e-mail from the guy, so no luck helping you there. If I do find it, I'll let you know.
I'd stick with the manual, but just shift quick, with the clutch, no powershifting or speedshifting. I have no doubt that is what broke it.
-Bob Hanvey
 

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Yup speedshifting will KILL YOUR WALLET for.1in1/4

I should know!! Three clutches,three tailshaft housings(shifter rod breaks in two),broken coutershaft bearings,broken shift pins,broken u-joints,two broken harmonic balancers caused from the bolt loosening even with loctite that is supposed to be heated with a torch to be able to remove it ,and TWO broken 280 crankshafts. But hey,it made my car run about .15 sec faster in the 1/4 so its worth it right? WRONG!!!! Lift when you shift, the wallet and parts you save will be your own!! Later,norm
 
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