Drilling tranny casing to eliminate cold 2nd gear problems

also, if you double clutch on the upshift, doesn't that pretty much take the syncro out of the equation? so if it was the syncro causing the cold shift issue, double clutching should make it shift smoothly when cold?

 

My trans was rebuilt less than 1000k ago. Replacing all the syncros made all the diff in the world. Shifts smooth now. It does take a little while to warm up though. I don't think I would drill a hole in the trans unless it was apart. Then I would need to think about it.

 

The good news is that drilling the hole can't do any harm. The hole allows oil to escape when the shaft enters the pocket rather than "hydraulic'ing" or allows air to enter when the shaft is exiting to prevent "suck'ing". It doesn't prevent oil from being in the hole - doing the good things oil does...

That said, I did mine while the motor/trans was apart and it just happened to be when issue 127 of Prancing Horse came out... (2001???) "I" wouldn't have made the hole by drilling from the exterior. I didn't like the idea of possibly leaving chips or potentially a broken drill bit in the trans.

Like Newman, on my second tear down (8 years later) I replaced all my synchros (two gears and some bearings). There was significant differences between the new parts and the ones removed. These parts do wear out. These transmissions do need to be rebuilt - is there an echo in here??? I can't wait to see how much better it "should" be when its drivable again.

Rick

 

Agreed.

I bought my 328 with 19,000km on it (12,000 miles) and 2nd was a pig when cold. There were no signs the car was ever abused in any way so I strongly suspect the syncros were just fine. If I ever have the gearbox apart I will do the mod. Or..... might even do it from the outside one day.

 

Good point. I know you can have those type of problems if you use gear oil that is too slippery for the application. That might relate somehow to gear oil that is too thin also.

 

Do you have a spec on the redline? Thanks.

 

+1

Ask Branko. We changed his gear oil to Redline's 75w90NS and he's been shifting butter-smooth when cold now for years. Dramatic shifting difference.

I use a more controversial Redline Lightweight Shockproof to achieve the same effect in my 348.

Also, make your first shift out of your garage be Reverse to 2nd gear. Let 2nd gear start your initial forward motion.

Higher rpms help, too.

Radical surgery on your tranny is typically *not* required to get great shifts when cold.

 

"Cold" really has to be defined/taken into consideration. "Cold" engines are cold based on the ambient temperature. The oils in a cold vehicle of an owner in Florida might be at 95 degrees while the cold oils of someones car in Wisconsin might be 40 degrees. Redline or other oil might help in the cold in one place but not in another. I don't think it's a certainty.

 

Do as the others say and I have done........

Redline 75/90NS x 4 quarts mixed with Redline 75/90 x 1 quart.
No diff chatter and smooth into second gear when cold.

Bob.

 

Do you have a url to Redline that you use ?

thanks

Lee

 

1 US Gallon here - http://www.redlineoil.com/product.aspx?pid=47&pcid=7

1 quart here - http://www.redlineoil.com/product.aspx?pid=133&pcid=4

Cheers,

Bob.

 

I imagine almost every 3X8 is garaged, kept on a battery trickle charger, and babied now days. Would it solve the 2nd gear problem to preheat the transmission oil via a preheater? I see these on older airplanes. It is a thin pad that attaches to the oil sump. The one on my plane is set to heat the oil to about 130 degrees. You just unplug it like a battery tender and off you go.

I just looked for an example, here you go:

http://www.aircraftspruce.com/catalog/eppages/ezHeater.php


Just an idea. Jeff

 

like the idea, not only using it for the transmission but for the engine as well

 

yeah, they have a similar idea for cars in northern Europe.

I find that the tranny shifts improves dramatically if I let the car idle for say 5 minutes, although I can't imagine the oil(s) are particularly warm at all.

Lee

 

Been thinking about the pre-heater thingy myself. Not only is it good for the tranny, but the motor would benefit from a little warm oil so I don't have to idle it as much (with all that carbon built up). But do you guys think we need two of them? Where would the heater typically be attached to?

Ace

 

I see the article was written by "Goldsmith" is this the original V12 transplant guy ??? If so he certainly has some credibility !!

 

Double clutching does work, it is just more difficult to do when cold.

Normally a sincro simply slows the shaft on an upshift alowing the dogs to engage. This is why you do not need sincros or double clutching for upshifts. The shaft naturally spools down and you can engage the dog gears when matched. However, when you push the clutch and shift through neutral with really cold thick oil the shaft spools down very quickly, so you may now be asking the second gear sincro to spool the shaft back up on the upshift, against the drag of the thick oil.

With the exception of first, second requires the highest shaft speed (relative to the output) and is therefore is the most difficult. In addition, the close ratio between first and second adds to the problem by giving you less time for the shift before the second gear shaft spools below the dogs. Why is third easier? Slower required shaft speed and more time for the shift (sincro needs only to slow the shaft).

You can raise the second gear shaft speed with engine rpm by double clutching but you will have to be very fast and precise to catch the dogs when you shift out of neutral in cold oil. It takes practice and a little extra engine rpm but double clutching will work on a cold second gear.

There is an old magazine article where they complain to the Ferrari test pilot about a difficult second gear. He says "without it, it wouldn't be a Ferrari"


Dave

 

For the record, while doing homework to rebuild my 308 GTB transmission (about 25 years ago...) I spoke to David Goldsmith (the 308 V12 conversion guy). He explained the where to look for the hydro-locking issue and where to drill. I did it from the inside. Bottom line, my car previously had the issue when going cold into 2nd gear, it transformed the gearbox, shifted perfectly cold or hot.

 

sorry ... I'm missing the point of your post ... I've rebuilt my gearboxes and they all shift smoothly hot or cold and I didn't drill anything.

share whyat you actually did

thanks man!

cheers

 

Its a fix from an old Prancing Horse issue... it doesn't so much help you get into second as helps you get out of first. It works.

Rick
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Interesting ... I wonder if they opened that hole up a bit on later cars ... I thought the "stiction" might be from the "pills" that shuttle back and forth that prevent engagement of 2 gears at the same time. I polish those parts and the ramps and haven't had the sticky shift problem.

cheers

 

Has anyone determined why some cars have this problem and others do not? I have not had any problems on the 1->2 shift at any temperature.

 

Here's a thought ... it appears that c'bore is a finnicky detail for the oil flow as explained.

On cars with any miles that c'bore gets sludge in it ... cars that have the problem may have more of a build up in there than others making it seal like a piston in there.

I'm not sure why a freshly rebuilt box would do it which is why I'm curious about that diameter ... they call out a very precision dia in that paper.

cheers

 

My issue is down shifting in to 3rd, but I think that's a syncro problem.

 

luckydynes-- Sorry if I wasn’t clear, the point of my post was to reinforce my experience to correct an issue many have when trying to shift from first to second gear when the transaxle is cold. The thread explains this as well, but on my prior 308 (a late Euro carb GTB), I experienced the cold shift issue years before I got into the transmission to replace worn syncro rings.

The 2nd/3rd Shift shaft is supported at one end by a blind hole in the outer transmission casing. When I was in the transmission to replace other parts (the syncro rings), Dave Goldsmith recommended I drill a pressure relieve hole. The 1/8th inch hole was from inside the transmission main area, to the bottom of the blind hole (simple pressure relieve breather hole). This allowed the 2nd/3rd Shift shaft to move into the support hole easier, especially when the trans was cold / i.e. during higher fluid viscosity. Again, this modification seemed to work well for my transmission, but this is only one data point.

I’ve got the engine/trans out of my GTS; here is a picture of the area we’re talking about, the red dot is approximate (it’s a USA carb GTS). Hope this helps…
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