Mike,

I am sure you don't recall back a few years we were talking about how the RPMs don't drop on a manual tranny F-150 when you clutch in. I had asked if it was feasable to have Superchips program the chip to drop the revs like the old carburated cars used to. You used to be able to be traveling 100 mph with the clutch in and the revs would drop to idle. These trucks have the revs drop gradually but never lower than about 1200 rpm. I am not sure of the exact rpm because of the tach error.

Well here goes. I believe the problem with the manual tranny dropping gears and syncros is caused by the RPMs not dropping fast enough to allow the syncros to catch up. When you up shift the engine has to slow down the input shaft speed to match the speed of the higher gear you are selecting. That is difficult to do when the engine speed doesn't drop fast enough, or low enough. Those of you with manual trannies try it some day. At 60 mph push in the clutch and watch the tach. You will notice that it is slow to drop.

Well I'm done.

Regards

Jean Marc Chartier

 

Well, I was hoping to see some responses to this post. I guess there aren't many of us with the manual transmission.

So... JMC, I'd say that sounds like a reasonable theory. I noticed that the rpm's don't drop right away but I hadn't connected this with the shifting issues. One thing that I noticed is that if I take off hard in first I get the "grind" into second, especially if the tires break loose. I think that your theory may apply here.

I was driving down the highway the other day trying to listen for the cause of the break smell I'm now getting. I got up to about seventy and put it in neutral. The rpm's did drop to idle, wich is 800 to 900 rpm. I didn't drop right away, but it did go to idle.

While were talking about manuals, do burning break pads smell anything like something burning in the tranny? Just thought I'd ask. I'll post that question in the transmissions section eventually.

 

Slipping Clutch smells just like burning brake pads.

JMC

 

Thanks JMC, I was afraid I'd hear that. I can tell no difference in breaking, no wierd noises. The clutch does seem to slip a bit lately, taking off in first. I noticed the smell after letting someone else drive it this past weekend.

I smell a clutch upgrade in my trucks future. I was hopeing it would wait till I could afford headers too. Oh well. I guess if your goin to play you've got to pay.


Any one, on the rpm control theory?

 

Hi JMC,

I don't think that has anything to do with synchros failing in your particular truck. That is a pretty rare occurance in these trucks overall, among our customers (which includes *many* manual tranny F-150 owners) it is very rare for us to hear about those kinds of failures, even with *superchargers* installed.

Yes, a few here & there do fail, but overall there aren't significant numbers of similar failures that we see among our customers, and I really don't think that has much if anything to do with the synchros failing in your truck, my friend.

In fact, I think that actually *helps* the synchros overall, as you have *less* speed-matching that the synchros have to do with the rpms "closer" like that.

Could that be altered? Sure, with specific R&D to find that specific function, but the chances of that getting done in reality are as slim today as they always have been.

 

Mike,

Now that you mention it the input shaft is disconnected as soon as the clutch disengages it from the fly wheel. But on the other tech forums syncro problems crop up on a rgular bases. The most often is the 2-3 or 3-4 shift. Mostly on the Ranger that use a similar Mazda built tranny. Besides, when you speed shift your foot never comes off the gas anyways. I will figure this one out yet. I wonder if Richmond would custom build one for me???? Maybe Manual tranny owners should go drive a BMW tranny to see the difference.

JMC