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Linkage or Transmission?

Posted by bushhog 
May 19, 2009 10:04AM
My '88 325is has developed a 3rd gear problem -- unclear to me whether it's linkage or the transmission itself. Problem is shifting, up or down, into 3rd, whether under load, acceleration or not. Seems as though the shifter doesn't move the internals far enough to engage, with a resulting nasty grinding sound. Occasionally goes in fine. Any opinions on the likely cause?

Thanks for any help!
May 19, 2009 11:15AM
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bushhog
My '88 325is has developed a 3rd gear problem -- unclear to me whether it's linkage or the transmission itself. Problem is shifting, up or down, into 3rd, whether under load, acceleration or not. Seems as though the shifter doesn't move the internals far enough to engage, with a resulting nasty grinding sound. Occasionally goes in fine. Any opinions on the likely cause?

Thanks for any help!

could be the linkage, but it could also be the transmission mounts being worn out.


May 20, 2009 05:55AM
A question for those in the know: could it possibly be the clutch not disengaging properly? There would probably be other symptons, right? Just putting the thought out there just in case.

Good luck, bushhog. And welcome!
May 20, 2009 08:51AM
Have you changed the tranny fluid recently?
rkj
May 20, 2009 11:40AM
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nomis3613
A question for those in the know: could it possibly be the clutch not disengaging properly? There would probably be other symptons, right? Just putting the thought out there just in case.

Good luck, bushhog. And welcome!

This is always possible but since his problem is isolated to third, probably not. Reverse is a good test for this.

bushhog, is there alot of slop in the shifter, and has this suddenly gotten worse or was it a gradual thing?

Rick
May 24, 2009 07:40AM
All other gears are A-OK. Problem only in third. Linkage doesn't feel noticably different -- except, as I described, it just doesn't seem to push far enough into 3rd to engage properly. Works OK sometimes -- doesn't seem related to acceleration, loading, etc. Just goes in sometimes, others I just get a grinding. It did seem to just start one day, can't say whether it's gotten any worse. Haven't gotten under the car yet to check tranny mounts, but the fact that there are problems whether or not there is engine torque leads me to doubt that the mounts are the cause.

I do have a tranny oil change ready that I have been putting off -- but I also question whether old fluid would cause this limited problem.

Thanks to all for the suggestions -- keep 'em coming!
May 24, 2009 01:27PM
If you double clutch does it go into third better?
Could it be the Synchromesh going out on third? I only suggest this because a decade ago when third gear became impossible to shift into on my Dad's E30, it was the synchromesh that had gone bad...or so the mechanic said. We never did get it fixed sad smiley
May 25, 2009 03:44AM
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Earendil
If you double clutch does it go into third better?
Could it be the Synchromesh going out on third? I only suggest this because a decade ago when third gear became impossible to shift into on my Dad's E30, it was the synchromesh that had gone bad...or so the mechanic said. We never did get it fixed sad smiley

its either the synchro or the transmission mounts. for it to be the linkage, the linkage would have to be majorly bent.


rkj
May 26, 2009 09:29PM
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daniel
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Earendil
If you double clutch does it go into third better?
Could it be the Synchromesh going out on third? I only suggest this because a decade ago when third gear became impossible to shift into on my Dad's E30, it was the synchromesh that had gone bad...or so the mechanic said. We never did get it fixed sad smiley

its either the synchro or the transmission mounts. for it to be the linkage, the linkage would have to be majorly bent.

Daniel, I wouldn't be so eager to give advice like this, the syncro in third could be wiped but in my many years of working with cars, anythings possible; my 86 325es had a hard time getting second only, it was sloppy linkage bushings which ails all thirtys at some time or other.

Shooting absolutes from here is iffy at best B)

Rick
May 27, 2009 12:49AM
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rkj
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daniel
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Earendil
If you double clutch does it go into third better?
Could it be the Synchromesh going out on third? I only suggest this because a decade ago when third gear became impossible to shift into on my Dad's E30, it was the synchromesh that had gone bad...or so the mechanic said. We never did get it fixed sad smiley

its either the synchro or the transmission mounts. for it to be the linkage, the linkage would have to be majorly bent.

Daniel, I wouldn't be so eager to give advice like this, the syncro in third could be wiped but in my many years of working with cars, anythings possible; my 86 325es had a hard time getting second only, it was sloppy linkage bushings which ails all thirtys at some time or other.

Shooting absolutes from here is iffy at best B)

Rick

you're right rick, what i was thinking of in my head was the actual shifter rod being bent, not the more fragile linkage pieces.


May 27, 2009 12:26PM
Thanks for all the comments. I plan to get under the car tomorrow to check the trans. mounts. Can I tell anything about the shifter bushings, etc. by pushing, pulling, etc. from underneath?

With respect to the synchro -- I have always understood (though I have never rebuilt a trans.) that a synchro. generally served two gears (e.g., 1st and 3rd, 2nd and 4th). If so, wouldn't the problem occur when moving into both gears?
May 27, 2009 10:29PM
Quote
bushhog
Thanks for all the comments. I plan to get under the car tomorrow to check the trans. mounts. Can I tell anything about the shifter bushings, etc. by pushing, pulling, etc. from underneath?

With respect to the synchro -- I have always understood (though I have never rebuilt a trans.) that a synchro. generally served two gears (e.g., 1st and 3rd, 2nd and 4th). If so, wouldn't the problem occur when moving into both gears?

There's a synchro for each gear. Shift hubs fit between the gears and work with one gear or the other depending on which gear you are in. That's why you push and pull the shifter back and forth between 1st and 2nd or 3rd and 4th. The synchro matches the speed of the gear and the hub as the hub engages the gear. It works kind of like a brake or clutch, which is why they eventually wear out.

You can probably feel looseness in the linkage. It might also be good to have someone in the car move the linkage through the gears while you watch under the car. You might see loose places that way. Or you might get dirt in your eye.

John
May 28, 2009 10:21AM
I guess when your in 3rd gear and you have more play in the stick than in other gears, it could be the linkage bushings. If there's no noticable difference, suspect the synchro.
May 28, 2009 01:01PM
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bushhog
With respect to the synchro -- I have always understood (though I have never rebuilt a trans.) that a synchro. generally served two gears (e.g., 1st and 3rd, 2nd and 4th). If so, wouldn't the problem occur when moving into both gears?
I wrote an article a while ago to explain how syncromesh works and why or when double-clutching should be used, but that got lost when the old BEN site went under. A copy of the article can still be found here in another forum.

Although the gear selector fork slides a single dog ring either one way to select one gear or the other way to select another gear, there will be a separate synchro cup on either of the two faces. So it is possible to have the synchro worn out on one face but not the other.
May 29, 2009 06:01AM
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Ferdinand
I wrote an article a while ago to explain how syncromesh works and why or when double-clutching should be used...

Good onya Ferd! That article motivated me to try double clutching. I've been addicted to heel-and-toeing ever since! Probably as much for the fun and challenge of it as for any reduced wear on the box...

(apologies for my off-topic post, bushhog)



Edited 2 time(s). Last edit at 05/29/2009 06:02AM by nomis3613.
rkj
May 29, 2009 06:44AM
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nomis3613
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Ferdinand
I wrote an article a while ago to explain how syncromesh works and why or when double-clutching should be used...

Good onya Ferd! That article motivated me to try double clutching. I've been addicted to heel-and-toeing ever since! Probably as much for the fun and challenge of it as for any reduced wear on the box...

(apologies for my off-topic post, bushhog)

It'll be a good thing to have in your bag of tricks if your clutch fluid ever goes away on the road. Can happen eye rolling smiley

Rick
May 29, 2009 09:50AM
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nomis3613
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Ferdinand
I wrote an article a while ago to explain how syncromesh works and why or when double-clutching should be used...

Good onya Ferd! That article motivated me to try double clutching. I've been addicted to heel-and-toeing ever since! Probably as much for the fun and challenge of it as for any reduced wear on the box...

(apologies for my off-topic post, bushhog)

i too double clutch all the time now, except for me it isn't really heel toeing, its more the left and right side of my foot.


May 29, 2009 11:39AM
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daniel
i too double clutch all the time now, except for me it isn't really heel toeing, its more the left and right side of my foot.
Me too. I use my right foot half on the brakes and half on the throttle, rolling it to the right to blip the throttle. We're lucky that our E30s have a pretty good pedal layout for this. Other cars have the pedals further apart and you have to reach with either your heel or toes to get to both pedals with one foot.

I know that you know, but many people tend to confuse the terms so I must make one small distinction. Double-clutching and heel-and-toe are two entirely different things. But they usually are performed simultaneously.

Double-clutching is normally only needed on downshifts and means you push the clutch pedal twice during the shift. Once to disengage the current gear and shift to neutral, then release clutch pedal and blip throttle to spin up the gearbox in neutral, then push the clutch pedal down a second time to select the lower gear just as the gearbox speed drops again through the correct matching speed so the shift lever slides into gear with no resistance, then possibly blip the throttle a second time to bring the engine speed to the correct matching road speed before finally releasing the clutch pedal to engage the lower gear. If you match the revs perfectly at each step, you don't actually need to depress the clutch pedal at all.

Sometimes you might need to downshift while climbing a steep hill or whatever and you wouldn't be using the brakes at the same time. You can double-clutch then without simultaneous heel-and-toe braking. But usually a downshift is done because you are braking into a corner and want to be ready in a lower gear when exiting the corner. In that case heel-and-toe is required as you need to blip the throttle while braking at the same time.

A lot of people never bother with either double-clutching or heel-and-toe. They just take their foot off the throttle and use it on the brakes. Left foot goes on the clutch and then jam the box into whichever gear is desired. Syncromesh transmissions will let you do that -- until the brass synchro cups wear out. After that you'll be crunching gears on each shift unless you perfectly match revs.

Always rev-matching the engine speed to the road speed, in whatever gear, before finally letting the clutch out ensures you don't get a big jerk at that point, reducing wear on your clutch, reducing shock loads on your U-joints, diff, and the rubber guibo joint between the transmission and driveshaft. But also first properly rev-matching the internal gear speeds of the transmission during the shift, double-clutching rather than simply jamming the shift lever into the next gear, saves wear and tear on the synchro mechanisms.
May 29, 2009 01:03PM
Ferdinand -- Great Article! It's about time my understanding of transmissions advanced beyond "it's magic"!
May 29, 2009 02:19PM
I'm so addicted to double clutching that I really need to concentrate to not do it. As Rick said, it came in real handy when I noticed the slave clutch had gone before a long trip. I use it to do one by one downshifts as well as skipping a gear. It wears out the clutch actuating system a bit quicker, but I'd rather keep doing it - even just for the sound of it - as it saves the transmission a bit, to compensate for the hard upshifts it has to go through at times.

The E30's pedals are ideal to just roll the foot sideways, when braking. In my former E30 I had the brake pedal position adjusted for even better control during hard braking. In some other cars it is better to do the heal and toe trick, depending on the pedal position.
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