Third gear grind is back

[beezee]

Earlier this year I completed a rebuild of the transmission in my '83 X. Once completed everything worked perfectly. Here is the link to the thread on the rebuild:

https://xwebforums.com/forum/index.php?threads/transmission-overhaul-5-speed.32084/

So after about 3k miles third gear is starting to grind a bit. I can avoid the grinding if I pause just a bit when shifting into third. So I am thinking I will need to pull the transmission apart once again this winter. Does anyone have any ideas on what could have gone wrong? I replaced third gear, synchro, slider along with some other gear box parts and filled the transmission with Redline MTL. Here is what I am currently thinking:

1) - I did not replace the synchro ring expander pieces but they did not seem worn. Could these pieces cause the snchro to fail early?

2) - Redline has two transmission oils, MTL and MT-90. Was MTL the wrong choice?

3) - Maybe the third gear bushing is causing too much drag preventing third from slowing down while shifting? I inspected all the bushings and did not see any excessive wear. Maybe the bushing is galled or debris is trapped?

4) - Maybe I have installed a poorly made aftermarket synchro ring?

I won't be pulling the transmission apart until the cold weather forces the car off the road (Novemberish), but any ideas on what could be the problem are welcome.

Beezee

 

[Rupunzell]

This is the reality and must do for any gear box with Porsche Syncros. They MUST have some time to sync before trying to engage the alternate gear. If not the Porsche syncro will be destroyed in short time. Read the story below, all applies to the exxe gear box.
http://blog.dietersmotorsports.com/?page_id=231

"Sometimes the problem is not a loaned car at all, but a car being driven by a misinformed owner. I had a friend of a friend bring a 993S in for me to look at because he said it made a bad grinding noise. He said the noise happened when he shifted the car from first to second and from second to third. After a very thorough test drive I could find no shifting problems with the car. As a matter of fact, this 32,000 mile 993S was like a new car in every way. So when he came to pick up the car we went for a test drive together with him at the wheel. After the first run through the gears it became apparent what the problem with the transmission was. The driver was shifting the car so fast that the synchros could not possibly do the job they were being asked to do. “How fast?” you ask. So fast that his hand started two inches below the shifter in second gear and got a running start towards the knob in making the 2-3 shift … (I know … almost brings a tear to your eye.)

After I screamed “STOP!” we switched seating positions and I showed him the “two finger rule”—how the car should be shifted using no more effort than can be applied with two fingers on the shift knob. It shifted perfectly without grinding or any other issues. This was his first Porsche and he had been told by a “friend” who knows all about Porsches (but had never actually owned one) that this was how a Porsche was meant to be shifted. I explained how a synchro works and he then understood the “what and whys” of the two finger rule. Now for a bit of what I told him.

“Synchro” is short for synchronizer. The official definition is “to cause to go on, move, operate, work, etc., at the same rate and exactly together”. That is precisely what it does. It makes gears spinning at different speeds match their rotation so they can smoothly engage. It does this with what looks like “Dog teeth” or engagement teeth. These are rings of pointy teeth that engage the gear to the shaft (like intertwining fingers as you bring your hands together). When gears grind, it is these dog teeth coming together, but not at the same speed. The sliders are, well, sliders that move along the input/output shafts. They engage power from the gear to the appropriate shaft."



Bernice

I can avoid the grinding if I pause just a bit when shifting into third.

Beezee

 

[beezee]

Thanks Bernice. Although it's hard to define how fast I shift the car, I never considered my shifting as "too fast". My daily driver is a Ford Ranger, and I can honestly say I don't shift my X any faster than the Ranger with it's long lever and somewhat slow mechanism. I'm in my mid-fifties so my youthful exuberance is now somewhat tempered. I did read the article you posted during my rebuild so I have been fairly gentle with the gearbox, in my opinion anyway.

Now my '76 Pinto on the other hand, that car I shifted fast.

 

[Dom.M]

Thanks Bernice. Although it's hard to define how fast I shift the car, I never considered my shifting as "too fast". My daily driver is a Ford Ranger, and I can honestly say I don't shift my X any faster than the Ranger with it's long lever and somewhat slow mechanism. I'm in my mid-fifties so my youthful exuberance is now somewhat tempered. I did read the article you posted during my rebuild so I have been fairly gentle with the gearbox, in my opinion anyway.

Now my '76 Pinto on the other hand, that car I shifted fast.

76 pinto now that's funny haha!

 

[MikeHynes]

Now my '76 Pinto on the other hand, that car I shifted fast.

I had a Pinto that I could pull the snifter out of the gear box on the fly. I could use it as a club to prevent a car jacking. Happy to report that no one ever attempted to car jack my Pinto!

 

[Cougar72]

Girlfriend in High school had a 74 Mercury Bobcat (Pinto-cough cough)

Merc-o-matic (Cruise-O-Matic) transmission - Ummmmmm - nuf said.
Factory Air Conditioning !!!! (more like a button that made the engine overheat)
Luxury group - painted bumpers !!
White Sidewalls !!!!
Vinyl Top !!!
122CI ( I think that was a 2 litre rated at like 85 Hp)

What a BEAUTY!!!

At a stop light - with the air conditioning on - as a passenger - You could open your door and wait for the green light - when the light turned green you could jump out and run across the intersection and be across it first! and dive back into the car as it caught up to you... - true story! You could even rev and "neutral drop it" - it did not matter. we tried several times to do this as a full rolling Chinese fire drill - but alas the car won with this method -but you could make it all the way around the front though, which led to a lot of betting in the school parking lot.

This thing was a real "sleeper" and I mean that literally

Driver would stomp the gas but you could almost count all your fingers and toes before it started to lumber forward. What engineer would take 2700? lb car with 80HP and put an automatic transmission and air conditioning on it.... Gotta love the late 70's

Gosh I remember a set of rich twin girls - WHO BOTH HAD NEW 1978 ? eXXy's and how we envied them. - but my 1971 RX2 was WAY quicker and faster!!! I remember 120Mph easy and had it tuned for 0-60 in 9 seconds - somehow I survived.

--- AND my eXXy Transmission is still in the shop - the dude opened it up - and then went on 3 day holiday weekend - I will go see it on Tuesday and update my thread. Before it exploded (see my thread) It would grind if you did not use the two finger technique from 1-2 --- third would never grind and you could shift it in fast if you wanted, but 2-3 always felt (on the stick) like you were shoving the stick into marshmallow cream - or molasses - it was very undefined.

 

[beezee]

Now my '76 Pinto on the other hand, that car I shifted fast.

I had a Pinto that I could pull the snifter out of the gear box on the fly. I could use it as a club to prevent a car jacking. Happy to report that no one ever attempted to car jack my Pinto!

Same here! On an overly exuberant shift into second I pulled the shifter out of the tranny. Never considered using it as a club though. I remember driving the Pinto to work and going through about 1/2 tank of gas in a 15 minute drive. Turns out the fuel line fractured and sprayed most of that fuel on the distributor cap and wires. I'm blessed to be still alive.

 

[beezee]

Girlfriend in High school had a 74 Mercury Bobcat (Pinto-cough cough)

Merc-o-matic (Cruise-O-Matic) transmission - Ummmmmm - nuf said.
Factory Air Conditioning !!!! (more like a button that made the engine overheat)
Luxury group - painted bumpers !!
White Sidewalls !!!!
Vinyl Top !!!
122CI ( I think that was a 2 litre rated at like 85 Hp)

What a BEAUTY!!!

At a stop light - with the air conditioning on - as a passenger - You could open your door and wait for the green light - when the light turned green you could jump out and run across the intersection and be across it first! and dive back into the car as it caught up to you... - true story! You could even rev and "neutral drop it" - it did not matter. we tried several times to do this as a full rolling Chinese fire drill - but alas the car won with this method -but you could make it all the way around the front though, which led to a lot of betting in the school parking lot.

This thing was a real "sleeper" and I mean that literally

Driver would stomp the gas but you could almost count all your fingers and toes before it started to lumber forward. What engineer would take 2700? lb car with 80HP and put an automatic transmission and air conditioning on it.... Gotta love the late 70's

Gosh I remember a set of rich twin girls - WHO BOTH HAD NEW 1978 ? eXXy's and how we envied them. - but my 1971 RX2 was WAY quicker and faster!!! I remember 120Mph easy and had it tuned for 0-60 in 9 seconds - somehow I survived.

--- AND my eXXy Transmission is still in the shop - the dude opened it up - and then went on 3 day holiday weekend - I will go see it on Tuesday and update my thread. Before it exploded (see my thread) It would grind if you did not use the two finger technique from 1-2 --- third would never grind and you could shift it in fast if you wanted, but 2-3 always felt (on the stick) like you were shoving the stick into marshmallow cream - or molasses - it was very undefined.

I knew a girl with a Pinto wagon, but it had the 2.8 V-6. That car went pretty good for a Pinto.

You're right about the late 70's. Even the Jap cars were terrible. It was pretty common to see fenders flapping in the wind and the roads were littered with exhaust systems, hupcaps, oil, anti freeze, etc, etc. Good times though...

 

[Appall]

I think this guy shows the "two finger rule" exactly.

[/QUOTE]

 

[Steve Hoelscher]

Haven't seen this before now.

Earlier this year I completed a rebuild of the transmission in my '83 X. Once completed everything worked perfectly. Here is the link to the thread on the rebuild:

https://xwebforums.com/forum/index.php?threads/transmission-overhaul-5-speed.32084/

So after about 3k miles third gear is starting to grind a bit. I can avoid the grinding if I pause just a bit when shifting into third. So I am thinking I will need to pull the transmission apart once again this winter. Does anyone have any ideas on what could have gone wrong? I replaced third gear, synchro, slider along with some other gear box parts and filled the transmission with Redline MTL. Here is what I am currently thinking:

1) - I did not replace the synchro ring expander pieces but they did not seem worn. Could these pieces cause the snchro to fail early?

Not likely. If the parts were not damaged they are likely fine and are not your problem.

2) - Redline has two transmission oils, MTL and MT-90. Was MTL the wrong choice?

Redline MTL is the only gear oil I recommend. It wouldn't cause the problem.

3) - Maybe the third gear bushing is causing too much drag preventing third from slowing down while shifting? I inspected all the bushings and did not see any excessive wear. Maybe the bushing is galled or debris is trapped?

Could be. A heavily worn sleeve can cause the gear to miss-align and cause missed shifts. That miss-alignment could also reduce the synchro's engagement. Did you check the clearance on the sleeve and gear?

4) - Maybe I have installed a poorly made aftermarket synchro ring?

This is most likely the cause of your problem. The quality of most aftermarket synchros and sliders is quite poor. Some of these parts are not worth using at all. It is quite challenging to find usable parts.

I won't be pulling the transmission apart until the cold weather forces the car off the road (Novemberish), but any ideas on what could be the problem are welcome.

Beezee

Would be interested to see what you find when you get it back out.

 

[Eugene Harvey]

I had a Pinto that I could pull the snifter out of the gear box on the fly.

Sounds just like my old Bug when I was a teenager. Best anti-theft device there was, simply take the gear stick with you. And no guess what my next car was, my first X, a 1980 1500 in Gold. You could say the driving dynamics were somewhat different.

 

[Eugene Harvey]

For what it's worth, in keeping with what's been said about '2 finger' rules, I've also got a GTV6 (well waiting to be resurrected after 17 years) that has a similar issue, in that neither like 'boy racer' changes, as both are 80's cars with excessively long shift linkages (the GTV6 because whilst engine's up front, the gearbox is in the rear). Both, especially the GTV, will crunch if you try to hurry your change. Shifting needs to be unfussed and precise, the change should almost fall into gear.
With the X being a revvy little engine, and under powered, you're always needing to change from 1st to 2nd at around 3500 to 4000 rpm, so you can imagine, rushed changes with a long linkage is a recipe for disaster, hence so many issues with 2nd gear on the X. I must admit, a few years driving the GTV forced me to be more considerate of the gearbox.

 

[myronx19]

The quality of most aftermarket synchros and sliders is quite poor.

The OE syncros were quite poor as well! My X1/9 was already baffed out at 40K kms (~25K miles). (specifically 3rd gear).

 

[Dr.Jeff]

Honestly I of the opinion that all of the old Fiat trans were/are of very poor design and quality. Just my view.

 

[Eugene Harvey]

old Fiat trans were/are of very poor design and quality

I tend to agree, and with the X I can't quite put my finger on it. Possibly it was its lack of power and low torque, but 1st gear is incredibly short, and you're doing 3,500 rpm after about 10 feet! Personally I believe it is to compensate for the weight of the X (as for a small car it's actually quite heavy) and low hp, so the only way to get it moving off the mark is with a low ratio and to use the revs. That being the case, changes from 1st to 2nd needed to be quite rapid to keep the X in that high rev band otherwise you lost momentum. This I believe is a major contributor to the 2nd gear failure. I also tend to find I end up driving in 3rd most the time round town in the 30-40mph range as the X really struggles under 3000 rpm.
I think the only real way to save an X Box (not the Bill Gates One) is to give up on any aspirations of getting briskly off the mark, and just be happy buzzing around once you're up to speed.

 

[bruakeman]

Hmmmm, I've owned at least 5 different kinds of Fiats and never had a gearbox issue. Lucky maybe, but there is something to be said of having a "deft" touch. You gotta feel the action, not just mash it.

This might sound crazy but I first learned to have a "deft" touch working on the incredibly soft alloy early 70s Japanese/Chinese bicycle components. Of course they did get their act in order and now pretty much dominate that market.

 

[Dr.Jeff]

but there is something to be said of having a "deft" touch

I understand that. However that's sort of my point. I've had numerous old German vehicles and never needed to have a "deft" touch. Seems like you could beat the crap out of them, even with larger engine swaps or adding a turbo and not have so many failures (as has been well documented on this forum).
On the other hand, I've also had a number of Italian vehicles including from the very expensive makers. And all of them had quite delicate transmissions. Ask any owner of a old Ferrari about not using second gear until the trans has become hot.

 

[Eugene Harvey]

Ask any owner of a old Ferrari about not using second gear

Try asking an Alfa GTV6 owner, where slow and deliberate was the call. Not so much from the actual gearbox, but the long vague linkage from the shifter to the box as that was mounted in the rear with the differential. This setup was poor and required careful and precise changes otherwise you'd end up with a box full of metal shaving. Now you could argue having the gearbox mounted in the rear was a stupid thing anyway, but Porsche managed it with the 924 and 944 without the same degree of hassle.

 

[Rupunzell]

Also owned and driven a pot full of older German motos, if the manual gear box is abused, they die just like any others. It should be appreciated that many vintage Italian cars with manual gear boxes have Porsche syncros in them and are subject to the same problems as any gear box with Porsche syncos. There is a tendency to believe then act as if more force at a higher rate of change will produce a faster gear change, this is simply NOT true in any way. Actions like this will only damage the gear box in various ways from minor to severe.

BTW, we have digested more than a few Porsche 901 gear boxes in LeMons racing with ease when powered by a Mazda 12A PP race rotary.

IMO, Borg Warner synchro design is better than the Porsche synchro design.

Force shift a dog ring gear box and the results can be pricy. The best dog ring gear box drivers have a remarkably deft touch and are sensitive to when to increase force required to engage the next gear, synchronized with deft clutch action or no clutch action and throttle control. These drivers can be remarkable indeed, but they do not "man-handle" the gear box.

What goes some ways to reducing gear box abuse is take one apart and fully understand how syncros and the gear box works. If the truth and reality of how gear boxes works is fully understood with their innate designed in limitations fully accepted, this can go a long ways to preventing gear box damage.

As for third gear grinding again, it is very possible this is due to poor quality aftermarket parts so very common today. When putting together a friend's 4 speed, the original Fiat parts syncros and all were still in very good condition. New spares where supplied, flat refused to use them as they were aftermarket parts of unknown quality.

It is also possible the expansion bands and blocks inside the Porsche syncro friction ring is not doing their job as they should. If the inner expansion bands do not properly assist the outer friction band, the syncro will not function properly.


Bernice

I understand that. However that's sort of my point. I've had numerous old German vehicles and never needed to have a "deft" touch. Seems like you could beat the crap out of them, even with larger engine swaps or adding a turbo and not have so many failures (as has been well documented on this forum).
On the other hand, I've also had a number of Italian vehicles including from the very expensive makers. And all of them had quite delicate transmissions. Ask any owner of a old Ferrari about not using second gear until the trans has become hot.

 

[Dr.Jeff]

Although a Fiat trans may use a similar design syncro as a Porsche box, that does not mean they are of the same quality, dimension, nor the exact same specification, so the longevity will differ considerably. Same with all of the other internal components. To put it into perspective, I was involved in off road racing for many years and we used Porsche transaxles in the race vehicles because they held up to the abuse without failures. And we shifted extremely hard with severe abuse, in extreme off road conditions. With excessive shock loads, frequent rapid up and down shifts, heavy acceleration with a lot of HP, very high temps, etc, etc. The most common failure was a cracked case due to being solidly mounted to the chassis, long before any internal losses. Naturally that isn't any scientific proof for anything, just relating the experiences we found over many years. On the other hand, during the years I was in the Ferrari club I knew of MANY Ferrari's with extremely low mileage, driven like they were made of 'paper' due to fear of a costly failure. And the trans could not be shifted into second gear until everything became fully warmed up (actually hot). Otherwise it would just grind and grind without ever going into gear. Seems an obvious difference to me. But I'm not an certified engineer, so these are only my opinions. Absolutely no offense to any Italian car lovers; after all I am one.