bad synchros?

[thor]

Hi,

I just recently finished rebuilding and installing a new engine in my 94 talon. I replaced the clutch with a new stock one. car is non turbo with manual trans

The tranny will grind considerably when shifting from 1-2 and from 2-3 when the car is warmed up.
3-4-5 are all fine and shift nicely.

When it's cold it doesn't do it at all. when its warmed up is when it is the worst. I can prevent it sometimes by letting the rpm's drop below 1200 before shifting, but it shouldn't be that bad.

The fact that 3-4-5 is ok leads me to believe it's not an adjustment, but bad synchros. I need confirmation on this though. I am running stock 75-90 oil in the trans.
would the synchromesh fluid help me at all? where do I get it?

I put new brass machined bushings at the trans end for the cables. But the fact that it doesn't happen when it's cold leaves me to believe that it's internal to the trans.

thanks for any responses.

 

[TwoLiterLaser]

Sounds like syncro's to me.

 

[Talonman92]

I agree. I think that our tranny's are known for having crappy 1-2 synchros. My 1-2 shift got so bad that sometimes it would deny me 2nd gear altogether and I'd have to double clutch\wait for it to return to idle to shift!

I reluctantly took it to a tranny shop and they rebuilt it.. costly but at least it works better. I am not satisfied with it still but I think its just the way the M\T comes stock is just different feeling than, lets say, ANY other manual car I've driven.

 

[thor]

ok and update..
I tried changing the trans fluid to a mix of 80-90 with equal synchromesh and it seemed to get worse. I changed again to the lucas brand 80-90 and it seems a little better, but not much. when it's cold it's great. once it's warmed up after a mile or 2 it starts again. I think I've found the best method by letting the engine rpm down to 1500 before shifting, but I can never shift normally.

follow up question: If I can baby it like this, how long will I be able to go without a rebuild and what will start happening when it becomes close to terminal failure? I just put over 1000 into a new motor and sensors and I don't have the money for a new trans right now. It's only a FWD car so it's not too hard to change, just not something I wanted to do after just changing an engine out.

 

[DSMedEG]

with sycromesh lube you should let it stay in there, it gets better as you drive and at almost 8$ its an exspensive flush. i think you should leave it in and be patient.

 

[Talonman92]

follow up question: If I can baby it like this, how long will I be able to go without a rebuild and what will start happening when it becomes close to terminal failure? I just put over 1000 into a new motor and sensors and I don't have the money for a new trans right now. It's only a FWD car so it's not too hard to change, just not something I wanted to do after just changing an engine out.

I babyed mine for a long long time (it actually came with a very very small hint of a grind in 2nd when i bought the car.) I pretty much shifted as you said at like < 2 grand so it wouldnt grind.(never raced after it was apparent what was going on.) As it gets worse it will grind a small bit no matter what rpm you are at. Also as it gets really bad it might just all out deny you 2nd gear if your rpm's are too high!

You should be able to milk it out untill you got the dough to get it rebuilt. I payed like 1k for my rebuild, but I think shepards does it for like ~800 with 80$ shipping.

Hope this helps!

 

[jongreene]

Redline shockproof is really thick, like the lucas, but better. Try mixing the shockproof with synchormesh, 1 qt of each. When cold its actually really mushy but gets way better when it warms up. Should help with grinding.

 

[itsover]

where did you get Redline shockproof from ? and how much a bottle ?

 

[groundPork]

ok and update..
I tried changing the trans fluid to a mix of 80-90 with equal synchromesh and it seemed to get worse. I changed again to the lucas brand 80-90 and it seems a little better, but not much. when it's cold it's great. once it's warmed up after a mile or 2 it starts again. I think I've found the best method by letting the engine rpm down to 1500 before shifting, but I can never shift normally.

follow up question: If I can baby it like this, how long will I be able to go without a rebuild and what will start happening when it becomes close to terminal failure? I just put over 1000 into a new motor and sensors and I don't have the money for a new trans right now. It's only a FWD car so it's not too hard to change, just not something I wanted to do after just changing an engine out.

I think you may be headed in the wrong direction. Our gear boxes DO NOT work well at all with heavy gearlube, and this may be why when it gets worm it gets worse and grinds. Switch to BG synchroshift, and never go back. If the fluid is too slippery and thick, it won't shear, and allow the sycros to match gear speeds, that's why it grinds. It really sounds like that's the problem. I bet if you poured ATF in there and tried it worm it'd improve. That's the friction modifiers.... But don't run it that way for very long... use BG.

 

[thor]

I guess i'm a little confused.
if it works better with thinner fluids it woud grind more when the fluid is cool then even out when it's warm, correct? when it's cold I can shift normally. Does the viscosity of cold regular fluid match the viscosity of warm synchroshift?
and is synchroshift the same thing as synchromesh? I tried the latter but I mixed it with 80-90

forgive my ignorance. I've been building engines for years, but this is my first manual transmission car. I just want to be sure i'm asking the right questions. I don't want my girlfriend to end up on the side of the thruway with a grenaded tranny.

keep the responses coming! I appreciate the input and it will be put to good use!
John

 

[jongreene]

It shifts good when colder because its thicker and providing adequate lubrication, so when it warms up it gets thinner no longer providing enough lubrication. When thicker stuff warms up it thins out to about the same shifting quality as cold thinner fluid...my case anyways. John Shepard actually recommends the shockproof synchromesh mix.
I got the shockproof from summit, for 8 bucks i believe.

 

[thor]

ok another update!!!

I went and ordered the Red line Shock Proof heavy duty fluid from Summit racing.

WOW!!- night and day difference!! now I know this is a band aid until I can get a new trans, but it shifts fine now, and I can even downshift if i'm careful. (3rd will grind downshifting 1 out of 10 times)

the lucas seemed to work a little better, but I didn't ever expect this stuff to fix the problem completely!! i'm amazed and pleased!

note: I ordered the fluid at 2pm on friday and I had it on saturday!! Summit sent it out fedex home delivery. I never expected that. UPS would have waited until monday.
8 bucks a quart was well worth the money spent.

so thanks for the suggestions and comments. I actually listened and took advice and it payed off.

 

[wallyman]

how many quarts did you purchase?

 

[thor]

just 2. that's all that came out of the trans.

it was an exact amount too. only spilled about a shot glass full once trans was full.

this stuff is thick as molasses though. it took me almost 20 minutes to put it all in via funnel and tube. sloooooowww and thick

 

[johnsheehan2006]

It sounds to me like the clutch fibers in the disc are expanding when it gets hot and is not quite letting go completely. This happened to me and a mechanic friend said that the 1-2 syncro were worn more and thats why it grinds more then the others. The other synros just havent caught up yet. They are still able to do their job and take out the extra rotation of the tranny. Try this, Get the car warmed up and leave it running, park, put it in neutral and let the clutch out, then push the clutch back in and immediatly try and put it in first and or second (try both) and if it grinds going in your clutch is hanging up, if not its your syncros. Hope this helps you out. If it does, rep points would be appreciated .

edit: Try reving it while its in neutral with the clutch out and be quick about pushing the clutch in and trying to put it into gear.

 

[thor]

It sounds to me like the clutch fibers in the disc are expanding when it gets hot and is not quite letting go completely. This happened to me and a mechanic friend said that the 1-2 syncro were worn more and thats why it grinds more then the others. The other synros just havent caught up yet. They are still able to do their job and take out the extra rotation of the tranny. Try this, Get the car warmed up and leave it running, park, put it in neutral and let the clutch out, then push the clutch back in and immediatly try and put it in first and or second (try both) and if it grinds going in your clutch is hanging up, if not its your syncros. Hope this helps you out. If it does, rep points would be appreciated .

its definately not doing it at a standstill. only when the car is moving.
yeah I suspected the clutch first because it was new, but i've actually tried that method and i'm sure the clutch is operating correctly.

my girlfriend is new to manual trannys and this wasn't how I wanted to break her in. The new fluid made all the difference to the point where I would have never suspected a problem with synchros if I was buying this car used. even she can't grind it.

points added. thank you