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fml 3rd gear synchro went out.

1K views 28 replies 13 participants last post by  saedrin 
#1 ·
just got my msm 6 speed tranmission rebuilt 4 months ago and my 3rd gear synchro just went out again last night.

how many msm guys have had this problem?

and is there anyway to fix the problem for good?
 
#3 · (Edited)
I hope you find a solution. I had a very difficult time getting my car in the lower gears heading down frontside last night. It took about 15 minutes for the trans to go back to it's normal notchy self once on the freeway.

I wonder if its a shift in the trans while turning or oil/heat causing these issues.

EDIT - Do you know if it could be the shift forks or syncro slider hubs?
 
#4 ·
im not sure we we had the transmission taken part last time it didn't look like there was a flaw in the design.

im getting it rebuilt with with different gears and scychro's.

well see how long this one will last.
 
#6 ·
Hm... Mine shifts just fine. Though sometimes down-shifting to second or going into third it grinds a bit even though I'm all the way in on the clutch. But it only happens once in a while.
 
#7 ·
You guys must be really doing it wrong. Even with 250hp, I have no problems with my 6spd. Learn to drive? :woolery:

Seriously though, what oil are you running in it? IIRC GL4 isn't so good, need to be GL5 fluid otherwise it will **** the bed. I'm running RL 75/90 but plan on switching to the all-being Ford SMTL eventually.
 
#10 ·
GL5 is a terrible recommendation much like assuming one does not know how to drive.

Zoltan drifts which explains 3rd being abused and more than likely a shift fork or slider hub breaking being the end result. The actual synchro itself is an expensive part and many rebuilders will say this is the part that needs to be replaced when in fact it is nothing but one of the failures I listed above.

After speaking with a rebuilder on this subject recently, he informed me out of the 100s of trannies hes done, 3 have had a bad synchro.
 
#15 ·
i have the msm 6 speed and im using GM synchro mesh oil that mike at 949 racing recommended.

oh ya it could just be because i just don't know how to drive....lmao :whistle:
 
#16 ·
O wait... I now see what you ment about that. The regular LS 6speed and the MSM 6speed... Duhh... lol
 
#22 ·
yea, I am working on fixing this with some stiffer mounts. I just got the msm engine mounts (I would rather get stiffer, but nothing is available thats not solid). I have a set of energy suspension diff mounts waiting to go on, but I am going to give myself a week with just MSM to see how they feel before I put on the energy.

If the MSMs & the energy aren't enough, I am going to do a Poly DIY engine mount as a last resort.

I suspect the mounts should make it much easier.


wooo weee iv never grinded 5th. only 3rd and reverse lol
Try shifting from 2nd to 5th at redline (missed 3rd shift). You will.
 
#25 ·
I could get into this, or I couldn't. But I won't really. They are not actually vibration isolating mounts and their functionality depends on how hard/much you tighten them down. A mount isolates vibrations, by connecting the engine and the chassis with a material like rubber or poly, not a bolt. Its just not the same design.

I am sure they "work" great, but they aren't for me. I supported the RT mounts, until I discussed it with my Mechanical engineering buddies.
 
#27 ·
I just noticed that every poster in here is in an NB. I am too. Why is it that my buddies' 10+ year-old NA's shift like their trannies are filled with Crisco and wet dreams. And our newer NB's are the one with problems. I crunch 1st through 4th 90% of the time. 1st to 2nd is exceptionally awful. I tried to remedy with Penzoil Syncromesh a few months back. That was a mistake. I just ordered a few quarts of RL MT90 yesterday, so hopefully that will work its magic. If not, my guess is the Syncros. Sorry for jacking, anyway hope you find some help.
 
#28 · (Edited)
I don't know what your complaint is...that it doesn't feel right? I am sure MT90 will work great, if you aren't satisfied then the end of the line is the motorcraft synthetic. I posted a link for it in a previous thread. are you the first owner of the car? how many miles are on it? are you using a 5-speed or 6-speed? do you know the previous history of the car?

PS I am 100% satisfied with my miata's shifting and the feel. Its extremely communicative, way more than my MS3 ever was. Its very smooth especially after replacing the 9 year old black slop that was in it before I bought it, with the Motorcraft Synthetic.

Slightly/Really off-topic:
The new engine mounts (i took them out for test drive #2 today) are working great. Other than some slight handling benefits and aural pleasures, the shifter is MUCH more manageable in the corners and I suggest the MazdaComps for anyone looking for those benefits...but they still leave a lot to be desired for someone like me (one who doesn't give a **** about comfort). I think I will do the DIY poly mount, just cause I am curious about even more improvement.

Not to entirely derail the thread, but what is the issue with RT mounts you are trying to get at?
If you want to know more details, PM me your e-mail. I will forward you my explanation that I sent to a few other miata forum members who became...curious. Better yet, if you know any MEs who work/specialize with vibrations, you can speak with them in person and they will be able to explain it better than I ever could!
 
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