While over time all of the other synchros in a T-5 received upgrades to a Carbon-Fiber design, the fifth gear synchro has remained unchanged from day one. This is the only brass synchro ring in the transmission and is rather WEAK...

Stressing it from 3-5 at high RPM may just be more than it can take...

What fluid are you using? Has it done this from the beginning when your T5Z was new?

 

Not sure of the exact fluid... it's conventional ATF, whatever kind the manual says. I always used what the manual specifies, and when I had the trans work done a year ago, I made sure they knew it uses ATF and not gear oil (they did).

Do you have a suggestion of a better one?

I bought the T-5Z used from a person locally who upgraded to a Tremec TKO a bunch of years ago (so I don't really know how many miles he had on it before I got it), and it always did the same. I just ignored it and took it easy shifting to fifth and it lasted a long time (probably close to 100k miles) that way... until the 5th synchro went out about a year ago. It would grind into fifth every time at any speed unless I waited several seconds in neutral (clutch depressed) before putting it in fifth.

That was when I took it to a trans shop. It worked great after that, and it apparently still does-- I'm gathering from this reply and the next one after that I am asking too much of the synchro and I should take it easy on them.

Thanks SPeace-ATL and joeswr400! I'll just not do the third to fifth shift and pause a bit going into fifth to let it slow down before hitting the synchro.

 

Mine did that too. Even after a rebuild with all Astro upgraded internals. Brass syncro probably not able to slow the stuff down inside fast enough to prevent the grind. 5th gear teeth are really, like , small/ narrow too. Might have something to do with it.

 

.....and the speed differential is exacerbated in the T5z because of the shorter 3rd gear (1.34 vs. 1.29) and the longer 5th gear (.625 vs. .675).....

 

Excellent point Michael!

There is a rare option of 0.73 for the T5Z (That's 0.72803 for purists!)
Also custom fifth gears are available in 0.78-0.81 depending on the manufacturer. One of these might close the gap and help it shift better.

Doing that will lower the fuel economy some while cruising, but add a little zip to fifth gear on the highway, or on that back-stretch at the road course!

 

Yup. There's some dyno testing by guys in the this forum that shows a pretty significant efficiency loss with a T56 compared to a T5 (in the 30 rwhp range) confirmed with both dyno and timed acceleration runs. Between the extra heft of the T56, the physical size and that additional parasitic loss, I'll be looking to see if there's a beefed up T5 that will stand up behind a 450HP/450 lb-ft LS3 when that swap time comes. For my use, there's plenty enough torque to make 5 gears work just fine instead of 6. Is there such a beast Stan?

 

The "Beastiest" T-5 Is the Astro A-5. The GForce units are stronger than the T5Z, but the Astro third gear holds up to more power.

Astro rates their A-5 gear set when used with a 9310 alloy main shaft at 575 ft/lbs and an estimated 650 HP. They don't advertise the Camaro input shaft for the A-5 but they make up a few to fill requests. If you like the light weight and power efficiency of the T-5 this would be the way to go!

 

Thx Stan! I presume if they're making the changes they make to deal with the torque - you also have some gear ratio options as well.

 

you also have some gear ratio options as well.

Yes, the Astro A-5 ratios are 2.95, 1.95, 1.36, 1.00 and for fifth there are several ratios:

0.60 (0.594915)
0.64 (0.637255)
0.73 (0.732727)
0.79 (0.786842)

 

I found their website lacking.....

 

Tony (astro guy) seems like an old school customer service dude. I have had some great talks with him over the last few years. Yes, the website needs updating to the 21st century.

 

I have the same issue. It was happening before my new clutch, flywheel and trans fluid replacement... so I'm betting on a worn synchro.

 

So far, so good

So what? Nah, that's something else.

I drained the trans and filled it with Pennzoil Synchromesh.

I did a couple of high-rpm shifts into fifth after driving 10-15 miles to get the new fluid distributed to all parts of the trans, and no grind. With the old fluid it would grind every single time.

If it stays like this, problem solved!

 

I drained the Amsoil ATF and filled it with Amsoil Synchromesh this weekend.

I only got one opportunity for a high-rpm shift into fifth this morning and no grind. So it looks promising thus far... thanks for the idea!

 

Synchromesh still working perfectly in my T-5 as well... no more fifth gear grinds! Thinking this should have been what they put in from the start instead of ATF! Thanks to SPeace-ATL!

 

Interesting results, guys!

It may not fix all fifth gear problems because if it has been scraping for a while, the fifth gear synchro hub teeth will be rounded off and need replacing to make it work right!

 

A lot of issues I've seen over the years with 5th gear grinds can be narrowed down to these reasons. first, shifting too quickly into 5th, like you would shift fast into 2cd or 3rd, remember it's an overdrive gas economy gear, not made for powershifts. next would be people 'rebuilding' the trans, replacing only the gear and blocker ring, and leaving the worn and beaten slider in place or vice versa. Either of these will grind, the first taking some time for the repeated hard shifts to wear the brass blocker down till it stops slowing the gear down fast enough. I put all my cars into overdrive as if I was 90 and it it was made of eggshells. Push in clutch, move shifter to neutral, move shifter over and easily(not really slowly, but not jamming it in either) put it into gear and then letting the clutch out. It allows rpms to fall and the gear to slow down to allow smooth engagement and not burn up the antique blocker.
I too, am going to try the Amsoil synchromesh. I just became an Amsoil dealer and want to try that stuff out.

 

I noticed my T-5z grinds when shifting into fifth gear if the input shaft speed(in other words, engine speed) is over ~3500-4000... I made a third to fifth shift when merging on the freeway, and it made a grrrrind. I'm certain the clutch is adjusted and I pushed it all the way.

I took the car back to the shop that did the synchro a year ago, and he could not make it do it... but he would not do a third to fifth shift, and on the 55 mph road we did the test drive on, you can't get going fast enough to get the input shaft really going in fourth. He did take it to 3500, he said (I was with him but I can't really see the tach from the passenger seat) and it didn't do it for him.

I could not get him to try the third to fifth shift. Without that, the trans performed perfectly for him. Based on the test drive he did, it looked fine to me too, but this is a Mustang, not a F-250 pulling a horse trailer!

Am I asking too much of a T-5z, or is something amiss?

Hopefully maybe you get this it’s like about 12 years later lol
I have and I see there’s a lot of people with or either had that problem or have that problem I have it right now exactly what everyone is saying and I was wondering if I could if you’re still reading this thread if I could speak to you about it basically first through fourth fine But third the fifth or fourth the fifth it just like grind I have to like slow it down and to let it go in same exact stuff and wanted to talk to somebody about it

 

Hopefully maybe you get this it’s like about 12 years later lol

Guess I came back at a good time!

The solution for me was to switch to GM Synchromesh in the T5 (after I called Tremec and verified that it was an approved lubricant for the T5 series). That solved it completely. I daily drove that car (my 1990 LX 5.0 with the T5z) until earlier this year, when I bought a 2013 GT (also manual), and that problem has never come back.

I know that Ford/B&W/Tremec presumably specced the ATF for mpg reasons (and I certainly appreciate getting as much fuel economy as I can out of it), and the Synchromesh is much thicker, but a couple of years ago I got my best ever gas mileage with the 1990 with Synchromesh. Not bad for an engine with well over 200k on it.

I still have and drive the 1990, and I don't plan to ever get rid of it (such sweet simplicity compared to the '13), but for a DD, I figured something a little newer would not be a bad idea. I've loved the retro look of the S197 series since it first arrived, and when I discovered I actually fit well in them with no modifications... been thinking of one ever since.

Of course, now I think of the 1990 as being kinda slow. I always thought it was pretty decent until a few months ago.

 

Before I get into the details I want to suggest to anyone that has an aftermarket shifter with the adjustable shift stops that they take a moment and be sure that the shift stops are adjusted such that the shifter lever doesn't quite touch the shift stop in any gear. Yes, each gear is a little bit different.

Now, For a T5 I have noticed that fifth gear is often a problem with wear to the synchro teeth. Both on the synchro slider as well as on the gear itself. Originally, in the T5 (NWC) all 5 synchro rings were single rings made of some form of brass or bronze. All of the gears were bad about wearing the synchro teeth. They went with lined rings for gears 1-4 in 1985 (WC) which was better. They even made gears 1 and 2 have double-friction cones!

In 1992 they went with carbon-fiber rings for gears 3 & 4 which was another improvement. Eventually in 2011 after they stopped making the T5 other than the new aftermarket T5Z units that we still see available today, they went with carbon fiber lined rings for the First and Second gears. Even better!

Well... Fifth gear is still back in the Non-World Class dark ages with he original weak brass rings. This is true even for a brand new T5Z transmissions being built today!

There now is an aftermarket fifth gear synchro ring that has the carbon-fiber lining and seems to be holding up well.

The only thing to do for the grinding fifth gear is to open the transmission and inspect/replace the fifth gear, that synchro slider and the synchro ring.

Unfortunately, Tremec no longer makes that fifth gear used in most of the WC T5 transmissions from 1985-1993. It is this gear for the V8 T5 transmissions with the 0.68 fifth gear ratio that we really need. Well, it turns out that this same gear pair was used in the 4-cylinder T5 from 1985-1993. For some reason a used 4-cylinder T5 (That has not been used behind a V8 engine) will often have a very nice fifth gear in it! Also a V-6 T5 from 1999-2004 will have this 0.68 fifth gear. Those transmissions are good for parts much like the 4-cylinder units. Note that a 1994-1998 V6 T5 will have a 0.73 ratio fifth gear. That will work, but the ratio will change to 0.73...

ENJOY!

 

More stuff to keep in mind the next time my T5 is out.

I've had an entire parts T5 i've been meaning to build into a Z-spec box, but unfortunately, it's just not very cost-effective given the torque rating these days.

 

The carbon fiber lined 5th gear ring does help with this issue although the size of the ring compared to the mass of the gear and the rotational speed of it is like trying to stop a garbage truck with drum brakes from a 1965 Mustang.

 

Where can you get the 5th synchro ring that is carbon fiber lined?

 

amp distributing

 

Thanks. I might pick one up as I'm tearing apart a T5 now for rebuild.


Have you seen any benefit throwing one on the reverse brake side of the synchro? Probably not a typical question but the T5 i'm working on has the brake and for $20 I wonder if would improve upon the barely adequate reverse brake setup any.