t56 reverse fix!
Thread Starter
Instructor
Joined: May 2007
Posts: 149
Likes: 7
From: Arkansas City Kansas
t56 reverse fix!
I have a 98 pace car I bought about a year ago 100k on the clock. I have had to hold it in reverse and ease out the clutch. It would then pop and slip into reverse. Tried all the easy fixes adjusting shifter, replacing fluid and nothing helped. Searched the forum and decided I would install a new reverse fork. While researching I came across this mod for the t56 on a mazda forum. Long story short replaced the fork and did the mod and all is well. I am also now all smiles.
http://forum.miata.net/vb/archive/in.../t-256530.html
quote:MX5.71st November 2007, 23:14
Any one using a t56 should do this easy mod while tranny is out.
http://www.thirdgen.org/techboard/tr...6-reverse.html
My car would not stay in reverse without holding it there and would still pop out or grind sometimes. :realmad: When you pull the tranny apart you will see that it is obviously a design flaw as the reverse fork comes an 1/8" shy of fully engageing (
don't ask me how this was over looked) while every other gear engages fully. I used a grinder with a sanding disc and ground the shift fork slow checking it with a dial caliper often. Then I placed a washer that was the excact same thickness of the material removed on the other side of the shift fork. It just moves the shift fork further down the rail so that it fully engages the reverse synchros. If you go on LS1 tech you can do a search and realize that hundreds of people have this reverse problem, I suppose it gets worse as the gear wears. Most will not take your advice when you say you have done this mod and it worked because they are cautious about mods to the tranny internals. I have put around 2k miles on since the mod and nothing but smiles. 
Hope this can help someone on here with simmular issues as mine maybe even before the tranny goes in.
http://forum.miata.net/vb/archive/in.../t-256530.html
quote:MX5.71st November 2007, 23:14
Any one using a t56 should do this easy mod while tranny is out.
http://www.thirdgen.org/techboard/tr...6-reverse.html
My car would not stay in reverse without holding it there and would still pop out or grind sometimes. :realmad: When you pull the tranny apart you will see that it is obviously a design flaw as the reverse fork comes an 1/8" shy of fully engageing (
don't ask me how this was over looked) while every other gear engages fully. I used a grinder with a sanding disc and ground the shift fork slow checking it with a dial caliper often. Then I placed a washer that was the excact same thickness of the material removed on the other side of the shift fork. It just moves the shift fork further down the rail so that it fully engages the reverse synchros. If you go on LS1 tech you can do a search and realize that hundreds of people have this reverse problem, I suppose it gets worse as the gear wears. Most will not take your advice when you say you have done this mod and it worked because they are cautious about mods to the tranny internals. I have put around 2k miles on since the mod and nothing but smiles. Hope this can help someone on here with simmular issues as mine maybe even before the tranny goes in.
Thread Starter
Instructor
Joined: May 2007
Posts: 149
Likes: 7
From: Arkansas City Kansas
I think it is the same transmission just a bit beefed up. After researching this is a common problem that a lot of t56 owners are having. Mine had got to the point I could barely hold it any more, was a 50/50 that it would go in or would pop out and grind. Finally said what have I got to loose. Just replacing the fork may help a bit but even with the new fork it was not going in all the way. I first tried a washer about 1/16 inch thick and it was better but still not quite there yet, so I went with one about 1/8 inch thick. All I know is now when I put it in reverse I can feel it go in and I just smile. Probably if you are not going to do the mod you better buy the fork and the gears as mine had lost the points from the grinding.
7th Gear
Joined: Feb 2012
Posts: 7
Likes: 0
I just finished fixing my 2000 6 speed, was jumping and grinding reverse. Replaced reverse gear and flipped sinchro assembly over as well as checked position of fork. It was approx. an 1/8 inch of (.112) off so I removed some off of fork with stationary belt sander. It did a very nice job and took very little time. Shimmed it up, got it together today and it works great! Update! 4/23/2012,,,,,, I have not had a problem with reverse since doing this! It used to be push hard on the shifter and ease out the clutch, pray it didn't grind and hope no-one standing around.
ALSO......put a bypass tube right in front of where the incoming exhaust pipe comes in to the muffler and then to the inside outlet pipe . It isn't too loud and should lower back pressure. Took a Bit To sculpt pipe to fit, then scribed around, cut into pipes, then welded bypass tubes in place. Cheap mod with a nice sound.
ALSO......put a bypass tube right in front of where the incoming exhaust pipe comes in to the muffler and then to the inside outlet pipe . It isn't too loud and should lower back pressure. Took a Bit To sculpt pipe to fit, then scribed around, cut into pipes, then welded bypass tubes in place. Cheap mod with a nice sound.
Last edited by Jst kuz; Apr 23, 2012 at 11:04 PM. Reason: More info
7th Gear
Joined: Feb 2012
Posts: 7
Likes: 0
I have a 2000 6 speed , did the same thing, the reverse synchro can be flipped to use other side, I replaced my reverse gear as such teeth we're rounded a bit. Then checked the reverse fork, placed tranny in reverse with fork in place without snap ring. It was about .112 inches off from engaging all the way in so I used a stationary belt sander and held it flat to remove same amount. Then found a bronze shim at local hardware store and sanded to same amount removed. Reassembled, and it now shifts into reverse properly and feels right when going in. Never been happier!
7th Gear
Joined: Feb 2012
Posts: 7
Likes: 0
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Racer
Joined: Oct 2011
Posts: 374
Likes: 1
From: Greenville NY
Definitely the right way to fix! I cheated, stood tube and tranny on it's nose and removed rear cover, made mod to fork, then replace reverse gear. Have pics of mod to fork (request by email, dkiefert@hotmail.com)
Thanks!!
Racer
Joined: Oct 2011
Posts: 374
Likes: 1
From: Greenville NY
Definitely the right way to fix! I cheated, stood tube and tranny on it's nose and removed rear cover, made mod to fork, then replace reverse gear. Have pics of mod to fork (request by email, dkiefert@hotmail.com)
Navigator
Joined: May 2012
Posts: 9
Likes: 2
From what I understand, this is a common problem with the c5's. Also going into first. I hear the clutch master cylinder are the biggest problem. There's a company called Tick performance who sells a adjustable clutch master cylinder, that adjust at the pedal, and has a non restrictive hose.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 28
From: Van Buren Arkansas
Wounded Warrior Escort '11
I would like to hear what RPM Transmissions thinks about this possible fix...introducing a washer where there wasn't one to begin with. My first though was thermal expansion of the metals taking up that distance would then cause problems but I'm no trans expert at all.
Intermediate
Joined: Feb 2009
Posts: 47
Likes: 0
From: Orange County California
Definitely the right way to fix! I cheated, stood tube and tranny on it's nose and removed rear cover, made mod to fork, then replace reverse gear. Have pics of mod to fork (request by email, dkiefert@hotmail.com)
Thread Starter
Instructor
Joined: May 2007
Posts: 149
Likes: 7
From: Arkansas City Kansas
Just an update on this fix well over a year later. I actually forgot I ever had a problem with popping out of reverse. This seems to be the solution to the problem as I am very happy with the results.
Pro
Joined: May 2013
Posts: 740
Likes: 82
From: MN
Bumping this very helpful thread back up for anyone else who might be doing a T56 rebuild this winter. I just reassembled mine after replacing all the worn parts associated with reverse, including new bronze fork pads. If I hold the reverse synchro ring fully engaged with my hand, there is definitely a gap between the reverse shift fork and the collar on the shift rail that engages the shift fork. So, without a spacer there, the fork cannot fully engage the synchro, which I believe is what caused the premature failure of reverse in my transmission and many others. I didn't measure because the batteries in my digital caliper were dead, but it looks like a little less than 1/8", as others have stated. I plan to find a washer to space the shift fork down the rail the appropriate amount. Thanks for the thread!
8th Gear
Joined: Aug 2011
Posts: 8
Likes: 0
Yeah my dad is starting to have this exact problem with the rebuilt tranny in the 09 GS, LS6, dart pro 1 heads, cam, full exhaust w/longtubes and some other odds and ends and i had remembered reading something about it years back and here is the thread, Thanks guys ill let him know the fix.
Drifting
Joined: Sep 2006
Posts: 1,335
Likes: 166
From: Truckee CA
Today I discovered the reason why many of you have found that the spacer works. In my case and maybe your's is the snap ring and spacer that holds tension on the reverse gear have warn (because of maybe poor lube or the 16 years of wear) causing the gear to have more travel on the shaft then is spec. The end effect is that when engaging reverse there isn't enough travel on the shift fork to apply enough pressure to engage the synchro. If you have done the spacer fix, it may not be long before the snap ring fails from wear.
Photos to follow.
Mark
Photos to follow.
Mark
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,396
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Today I discovered the reason why many of you have found that the spacer works. In my case and maybe your's is the snap ring and spacer that holds tension on the reverse gear have warn (because of maybe poor lube or the 16 years of wear) causing the gear to have more travel on the shaft then is spec. The end effect is that when engaging reverse there isn't enough travel on the shift fork to apply enough pressure to engage the synchro. If you have done the spacer fix, it may not be long before the snap ring fails from wear.
Photos to follow.
Mark
Photos to follow.
Mark
Pro
Joined: May 2013
Posts: 740
Likes: 82
From: MN
Hmm. Mine was a low-mileage tranny (30k, according to the guy I bought it from), and the reverse gear spacer ring and snap ring were both in good shape. I bought a new one of each, because I wasn't sure whether my old ones were worn, but when I compared the old and the new, they were the same thickness. I did the shift fork spacer and I think the synchro engagement looks a lot better now.
Can't deny that yours is seriously worn, though. I guess we're dealing with multiple root causes that lead to the same type of failure. Thanks for the pics, and good luck with your transmission!
Can't deny that yours is seriously worn, though. I guess we're dealing with multiple root causes that lead to the same type of failure. Thanks for the pics, and good luck with your transmission!
Last edited by TastyBacon; Apr 8, 2016 at 02:23 AM.