Any useful info on this....
Any useful info on this....
I have an 04 evo and i ended up rebuilding my transmission because it was grinding when i tried to go from 4th to 5th. I have had this transmission in my car for a few months now with no problems. I also installed an exedy twin disc as well since i had the tranny out. So just the other day i was getting on the highway and the damn thing grinded from 4th to 5th. I was like WTF. I started searching and saw a thread where they had a recall on the syncros. So i called the place where i had the tranny rebuilt and they said they installed the new up to date syncros. So my question to you guys is what the hell could be doing this. If the syncros are going out again already what could cause this? I had my car for like 20000 miles before it started grinding before. Now i have had the new rebuilt tranny for maybe 4000 miles and its starting it again. Any help would be greatly apprecitated.
thanks
Josh
thanks
Josh
Last edited by evolancer04; Jul 30, 2007 at 08:24 PM.
Send the trans the Buschur Racing and let Dan fix it for ya. You wont be dissapointed
Did you rebuild it? My guess is that you did not use the newer syncro's, used sh*tty oil, you cant drive very well, or you assembled it incorrecly
Did you rebuild it? My guess is that you did not use the newer syncro's, used sh*tty oil, you cant drive very well, or you assembled it incorrecly
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I build these trannies. I have seen several trannies now that are low mileage but have completely worn out 3rd or 5th gear. I dont know what the cause is. But I can tell you the mitsu updated syncro wont do squat for a problem like this.
If I had to make educated guess what is happening I would say the syncros on those two gears are dragging while cruising. This would be the eqivalent to driving with a break caliper that does not release. The brake pad wears out quickly. In the tranny if the syncros dont release the syncro is going to wear down. This is maybe a far fetched possibility but is possible.
Second more likely problem is the syncro ring gets strecthed on a hard shift. When I inspect the worn out syncros they look new still. They just fit loose. The clutch rotational mass is very high on evos. The syncros job is to stop this rotating mass so the gear can be engaged. If clutch drags this rotational mass goes way up. If this theory is correct then it is essentially driving style that is at fault. The problem does not exist for 2 and 4 gears because those gear shifts are very easy to engage quickly because of shift pattern. 3 and 5 are hard to engage and take more time. You may want to try slowing down your 3 and 5 shifts to avoid this problem.
Shift timing is different for 3 and 5 than it is for 2 and 4. If you use shift timing of 2 and 4 for your 3 and 5 shifts your syncros are going to take a beating. Correct shift timing for 3 and 5 require your clutch foot to stay on the floor longer to allow the slower shift pattern of 3 and 5 to happen with correct timing.
If I had to make educated guess what is happening I would say the syncros on those two gears are dragging while cruising. This would be the eqivalent to driving with a break caliper that does not release. The brake pad wears out quickly. In the tranny if the syncros dont release the syncro is going to wear down. This is maybe a far fetched possibility but is possible.
Second more likely problem is the syncro ring gets strecthed on a hard shift. When I inspect the worn out syncros they look new still. They just fit loose. The clutch rotational mass is very high on evos. The syncros job is to stop this rotating mass so the gear can be engaged. If clutch drags this rotational mass goes way up. If this theory is correct then it is essentially driving style that is at fault. The problem does not exist for 2 and 4 gears because those gear shifts are very easy to engage quickly because of shift pattern. 3 and 5 are hard to engage and take more time. You may want to try slowing down your 3 and 5 shifts to avoid this problem.
Shift timing is different for 3 and 5 than it is for 2 and 4. If you use shift timing of 2 and 4 for your 3 and 5 shifts your syncros are going to take a beating. Correct shift timing for 3 and 5 require your clutch foot to stay on the floor longer to allow the slower shift pattern of 3 and 5 to happen with correct timing.
Last edited by 94AWDcoupe; Aug 2, 2007 at 08:33 AM.
I build these trannies. I have seen several trannies now that are low mileage but have completely worn out 3rd or 5th gear. I dont know what the cause is. But I can tell you the mitsu updated syncro wont do squat for a problem like this.
If I had to make educated guess what is happening I would say the syncros on those two gears are dragging while cruising. This would be the eqivalent to driving with a break caliper that does not release. The brake pad wears out quickly. In the tranny if the syncros dont release the syncro is going to wear down. This is maybe a far fetched possibility but is possible.
Second more likely problem is the syncro ring gets strecthed on a hard shift. When I inspect the worn out syncros they look new still. They just fit loose. The clutch rotational mass is very high on evos. The syncros job is to stop this rotating mass so the gear can be engaged. If clutch drags this rotational mass goes way up. If this theory is correct then it is essentially driving style that is at fault. The problem does not exist for 2 and 4 gears because those gear shifts are very easy to engage quickly because of shift pattern. 3 and 5 are hard to engage and take more time. You may want to try slowing down your 3 and 5 shifts to avoid this problem.
Shift timing is different for 3 and 5 than it is for 2 and 4. If you use shift timing of 2 and 4 for your 3 and 5 shifts your syncros are going to take a beating. Correct shift timing for 3 and 5 require your clutch foot to stay on the floor longer to allow the slower shift pattern of 3 and 5 to happen with correct timing.
If I had to make educated guess what is happening I would say the syncros on those two gears are dragging while cruising. This would be the eqivalent to driving with a break caliper that does not release. The brake pad wears out quickly. In the tranny if the syncros dont release the syncro is going to wear down. This is maybe a far fetched possibility but is possible.
Second more likely problem is the syncro ring gets strecthed on a hard shift. When I inspect the worn out syncros they look new still. They just fit loose. The clutch rotational mass is very high on evos. The syncros job is to stop this rotating mass so the gear can be engaged. If clutch drags this rotational mass goes way up. If this theory is correct then it is essentially driving style that is at fault. The problem does not exist for 2 and 4 gears because those gear shifts are very easy to engage quickly because of shift pattern. 3 and 5 are hard to engage and take more time. You may want to try slowing down your 3 and 5 shifts to avoid this problem.
Shift timing is different for 3 and 5 than it is for 2 and 4. If you use shift timing of 2 and 4 for your 3 and 5 shifts your syncros are going to take a beating. Correct shift timing for 3 and 5 require your clutch foot to stay on the floor longer to allow the slower shift pattern of 3 and 5 to happen with correct timing.
Thanks for the good info. Im never hard on the car in 5th though. It has only been to the track twice since the rebuild and i dont get into 5th at the track. 5th gear is always a normal shift. If i shift real slow it wont grind only if i shift normal. But i shouldnt have to do this. I know there has got to be some kind of fix for it. I am more leaning towards your first suggestion, since the tranny has only been in for about 3000 miles and its starting the same problem all over again. Is that something that should have been caught on the rebuild?? Could this also happen because the length on the 5th/reverse fork is off?? And if so should the shop checked that on the rebuild.
Thanks for the info
Josh
I would definately not blame the builder. These trannies are quite easy to service. Prolly the easiest on the planet actually. I wish I could say for sure what causes this. The trannies I have serviced that had this problem looked other wise perfect on the inside. Its very strange to see just one syncro wear out fast. Brass is an extremely hard surface to wear that is why syncros are made of this material. Nothing in the tranny is giving a clue as to why it happens. I can only offers theories as I still trying to pinpoint what the root cause is.
One of the most common problems that cause grind on these cars is simple misadjustment of the clutch (rod at the clutch master cylinder). Since the clutches get pretty beat (yes even the Exedy twin) the surfaces get warped and then it takes more travel to release completely. In your case, a simple adjustment is worth a shot since it only takes a few minutes to adjust it and determine whether it helps or not.