M47: reverse grinds/1st & 2nd hard to engage
#1
M47: reverse grinds/1st & 2nd hard to engage
Hey everyone,
So I have an 89' 240 DL with a M47 5-speed. The only problem I have with it is that sometimes it's basically impossible to get into 1st or 2nd gear from a standstill unless I put it in 3rd or 4th before trying 1st or 2nd again. The reverse gear grinds maybe 90% of the time trying to get it in, but it goes in without a problem when the engine's off.
I've adjusted the clutch cable at the fork, adjusted the reverse lockout plate, and replaced the transmission fluid.
So what my real question is, how can I be sure this is a problem related only to the clutch and not the gearbox? I'm sure the clutch could probably use a replacement, but I don't want to get done with that to find out it's the gears that are bad..
So I have an 89' 240 DL with a M47 5-speed. The only problem I have with it is that sometimes it's basically impossible to get into 1st or 2nd gear from a standstill unless I put it in 3rd or 4th before trying 1st or 2nd again. The reverse gear grinds maybe 90% of the time trying to get it in, but it goes in without a problem when the engine's off.
I've adjusted the clutch cable at the fork, adjusted the reverse lockout plate, and replaced the transmission fluid.
So what my real question is, how can I be sure this is a problem related only to the clutch and not the gearbox? I'm sure the clutch could probably use a replacement, but I don't want to get done with that to find out it's the gears that are bad..
#3
I have exactly the same issue with my 91 240 with m47 tranny. It works perfectly when cool, but becomes hard to get into 1st and reverse grinds after driving it for awhile.
I've adjusted the clutch and changed out the oil with synthetic and it got better, but the issue is still there. Did you resolve the issue with a clutch change or was it the transmission that had to be rebuilt?
I don't want to change the clutch only to find out that the transmission was what needed to be rebuilt.
Thanks in advance!
I've adjusted the clutch and changed out the oil with synthetic and it got better, but the issue is still there. Did you resolve the issue with a clutch change or was it the transmission that had to be rebuilt?
I don't want to change the clutch only to find out that the transmission was what needed to be rebuilt.
Thanks in advance!
#4
I'm going to make a few assumptions here to explain a few things about shifting technique. I think if you do that, it will make things shift easily.
Assuming that the clutch has been adjusted properly:
First, reverse is not synchronized and will always make a little noise going into reverse. To minimize it, come to a stop before shifting. If you are moving at all, a new M47 will grind the same.
Second, I guessing that you have two hard shift scenarios, the first being when you are completely stopped and trying to put the car in gear, like at a stop light. If you hold the clutch in for a long time and have the car in neutral, the transmission will come to a stop. The gears will not be spinning so the teeth will not be able to line up allowing you to shift into gear. The get it to shift, let the clutch out in neutral then put it back in (this spins the gears) and then try putting it in first.
The other shifting scenario is when you are coasting but you are still moving and you go to put it in a low gear and it doesn't really want to go in. This is normal for worn out syncros, but if you double clutch, you make it work fine. What's happening here is that the gears are spinning at really different speeds and the syncros are worn out, so they don't match them up. For example, if you go to put the car into first at 10mph, it may not seem like much, but the matching engine speed for that gear's speed is around 2000rpm. If the engine is idling (850rpm) there is a pretty big difference. You can match the gears yourself. Let out the clutch in neutral and blip the throttle. You just do it to speed the engine (and the input shaft of the transmission) up to the matching 2000-ish rpm. Then put the clutch in and pop it in gear. You do the same thing with second gear, put scale the engine speed back. You don't have to perfect top get it. This double clutching technique is how truckers are able to shift without using the clutch. They match it themselves.
If your transmission had damage, it would whine in certain gears or pop out of gear due to excessive wear. If it does not do those things, the gears and teeth should be in good shape. It just sounds like years of making the syncros doing all the matching have taken it's toll. They have on my car, but a little advanced shifting technique will make for smooth problem free shifts. And you can impress your friends.
Assuming that the clutch has been adjusted properly:
First, reverse is not synchronized and will always make a little noise going into reverse. To minimize it, come to a stop before shifting. If you are moving at all, a new M47 will grind the same.
Second, I guessing that you have two hard shift scenarios, the first being when you are completely stopped and trying to put the car in gear, like at a stop light. If you hold the clutch in for a long time and have the car in neutral, the transmission will come to a stop. The gears will not be spinning so the teeth will not be able to line up allowing you to shift into gear. The get it to shift, let the clutch out in neutral then put it back in (this spins the gears) and then try putting it in first.
The other shifting scenario is when you are coasting but you are still moving and you go to put it in a low gear and it doesn't really want to go in. This is normal for worn out syncros, but if you double clutch, you make it work fine. What's happening here is that the gears are spinning at really different speeds and the syncros are worn out, so they don't match them up. For example, if you go to put the car into first at 10mph, it may not seem like much, but the matching engine speed for that gear's speed is around 2000rpm. If the engine is idling (850rpm) there is a pretty big difference. You can match the gears yourself. Let out the clutch in neutral and blip the throttle. You just do it to speed the engine (and the input shaft of the transmission) up to the matching 2000-ish rpm. Then put the clutch in and pop it in gear. You do the same thing with second gear, put scale the engine speed back. You don't have to perfect top get it. This double clutching technique is how truckers are able to shift without using the clutch. They match it themselves.
If your transmission had damage, it would whine in certain gears or pop out of gear due to excessive wear. If it does not do those things, the gears and teeth should be in good shape. It just sounds like years of making the syncros doing all the matching have taken it's toll. They have on my car, but a little advanced shifting technique will make for smooth problem free shifts. And you can impress your friends.
#5
thanks Joe for taking the time to explain different ways to shift. Both of your suggestions do not make a difference in shifting.
What I've been doing to get into 1st after the car is started and rolling is to apply slight pressure into 1st as the car comes to a stop with the clutch in. If I don't do this while the car is slowing down it is very hard to put into 1st...even with your suggestion of "let the clutch out in neutral then put it back in (this spins the gears) and then try putting it in first".
As for reverse...it will grind no matter how long the car is not moving (clutch in, motor running). Even if I put it into 1st prior it still grinds. If I need to reverse I put it into gear with the motor off. Not being able to reverse easily is the real issue that makes me want to deal with the problem.
From reading other posts here of others with similar issues I would conclude that it is not a worn syncro/gears as the problem extends to the reverse gear that is not syncronized.
I also read a post on the same issue with the M46. I know it's a different transmission, but most pointed to clutch adjustment, release fork and clutch parts/pilot bearings:
740 m46: grinding into reverse, hard shift into 1st. Help! - Turbobricks Forums
Something is not disengaging properly with the clutch in and allowing gears to continue to spin more than usual. Am I correct in thinking this? Is it possible that it's something other than the syncro gears?
Thanks in advance!
What I've been doing to get into 1st after the car is started and rolling is to apply slight pressure into 1st as the car comes to a stop with the clutch in. If I don't do this while the car is slowing down it is very hard to put into 1st...even with your suggestion of "let the clutch out in neutral then put it back in (this spins the gears) and then try putting it in first".
As for reverse...it will grind no matter how long the car is not moving (clutch in, motor running). Even if I put it into 1st prior it still grinds. If I need to reverse I put it into gear with the motor off. Not being able to reverse easily is the real issue that makes me want to deal with the problem.
From reading other posts here of others with similar issues I would conclude that it is not a worn syncro/gears as the problem extends to the reverse gear that is not syncronized.
I also read a post on the same issue with the M46. I know it's a different transmission, but most pointed to clutch adjustment, release fork and clutch parts/pilot bearings:
740 m46: grinding into reverse, hard shift into 1st. Help! - Turbobricks Forums
Something is not disengaging properly with the clutch in and allowing gears to continue to spin more than usual. Am I correct in thinking this? Is it possible that it's something other than the syncro gears?
Thanks in advance!
#6
Hmmm, then I thought that you adjusted the clutch. It sounds like your clutch is adjusted improperly. It's not completely disengaging the motor from the transmission. I'm not familiar with the adjustment of the cable clutch in a 240, but I would say that there is either too much end play in the cable or something (like a floor mat) is blocking the full movement of the clutch pedal.
As a note, from what I understand the M46 and M47 are very similar, but overdrive is just another gear inside the transmission rather than a separate unit. The ratios are exactly the same (except overdrive, the M46 has a slightly taller ratio).
As a note, from what I understand the M46 and M47 are very similar, but overdrive is just another gear inside the transmission rather than a separate unit. The ratios are exactly the same (except overdrive, the M46 has a slightly taller ratio).
#7
What I've been doing to get into 1st after the car is started and rolling is to apply slight pressure into 1st as the car comes to a stop with the clutch in. If I don't do this while the car is slowing down it is very hard to put into 1st...even with your suggestion of "let the clutch out in neutral then put it back in (this spins the gears) and then try putting it in first".
As for reverse...it will grind no matter how long the car is not moving (clutch in, motor running). Even if I put it into 1st prior it still grinds. If I need to reverse I put it into gear with the motor off. Not being able to reverse easily is the real issue that makes me want to deal with the problem.
As for reverse...it will grind no matter how long the car is not moving (clutch in, motor running). Even if I put it into 1st prior it still grinds. If I need to reverse I put it into gear with the motor off. Not being able to reverse easily is the real issue that makes me want to deal with the problem.
I haven't done anything to the car besides routine maintenance and it still runs like a champ, besides the squealing release bearing and the tough shift into 1st.
Your description of trying to get into 1st gear when stopped exactly explains my problem. I can get into 1st just fine if the car is rolling, but when I stop fully, it's damn near impossible to get into 1st without running the transmission through 3rd or 4th. I guess I've just gotten into the habit of shifting 3 times every time I stop. With reverse I have to run it through 3rd and 4th too, but it works fine after that.
Anyway my problem is still there, and I'm pretty sure it's the pilot bearing; it's been screaming at me here and there. I wasn't sure if replacing it would actually fix it, seemed more like a gearbox thing to me, but your research seems to make it so. I wish I would've been able to help with definite answer, but I guess life would be a lot easier for both of us if we just got in the garage and did it.
#8
Thanks for your response!
So you've lived with it for some time now? wow! I've done so for 6 months and it's next to impossible to get into reverse unless I do so before starting the car. This has become quite annoying so I decided to bite the bullet and have my mechanic change out the clutch and related bearings yesterday. Even he thought it was the gears in the transmission.
This was a hard decision as the clutch was not slipping and worked fine otherwise.
When he opened everything up the bearings did not appear to be abnormally worn. The pressure plate had some wear, but he said that it was not too bad. Everything back together and the transmission is working like new! No grinding into reverse or hard shifts into 1st from a stop
So I would guess, just as you have, that the problem would be fixed with new clutch parts.
Thanks again for everyone's help!
So you've lived with it for some time now? wow! I've done so for 6 months and it's next to impossible to get into reverse unless I do so before starting the car. This has become quite annoying so I decided to bite the bullet and have my mechanic change out the clutch and related bearings yesterday. Even he thought it was the gears in the transmission.
This was a hard decision as the clutch was not slipping and worked fine otherwise.
When he opened everything up the bearings did not appear to be abnormally worn. The pressure plate had some wear, but he said that it was not too bad. Everything back together and the transmission is working like new! No grinding into reverse or hard shifts into 1st from a stop
So I would guess, just as you have, that the problem would be fixed with new clutch parts.
Thanks again for everyone's help!
#9
I'm going to make a few assumptions here to explain a few things about shifting technique. I think if you do that, it will make things shift easily.
Assuming that the clutch has been adjusted properly:
First, reverse is not synchronized and will always make a little noise going into reverse. To minimize it, come to a stop before shifting. If you are moving at all, a new M47 will grind the same.
Second, I guessing that you have two hard shift scenarios, the first being when you are completely stopped and trying to put the car in gear, like at a stop light. If you hold the clutch in for a long time and have the car in neutral, the transmission will come to a stop. The gears will not be spinning so the teeth will not be able to line up allowing you to shift into gear. The get it to shift, let the clutch out in neutral then put it back in (this spins the gears) and then try putting it in first.
The other shifting scenario is when you are coasting but you are still moving and you go to put it in a low gear and it doesn't really want to go in. This is normal for worn out syncros, but if you double clutch, you make it work fine. What's happening here is that the gears are spinning at really different speeds and the syncros are worn out, so they don't match them up. For example, if you go to put the car into first at 10mph, it may not seem like much, but the matching engine speed for that gear's speed is around 2000rpm. If the engine is idling (850rpm) there is a pretty big difference. You can match the gears yourself. Let out the clutch in neutral and blip the throttle. You just do it to speed the engine (and the input shaft of the transmission) up to the matching 2000-ish rpm. Then put the clutch in and pop it in gear. You do the same thing with second gear, put scale the engine speed back. You don't have to perfect top get it. This double clutching technique is how truckers are able to shift without using the clutch. They match it themselves.
If your transmission had damage, it would whine in certain gears or pop out of gear due to excessive wear. If it does not do those things, the gears and teeth should be in good shape. It just sounds like years of making the syncros doing all the matching have taken it's toll. They have on my car, but a little advanced shifting technique will make for smooth problem free shifts. And you can impress your friends.
Assuming that the clutch has been adjusted properly:
First, reverse is not synchronized and will always make a little noise going into reverse. To minimize it, come to a stop before shifting. If you are moving at all, a new M47 will grind the same.
Second, I guessing that you have two hard shift scenarios, the first being when you are completely stopped and trying to put the car in gear, like at a stop light. If you hold the clutch in for a long time and have the car in neutral, the transmission will come to a stop. The gears will not be spinning so the teeth will not be able to line up allowing you to shift into gear. The get it to shift, let the clutch out in neutral then put it back in (this spins the gears) and then try putting it in first.
The other shifting scenario is when you are coasting but you are still moving and you go to put it in a low gear and it doesn't really want to go in. This is normal for worn out syncros, but if you double clutch, you make it work fine. What's happening here is that the gears are spinning at really different speeds and the syncros are worn out, so they don't match them up. For example, if you go to put the car into first at 10mph, it may not seem like much, but the matching engine speed for that gear's speed is around 2000rpm. If the engine is idling (850rpm) there is a pretty big difference. You can match the gears yourself. Let out the clutch in neutral and blip the throttle. You just do it to speed the engine (and the input shaft of the transmission) up to the matching 2000-ish rpm. Then put the clutch in and pop it in gear. You do the same thing with second gear, put scale the engine speed back. You don't have to perfect top get it. This double clutching technique is how truckers are able to shift without using the clutch. They match it themselves.
If your transmission had damage, it would whine in certain gears or pop out of gear due to excessive wear. If it does not do those things, the gears and teeth should be in good shape. It just sounds like years of making the syncros doing all the matching have taken it's toll. They have on my car, but a little advanced shifting technique will make for smooth problem free shifts. And you can impress your friends.
#11
Hope this helps, and thanks for all the replys guys.
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07-12-2013 11:38 PM