!$&*! Losi - Can anybody knowlegeable please help?
05-28-2011, 08:07 PM
#1
!$&*! Losi - Can anybody knowlegeable please help?
Hello,
Anybody that knows me knows I've been driving Losi trucks for years. I wrench and build my own trucks and always have, so I'm no dummy . . . but I feel like one right now. I'm so mad I'm about ready to smash this thing!! I have a XXXTCR. Rebuilding the transmission - have done it many times with past Losi trucks - MF1, MF2, etc. Have rebuilt this one before too. Usually easy stuff.
Noticed after the last time I ran it that the diff was getting very stiff so thought it was time to rebuild it. When I took it apart I noticed the top shaft was very very tight, almost not turning. Upon closer inspection I noticed my transcase on the right side (the side where the top shaft comes out) was cracked. Figured that might be what was causing the problem. The rest of the trans needed rebuilding anyway. So I replaced everything but the top gear, shaft and bearings. New trans case too. I already had the parts. Noticed that the fit of the top shaft was tight into the bearing where the shaft goes out of the case. I took that apart, inspected the bearing and the bushing. I sanded the bushing on both sides to smooth it out, put it all back together with all new gears and it still was too hard to turn. Took it back apart, switched the two shaft bearings, and it is still the same. I then loosened the screw that holds the case to the motor plate thinking that may be binding and didn't over tighten the 3 transmission screws. No change. The gears don't appear to be rubbing on the case either. I have the very thin spacer on the outdrive like I have always had. Tried it with it, tried it without, and even switched sides for the thin washer. I've about had it. I realize that Losi is the bottom of the heap now and that next to no one drives them, let alone Losi trucks. Is there anybody out there that has had that problem that can give me some ideas. I've run out things to try and it is just binding way too much. I have rebuilt many Losi transmissions and NEVER had this happen before. Maybe I should just run it that way, but I hate to burn up motors with that much resistance. It really is a lot. I'm about ready to pull my hair out. Any other ideas - other than buying something other than Losi? Got too many parts for Losi over the years and no money to buy into anything new until I find work. At this point, I don't race anymore, but want the truck operating properly so I can at least have fun with it.
Please reply with only constructive and sincere help, please. Thank you!
Anybody that knows me knows I've been driving Losi trucks for years. I wrench and build my own trucks and always have, so I'm no dummy . . . but I feel like one right now. I'm so mad I'm about ready to smash this thing!! I have a XXXTCR. Rebuilding the transmission - have done it many times with past Losi trucks - MF1, MF2, etc. Have rebuilt this one before too. Usually easy stuff.
Noticed after the last time I ran it that the diff was getting very stiff so thought it was time to rebuild it. When I took it apart I noticed the top shaft was very very tight, almost not turning. Upon closer inspection I noticed my transcase on the right side (the side where the top shaft comes out) was cracked. Figured that might be what was causing the problem. The rest of the trans needed rebuilding anyway. So I replaced everything but the top gear, shaft and bearings. New trans case too. I already had the parts. Noticed that the fit of the top shaft was tight into the bearing where the shaft goes out of the case. I took that apart, inspected the bearing and the bushing. I sanded the bushing on both sides to smooth it out, put it all back together with all new gears and it still was too hard to turn. Took it back apart, switched the two shaft bearings, and it is still the same. I then loosened the screw that holds the case to the motor plate thinking that may be binding and didn't over tighten the 3 transmission screws. No change. The gears don't appear to be rubbing on the case either. I have the very thin spacer on the outdrive like I have always had. Tried it with it, tried it without, and even switched sides for the thin washer. I've about had it. I realize that Losi is the bottom of the heap now and that next to no one drives them, let alone Losi trucks. Is there anybody out there that has had that problem that can give me some ideas. I've run out things to try and it is just binding way too much. I have rebuilt many Losi transmissions and NEVER had this happen before. Maybe I should just run it that way, but I hate to burn up motors with that much resistance. It really is a lot. I'm about ready to pull my hair out. Any other ideas - other than buying something other than Losi? Got too many parts for Losi over the years and no money to buy into anything new until I find work. At this point, I don't race anymore, but want the truck operating properly so I can at least have fun with it.
Please reply with only constructive and sincere help, please. Thank you!
05-28-2011, 09:03 PM
#2
Tranny
Diane, Two things come to mind.
1. Sounds like there is something that is stopping the bearing from fully seating in the case.
Or 2. has the truck taken a hit to the tranny area ? and maybe tweaked the top shaft and when assembled the bearings are bound up?
I would think that it is possible to have a bent top shaft since it was bound up in the old case.
Also, check to make sure that the bearings seat completly on the shaft prior to installing it in the tranny case.
Hope this helps, with out having it in my hands its hard to tell what it is.
Tom
1. Sounds like there is something that is stopping the bearing from fully seating in the case.
Or 2. has the truck taken a hit to the tranny area ? and maybe tweaked the top shaft and when assembled the bearings are bound up?
I would think that it is possible to have a bent top shaft since it was bound up in the old case.
Also, check to make sure that the bearings seat completly on the shaft prior to installing it in the tranny case.
Hope this helps, with out having it in my hands its hard to tell what it is.
Tom
05-28-2011, 09:12 PM
#3
hey there Diane, try loosening all the transmission case screws 1/4 turn each. I've had similar problems with the Losi transmission when the transmission case screws are all overtightened.
05-28-2011, 09:42 PM
#4
saw a video on youtube of a guy breaking in diffs on an 1/8 scale on a treadmill, just tethered it on to the treadmill and ran it for like two miles.
run it, check temps and see what happens.
I do have to agree though, sounds like a bearing may not be seated all the way.
run it, check temps and see what happens.
I do have to agree though, sounds like a bearing may not be seated all the way.
05-28-2011, 10:08 PM
#5
Hi Gary,
Yeah, that is one of the first things I did was loosen the trans screws. that's just a given for Losi anyway. No improvement.
Tom, I have wondered about the top shaft since the case was broken near that. The shaft looks straight, the bearings seem to be okay, but I do still wonder. I also wonder about the motor plate, although it does look okay. I'm not too sure if I have a spare motor plate though hanging around somewhere. I will look for two completely different bearings in my parts for the top shaft, but not too sure that would be it. I was also wondering if it could be that the new 51 tooth diff gear could be possibly sized wrong? You know, out of round just a little, but I haven't seen anything obvious. But then, it was almost completely jamed when I first discovered this. I hate to put out the expense of the one piece aluminum top shaft when I'm not working, but may have to do it anyway - that or just part that puppy out and go back to my MF1. I'm not terribly impressed by the CR anyway, but I hate to give up on it. Thanks all for your suggestions, and Ken, I have thought about just running the piss out of it and seeing what happens, but I would be afraid of overtaxing the motor with that much resistence. I am still using the 10.5 I got from you last year
. It would feel so good to take my anger out on that truck though and abuse the crap out of it. 
- but I won't.
Any other ideas that come up, please let me know. For now, I've bagged it up. Tired of looking at it.
Yeah, that is one of the first things I did was loosen the trans screws. that's just a given for Losi anyway. No improvement.
Tom, I have wondered about the top shaft since the case was broken near that. The shaft looks straight, the bearings seem to be okay, but I do still wonder. I also wonder about the motor plate, although it does look okay. I'm not too sure if I have a spare motor plate though hanging around somewhere. I will look for two completely different bearings in my parts for the top shaft, but not too sure that would be it. I was also wondering if it could be that the new 51 tooth diff gear could be possibly sized wrong? You know, out of round just a little, but I haven't seen anything obvious. But then, it was almost completely jamed when I first discovered this. I hate to put out the expense of the one piece aluminum top shaft when I'm not working, but may have to do it anyway - that or just part that puppy out and go back to my MF1. I'm not terribly impressed by the CR anyway, but I hate to give up on it. Thanks all for your suggestions, and Ken, I have thought about just running the piss out of it and seeing what happens, but I would be afraid of overtaxing the motor with that much resistence. I am still using the 10.5 I got from you last year
. It would feel so good to take my anger out on that truck though and abuse the crap out of it. - but I won't.Any other ideas that come up, please let me know. For now, I've bagged it up. Tired of looking at it.
05-28-2011, 10:11 PM
#6
Oh, and I forgot. I did seat the bearings all the way in that top shaft and checked the diff bearings where the outdrives go out. The look normal to me, but I still pressed them harder. They didn't move and the look even. 
05-28-2011, 10:42 PM
#8
Thanks, Ken. I may take you up on that - this is Ken isn't it? Don is supposed to pick up a car from Kevin, so I may come with him. I am just thoroughly disgusted with this thing - and i don't discount that I may have done something wrong, but I just don't know what. What time do you plan on being down there?
05-28-2011, 11:48 PM
#9
I would try checking the top shaft on a dremel or cordless drill. they are made of 7075, but I have had some get tweaked before. You can try chucking it up and spinning it at a moderate rpm and see if you notice any wobble.
Have you also tried putting in just hte bearings and topshaft, without the idler and diff gear and see if it spins free. If it does then reassemble with the idler and check. Then reassemble with the diff, at this point everything should hopefully still spin well.
Also you said you still have your MF1 so you could always swap out the transmission from that.
Have you also tried putting in just hte bearings and topshaft, without the idler and diff gear and see if it spins free. If it does then reassemble with the idler and check. Then reassemble with the diff, at this point everything should hopefully still spin well.
Also you said you still have your MF1 so you could always swap out the transmission from that.
05-29-2011, 12:06 AM
#10
Hi Tim, nice to hear from you!
The shaft and gear are a one piece and are made of aluminum. Don has a dremel, but I'm not sure he has a chuck that would fit it. I can ask him. Yes, I do have an MF1, but I believe the way the dog bones fit are different as the MF1 used the smaller CVs, so I'm not sure if the outdrives are the same circumference. Would have to check. Not sure, even though it is basically the same trans. But to be truthful, given the two trucks, I much prefer my MF1. I have it set up for oval but can change it if I have to. I only have one set of electronics so it is easier just to leave them in the CR. I also don't have the variation of clay tires for the MF1 that I do for the CR. But I'm not so sure the trans would fit with the rear configuration of the CR. However, I really don't want to tear down and parts out my MF1 for the CR. Thanks for the suggestion though. I am tearing the trans down as we speak to triple check it yet again for a few things - triple check brearing seating and Don wants to check the top gear with a straight edge. Not sure that would prove anything though. But your dremel idea is a good one. I may see if he can do that. I was going to wait til morning, but it is bugging me so I will probably do it tonight. I will probably bring it down to the track if I can't get it improved any tonight. This thing is driving me crazy! Thanks for your suggestion, Tim. Take care.
The shaft and gear are a one piece and are made of aluminum. Don has a dremel, but I'm not sure he has a chuck that would fit it. I can ask him. Yes, I do have an MF1, but I believe the way the dog bones fit are different as the MF1 used the smaller CVs, so I'm not sure if the outdrives are the same circumference. Would have to check. Not sure, even though it is basically the same trans. But to be truthful, given the two trucks, I much prefer my MF1. I have it set up for oval but can change it if I have to. I only have one set of electronics so it is easier just to leave them in the CR. I also don't have the variation of clay tires for the MF1 that I do for the CR. But I'm not so sure the trans would fit with the rear configuration of the CR. However, I really don't want to tear down and parts out my MF1 for the CR. Thanks for the suggestion though. I am tearing the trans down as we speak to triple check it yet again for a few things - triple check brearing seating and Don wants to check the top gear with a straight edge. Not sure that would prove anything though. But your dremel idea is a good one. I may see if he can do that. I was going to wait til morning, but it is bugging me so I will probably do it tonight. I will probably bring it down to the track if I can't get it improved any tonight. This thing is driving me crazy! Thanks for your suggestion, Tim. Take care.
05-29-2011, 12:24 AM
#11
Update for Tim
Hey Tim,
I guess I need to clear up that when the top shaft is in BY ITSELF, it binds and turns hard. We did put the top shaft into the dremel per your instructions. It doesn't look bent to the eye otherwise, but when we put it in the dremel and did it as slow as possible, it did wobble. This was putting the threaded part into the dremel chuck. If spinning faster, then you couldn't notice it, but slowly we could see it wobble. Now I wonder if it could be the threaded piece that goes into the shaft making it do that, but it looks straight? I don't necessarily want to remove it since it is lock tighted in, and I'm not sure we can get the regular shaft to fit into the dremel chuck. Don was going to try to insert the tip of the gear to see if it was the shaft or the threaded part, but it wouldn't fit. Would a slight wobble cause all this trouble? The part that sticks as it goes through the bearing clears the bearing, so I wouldn't think that would cause the bind, but maybe so. There are some scrapes on the motor plate where the paint has worn off, even though I don't see the clutch plate necessarily wobbing much. I wish we could try a steel shaft and gear just to see if that was it, but they don't fit - different tooth count, and a two piece mechanism - too big. But it seems like we are making progress. Thanks for the suggestion.
I guess I need to clear up that when the top shaft is in BY ITSELF, it binds and turns hard. We did put the top shaft into the dremel per your instructions. It doesn't look bent to the eye otherwise, but when we put it in the dremel and did it as slow as possible, it did wobble. This was putting the threaded part into the dremel chuck. If spinning faster, then you couldn't notice it, but slowly we could see it wobble. Now I wonder if it could be the threaded piece that goes into the shaft making it do that, but it looks straight? I don't necessarily want to remove it since it is lock tighted in, and I'm not sure we can get the regular shaft to fit into the dremel chuck. Don was going to try to insert the tip of the gear to see if it was the shaft or the threaded part, but it wouldn't fit. Would a slight wobble cause all this trouble? The part that sticks as it goes through the bearing clears the bearing, so I wouldn't think that would cause the bind, but maybe so. There are some scrapes on the motor plate where the paint has worn off, even though I don't see the clutch plate necessarily wobbing much. I wish we could try a steel shaft and gear just to see if that was it, but they don't fit - different tooth count, and a two piece mechanism - too big. But it seems like we are making progress. Thanks for the suggestion.
05-29-2011, 02:09 AM
#12
Well Diane,
It is possible that only the threaded section is bent, as it is the thinnest section and it is the furthest away from the bearing support.
I think to really pin-point the issue the top shaft needs to be put in a transmission case that is known to be good(a new one perhaps). With the top shaft bearings properly seated place the top shaft in and put the transmission halves together and see if the top shaft spins smoothly. If it does not then it is your top shaft. If top shaft is bent it will be more difficult to turn and with an idler gear installed it should be a cyclical increase in difficulty turning followed by a release in tension (simpilar to a piston going from BDC to TDC).
I wouldn't worry too much about the motor plate wear, but I would keep an eye on how tight each of the bolts are that thread into the motor plate. It is not uncommon for the motor plate to be slightly angled relative to the slipper plates, but in sever cases they can rub on the motor plate.
It is possible that only the threaded section is bent, as it is the thinnest section and it is the furthest away from the bearing support.
I think to really pin-point the issue the top shaft needs to be put in a transmission case that is known to be good(a new one perhaps). With the top shaft bearings properly seated place the top shaft in and put the transmission halves together and see if the top shaft spins smoothly. If it does not then it is your top shaft. If top shaft is bent it will be more difficult to turn and with an idler gear installed it should be a cyclical increase in difficulty turning followed by a release in tension (simpilar to a piston going from BDC to TDC).
I wouldn't worry too much about the motor plate wear, but I would keep an eye on how tight each of the bolts are that thread into the motor plate. It is not uncommon for the motor plate to be slightly angled relative to the slipper plates, but in sever cases they can rub on the motor plate.
05-29-2011, 07:17 AM
#13
Thanks, Ken. I may take you up on that - this is Ken isn't it? Don is supposed to pick up a car from Kevin, so I may come with him. I am just thoroughly disgusted with this thing - and i don't discount that I may have done something wrong, but I just don't know what. What time do you plan on being down there?
05-29-2011, 10:16 AM
#14
Thanks, Tim.
I was hoping it might just be the threaded portion; however, it is extremely hard to get the shaft part throughh the bearing, so I am thinking it may be the shaft. Losi parts house has it for 10.95, plus shipping. I didn't notice if it included the threaded portion, but I assume it does. Thanks again, Tim, for your great insight. You are probably the one that hit the nail on the head.
Ken, Don and I will be down probably around noon or so. Don is picking up a car from Kevin and he won't be there til noonish. We'are kind of slow moving this morning. Thanks again - all of you - for your help.
I was hoping it might just be the threaded portion; however, it is extremely hard to get the shaft part throughh the bearing, so I am thinking it may be the shaft. Losi parts house has it for 10.95, plus shipping. I didn't notice if it included the threaded portion, but I assume it does. Thanks again, Tim, for your great insight. You are probably the one that hit the nail on the head.
Ken, Don and I will be down probably around noon or so. Don is picking up a car from Kevin and he won't be there til noonish. We'are kind of slow moving this morning. Thanks again - all of you - for your help.
05-29-2011, 08:18 PM
#15
UPDATE - SUNDAY RESULTS :(
Hi all,
I went down to the track today and several people looked at my transmission. Ken Crouse, Derek Lovenstein, Justin Iverson and a few others. I thought we had it figured out. It was still stiff but Derek and Ken both said to go ahead and try to use it to see if it loosened up. I did run it out front of our house for approximately 3 minutes, probably a little less than that, with a 10.5 motor with 22 tooth pinion/78 tooth spur. It had good speed and was quiet after I readjustued the diff (the normal after rebuilding). The temp after around 3 minutes, maybe less, was about 115 just for that short time.
After I tightened the diff, it was quiet and seemed to work well. No loud noises or grinding. Decent speed. Seemed almost normal. But still very stiff when I released the pinion to see how much resistance there was without the motor. Totally different than my MF1. My MF1 freely spins and spins. Not the CR. But now after running the CR I notice a loud squeeking noise when I rotate the tires on the CR with the pinion released. It appears the squeeking is coming from the transmission. Not a diff bark, a squeeking sound. Never had that before. So I guess I will try to replace that shaft, plus both 3/8 bearings with new ones. If that doesn't do it, it will either become a parts car for whatever I can use on my MF1, or I will be selling the damn thing. This truck did take a hard hit last week at the track, so I wonder if that did affect it. But it continued running the rest of that day just fine. But I've about had it with it now if the new shaft and bearings don't work. Everything else has been replaced.
Thanks again everyone for all your help. I really appreciate it. Guess I need to find a different hobby. Have a good 3-day weekend everyone, and congratulations to Aspen for her win today - awesome!
I went down to the track today and several people looked at my transmission. Ken Crouse, Derek Lovenstein, Justin Iverson and a few others. I thought we had it figured out. It was still stiff but Derek and Ken both said to go ahead and try to use it to see if it loosened up. I did run it out front of our house for approximately 3 minutes, probably a little less than that, with a 10.5 motor with 22 tooth pinion/78 tooth spur. It had good speed and was quiet after I readjustued the diff (the normal after rebuilding). The temp after around 3 minutes, maybe less, was about 115 just for that short time.
After I tightened the diff, it was quiet and seemed to work well. No loud noises or grinding. Decent speed. Seemed almost normal. But still very stiff when I released the pinion to see how much resistance there was without the motor. Totally different than my MF1. My MF1 freely spins and spins. Not the CR. But now after running the CR I notice a loud squeeking noise when I rotate the tires on the CR with the pinion released. It appears the squeeking is coming from the transmission. Not a diff bark, a squeeking sound. Never had that before. So I guess I will try to replace that shaft, plus both 3/8 bearings with new ones. If that doesn't do it, it will either become a parts car for whatever I can use on my MF1, or I will be selling the damn thing. This truck did take a hard hit last week at the track, so I wonder if that did affect it. But it continued running the rest of that day just fine. But I've about had it with it now if the new shaft and bearings don't work. Everything else has been replaced.
Thanks again everyone for all your help. I really appreciate it. Guess I need to find a different hobby. Have a good 3-day weekend everyone, and congratulations to Aspen for her win today - awesome!