| Author | Message | ||
     Brokengq |
Exactly like the title says. When my sprag failed it tore up the sprag housing, but left the starter gear untouched. So, I thought "why replace what isn't broken?" And didn't get a new starter gear. Now my new sprag doesn't fit my old starter gear. I can get the old one on without a problem. Any tips? | ||
| Brokengq |
I'm beginning to think this thing is defective. I took it all back apart and can get the sprag on the starter gear, but once I do that I can't get the housing to go on :/ | ||
| Brokengq |
Ok I got it to go on. Required some grunting. More than I thought it would. Now, the starter gear doesn't spin on the back of the rotor. In either direction. Is all of this normal? | ||
| Stevel |
Wow, you have really made a meal of this repair. In order to help, I need more info. Just what was delivered when you bought the new sprague? Was it just the sprague itself or was it delivered with the outer housing with the 6 threaded holes? The sprague is a press fit in the outer housing, which means that the sprague OD is slightly larger than the housing ID it runs in and the fit is critical. The press should be done with a hydraulic press and must be pressed in squarely. If you used a hammer or it was pressed unevenly (raising a burr), the fit may be too tight, which would reduce the running clearance. The rollers you see in the sprague are actually oval not round in shape. In use they lay down in one direction and rock up in the other, jamming themselves between the two ground, polished surfaces. One of those surfaces is in the outer race. The other surface is on the hub of the gear. These surfaces are at least 65 on the Rockwell C scale (HRC) in hardness and very smooth (finish ground). In order for this sprague to function properly, the running clearance must be correct. Too large and the sprague slips. Too tight and the sprague jams. If this assembly fails in use, both running surfaces as well as the oval rollers must be changed, as all of them will be worn. Since the inner running surface is on the starter gear, it should have been changed as well, as a set. When fitting the gear and inner hub to the sprague, you must present the hub squarely to the sprague, holding the hub and gear in your right hand and the sprague and housing in your left hand. Then lightly press them together turning the gear counterclockwise at the same time. It is a bit fiddly, but be gentle and patient. Eventually, the rotating motion will cause the rollers to lay over allowing the hub to gently slip into the sprague. No greater force should be used or you will damage the parts. When fitted properly, the hub will slip with very little resistance in the counter clockwise direction and firmly lock up in the other. also when the gear is pressed firmly onto the Sprague housing, you will note that the running clearance between the inner gear face viewed through the holes runs very close to the housing face. That clearance is no more than .002". If this face touches, it can also cause the pieces to jam together. | ||
| Brokengq |
Stevel, I appreciate your detailed response, however insulting it was. I know, and agree with everything that you said except for one part. The sprag bearing itself does not (at least did not) need to be pressed into the outer race. Yes the outer race with the six holes is new. No the starter gear is not. My sprag never "failed" per se. Some of the outer surfaces of the sprag had flattened out, and ground into the outer race. The starter gear survived without a scratch. However on removing my old sprag from the old housing (it just popped out with my fingers) the spring that runs the circumference of the sprag was showing some heavy signs of distress. Where I disagree with you is on the new sprag being installed into the new outer race (housing). I set the sprag housing on to the sprag and reached through the housing with a set of snap ring pliers. Took just a slight amount of pressure off the snap ring, and the housing dropped over it with no effort. I didn't even have to push, it just fell on. When I released the snap ring back into its original position, it didn't fall out of the housing, and rotated in one direction with a bit of effort. My old one required no effort to spin in either direction (just the sprag in the housing, nothing else, no pressure from inside the bearing to lock it). Regardless, I could assemble my old sprag assembly, bolt it to the rotor, and drop the starter gear in using the counter-clockwise method, and it worked. Same steps with the new one (a bit of hand effort pushing the gear on while twisting), and it doesn't turn at all. My thoughts are towards a defective sprag housing. If someone else could chime in (no offense stevel, I really do appreciate your response) on the press/no-press issue on installing the sprag I would appreciate it. The manual does not have any information on removing or installing the bearing itself. | ||
| Brokengq |
Nice breakthrough here. I just measured the ID's of the old and the new sprags. I measured in between the rollers to try and get a measurement in as close to a non-wear area as possible. The difference came out to ~4 hundredths of an inch. I'm no rocket scientist, but that's more than I would consider to be just wear IF that area even wears. The points I measured do not make direct contact with any other parts in the bike, so, correct me if I'm wrong, but this sprag looks defective to me. Just as a side point: Old sprag + new housing = starter gear fits New sprag + old housing = gear doesn't fit I don't like using that comparison though, I feel like its apples to oranges. Just more info though in case it does make a difference. (Message edited by brokenGQ on May 26, 2014) | ||
| Froggy |
Did the components you get come off another 08? Perhaps it is one of the parts that changed over the years, I'll check my parts book to confirm. Edit - appears all years use same part numbers, so it is unlikely there was a change. (Message edited by Froggy on May 26, 2014) | ||
| Brokengq |
Part numbers were y0536.1am and y0537.1am for the sprag and sprag housing respectively. The OD for the new sprag is within .002 of the old one. The ID's are .04 off of each other, with the new one being smaller. Honestly I mean no offense to anyone, but I think Q and C were out back smoking a jay on this one. | ||
| Stevel |
Brokengg, Please accept my apologies. Insulting you was not my intent. It was simply an observation. This repair should never be more than 1 hour end to end. However, I am not there. I have a spare engine in the shop and I will remove the sprague for comparison and get back to you. Hopefully, we can identify the problem then. | ||
| Stevel |
OK, done it. Sprague in my hand in 30 minutes. I apologize again, I incorrectly assumed the outer race was a separate piece to the housing, where in fact the outer race is the housing itself. I think the best way to measure the sprague is to measure the OD and ID of the inner retainer (opposite side to the flange), not the rollers. It should be enough to determine if you have the correct part. The OD is 68.3 mm or 2.689". The ID is 51.95 mm or 2.045". This part is a stamping so there will be some variance, but not more than .010". I measured this with a digital caliper. Further, the flange side has 2 stampings 180 degrees apart, NW and a directional arrow. | ||
| Brokengq |
Stevel, thank you very much sir. Those measurements are very helpful. Unfortunately for my theory, they match my new sprag. I got 2.053 ID and 2.691 OD. I cannot figure out for the life of me why I cannot fit the starter gear then. Do you possibly have measurements of the race in the housing? | ||
| Stevel |
I have 2.6915 for the race ID in the housing and the hub OD is 2.0345 with the Mitutoyo caliper. I can be precise to the 4th digit, but I would have to dig out the micrometers. My parts are new with no wear. They slip together easily and function as designed. | ||
| Brokengq |
Thank you very much Stevel. I'm going to measure everything after work tonight. There has to be some reason my new parts are not functioning. My steps are: Install sprag into housing by relieving tension from the circlip. Bolt housing (sprag flange side toward rotor) to the rotor. Install starter gear hub by setting it flush with the sprag and using small counterclockwise movements. For some reason the last step does not work with my new parts, but does with my old. | ||
| Stevel |
I think you should change the sequence. Slip sprague into the housing. Then slip hub of gear into the Sprague. Make certain all is well, then install housing with bolts to the rotor. In that way you will immediately tell if there is a problem in function with the Sprague. If that works out and the bolting of the rotor to the housing does not, you have another issue. | ||
| Brokengq |
I actually already tried that. It didn't help. Then I made sure the sprag will fit over the hub by removing it from the housing and just slipping it on to the hub. It goes on fine. But for some reason, it will not go on while it is in the housing. | ||
| Brokengq |
OH MY GOD STEVEL I FOUND THE PROBLEM and I have never been more ecstatic to say I found a problem in my life. After screwing with this thing for another hour I finally tried laying the rollers down by hand while installing it. Then I noticed one of the rollers wouldn't lay down. I removed the new clutch and compared it to the old one. 6 of the rollers are installed on the sprag BACKWARDS! if you look along the the outside circumference of the bearing you will notice a line going perpendicular to the direction of travel on each roller.On the old sprag they all face the same direction. 6 of the rollers on the new bearing (in completely random spots of the bearing...3 of them are right next to each other) have the line on the wrong side. I tried moving these rollers and they obviously lock in the wrong direction! Hahaha! You should see the smile on my face. I'm so glad I finally figured this out! | ||
| Shawns |
Success at last?  | ||
| Stevel |
I'm proud of you! Good job! Logical deduction in the end. Hopefully, this will generate enough confidence not to be afraid to take something apart next time. Just remember, if someone put it together once, so can you. I guess I can reassemble my motor, until next time. There is still the original fault that caused the old Sprague to give up. When assembling everything, make certain the gear does not touch the housing. The clearance is very close. Also if your engine is a late model, you will have an oiling hole in the spline of the crank that drives the rotor. I really need to know the size and the location on the spline of that hole. I have asked on this forum multiple times as well as EBR without any response. I believe that hole is super important, not just to cool the late model stators, but to give that extra bit of oil to the Sprague, which may be the cause of your failure as well. Remember that after the engine starts, that gear stops and the crank is left spinning within the now stationary Sprague. It needs a continuous source of oil to maintain that oil film. The only source of oil without that hole is waste oil from the crank main bearing and it is on the wrong side of the Sprague for penetration. The early cranks do not have that hole and it is not reflected on the original crank drawing from Rotax either. If your crank is the new style, please measure that hole for me. | ||
| Brokengq |
Stevel, I will check for you, but my bike is a July 08 model, which I would consider to be "early" model. In the car world we consider August to be the late model for the year. | ||
| Brokengq |
Stevel, update for you. I haven't gotten back to you on that size because I decided it would be in my best interest to send that sprag back as "defective". I know I could have removed and replaced the rollers in the correct direction, but if for some reason I stretched the spring or damaged it in the process, I would have been out $200. New Castle received my defect and the new one to send to me today, and they are ensuring me that this new part is correct. I should have it by Monday. I will let you know my findings next week. | ||
| Oldog |
hey Chris your alternator rotor is off? if so is there a hole in the splined area of the shaft where the rotor fits? yours is an '08? | ||
| Brokengq |
Stevel & Oldog, the new sprag came in today and fit like it was meant to. I did as you requested and measured the hole. It is located in the middle of the double spline that aligns the rotor for installation. I looked at it with a magnifying glass and measured it with the only tool I had that could attempt to measure it. The hole appears to be tapered and gets smaller as it goes down. The top of the hole measured at 3.15mm and the smallest measurement I gathered was ~2mm. The hole is smaller at the bottom, but I could not reach it with my tool. Eyeball measures it right around 1mm at its smallest. Hope this helps, Chris | ||
| Stevel |
Chris, The correct way to measure this hole is to use pin gauges, but I would be surprised if you had access to a set. In lieu of the pins, you can be very close using a simple set of numbered drills (1-60) as a go/no go test. The #60 drill is .040", which is 6 tenths larger than 1mm. I suspect the hole is slightly larger than 1mm, but not much. This diameter is very important, because it will throttle oil flow so not to starve the crank bearings of oil pressure. |
