O.s. .12

[7sracing]

I am looking into buying a O.S. .12 With a slide carb for my rc10gt has anyone used one? how did you like it ? Is it worth $125.00. Any input will help
Thanks

[RobertF]

I got a CV-R.12 and a TR.12.........both have rotary carbs though. I'm not big on slide carbs for off road but it might work fine for oval. My hobby shop sells a CV-R for $90 bucks.

[races65]

The TR would be fine for your GT. Very dependable engine, decent power and is easy to tune.

[Mark Leber]

Which model .12 is it? If it is the .12TR and it is brand new than it is worth $125. I have had several OS motors. They all ran great and were very easy to tune. The TR is the best of the bunch and the only one that has rear exhaust. The TR sold for about $125 new but has since been discontinued and replaced by the new TZ. The CV's and CVR's were good motors too but probably not quite worth the $125. Hope this helps, Mark Leber

[7sracing]

Yes it is the TR. I think I am going to pick it up today.

Thanks

[Dirtdog]

Here is something to think about. I think the TR only comes in a slide carb/SG crankshaft version. We run SG crank engines in our OFF sprint cars, and they work great. The problem is the length of the SG crank. We use the RC10GT SG shaft engine mount that Dennis Klein makes to solve this problem. The motor mount moves the engine away from the spur gear so the SG clutch set-up aligns with the spur gear. I am a big fan of the O.S. TR. If you shop around you can still find them for sale.

[races65]

The OS TR .12 also comes with a Standard crank.

[Dirtdog]

If that is the case, then I highly recommend the O.S. TR.

[7sracing]

I bought it today the only set backs I am having is I had to order new bearings for the clutch bell the ones on the RC10 are to small and I have to make new linkage for the slide carb. Has any one ran into these set backs

[antilley]

New bearings :confused: ?.... did you get a threaded or SG shaft? If the later you will need a different engine mount as well. I can't think of a reason you need a different bearing for the threaded shaft unless you went to a Traxxas clutch?

[7sracing]

Yes it is a threaded shaft. The bearings on the old on was to small to slide over the crank. I went to the shop I bought the engine from and they said I needed bearings

[7sracing]

I was just compairing the two engines and I found that the O.S. engine the crank is threaded all the way out and the asso is smooth up to the fly wheel nut and that is why the bearings dont fit. Should I grind the threads until smooth or just replace the bearings and keep the threaded surface

[Slacker]

I ran into a similar problem with my MT .12 that I was tring to put a GT bell on. You will find whatever you need at www.bocabearings.com (http://www.bocabearings.com) You just need to know your ID and OD weather its flanged or not and they will have what you need. There real helpful too if have any questions.

[antilley]

I must be missing something --- but, you might have an issue with your clutch nut --- as if I remember correctly AE makes 2 kinds of clutch nuts for threaded shaft motors (one is bottom tapped .. one is not) But, for the life of me I can't figure out why you would need to change your bearings for a different size if you are still using a standard GT and GT clutch nut?

Making the assumption that the first engine was a threaded shaft engine....

unless you had a SG shaft to begin with? if so did you pick up a clutch nut for the threaded shaft motor?

[7sracing]

Just for the heck of it I miked the two shafts and the O.S is a little bigger. But if I was to take the threads down smooth and make it look like the Asso they would be the same. The Asso crank only has a few threads after the nut after that the shaft is smooth with only a notch for a keeper clip at the end of the shaft

[Mark Leber]

7sracing,
DONT gring on your new crank just yet!! Sounds to me like your original motor was the Associated .15 that they install in the RTR's. That engine has a crank design that is unique only to those motors. It is similar to an SG but is not the same. Sounds like your new motor has a standard threaded crank. All your stock clutch parts will work except for the clutch nut.

You will need one of these clutch nuts:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LX3371&P=7

You will have to cut your crank down to the short threaded length which is easy to do with one of these:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LX3382&P=7

Simply install your existing collet and flywheel and then the special cutoff nut and cut off any remaining threads flush with the nut. Then remove the cutoff nut and install your new clutch nut. Now your stock bearings, clutch bell and clip will fit perfectly.

This is all assuming that your original crank looked like this:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXUP77&P=7

And your new crank is similar to this:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXWX99&P=7

Your crank should look like this when you are finished cutting it:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXWY00&P=7

Hope this helps!!
Mark Leber

[7sracing]

Mark

You hit the nail on the head. Yes it was a RTR. I did not know they where differant. Thanks alot I will go pick up the parts today
Thanks Again

[Mark Leber]

Cool! Glad I could help. Have fun!!