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Team CRC Xti 1/12th Scale!!

Old 11-06-2017, 09:34 AM
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Originally Posted by gmintimidator View Post
I want you measure from the underside of the front arms at the outside edge. This ensures they're bolted to the car correctly. Everything is built off of them being installed flat and parallel. I did this during the last rebuild and the distance from the glass to the arms, balls, and king pins were all equal side to side. I read somewhere that someone had a slightly cracked arm that did not show until under pressure so I switched out the lower arms to check. I found nothing wrong with the older ones so I kept them for spares.

I was under the impression you had different ride height at the front of the car. Sometimes I do when testing but for our track I usually try to match the back to the front at about 4mm or so depending on the tire diameter. But my earlier observation was for left to right. I've tried lower rear and higher rear to see what the effects on handling are and it seems like a slightly lower rear is better for me. This adjustment has had no effect on the left/right pull.

That pod should be flat when assembled. It is pretty flat on the glass. Was the chassis sealed? Is there any glue on the plate causing the issue? Either the bottom or where the uprights mount causing the tweak? No I dont seal any of my carbon fiber. Seems unnecessary and I've not had any problems with any of my other CF parts on many other 1/10 chassis before. What happens if you crack all the screws off enough so they're not tight, but not hanging below the counter sink? Is it flat? I'm wondering if the way you're tightening it is tweaking the assembly possibly? For the rear pod I hold it on the glass while tightening so its flat when done. For the main chassis I can over hang it to get to the bottom screw and nut at the top but can really only alternate left to right tightening in an effort to keep it untweaked. The main chassis still seems pretty flat to me when set on glass.

Short of that, Im not sure if you tried another servo to rule that out? No I havent as I hate to spend $100ish just to see if thats the problem. I'm assuming there's no slop in the steering/servo saver assembly and the servo consistently centers when releasing the wheel? Its not perfectly tight but its not sloppy either, there is a small amount of play. I do have a new servo saver on it from the original because the holes I drilled in the original where slightly off height wise but it didnt help with the left/right pull problem. It sounds as if the car has been thoroughly checked so maybe the servo is glitching under load? I believe that I have checked everything and admit that I may still be missing something terribly obvious but I have made a good effort to follow all the suggestions from all that have offered them. There are some things that I just was not willing to do at the time such as buy a new rear pod or servo. So it really could still be one of those things and until I'm willing to swap them out to test I wont know for sure. This was the main reason I got the new CK25 chassis. I feel like assembling it and only moving over the electronics should eliminate or highlight them as the culprit. If the new car does exactly the same thing I will have to start swapping out the electronics. I do have other ESC's, and receivers to try so thats easy. And if I get the new car working good I will be rebuilding this one for asphalt in the spring maybe As desert is saying, it's weird you haven't corrected it after going through the car so many times.
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Old 11-06-2017, 09:39 AM
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Originally Posted by davidl View Post
Do NOT use the servo from the old car when you construct the CK25. Also, find a way to check your transmitter for issues that would prevent re-centering the servo after a corner.
I dont think the servo is the problem but if putting it into the new car gives the same results I will know for sure. I do have some other receivers I can swap out from other cars. I have already changed out the ESC's and both brands did the same thing. I use the same radio for all my cars and none of the others have ever had a problem like this so I'm reasonably sure its not the radio. I will however create a new model memory for it and see if its something in the setting for that model causing the problems. I doubt it but its a free and easy thing to do.

What servo do yall suggest I get for the CK25 when I do get a new one?
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Old 11-06-2017, 09:55 AM
  #2343  
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What servo do yall suggest I get for the CK25 when I do get a new one?[/QUOTE]
There are some that are smaller and lighter, newer and maybe even a little faster too.....but the Futaba 9650 is a great option. They are reasonably priced, readily available, ultra reliable, and have been the servo of choice for lots of guys for years. Falls under the category of not fixing what ain't broke.
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Old 11-06-2017, 10:03 AM
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That is, of course, unless you want the option of running your servo in the reversed position....ahead of the tierods and between the front arms. If you want that option, then you'll need one of the extra small (and usually more costly) servos. CRCs instructions give you the model number(s) for the tiny servos that do fit the front mounted holes in the chassis plate. Personally, I prefer and recommend the "normal" mounting position behind the tierods since I've never seem to liked the feel of adding any unnecessary weight to the nose of my car(s).
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Old 11-06-2017, 10:18 AM
  #2345  
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Originally Posted by RussF View Post
Still having trouble getting my car to go straight both on and off power. Recap of problem is that on power it pulls left and off power it pulls right.

I've tried everything I can think of such as a diff rebuild, new bearings and front end parts everywhere. The one thing I didn't do before trying it last time out was center the servo, which has since been done but not tested. One thing that made me crazy was that looking at the car it appeared the right side had much less caster than the left. With two shims back and one front the right was practically vertical. The left was slanted back noticeably further. The car was still very difficult to drive that way and we put all three shims in the back and added about 2mm more rear pod droop. This helped alot to make the car more derivable. but did not eliminate the pulling left/right problem. Funny thing... everybody broke during the mains so it was just me running all by myself with all eyes on my line. The general comment was that I could not hold a straight line, which is accurate, the car is a handful.

So I went back to disassembling the front end to correct or find the source of the unequal caster and install the servo centered. Each and every part to me seems perfectly matched the same left to right. but when assembled the right definately has less caster than the left.

This is the view from above. See how the right knuckle appears more vertical than the left?


This is the side view of the right. It has about 3.5 - 4 degrees of castor based on my rough comparission to the camber gauge in the pic. I show about 5 degrees but its pretty clear that its not actually that much.



This is the left side compared to the same 5 degree gauge. Its pretty clear that it is at least 5 degrees maybe 6 or 7. At any rate its more than the right side.


This is my knucles in as straigt of a line as I can get.


This is my caster blocks (the least angled ones) and they look same.


This is the caster blocks with pins sitting on camber gain shims and they look the same.


This is my upper arms. They seem the same size.


So the big question.... What the (expletive) have I done wrong here??!! Is it me or is there something wrong with the way my kit or parts manufactured?
Check your rear axle to make sure it isn't too tight and that the bearings are good. When you put on the right side hub it shouldn't be tight against the bearing...in fact the axle should have a very slight amount of play. If the axle is too tight or the bearings are not smooth then the axle to the left side of the differential will have drag on it. This will cause the motor to drive the right rear wheel harder causing your on-power to the left issue. When you trim the steering to compensate now you have off-power to the right. Also if using the slider style rear pod I found it works best if you use 2 ride height gauges to set the height. That will help to ensure the bearings stay aligned properly.
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Old 11-06-2017, 10:46 AM
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There are some that are smaller and lighter, newer and maybe even a little faster too.....but the Futaba 9650 is a great option. They are reasonably priced, readily available, ultra reliable, and have been the servo of choice for lots of guys for years. Falls under the category of not fixing what ain't broke.[/QUOTE]

I agree. The 9650 is a great servo, been using them in my 1/12th scale cars for years, they are hard to beat.
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Old 11-06-2017, 03:58 PM
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What servo saver do you guys like with that 9650?
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Old 11-06-2017, 04:03 PM
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Originally Posted by InspGadgt View Post
Check your rear axle to make sure it isn't too tight and that the bearings are good. When you put on the right side hub it shouldn't be tight against the bearing...in fact the axle should have a very slight amount of play. If the axle is too tight or the bearings are not smooth then the axle to the left side of the differential will have drag on it. This will cause the motor to drive the right rear wheel harder causing your on-power to the left issue. When you trim the steering to compensate now you have off-power to the right. Also if using the slider style rear pod I found it works best if you use 2 ride height gauges to set the height. That will help to ensure the bearings stay aligned properly.
Yes mine is good. It has a tiny bit of play side to side and I also use 2 ride height gauges when setting the rear ride height. It makes it much easier to get set equal left to right. There doesnt seem to be a bind in the bearings when free spinning the axle without a pinion on. I have always felt like the motor drives one wheel harder than the other on all solid axle diffs. Judged by the non scientific holding one wheel at a time and see how the other spins under power.
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Old 11-06-2017, 04:21 PM
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Originally Posted by RussF View Post
What servo saver do you guys like with that 9650?
For a Futaba servo, I often use the small kimbrough #KIM114 . Use caution though, because the small Kimbroughs need to be purchased with the correct number of splines to match up with whatever brand of servo you go with). Or, even better, you can also use a kimbrough medium, which comes with little interchangeable insert adapters so that it will fit most any servo. AMain sells #KIM200 which comes with no holes for the tierod ends.....so that you can drill your own tierod end holes wherever you want them. I drill mine to keep the inner tierod ends as close together and as low as possible. They also sell a #KIM201, which comes with tierod end holes already drilled, so itís easier to fit. But IMO the predrilled holes in that version are a bit too high and too far apart. So I find that itís worth the extra afford toget the plain version and drill my own tierod end holes.
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Old 11-06-2017, 06:34 PM
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RussF

while you are not new to pan cars, on 12th link cars, slight things are hand grenades compared to 1/10. i assume all springs are per kit. your servo puts 29 grams way forward in your current position. some things to consider or do...your option

- set front to slight toe out, but damm close to zero
- servo weighs 7 grams more than the SRG-HR servo the guide shows in the position you put a heavier servo. i would move the servo per instructions to where your xponder is. servo in the position you have it in, generates alot of steering. some prefer this others can't deal with it...not a insult
- transmitter DR or Balance should be in 55-70% so car does a 4-5ft arc left and right
- expos /curve go with 50%- to slow responses
- front tires....new....no sauce
- sauce on fronts in not mandatory, it's a tuning aid for your driving
- set diff on looser, but no slip, same as your 1/10th pans
- set front to neg 1 to 1.5 camber, zero or pos camber will make car overly responsive / twitchy any surface

all this should set up you car up with a push, but driveable, then work on adding steering back, sauce etc

also check

- tweek pod side spings, too tight and sprung will cause wandering throt on and off
- remove center shock to ensure pod and links float freely per guide
- some servos can have issues if the screw used to mount servo arm/saver is too long, it will cause servo issues that seems like random glitching or odd responses to your inputs
- if center spring is set too soft, on punch you can get chassis smack/rub,this can cause issues in power on and off. compare to other drivers cars you have tested

Last edited by fast-ho-cars; 11-06-2017 at 08:17 PM.
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Old 11-07-2017, 09:19 AM
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Originally Posted by fast-ho-cars View Post
RussF

while you are not new to pan cars, on 12th link cars, slight things are hand grenades compared to 1/10. i assume all springs are per kit. your servo puts 29 grams way forward in your current position. some things to consider or do...your option

- set front to slight toe out, but damm close to zero Currently zero maybe .25 out
- servo weighs 7 grams more than the SRG-HR servo the guide shows in the position you put a heavier servo. i would move the servo per instructions to where your xponder is. servo in the position you have it in, generates alot of steering. some prefer this others can't deal with it...not a insult. Agreed!! I have always had way too much steering and have fought to eliminate it by "dumbing down" the front end. I assumed the forward location for the servo was the stock and only location as per the instructions. The hobby shop that sold me the whole first package said the Savox would fit and although I was able to get it to work I had to cut off a tab and tape it down. It was never centered so one of the latest things I did was center it and glue it down. Unfortunately it didnt help my situation. I should have moved it to the back location and centered it there. I like the new servo mount the CK25 has because it looks like it will be alot easier to do.
- transmitter DR or Balance should be in 55-70% so car does a 4-5ft arc left and right Check
- expos /curve go with 50%- to slow responses Check
- front tires....new....no sauceAgreed, Check
- sauce on fronts in not mandatory, it's a tuning aid for your driving
- set diff on looser, but no slip, same as your 1/10th pansCheck, tried all variations. I like it towards the loose side
- set front to neg 1 to 1.5 camber, zero or pos camber will make car overly responsive / twitchy any surface Well this is news, I thought more camber was more steering. I have mine set about 0 now. Will try 1 to 1.5.

all this should set up you car up with a push, but driveable, then work on adding steering back, sauce etc I like a more pushy car for my driving style, too twitchy and I tend to over drive it.

also check

- tweek pod side spings, too tight and sprung will cause wandering throt on and off They seem good, just barely touching to start then adjusted if needed to eliminate any tweak.
- remove center shock to ensure pod and links float freely per guide Pod seems great to me and others that have checked it.
- some servos can have issues if the screw used to mount servo arm/saver is too long, it will cause servo issues that seems like random glitching or odd responses to your inputs Hmmm... will have to check. Seems to me the Savox will bottom out so it should be ok with what I have there now.
- if center spring is set too soft, on punch you can get chassis smack/rub,this can cause issues in power on and off. compare to other drivers cars you have tested. I will, Currently have a very soft spring to eliminate steering and increase rear traction. Also have a lot of droop. Those changes did help the car handle but nothing gets rid of the on power pull.
Thanks, Responses in Red.
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Old 11-07-2017, 09:30 AM
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The problem is in the rear of the car, nothing about the servo or caster blocks being slightly out of perfect can cause this. Have someone you trust check it over for you.
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Old 11-07-2017, 09:41 AM
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Originally Posted by vafactor View Post
What servo do yall suggest I get for the CK25 when I do get a new one?
There are some that are smaller and lighter, newer and maybe even a little faster too.....but the Futaba 9650 is a great option. They are reasonably priced, readily available, ultra reliable, and have been the servo of choice for lots of guys for years. Falls under the category of not fixing what ain't broke.[/QUOTE]

Perry we've been running this servo...I havent had any issues with it, I do know it's more sensitive than the futaba, for me at least

https://www.amainhobbies.com/sanwa-a...53252b/p587622
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Old 11-07-2017, 09:45 AM
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Anyone know if and where the case for the mini sanwa can be purchased? My cousin tore both ears off the bottom of my spare in a crash.
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Old 11-07-2017, 09:51 AM
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Originally Posted by vafactor View Post
For a Futaba servo, I often use the small kimbrough #KIM114 . Use caution though, because the small Kimbroughs need to be purchased with the correct number of splines to match up with whatever brand of servo you go with). Or, even better, you can also use a kimbrough medium, which comes with little interchangeable insert adapters so that it will fit most any servo. AMain sells #KIM200 which comes with no holes for the tierod ends.....so that you can drill your own tierod end holes wherever you want them. I drill mine to keep the inner tierod ends as close together and as low as possible. They also sell a #KIM201, which comes with tierod end holes already drilled, so itís easier to fit. But IMO the predrilled holes in that version are a bit too high and too far apart. So I find that itís worth the extra afford toget the plain version and drill my own tierod end holes.
so I'm looking into getting a new servo before trying the old one in the new car. I am comparing the Savox SH-1350, SH-1257MG, and Futaba S9650. The 1257 has the best specs. The Futaba is the most expensive. Based on the recommendations here I'm leaning towards the S9650. For the servo saver I could do what you suggest and drill the holes but that didnt go so well last time I tried it and I ended up getting a new one and one of these CRC4088 Braces.. I'd rather stay with pre-drilled and use this brace again. With that said I guess I should get the KIM114? I think thats what I already have though on the old Savox.
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