XRAY - Model racing cars
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high speed "pull"
http://forum.teamxray.com/viewtopic.php?f=8&t=6573
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Author:  Edwin Pibal [ Mon Nov 12, 2007 05:15:25 ]
Post subject:  high speed "pull"

Hi Everyone

ive retired my tfk04 and am now useing a t2

I am having a probelm where if at speed, the car will pull to the left.

it does not do this at low speed.

I have the milti diff set in the spool setting

this is the first time on the track, as its new out of the box

can any one sugest any thing?

thank you

Edwin

Author:  Martin Hudy [ Mon Nov 12, 2007 13:24:59 ]
Post subject: 

please check if the tweak of the car is good because this may cause that car does not go straight. The problem can be also in the bearings, please check if all the bearings are working properly.

Author:  Edwin Pibal [ Tue Nov 13, 2007 11:17:32 ]
Post subject: 

Martin Hudý wrote:
please check if the tweak of the car is good because this may cause that car does not go straight. The problem can be also in the bearings, please check if all the bearings are working properly.


Thank you for the information Martin.

i had both of these probelm, one bearing on the left side was noisie and slower compared to the rest, AND i had lots of chassie tweak.

thank you again

Edwin

Author:  Edwin Pibal [ Tue Nov 27, 2007 23:39:29 ]
Post subject: 

Hi again.

after a string of bad weather i was able to take the car to the track and test.

i found i still had the same problem, but noticed that one wheel had alot of sideways movement casuing the car to turn the way it does.

i took out the multidiff and put in a normal diff, and the car drives fine now

what could be wrong with the multidiff ??

thanks.

Edwin

Author:  Tonyv [ Wed Nov 28, 2007 16:33:30 ]
Post subject: 

It could be that one of the outdrives is slipping on its one-way bearing. Is your problem only under acceleration? If so, clean the one-ways using brake or motor cleaner and after letting them dry for a few minutes apply a drop of one-way bearing oil to each before reassembling. You should be fine after that.

Author:  Edwin Pibal [ Wed Nov 28, 2007 21:22:40 ]
Post subject: 

Tonyv wrote:
It could be that one of the outdrives is slipping on its one-way bearing. Is your problem only under acceleration? If so, clean the one-ways using brake or motor cleaner and after letting them dry for a few minutes apply a drop of one-way bearing oil to each before reassembling. You should be fine after that.


Hello Tony, thanks for your reply.

if i drive the car at low power it seems fine, but under full power it pulls to the left.

thank you for your solution, i will try it .

Edwin

Author:  Edwin Pibal [ Fri Jan 04, 2008 08:39:07 ]
Post subject: 

Hello everyone

I am having a most fustrating time with my t2, i have still NOT managed to fix the car pulling to the left.

i have done the following

replaced all the bearings in the car
replaced the multi diff with a normal diff
rebuilt all the shocks and set them with a micrometer
removed and checked the sway bars
checked, checked and re checked the chassis for tweak
checked the toe (-1 degree), caster (4 degree hubs), camber (-2 degrees)
replaced the servo horn.

I am lost as to what the cars problem could be.

is there something i am missing or not checking

please help me.

thank you
Edwin

Author:  Hurrle [ Fri Jan 04, 2008 12:19:02 ]
Post subject: 

Have you checked the weight balance?

Author:  Edwin Pibal [ Fri Jan 04, 2008 13:17:24 ]
Post subject: 

Hurrle wrote:
Have you checked the weight balance?


hello

no, i hadent checked that, and have just done so now.

the car is almost perfectly balanced and at the legal weight

thank you for sugeting it, its something i had not thought of.

Edwin

Author:  Tonyv [ Fri Jan 04, 2008 13:22:12 ]
Post subject: 

Hmmm, very very strange. You might want to check that you have the wheelbase set the same left and right although I suspect you already did that. Same goes for the drive shafts. If one of them is binding (possibly left front in your case) the car could pull to that direction. And as Hurrle indicates there is the left-right weight balance. However the difference would have to be pretty significant to give you this effect.

One thing that could also be the problem is the electronics. This would still be primarily under acceleration. What would be happening in that case is a drop in voltage going to the receiver which can result in the servo temporarily turning the car left. You should be able to see that when you give full throttle with the wheels of the ground as well.

Is the car pulling to the left on the main straight only, or is it on all straight lines? Are we talking indoor on carpet?

Author:  Edwin Pibal [ Sat Jan 05, 2008 06:08:04 ]
Post subject: 

Tonyv wrote:
Hmmm, very very strange. You might want to check that you have the wheelbase set the same left and right although I suspect you already did that. Same goes for the drive shafts. If one of them is binding (possibly left front in your case) the car could pull to that direction. And as Hurrle indicates there is the left-right weight balance. However the difference would have to be pretty significant to give you this effect.

One thing that could also be the problem is the electronics. This would still be primarily under acceleration. What would be happening in that case is a drop in voltage going to the receiver which can result in the servo temporarily turning the car left. You should be able to see that when you give full throttle with the wheels of the ground as well.

Is the car pulling to the left on the main straight only, or is it on all straight lines? Are we talking indoor on carpet?


Hello Tony, thanks for the reply.

on your advise i have rebuild both the drive shafts and both apeared to be fine, but i rebuilt them anyway.

electronics was something else i haddnt thought of, as i brought everything across from my tfk04.

the car pulls to the left all the time, and the surface is outdoor tarmac.

thanks for your time

Edwin

Author:  teamgp [ Sat Jan 05, 2008 06:16:30 ]
Post subject: 

Try another servo. Over the years, I've had several stop centering correctly. :wink:

Author:  YELLOWSHARK [ Sat Jan 05, 2008 14:43:22 ]
Post subject: 

Hi Edwin, this is a phenonoma we have experienced in the past, it might not be quite the same but we were finding the steering alignment was changing as the speed of the car changed.

I would suggest; swap the servo; check your steering angle, if the inside wheel is 20 degrees, get it down to 16-17 degrees - no idea why but this worked for us. Swap the wheels around, one could be warped; no idea if this would give you your symtons but worth a try.

Author:  adamg [ Sat Jan 05, 2008 18:14:28 ]
Post subject: 

I would also try loosening all the topdeck and bottomdeck screws. It is possible to get a left bulkhead bolted to the bottom chassis at a different angle than that right bulkhead.

Author:  Tonyv [ Sat Jan 05, 2008 22:05:24 ]
Post subject: 

I think your "symptoms" are consistent with a servo problem. How old s the servo?

Warping of the (especially front) wheels can also be a cause. However since you"ve had this for a while now I assume you have already tried different sets?

Author:  Edwin Pibal [ Sun Jan 06, 2008 00:17:12 ]
Post subject: 

YELLOWSHARK wrote:
Hi Edwin, this is a phenonoma we have experienced in the past, it might not be quite the same but we were finding the steering alignment was changing as the speed of the car changed.

I would suggest; swap the servo; check your steering angle, if the inside wheel is 20 degrees, get it down to 16-17 degrees - no idea why but this worked for us. Swap the wheels around, one could be warped; no idea if this would give you your symtons but worth a try.


yes, this is exactly what is happening.

I will buy a new servo this week and do what you have sugested

thanks for your time.

Edwin

Author:  Edwin Pibal [ Sun Jan 06, 2008 00:20:01 ]
Post subject: 

teamgp wrote:
Try another servo. Over the years, I've had several stop centering correctly. :wink:


this would appear the next best logic step, i will by a new one this week and try.

thank you for your time.

Edwin

Author:  Edwin Pibal [ Sun Jan 06, 2008 00:20:54 ]
Post subject: 

adamg wrote:
I would also try loosening all the topdeck and bottomdeck screws. It is possible to get a left bulkhead bolted to the bottom chassis at a different angle than that right bulkhead.


hello.

I will try this too.

thanks for your time.

Edwin

Author:  Edwin Pibal [ Sun Jan 06, 2008 00:24:18 ]
Post subject: 

Tonyv wrote:
I think your "symptoms" are consistent with a servo problem. How old s the servo?

Warping of the (especially front) wheels can also be a cause. However since you"ve had this for a while now I assume you have already tried different sets?


the servo is about a year old, and has done 10 rounds and one national meeting.

when you say warping, do you mean bending or bent wheels ?

i am useing the set of starburt wheels that came with the car in combination with team sorex 28rs and medium inserts.

thank you for your time, im most greatful

Edwin

Author:  Tonyv [ Mon Jan 07, 2008 14:29:33 ]
Post subject: 

Right, bent wheels. When the wheels are bent you are effectively running continuously changing camber and toe-in as the wheels turn. That will cause the car to deviate from the straight line you actually want to run. That problem also increases the faster you go.

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