12LikesYokomo MR-4TC SD
05-11-2003, 11:34 PM
#1231
The Teacher: I have not worked on the car since Sat. I will try to solve the problem today. I just rebuild the rear unit and see what happens...
Greets
IH
Greets
IH
05-12-2003, 03:00 AM
#1232
I'm running my Fantom version of the monster at 21/75 (8.1-ish overall) on a 10s indoor track.
Chassis stiffness - my impression is that front to rear the car is solid as a rock, however there is a small amount of give when you twist it. Seems to have more flex than a solid-top deck early X-ray, probably more flex than a Losi as well. Because of the car's design and precision, the flex is very progressive, you don't get the sensation that different parts of the car are flexing at different rates. The SSG plate is pretty soft for 3mm carbon.
Chassis stiffness - my impression is that front to rear the car is solid as a rock, however there is a small amount of give when you twist it. Seems to have more flex than a solid-top deck early X-ray, probably more flex than a Losi as well. Because of the car's design and precision, the flex is very progressive, you don't get the sensation that different parts of the car are flexing at different rates. The SSG plate is pretty soft for 3mm carbon.
05-12-2003, 03:09 AM
#1233
Tech Adept
hey guys, does anyone know where i can download a softcopy of MARs Ko Propo Ex-1 manual? thanks in advance
05-12-2003, 04:31 AM
#1234
IH, figured out my drive train problem. It seems that my spur gear adapter, when locked down on the input shaft, was pushing up against my motor mount bearing thus causing the drive train to bind. I played with the pin that slides through the spur gear adapter and found that in the right position it allows the adapter to slide further back on the shaft creating space between the bearing and the adapter as a result freeing up my drivetrain. Hope that helps.....
05-12-2003, 05:40 AM
#1235
Hi guys. greetings from Malta.
Last I logged in was Thursday to say I was expecting the couriers that afternoon. Well it arrived. I built it Thursday afternoon, continuing Friday morning, tested it Friday (4 packs) afternoon, then again Saturday (4 packs) afternoon after some mods, and decided to race it Sunday.
BUILDING.
I'm impressed. I've built plenty of Yokes over the years but this is such an improvement. Everything fell into place and the only reason it took me so long was because of the many mods I put into it in the initial build. Waiting for 2 months has given us all plenty of time to think about such things!
I put titanium screws everywhere straight away, triangulated the front top arms as I do on all my cars, turned the servo through 90 degrees, replaced the steel drive shafts with alloy, and used the alloy MR4 Special battery hold down which looks more trick and is a virtually straight fit.
One other thing, which I have always done to my MR4s: I used Associated TC3 shocks with unobtranium shafts, just using the new SD shock top caps with the diaphrams. The reason for these shocks is that a) they are longer and more suited to the car, and b) they hold more oil.
SET UP.
As my belt drive car handled so well, I tried to copy all the settings into the SD. Same springs - Fastrax orange all round, same 50 shock oil, no kick up front or rear, 2 degree rear toe in, shocks angled as much as possible, top arms as long as possible for negligible camber change. I also raised both front and rear lower arms by 2mm all round to change the roll centre, again as much in line with the belt drive car.
TESTING.
The result was good. I ran a pack with the belt drive car, lapping in the early 17s and very late 16s as usual, just to see that the track condition was normal. Then straight onto the SD for a direct comparison. My reaction, with a lousy pack of 3000 cells was that the car was remarkably free, but I wasn't as comfortable with the handling. It was more nervous on the straights, and you seemed to gave to straighten it up after each bend instead of it straightening itself up. Clearly all the signs of more caster needed. this is understandable for the BD car runs 7 degree blocks and 1 degree kick up.
I calculated the same gearing for 21 turn stock motor - which is our control motor in the stock class, but found it too high geared.
SATURDAY MORNING.
Rebuild the motor. Fit 7 degree MR4 BD front C hubs. 1 degree front to out. Replace 88T spur with 104 - 64DP. Spur gear change took quite a bit more than the suggested minute but will get quicker with regular changing, and doesn't matter all that much anyway. And off to test again.
SATURDAY AFTERNOON.
Quite a few guys at the track since we are racing Sunday. The Sd causes quite a sensation.
On track it immediately feels better and more driveable. I am able to go deeper into corners, and can power out quicker in the knowledge that the car is going to straighten out quicker. On the straight the car is more reassuring too.
A look at the brushes shows that I can bring the gearing down further so a pinion change is made. The car is faster with lower gearing and gives almost 100 seconds more duration than the BD car, not that duration is ever a problem with 5 minute stock racing. Also, with a good pack of cells I am down in the late 16s.
After a couple more packs and a few laps with other guys there practicing I decide to run the SD on Sunday. Just skim the comm and a new set of brushes is all it needs.
SUNDAY.
Race 1. The SD shoots off the line from pole and I build up a 5 second advantage in 3 laps. On CS27s on a hot track the grip is up right away. In fact it gets so good that I grip roll and have to be marshalled. Two cars overtake and I start chasing and catching. Then on lap 10 the car lost it's steering and flew straight on into a wall at very high speed. End of race.
Damage. I broken front shock mount.....only. I couldn't believe it. In all my years of RC racing I have never seen such an impact.
Further examination showed what has caused it. My fault. I forgot to tighten the servo horn after adjusting it, and the screw fell out, and then the horn, and then no steering.
Checking my lap times i found that i had been lapping regularly in 17.1 and 17.2. Can't be bad.
Race 2. I ran old faithful in race 2. Started from the back of the grid.........and won. Best lap 16.89.
My immediate reaction. Considering I have been perfecting the BD car for 3 years, this SD car is pretty good already with just 8 packs run.
I'll keep you all updated.
regards
Joe from sunny Malta.
Last I logged in was Thursday to say I was expecting the couriers that afternoon. Well it arrived. I built it Thursday afternoon, continuing Friday morning, tested it Friday (4 packs) afternoon, then again Saturday (4 packs) afternoon after some mods, and decided to race it Sunday.
BUILDING.
I'm impressed. I've built plenty of Yokes over the years but this is such an improvement. Everything fell into place and the only reason it took me so long was because of the many mods I put into it in the initial build. Waiting for 2 months has given us all plenty of time to think about such things!
I put titanium screws everywhere straight away, triangulated the front top arms as I do on all my cars, turned the servo through 90 degrees, replaced the steel drive shafts with alloy, and used the alloy MR4 Special battery hold down which looks more trick and is a virtually straight fit.
One other thing, which I have always done to my MR4s: I used Associated TC3 shocks with unobtranium shafts, just using the new SD shock top caps with the diaphrams. The reason for these shocks is that a) they are longer and more suited to the car, and b) they hold more oil.
SET UP.
As my belt drive car handled so well, I tried to copy all the settings into the SD. Same springs - Fastrax orange all round, same 50 shock oil, no kick up front or rear, 2 degree rear toe in, shocks angled as much as possible, top arms as long as possible for negligible camber change. I also raised both front and rear lower arms by 2mm all round to change the roll centre, again as much in line with the belt drive car.
TESTING.
The result was good. I ran a pack with the belt drive car, lapping in the early 17s and very late 16s as usual, just to see that the track condition was normal. Then straight onto the SD for a direct comparison. My reaction, with a lousy pack of 3000 cells was that the car was remarkably free, but I wasn't as comfortable with the handling. It was more nervous on the straights, and you seemed to gave to straighten it up after each bend instead of it straightening itself up. Clearly all the signs of more caster needed. this is understandable for the BD car runs 7 degree blocks and 1 degree kick up.
I calculated the same gearing for 21 turn stock motor - which is our control motor in the stock class, but found it too high geared.
SATURDAY MORNING.
Rebuild the motor. Fit 7 degree MR4 BD front C hubs. 1 degree front to out. Replace 88T spur with 104 - 64DP. Spur gear change took quite a bit more than the suggested minute but will get quicker with regular changing, and doesn't matter all that much anyway. And off to test again.
SATURDAY AFTERNOON.
Quite a few guys at the track since we are racing Sunday. The Sd causes quite a sensation.
On track it immediately feels better and more driveable. I am able to go deeper into corners, and can power out quicker in the knowledge that the car is going to straighten out quicker. On the straight the car is more reassuring too.
A look at the brushes shows that I can bring the gearing down further so a pinion change is made. The car is faster with lower gearing and gives almost 100 seconds more duration than the BD car, not that duration is ever a problem with 5 minute stock racing. Also, with a good pack of cells I am down in the late 16s.
After a couple more packs and a few laps with other guys there practicing I decide to run the SD on Sunday. Just skim the comm and a new set of brushes is all it needs.
SUNDAY.
Race 1. The SD shoots off the line from pole and I build up a 5 second advantage in 3 laps. On CS27s on a hot track the grip is up right away. In fact it gets so good that I grip roll and have to be marshalled. Two cars overtake and I start chasing and catching. Then on lap 10 the car lost it's steering and flew straight on into a wall at very high speed. End of race.
Damage. I broken front shock mount.....only. I couldn't believe it. In all my years of RC racing I have never seen such an impact.
Further examination showed what has caused it. My fault. I forgot to tighten the servo horn after adjusting it, and the screw fell out, and then the horn, and then no steering.
Checking my lap times i found that i had been lapping regularly in 17.1 and 17.2. Can't be bad.
Race 2. I ran old faithful in race 2. Started from the back of the grid.........and won. Best lap 16.89.
My immediate reaction. Considering I have been perfecting the BD car for 3 years, this SD car is pretty good already with just 8 packs run.
I'll keep you all updated.
regards
Joe from sunny Malta.
05-12-2003, 06:34 AM
#1236
Hi Teacher,
you´re pefectly right. I jdid was you have suggested and it solved my problem!
Thanks!
you´re pefectly right. I jdid was you have suggested and it solved my problem!
Thanks!
05-12-2003, 06:58 AM
#1237
John Bull, can you directly adapt the mr4tc's C-hubs on the SD without mod.?
I broke 2 C-hubs and i am thinking replacing it with Suzuki's mr4tc's C-hubs(5 or 7°) .
I broke 2 C-hubs and i am thinking replacing it with Suzuki's mr4tc's C-hubs(5 or 7°) .
05-12-2003, 07:33 AM
#1238
UTIEH.
Yes, they are a direct fit.
In fact I used the Suzuki / Fastrax 7 degree, with no kick up.
Just had a look at the BRCA webpage. I see there were 2 SDs in the top 10 and Adam Rogers placed 2nd. He got his car last week too.
Regards
Joe from sunny Malta.
Yes, they are a direct fit.
In fact I used the Suzuki / Fastrax 7 degree, with no kick up.
Just had a look at the BRCA webpage. I see there were 2 SDs in the top 10 and Adam Rogers placed 2nd. He got his car last week too.
Regards
Joe from sunny Malta.
05-12-2003, 07:43 AM
#1239
thanks .
is it possible to order them from Europe, the japanese online store where i bought my sd doesn't carry them, and it s quite difficult to find their products.
Gilles
is it possible to order them from Europe, the japanese online store where i bought my sd doesn't carry them, and it s quite difficult to find their products.
Gilles
05-12-2003, 09:21 AM
#1240
Tech Adept
MR4TC-SD Black Special
Yokomo will be showing a new Black Carbon Graphite car at Shizuoka Hobby Show this month. It sounds like a molded(tub) chassi that is stiffer than SSG will be used for a kit. Available in Japan around end of May. I am sure we will hear more about this car later.
D.
D.
05-12-2003, 10:24 AM
#1241
Gilles,
I should have some in stock later this week, and can post you a pair then. I will let you know when they come.
regards
Joe
I should have some in stock later this week, and can post you a pair then. I will let you know when they come.
regards
Joe
05-12-2003, 12:33 PM
#1242
johnbull,
i was reading your comments on your 1st impression of the sd, and i noticed that you weren't running kickup in the front. i believe i only have the f+1. can you tell me how to achieve the 0 kickup?
also, is the stock setup a total of 5 degrees castor?
thanks,
D
i was reading your comments on your 1st impression of the sd, and i noticed that you weren't running kickup in the front. i believe i only have the f+1. can you tell me how to achieve the 0 kickup?
also, is the stock setup a total of 5 degrees castor?
thanks,
D
05-12-2003, 01:20 PM
#1243
Originally posted by johnbull
UTIEH.
Yes, they are a direct fit.
In fact I used the Suzuki / Fastrax 7 degree, with no kick up.
Just had a look at the BRCA webpage. I see there were 2 SDs in the top 10 and Adam Rogers placed 2nd. He got his car last week too.
Regards
Joe from sunny Malta.
UTIEH.
Yes, they are a direct fit.
In fact I used the Suzuki / Fastrax 7 degree, with no kick up.
Just had a look at the BRCA webpage. I see there were 2 SDs in the top 10 and Adam Rogers placed 2nd. He got his car last week too.
Regards
Joe from sunny Malta.
Any pix of your SD's front-end?
05-12-2003, 01:54 PM
#1244
DickemDown - the standard caster is 5 degrees (1 kickup and 4 block). You can adjust the kickup by using the notched washers on the suspension mount sprue - each one is worth one degree when placed under the suspension mount.
