Tamiya America Raceway

I had the opportunity to run at the Tamiya America Raceway in Aliso Viejo this past weekend. The race was quite a bit of fun, and there was a ton of interest in the A700. As always the diff housing and the rear axles were getting the most attention. ;-)

First round my car was close to on pace, only off by about .3 compared to TQ, Rick Howart. After the kink in the middle of the track there is a tear drop 180 that had a quick entry (if kink done right), my car would get loose in the rear pretty easily going into this turn, making it pretty hard to drive consistently. The track was in pretty good condition, with most having no traction issues, depending on tire/sauce choice of course.

Second round, to try and solve the looseness issue, I added a half millimeter shim under the rear upper inside links, lowering the roll center a little bit to try and get more roll in the car. The car felt better, but it might have simply been the traction having come up as the weather got a little better. Unfortunately, my lap times dropped a couple tenths, though I only got in about 6 laps before I got into the before mentioned kink in the middle of the track and broke out of the heat. This obviously sucked, as the second round was basically the rocket round and I was pushed out of the A.

I ended up qualified 3rd in the B, and while I was pretty disappointed with that, I thought I had a good chance of winning that race at least. Unfortunately (yes that's the theme of this email :-), a couple of odd things happened. First, the car seemed to be hopping quite a bit coming on to the straight away. While it is a little bumpy and many of the cars were hopping, mine was by far the worst offender. Second, for reasons yet to be discovered, the car seemed to have a hard time centering. I've checked my servo, steering rack, everything seems to be free, it felt like something must have been binding somewhere as after turning left the car would stay trimmed slightly to the left, and vice versa after turning right. Very odd. I've had this type of behavior before when the steering rod was hitting the top deck, but I don't believe that issue is happening this time.

Finally, and to be honest I've felt this nearly every time I've run my A700, I feel like the car doesn't carve the way my Xray used to, it just doesn't seem to dig in on turns like I'm used to feeling. It's almost like the car is floating a little bit, I don't know if it's a lack of roll in the car or something I have wrong, but I'm definitely interested in other's opinions on that matter. I've attached my setup for reference.

The car did feel really good one time, which was at my home track after the race when the temperature dropped (happy hour, as we call it), the car really started to carve in the corners, and I was on pace with the others. That was a change from earlier where I was off pace by .3-.5 and the car had that floaty feel. The first few times I ran I was sure that I had done something wrong with tires, or had the setup all wrong (which may still be true), but this feeling has been pretty consistent now.

To try and fix this, next things I'm going to try are running quite a bit softer, closer to Freddy's settings, and I'm going to try running transverse, in the hopes that will generate more roll.

Thanks in advance for any advice.

Ethan

As far as your centering issue, are you running the supplied servo saver ? If so, I used to own a 416 and had severe issues with the Tamiya servo saver not centering, and started having the same issues with the A700's ( which is a Tamiya servo saver ). Recently I replaced the A700's with the new stiff X-ray servo saver ( unfortunately it requires a few clearance modifications ) and haven't had any centering issues since.

Yea, I am running stock servo saver. Thanks for the tip, I'll try that out.

You could also just pull apart the tamiya saver and grease the rings ( springs ). That may solve the issue.

If you end up trying the X-ray servo saver you have to shave off 1-2 mm off of one of the screws that holds the servo bracket because it will rub the large diameter of the X-ray saver. Also, you need to recess the ball stud into the saver or the angle of the rod between the steering rack and the saver will be too severe and cause a collision with other suspension parts.

I ended up qualified 3rd in the B, and while I was pretty disappointed with that, I thought I had a good chance of winning that race at least. Unfortunately (yes that's the theme of this email :-), a couple of odd things happened. First, the car seemed to be hopping quite a bit coming on to the straight away. While it is a little bumpy and many of the cars were hopping, mine was by far the worst offender. Second, for reasons yet to be discovered, the car seemed to have a hard time centering. I've checked my servo, steering rack, everything seems to be free, it felt like something must have been binding somewhere as after turning left the car would stay trimmed slightly to the left, and vice versa after turning right. Very odd. I've had this type of behavior before when the steering rod was hitting the top deck, but I don't believe that issue is happening this time.

Tamiya is one of my favorite tracks of ALL TIME. I think I have hundreds of packs on that track. Some of my most memorable tracks. I would have loved to run the A700 there.

With that experience - I would have tried a few other things.

• Going with ASYM on the front and rear shocks. Similar to what we have done with Tamiya shocks for years by drilling shock tops - the ASYM provides a softer initial feel which would have been helpful navigating chicane and onto the straight.

Interesting, I haven't really played with asymmetric, I assumed it would make the car react more quickly.

• Add more droop to the car. At 6 and 5 - that would have made my car feel really limited roll.

Will more droop I felt like it really reduced my on power steering. I'll try it again. Do you notice the A700 needing more droop than other TCs? Maybe the measurement point is different enough from other cars that a 6/5 from an Xray for instance is different from the A700, I haven't measured things.

• Swaybars - Im on the fence about them right now. I am trying to get the car to work without them...

When adding the front bar my car got more responsive, and I haven't taken it off yet. I agree that they shouldn't really be as needed given the low center of gravity.

• Remove 2 front bottom screws and 2 rear bottom screws. Always felt to have more bite without them

Last time I ran I was on very high bite, so putting them back in gave me more stability, but yea it could have been a problem at Tamiya.

• Have not been a fan of reactive caster with IAS. Generally - the exaggerated ackerman with the reactive caster just made the car push. The good/better/best: Good - Reactive with IAS

Better - Reactive with standard rack

Best - Non-reactive with IAS

I'll remove the reactive caster and give it a shot.

• Camber-rise looks good in the back. Did you try adding shims under the rear arm mounts?

You want me to raise the roll center of the rear of the car? To me that would cause less roll, which I think would exaggerate that floating or sliding feeling.

• Lighter oil in rear gear diff. I am usually 60-120. At 200 or 2000 CST my car will not rotate.

I was doing side by side comparisons with an Xray diff and the A700 diff just felt thinner at 1000 compared to the Xray. I went to 2000 and it felt better on the bench, but it could have had a negative effect as you said on rotation.

• Shock setting - still TBD on this, unlike carpet and on asphalt I believe will end up with a differential of that will be within 10gF/mm front to rear but with the front being stiffer. Especially if we start fighting for rear grip.

I've not seen any setups with the front stiffer, I think that would have made the car more responsive but less mid-corner, I guess I'll have to experiment.

• Tires - for Tamiya - the best options were always Sorex 36 or 32 with soft inserts. Lots of air gap. Why didn't you run the RROC tire?

I did try Sorex 32s, the Schumacher premounts. They just weren't as good as RP30s, but that opinion varied throughout the track.

Couple of things to help get the car to dig more.... more droop, and softer dampers. Droop wise, 5.5F 5R, or even 5F 4.5R seems to work well to get the car to move about more, and stop the skating feeling. Also, the damper settings you have are pretty hard, along with the front spring, which would help to explain the "hoping" you've experienced. Try A= 1F 2R, with B= 2F 1R, and see how that feels. Those are a little harder than Freddy and Steen's settings, but a good starting point to go with (and the F-R spring split will be a little softer than you currently run). Otherwise, just go the whole hog, and A= 0F 1R, B= 2F 0R...

You'll find the car then rolls a lot more and digs in well. With really soft springs and dampers, the roll bars help to keep corner speed up, whilst still allowing the car to pitch into the corners... the "dig" you mention.

Once you've got the springs and dampers, then start working on the settings. Something else to help make the car a little more stable would be to lengthen the rear wheel base as well, maybe try 2° or 0° on the castor setting.

Oh, and as others have mentioned, the Tamiya saver can get loose after some big hits. Either replace the plastic bits, or go solid horn (it's what I'm running, no issues )

HiH Ed