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Old 05-07-2007, 09:51 PM   #1231
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There are new Mamba and front end reports on the previous page

Joe- I just don't think so. My experience on the touring cars is the long arm cars have a little better traction on asphalt. The long MiniT arms should have excelled on asphalt. I also ran the lower arm with stiff Aluminum for a while. This had no effect. I think the differences are outboard rather than inboard. My Losi JRXS sucked on my track due to the very short arms. It would only hook up when traction was high. The Tamiya 414 (or 415?) with the long arms or the Losi XXXS shined. On carpet it probably would be the reverse.

Anyway, I measured and the two lower arms are identical in length from pivot to pivot for the two Prototypes. The upper arm is shorter on the Associated based front end.

There are some guys working on front ends for this type of car so I thought I would continue to report my results.

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Old 05-08-2007, 02:06 PM   #1232
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Here is version 3 of the front suspension. It has the adjustability of the Aluminum Suspension Block combined with hopefully the great performance of the Associated based arms. The shock is close to kingpin; it has a high outboard upper pivot of the first suspension. I need to order a couple of trailing axles for it. I may or may not have good steering link clearance. I'll see.
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Old 05-08-2007, 03:19 PM   #1233
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Quote:
Originally Posted by John Stranahan
[color=red][b]Anyway, I measured and the two lower arms are identical in length from pivot to pivot for the two Prototypes. The upper arm is shorter on the Associated based front end.
This probably has more to do with it then the outboard I would think. Your camber change over suspension movement is going to be greater with the shorter upper arm then it will with the longer upper arm.
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Old 05-08-2007, 04:49 PM   #1234
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Hey John,

that front end looks interesting I am used to the old non adjustable ones

anyways for the touring tires I meant Trinity spec type foam tires which were placed on pan car wheels that were narrower.

I dont even know if they make those wheels anymore..
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Old 05-08-2007, 06:19 PM   #1235
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I have not seen those Trinity narrow tires available.

Inspgadgt. I agree with you that there is more camber change with roll with that short arm and I did state that short arm as one of the three important differences in the two suspensions.
I do believe that most of the magic is somewhere else, though. I have tinkered with the upper arm length on the touring cars and it makes but a small difference. The RC cars in general are insensitive to camber changes. That's why we make camber changes just to even the tire wear. The difference in performance between the two front ends is dramatic.
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Old 05-08-2007, 08:28 PM   #1236
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I used to think that was so until I started racing F201s. I found with the F201 it is very sensitive to camber change and found that by reducing the roll of the car, thus reducing the camber change, made a huge difference in the way the car handled. On my pan cars I'm starting to play with camber a bit more to see what the changes will do. I used to do that a lot more extensively back when 1/10th wide pan cars were still popular. What I find most RCs today are insensitive to is spring rate (pan cars being the exception). I find with my F201 and TCs that spring rate seems to be better used to control camber change rather then the old way of thinking of softer spring rate gives more traction.
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Old 05-08-2007, 09:17 PM   #1237
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Inspgagt-I see your point and I am glad I am incorporating the original arms. The small difference in camber gain could be important. Now what if I tell you the upper Associated arm is only .15 inch longer than the Losi Mini T arm. That's less than the width of a 4-40 button head screw head. There must be more to it than that. The pivots at the kingpin instead of inboard must have something to do with the better performance.


I still don't like the pivot balls much as there is a wear problem on the lower joint, but this can just be solved with regular maintenance on that rod end and ball.

Almost done with version 3. I need only to drill new mounting holes in the chassis to correct length and width.
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Old 05-08-2007, 11:06 PM   #1238
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Well here is the new front suspension version 3. Outboard it is very similar to version I. Inboard it is more like version II. This gives me a stronger lower suspension arm mount. Better Roll Center adjustability. Small width adjustments are possible. I still have a few adjustments to make on it. Will test it when the GTB comes back from non warantee replacement.
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Old 05-09-2007, 06:17 PM   #1239
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Track Report: Air Temp 89, Track Temp 127F!, starting to get hot. Traction Medium. I revived a sugar water treatment from 5 days ago with a hot water dampening spray.

Mamba Max plus Novak 4.5R

Maximum motor temp 180 F with a 90/14 and large tire.
This combination topped out about mid straight. It had excellent acceleration from a rolling start: it would pull the front wheels up on occasion mid short straghts. A little on the twitchy side. Run time 8 minutes 30 seconds with a new 4000 mA-h pack. Mamba Max temperature on its side was 140F. I have a suspicion that it gets hotter on the bottom as it has been melting my servo tape. Three brands now. I have it secured with a wire tie and tape now.

Geared 90/15. This is what I used to run this motor at with a mostly stock pan car. It felt better on the track. Top speed was only a little higher but throttle application was smoother on the other parts of the track. The motor temperature was 175 F after a seven minute run, but the track had cooled to 111F.

The Mamba still had some troubles. I tapped a flapper board one time and it took 3 little squirts on the throttle before it would take off. I had the car at a slow roll to adjust my brakes in a second incident, the Mamba had trouble starting from this slow roll. The best part was that the Speed Control was NOT ON FIRE at any time during the testing as can happen with some others at this high track temp. I had better luck with the Mamba mid corner this time probably due to some unconcious adjustment I have made in applying and increasing throttle mid corner. I am using quite a bit more today as the car was HOOKED UP.

Interestingly, I had swaped between Prototye II back to Prototype I last session. Same tires. It was not 2 full runs before I noticed my nice wear pattern on the front foams (ripples lined up with the circumference). This coincides with the car having really good grip in the corners. I never achieved this full hookup or wear pattern with the MiniT suspension.

So how does this 4.5 motor compare to the 3.5 in the same chassis. Well the 3.5 is a tad faster early on the short straights, slightly faster at the end of the longest straight. The power delivery is smoother and more suited to a light rear wheel drive pan car. This 3.5 motor requires a hardcoated steel pinion on our track, so I will be running the 4.5 for a while. The hard coated pinion is no longer available.
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Old 05-09-2007, 07:46 PM   #1240
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The Mamba ESC is getting a software/firmware upgrade soon, which will solve the twitching issue with sensored motors like Novak and LRP. The MM esc was designed w/ un-sensored motors in mind, and it work awesome with the mamba motors, especially the 7700kv and the 6900kv motors. Those motors gave no cogging or twiching pblms, and were really smooth and really fun to drive...but the man can the Mamba handle the heat and power like no other...and its so cool to set up and program...I'd try the 7700Kv motor and see how it does...
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Old 05-09-2007, 10:00 PM   #1241
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yyh, you still believe that update is coming? I stopped believing their lies three months ago. They have the disease common to R/C manufacturers: late delivery.

John, you should give the Mamba Max 7700 a try. Also, what are the maximum dimensions on the lipo pack for your car?

-Adam
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Old 05-09-2007, 10:19 PM   #1242
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Thanks for the posts
Adam- Here is a link to the Max amp pack I am using. There are dimensions there. It is quite slim. Even though my electronics are above them they are not that high off the chassis.

Now here is what I think at this point in time. I have tried a sensored and sensorless motor with my Mamba. There is no way for the Mamba to know that one is sensored and one is not. It treats both as sensorless motors. Both motors with the Mamba have the behaviour irregularities that LRP and Novak eliminated by adding sensors. Tekin is working feverishly on these same irregularities. Thus no R1 Pro is available. I suspect that If I put the Mamba motor in my pan car it would still have these irregularities like starting backwards on occasion. Loss of the rotor position with a bump. Irregular starting from slow speed on occasion; This does not happen often for me now, but occasionally. I don't plan to purchase any more sensorless stuff. I have invested in a brand new GTB which should arrive shortly. It should work fine with my 4.5R. I do await any software upgrades for the Mamba and will try them when they are available. In August track temperatures will climb to 140F-150F I may be using the Mamba again then if my GTB thermals with the 4.5. The sphere comp worked fine through all of last August when limited to a 4.5R motor. It only had trouble in the pan car with a 3.5R. Sadly my 3.5R is shelved for lack of suitable hardcoated 12tooth pinions.
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Old 05-09-2007, 10:42 PM   #1243
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That pack shows as 44x137x14. Would a 15x148x44 pack fit?

To some extent what you say about inherent problems with sensorless is true. But some of the problems you are seeing are unique to the combination of the motor and ESC, and they don't exist with other motors. The Novak motors are substantially different in many ways from the Mamba motors that the Mamba ESC is designed for.

I run the MM 4600 and 5700 (depending on track size and how good I'm doing that day) in my touring car (carpet, foam). I've never had the motor lose rotor position after a bump or during slow rolling. I do have slightly lengthy starts from dead-stop, which does cost me a few car lengths in Main starts. Brake feel, that's a hard one to communicate and know how to judge.

Anyhoo, just keep an eye open for used 7700 motors. You can buy one, try it, and sell it for practically no cost.

-Adam
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Old 05-09-2007, 11:06 PM   #1244
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Adam-I want to believe you. I will wait on the software.

In a touring car these bumps on the flapper board break the electric car (TC's not the pan car) on my track so maybe that's why you don't notice. That difficult start is a problem in the main. In high traction situations (carpet) you don't need the fine control of part throttle to go around a slippery corner. You use more like medium throttle to maintain speed. This may mask the problem as well. Today I had better traction than in my previous session and I had no incidents mid corner.

Not sure what you mean if that battery will fit. For a stock Pantoura the LiPo will fit as long as it is not longer than a 6 cell NiMH pack. Length of 140 mm fits fine 148 maybe not. You may be pushing on the rear football (center pivot).
My car and the stock Pantoura will hold two of these batteries side by side so width is not a problem. The height of the battery strap support on the Pantoura is 19 mm so a 15 mm height is OK. I have set my battery strap to 14 mm high to fit these Max Amp batteries. You can use spacers to go higher.

My car has no football or center pivot or T-plate as it is a custom 3-link suspension so I can use the longer battery you mentioned in my car.
John

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Old 05-09-2007, 11:19 PM   #1245
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It's disappointing that GM's Genius 95 (100?) isn't more readily available in the states. I'm inclined to think maybe they've got the sensorless thing working better than other companies. The drivers that used it at the recent LRP race (appeared to be a prototype Genius 100) all opted to go sensorless based on the pictures, and they had a choice, as the ESC supports Hall sensors as well. What little I've read about their gear has been extremely positive. Maybe Orion will OEM it like they seemed to be working on a while back.
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