Dark Impact Gearing Help
 

Hi there,

I have a dark impact and Im stuggling to find the correct gearing for it. I'm running a 12 and 13 double with Tamiya 0.5 module pinions and spurs.

Can any one suggest a pinion and Spur combination for me for a tight and twisty track like Kidderminster?

Cheers.
Mark
:)

Any one?.......

Mark

I dont suppose you know the internal ratio of this car do you mate?

Well... using this formula

Overall Drive Train Ratio = (# teeth on spur gear / # teeth on pinion gear) x Tranny Gear Ratio

and using a 78 spur and a 26 pinion the manual says it gives a overall gear ration of 9.17:1

So Ive worked it out that the internal gear box ration is 3.05:1.

Plugging this back into the formula gives a Overall ration of 9.15:1 so I think its right.

and who says you'll never use A-Level maths again :) (actually I think that was more GCSE level :D )

Mark

I didn't see that ratio in the manual, but then I didn't finish building the car yet! haha

I installed the 85t spur when building because the kit gearing is for the kit 540 motor. Even with the larger spur I thought it might be a little over geared so something smaller than the kit pinion might be in order.

I'm not really the best person to advise since I have the gearbox built and thats about it.. :p

I would guess, trying a 24tooth first and working up, the biggest hangup for the car, is heat build up on the motor.

Normally I'd be all over this thread, BUT I don't think I should comment as I'm only bashing with SPEC motors.

I have an Excel gear chart and graph if you are interested.

The kit pinion and larger white kit spur will give you a final drive of 10.00. It will fit with a little extra dremeling.

I think I'm running a kit pinion (26t) and the black slipper spur to give me a ratio of 9.64, but it's not as fun as the 25t pnion, final drive 10.02.

Elliott.

Cheers Guys,

Jimmy - just underneath where it states what pinion you need (column on the left it states what ratio it give.

I can get it geared right for my 19T (I think I used 25 or 26 with 82T) but I had a 12 double and now a 13 double and it doesn’t seem to be working right.

I took it out on the street a couple of days ago with the 13 Double in it with 23/85 (the lowest kit gearing possible) and it seems that that was a bit over geared as it only lasted about 3 mins before it stated to die (stated to low and I would loose steering when on full power), and that’s on-road, so no way would it be able to last in a race. I don’t think its the batteries as they are new IB4200's the motor was new and run in, the ESC is not new (LRP Quantum
Pro Sport - 7T limit) but should be ok for the job. I checked the gearboxes and they don’t seem to be binding so the only think I can think it is, is the gearing.

I have got the lower tooth pinions (down to 17t i think) in the 0.5 module but I was thinking that this might be too low?

The manual that came with my motor suggested that for off road the gearing should be 10.4:1. I tried this at Kiddy (24/82), the first lap was great but by the 3rd lap it was getting slower and by the 5 I had to stop as I was loosing stearing. Which I think is a sign of too much battery drain. When I did stop there was smoke/steam coming from the motor.

So..... Does the symptoms sound like over gearing or could it be something more sinister and expensive?

Cheers :)

Mark

Yeah I have already had the dremel out cutting the mounting slots longer so I can use the smaller pinion which I was told you need to do.

I know the car can fly as there was another one at the Kiddy MAM im just kicking myself now for not asking the guy what gearing he was using! Doh!! :)

I might just try the std silver can with the kit gearing to see what its like...

Mark

We're runnning the same gearing for SPEC motors then.

Did you get the Super Astute pinions?

Elliott.

Yeah I got them of ebay but I havent used them yet as I though it might make it too under geared but Im thinking I may be wrong....

Mark

Don't forget the wheels and tyres are bigger than average too and the back ones are heavy (I weighed them to compare).

Probably doesn't make that much difference.

Elliott.

I will confess, when I first bought it and run it, I thought I had checked in an Integy Stock motor in it, but in my hurry, it was an 11x3 and it lasted 5 mins no problems at all, even with the kit tyres on a tight grass track.

Hummmm... was that with the stock gearing from the manual as well?

Mark

Yes, hence the thinking I put a stock in there.

What gear are you using, maybe there is an issue somewhere, causing the problem.

using an 11x2 on saturday night with the large spur and a 23 tooth pinionthe fimal ratio was around 11 that iswhat richard isherwood reccomened it was a little under geared so next is a 25 tooth which gives final drive of around 10.39,and the car had no probs with five minutes plus 2 practice laps

You still running the 48dp pinions with the kit spur darryl?

Umm Thats what I started off with and its was a no go... I'll do a strip down and rebuild and see if I can find any gearbox issues.

Cheers

Mark

Complete list.
 

Hi.

In this link from tamiyaclub one guy speack about the Super Astute pinions and show a complete chart about the gearing until the 20T pinion. I think that is easy to calculate the ratio for the 18T and 19T pinions using this chart as reference.

http://www.tamiyaclub.com/showroom_m...53812&id=17039

Anyway I take this pinions until te 18T. I hope this helps.

Bye. :)

still tryin to get hold of the tamiya pinions as as you heard its a little on the noisy side using 48dp,but no damage to the spur gear which is quite fortunate

I'll see if I can get a B4 spur on the tamiya slipper when it arrives. I noticed the noise on mine yeah - there was some plastic dust coming off the spur when I first ran the motor, but it seems to have calmed down now. I imagine it wont last forever though.

got the tamiya slipper coming for mine too,but not sure if an after market spur will fit on,was looking at a schumacher spur gear yesterdy with the slot in the back but pete only had 95 tooth ones but they were way to big to fit under the gear cover

Kawada make a 48dp spur (spurs) for the Tamiya slipper - I haven't seen one for sale myself but I have seen them on various sites and talked about.
If I can't get the B4 spurs on then I will hunt out a kawada version.

Not sure if this is the one or not:

http://www.kawadamodel.co.jp/partsli...h_tba101_2.jpg

This uses 'pucks' in the spur rather than slipper pads and is only 80t. I am not sure how easy I will be able to gear a brushless on a smaller spur like that

Tamiya are missing a trick not releasing smaller pinions.

Elliott.

Its these small spurs that are worrying me.. I can mesh with the large 85t spur, but the smaller spurs in the slipper kit worry me.


DCM, what size B4 spur can you fit?

The gearbox is noisy-ish. But I thought it was the layshaft gear on the counter/idler gear and the lack of grease.

I'll check tonight.

Elliott.

I think I slammed a 78 on as that is what I had spare, but 81 is fine too. From what I understand, the Tamiya slipper is just a 'metric' version of the B4, so you could use the B4 spur, but you will have to ream out the centre hole to 5mm, and the pads might need a little trimming.

The stock spur gear put lots of effort in grinding itself down and making a noise than driving the car, also, when you got CVD's on, on lock, the front axle becomes noisier.

Finally!!!!! Result
 

Well..... after 2 weeks of the car sitting on the shelf I seem to have figured out what the problem was!
It seems that one of the front wheel hex's was fouling on the bearing/hub. Now its all nice and free.. :)

Now just have to cure the interference problem!!
Seems now I can enter both the 4wd and 2wd regional's now :)

Cheers Guys
Mark

I'm now running a 48dp B4 spur and the car is a lot quieter. Drilled the centre out to 5.2mm and all is well.

Elliott.