InitialD

1/8 scale cars are usually equipped with solid axle rear with very wide tires. Cornering with a solid axle scrubs off speed which is what you probably call sideways drag... In that way you do not need to slow down a lot by physically applying brakes. I believe you drive solid front and rear in your Yokomo?

Also, besides making the car faster, using solid rear axle makes braking in a straight line better as there is no diff action between the left and right wheels when braking as the solid rear does not permit this. The wheels therefore do not unload due to uneven tire wear, uneven ground etc even when you brake hard.

I think that is why even on smaller and tighter tracks, some people prefer the solid rear axle because of this.

InitialD

Mark, it seems that your track is a little loose on traction. Normally with a one way front diff, set the brakes loose like what the other guys have advised. Just enough that the rear wheels do not lock up.

One trick I learned is to simulate ABS by tapping on the brake a few times to get the car to slow down quickly before a corner. Using ABS function in your remorte (if it permits) would do the job but somehow many people do not advise this as it wears the throttle / brake servo out prematurely. Also, you need to get off the gas sooner before a corner and brake a little longer. Braking at the last minute is a no no.

If you set your brakes soft enough, you might use to aid you in your cornering. Braking and taking a sharp corner hairpin at the same calls for a lot of dare devil guts and a lot of practise but once perfected, the cornering will be sharp, fast and very deadly The brakes when engaged will be very soft. Something like a brake fade...

InitialD

If you're using stock 16T/19T pinions, try changing to 15T/18T. Try it out. Most of the time, the 15T/18T pinions are sufficient. If the car is still overgeared at the end of the straights, use the 17T side pulley, 22T brake pulley and the 47T diff pulley combination.

With a one way front diff, I believe it is more important to get the right gearing for the straights because the car needs to peak way before the hairpin corner (about 3/4 lengths before the hairpin) before you have sufficient time to apply brakes and set the car to slow the car down and glide around the corner.

InitialD

Yup, snappy acceleration You wouldn't believe the amount of hassle I went through to find how to get max acceleration out of the 705..

Anyway, sorry not Germany but Austria. In fact it's Serpent Austria. The link is as follows;

http://www.serpent.at/news/news.actionline.html

Scroll further down and you can see 14T first gear pinions and 17T second gear pinions.

DSR

So, if I just run this set-up, don't I still have to change the 2nd gear spur & pulley? Also, will this set-up work without any necessary mods.?

I really appreciate your thorough response.

InitialD

Yes, you will not need any other modifications when you use the 22T brake pulley, 17T side pulley and the 47T read diff pulley. The rear belt fits the same. This is a Serpent approved mod

When you do the above mod, the stock spurs (49T / 45T) can be left alone with the 15T/18T pinions (stock is 16T/19T). If you want slightly more acceleration, you can bump up the 49T 1st gear spur to 50T. It all depends on your track requirements.

If your track is that long that the engine runs out of breath half way down the straights, bump up the second gear pinion from 18T to 19T. This will give a nice jump in top speed. Make sure that the difference in the number of pinion teeths between 1st and 2nd is about 3 to 4 teeths to avoid your engine bogging down.

You can also change your 2nd gear spur by reducing it from 45T to 44T to get more top speed but note that changing spurs gives very subtle difference to the ratios. Changing pinions have a more drastic effect. Changing spurs for me is more of a fine tuning thing.

DSR

Thanks for the response, InitialD.

DSR

InitialD,

The 705 already comes with the 22T brake pulley, correct? Also, I can't seem to find a part # for the 47T rear diff. pulley.

Would it be OK to run 15T/18T pinions, with 50T/46T spurs?

nizee

The 705 comes with 23T brake pulley. The part part number for 47T Pulley 808376. The 22T pulley is 808376.

The very first kits shipment of 705 have mistakenly have 22T brake pulley somewhere around Oct ~ Nov time frame. So, if you purchase after that, i would assume you got the 23T, you might want to check it first.

nizee

btw, see the site below for more info on the 705 gearing.

http://www.mytsn.com/publ/publ.asp?pid=7186

DSR

Thanks for the heads up, Nizee. The reference guide that came with my kit says that the pulley is 22T, #909242. Could this be correct? I got my kit in Februrary.

InitialD

Don't believe the reference guide too much. Even the updated one on mytsn still contained some errors.

Anyway, as nizee mentioned, the kit should come with a 23T brake pulley (9616). Serpent actually intended to put the 22T brake pulley (909242), 47T diff pulley and the 17T side pulley in the kit. Somehow somewhere some parts got screwed up and they landed with the old pulleys back into the 705 kit. So somewhere between changing this, the parts got mixed up and some users reported that they had the 22T brake pulley which is only in the earlier batch.

Check to see and count it physically if you have 22T or 23T brake pulley. Check also if the diff pulley is 46T or 47T. The 22T brake pulley will pair up nicely with the 47T diff pulley. The 23T will pair up nicely with a 46T diff pulley. If your rear belting seems too tight, it could be that you got either pulleys wrong.

As for the pinions and spurs, all 1st gear Centax pinions (i.e. 15T, 16T and 17T) have the same diameter. The 2nd gear Centax pinions also are the same diameter (18T, 19T and 20T). The same goes for the 1st gear spurs (50T, 49T, 48T and 47T) and the 2nd gear spurs (46T, 45T and 44T).

Because of this, it does not matter if you pair up 15T/18T pinions (3 tooth split) with 50T/46T spurs (4 tooth split). They will mesh up properly. You can even use 15T/19T pinions and 50T/44T spurs if your track permits.

paulfitipauldi

I bought my kit in february too,, and it comes with a 22t pinion and a 46t in the ball diff....

nizee

That is sad !

You can either keep the 22T and get the 47T to change the gear ratio and get gd belt fit OR you can call your country Dealer/Distributor to change for the part to 23T. Serpent had made the announcement on the mytsn.com that they will replace the wrong part.

paulfitipauldi

SORRY!! A CORRECTION HERE!! MY KIT CAME WITH A 23T AND A 47T IN THE SPUR,, THE ONLY THING THAT I CHANGE WAS THE 23T FOR THE 22T THAT I HAVE SPARE IN MY TOOL BOX!! SORRY FOR THE MISTAKE!!