Luke's Procat rebuild

[kaszal]

I used some M3 hexagon head bolts to mount the new Yokomo wheels.

I cut the thread down to about 22mm

[kaszal]

These diff outdrives are ace - deep enough for the thrust bearing and 4 large disc springs so the dust cap can fit. The other side is basically one long plastic lock nut - very secure. No problem fitting them to the Procat. Thanks to Eduardo in Spain for the part number

[kaszal]

Latest video clip of the Procat in action...

http://youtu.be/a_9GoO_OGMg

[Jay Dub]

Motor looks good . What oil in the rear?

[kaszal]

Front - TRF drilled 2 x 1.1mm hole pistons, 40wt oil, AE blue springs
Rear - TRF 2 x 1.3mm hole pistons, 30 wt oil, Losi pink springs

[kaszal]

Broke the rear wishbone practising. Does anyone have U1128 in new or mint condition? PayPal or trade. Thanks

[moozo]

Luke i'll have a look tomoz will let you know

[Jay Dub]

Bummer . Just looking at the video, the rear looks a tad light. Maybe you try 35wt and see if you like better. What motor btw? Good job -Jeff

[kaszal]

Thanks. Jay, will that make is hop up less at the back?

[Jay Dub]

Definatelly. Hard to tell from the video, but looks like the rear spring could also be a little light. It appears the car is driving rear end loose because the rear end is transfering too much weight in comparison to the front. -Jeff

[kaszal]

Cheers Jeff, I thought it was just the ruts in the astro and bumps in the concrete that were making the back end hop about.

The rear springs are Losi Pink 2.3 lb/in (similar to AE grey) but I've got some rear Losi red springs 2.5 I could try. Is it generally best to change springs and oil together?

The front springs are AE blue 4.2 lb/in (seem to work well so far)

I'm running a 5.5 Novak Velociti with 6.6v Li-Fe cells. The transmission's holding up well too... must be the guy who built it

[kaszal]

Luke i'll have a look tomoz will let you know

Thanks. I've just ordered these from Schumacher.

U1133 Rear Wishbone - Big 6 (pr)

According to the Bosscat manual they fit.

[Jay Dub]

Generally a bumpy track will cause the car to move around a bit, but not that excessivelly. And no, you don't generally change both oil and springs as a rule. But, it does happen. What does your rear droop look like BTW?

I hope to have some of my old cats running soon. I have a Bosscat on the bench right now, just waiting for my fastener order to show up . I will post a thread on it when it is done.

[kaszal]

There's a good amount of rear droop... I'll try to get a video clip up so you can see.

Thanks for your input. I've still got a lot to learn about getting the suspension right.

It seems counterintuitive... I thought softer oil would allow the wheels to move quicker over the bumps so your advice is to try a slightly heavier oil in the rear?

Another question - how does the anti-roll bar affect the behaviour of the rear?

I look forward to seeing your vintage racer up and running too

[Jay Dub]

A still image of the rear of the car with the rear in the air should suffice.

As far as the sway bars are concerned, how they cause the car to react is rather complicated. First the obvious. The sway bar will help to keep weight from transfering left to right as easily as just the springs on the car would. it will also return the weight more quickly and give the car a feeling like it "centers up" (returns to middle) more quickly coming out of a turn. This alone can give the car more traction (in the case of a car that is undersprung or has too much droop).

The less obvious is this: when the outside suspension is compressed, the force is transfered to the inside suspension system via the chassis. Well the outside suspension cannot lift the inside suspension off the ground, so what happens? Well, the chassis is forced down as the outside suspension is compressed. What this does is keep the weight transfer on that (front or rear) end of the car as it is turning. This alone will help to keep traction on this end of the car, simply because the weight is being mechanically limited from transfering to the oppposite end. In 4wd, I almost always run a sway bar on the rear, and almost never on the front. Taking the sway bar off the front will usually allow for on power weight transfer to the rear, by lifting the front under power in a corner.

This is situational however, and in really high bite (blue groove for e.g) situations it is not out of the question to run a sway bar on the front because of on power push. This is especially compounded if the track is rough, as the extra travel you would normally run to make the car smooth can also cause push.

That is not to say you can't get a sway bar to work in most situations, it just makes the car a little less forgiving as conditions change.

I would say try taking off the front sway bar and see what happens. Also, try a rear sway bar, and take notes of how the car reacts. -Jeff