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Pro Cat revisited 20 years later

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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 11 March 2012 at 6:16pm
I may try the yellows outdoors, on the carpet last night the blues gave pretty good grip in fact it grip rolled a couple of times! I certainly didn't struggle to turn in at all nor did the back end kick out, I could pretty much choose the line I wanted. The only thing I really struggled with was the car getting hot. I was thinking of putting some holes in the shell or installing a fan. Indoors only has a couple of tame jumps but they go outdoors to their purpose built track in April. Some tips on setting up for outdoors would be good, especially clearing triples without bottoming out or smashing it to pieces? Here is a link to the Broxtowe outdoor track:
 
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kaszal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 11 March 2012 at 6:28pm
They say boiling 20 year old plastics is a good idea to make them less brittle. Something to do with relieving stress from moulding and/or absorbing moisture... but I'm not a chemical engineer.

Mine also tends to bottom out and doesn't fly well (could be the driver). Maybe you could try thicker oil and more droop? Personally, I wouldn't try to clear a triple because spares are too precious.

For a moment there I got excited because I thought it was a video of your Procat racing.
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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 11 March 2012 at 6:48pm
I am tempted to keep my procat for indoors and look to get an SX/SX2/SX3 or whatever comes up cheap second hand. What different spring rates have you tried outdoors as, from my experience of working on full sized race cars the stiffness should be controlled by the spring rather than damping. The damping should be as soft as you can get away with, its a misconception to make the car stiffer by increasing the damping certainly on a 1:1 scale
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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 12 March 2012 at 8:36pm
Originally posted by Dazzieboy Dazzieboy wrote:

Thanks Luke, not sure where to start with the settings as I don't know spring rates only oil (losi 30wt) and shock positions, ride height etc. When I give the car a once over during the week I will post some pictures and take some measurements. I can tell you that I don't use a roll bar front or rear and I was using mini pin blues front and rear.
I've had a quick measure up of the ride heights and the front is around 24mm from floor to bottom of the front bumper (that's around 7mm of droop). The rear is around 14mm from floor to undertray (around 17mm of droop). So it is sat down quite a bit at the rear but I did that to clear a particularly nasty hump that if taken at any kind of speed would just kick up the rear then nose dive and cart wheel. Here are some rather crappy pictures of the front and rear so that you can see the shock positions etc:
It seemed to work quite well and stayed really neutral around the bends, I was making up time on the modern cars through those bits then loosing down the straight. My plan is to get the slipper clutch installed then look at doing the 6mm belt mod so that I can graduate to a brushless motor / esc combo. Bearing in mind that I am running an 11 triple brushed motor at the moment, what brushless could I get away with? Nothing too hot that it shreads belts / gears.
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kaszal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 12:42pm
I've got my Procat set up as follows...

Front: Losi 30wt oil, 2x1.3mm dia. pistons, Schumacher 3.5 grey springs

Rear: Losi 30wt oil, 2x1.4mm dia. pistons, Schumacher 3 grey springs

Have a look at the photos below for ride height, droop and shock positions. What do you think?

I see you're using the Shotgun rear hubs. I'm thinking of changing back to those to see how it will affect the handling. The rear kicks up on mine too. I've got a 6.5T in mine at the moment. I recently loosened the long belt a little by sanding 0.2mm off the front gearbox spacers.













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kaszal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 12:47pm
It looks like we're both setting the ride height to drive shafts level.

I think I'm not getting the right camber gain with the angles on the Work rear hubs. The Shotgun hubs look better for that... but my knowledge of suspension geometry is very basic.
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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 2:06pm
There is certainly a lot less negative camber on the rear of mine than at the front (the front being standard and therefore not adjustable). Have you tried running without roll bars as that will soften things up no end and should improve grip on slippy tracks? I knew my rear hubs were not standard as they didn't match what was in the manual I downloaded but didn't know what they were from or what advantage they gave. I like how you have put a bolt through the rear gearbox to hold the lower wishbones on I was thinking the same as one of mine pulled out on saturday whilst racing, do you have a spec for size and length? M2?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 2:34pm
The front camber is adjustable if you put some washers between the front upright spacers like Phil Davies (see photo below)

Thanks for the tip. I don't normally use a front roll bar. I'll try mine with and without the rear roll bar.

It looks like you're using U1000G Shotgun hubs. With my Works hubs I'm concerned the camber link is rubbing on the inside of the wheels.

You need an M3 x 70 bolt. The Robbe part number is S0107. Let me know if you find a supplier!


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kaszal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 5:11pm
Forgot to say the bolt needs to be cut down to 64mm length (excl. head)

I have a spare if you want one. It's used. I'll just post it to you now Wink


Edited by kaszal - 13 March 2012 at 5:25pm
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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 6:31pm
Thanks I found this so may order some so I have spares:
http://www.modelhelicopters.co.uk/m3-x-70mm-bolt-pkt-5.html
I notice that your front shocks are more horizontal than mine due to being in the further out holes on the wishbones, they also look longer than an original shock? What is it that you are trying to achieve or overcome with the setup? If I know that I might be able to help
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kaszal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 7:26pm
Wow, those bolts are expensive!

The shocks are longer than the original Schumacher so I have to lay them down to get them to fit. I changed them long ago so I could get spare seals, shafts, springs etc. The other reason is to get the roll stiffness I need without the roll bar.

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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 7:48pm
I have a bolt company near me i might try them. Are they threaded all the way down or a straight shank? If so what is the length of the shank before the thread starts?
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kaszal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 13 March 2012 at 7:51pm
52mm is unthreaded then about 12mm of thread. They are black and seem stronger than stainless so do you reckon they are high-tensile steel?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 19 March 2012 at 9:23pm
Darren, are you able to compare the Schumacher rear springs you're using with some modern ones? With trial and error you could probably estimate the spring rates to within 0.5 lb/in. Also, if you squeeze two springs together end-to-end you can see which one compresses more and is therefore less stiff. I reckon my front F6 springs (kit standard I believe) are about 4.5 lb/in.




Edited by kaszal - 19 March 2012 at 9:24pm
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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 23 March 2012 at 7:34pm
So today I made some shafts to hold on the lower rear wish bones:
I did this by getting some 3mm steel bar and cutting to 65mm. Then I cut around 3-4mm of thread on either end and secured with two nyloc nuts.
I then drilled through both holes on the car with a 3.5mm drill
Looks pretty neat I think and should strengthen the back end up for when I go outdoors. Thanks Luke for the idea Clap
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kaszal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 23 March 2012 at 7:37pm
Those are very nice, well done. What steel is that? I had some in stainless steel but they were softer than the Robbe bolts I have now.

I guess you don't have the alloy inner trans hsg but you have the alloy z-bracket. Nice.


Edited by kaszal - 23 March 2012 at 7:41pm
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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 23 March 2012 at 7:45pm
Its only bright mild steel as I messed up the order and should have ordered stainless instead. My thinking was that it is better to bend than snap so didn't want something too hard. I may upgrade to stainless when I can get hold of some
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kaszal View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kaszal Quote  Post ReplyReply Direct Link To This Post Posted: 23 March 2012 at 8:10pm
It is a weak point, especially when you start hitting those big jumps!

When you next taking her out for a spin?
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Dazzieboy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 23 March 2012 at 8:24pm
Not sure, I couldn't race last weekend as we were visiting family in Kent and can't go tomorrow as the wife is away on a hen weekend. I think tomorrow night is the last one indoors before they have a month off then start outdoors so I might try and get down the outdoor track for some practice
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dazzieboy Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2012 at 12:58pm
So I got myself some Cat SX shocks cheap on ebay which came with an almost full set of springs (only the blue and black missing from the rear). So I set about fitting them last night starting with the fronts:
As can be seen the SX fronts are quite a bit longer than the Procat fronts and as a result provide a lot more droop when fitted:
However still compress to the same point:
Comparing the springs, the Procat spring was about the same as the black spring in the set which is the hardest available. I decided to go with the grey which is about halfway so it is sprung much softer. Along with the fact that the piston has 2 holes instead of one means there is also less damping when using the same 30wt oil. To reduce the droop and get a rideheight similar to before I moved them out a hole on the wishbones:
When rebuilding them I found one of the diaphragms was split so I replaced both with new and put in some 30wt oil that I had left over from rebuilding the Procat shocks.
 
Rears to follow........
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