Help!! What oil and pistons for Tamiya dampers on Procat?

[kaszal]

OK I give up... I really need help setting up the shocks in my Procat. It's been running well (transmission's holding up and even raced it a bit at Stotfold) but I can't seem to get it to handle or land right. I'm probably fighting a losing battle (I'll probably get a modern car next summer) but I'm sure I can get it to handle better.

I'm using the Tamiya aeration buggy dampers, which are the same as on the 501x and DB01-R. I've drilled the bleed caps so they can be used. The problem with the front of the Procat is the shocks are very layed down and there's virtually no adjustability. I've removed the anti-roll bar so I could move the lower shock mount out and the ride height is OK now. I've had to use No.2 piston and 60wt oil just to firm it up and stop it bottoming out... but it feels odd. Using black Losi springs at the moment.

At the rear I was using No.4 piston and 40wt oil. Losi yellow or pink springs. The rear is bottoming out after jumps and bending the rear wishbone carrier bolt. I've just changed the piston to No.3 with 30wt oil. There's a bit more adjustability in the rear shock mount positions. Do I just need to raise the ride height or stick with No 4 piston and a heavier oil?

Has anyone else experienced this frustration? Anybody remember how they set up their Cat or Procat? Any help appreciated. Cheers

[dangermouse]

Those shocks look too long.

I used to run my cars with a setup similar to what Phil Davies used on his Procat which worked very well. http://www.rc10talk.com/search.php?st=0&sk=t&sd=d&sr=posts&keywords=phil+davies&start=15

[kaszal]

Thanks for the feedback.

So I need shorter shocks at the front (so I can get the roll bar back on) and shorter, stiffer springs too.

Which make could I use? (sorry I don't have any originals!)

[Jay Dub]

Well, without being able to watch the car running I can only offer a few hints. First, your oil is too heavy. In most situations, you sould never go heavier than 40w in the front, and 35w in the rear (unless the track is REALLY rutted). This means that you will most likelly need to change piston as well. Second, the front springs are propably too long. I would find a shorter substitute, or cut off 2-3 coils on the existing set. Also I would try fitting a rear, and possibly a front sway bar . -Jeff

[uzzi]

Hi Luke,

Based on what you have said (and not knowing what those piston numbers or springs mean) and having a close look at your car may I suggest a few things? Instead of looking for new shocks you may consider using shorter ball joints for the front shocks to shorten it. Agreed with the shock oils being too heavy.....perhaps build the shocks with more rebound as well. This will make shock movement harder when compressed with lighter oils. Have you added weights to your car? I believe you are running LiFe battery packs which are very light compared to the nicads batteries the original car was designed for. Perhaps look at where you place them to change the balance. Also cars do not jump well when they are running very low clearance, run more ride height and use sway bars to stop it rolling. However, set the car for handling and not for jumping; try to drive around the issues with the jumps.

You probably know this but look at your driving as well.....do the jumps have landing transitions or are you are landing on flat ground? If you are landing on flats it is pretty much a given that you will chassis slap the ground (not much you can do there). Maybe just slow and bunny hop over those jumps. If you have transitions then try to land on the down transition section (watch videos of Jared Tebo in action). Do you need more of a run up to clear certain jumps? you will have to change your lines if that is the case. You can change the attitude of the car by applying brakes and also gassing it whilst it is in the air (once again watch Tebo at work).

Mate hope these tips helped.....cheers!

[kaszal]

That's great, thanks Chris and Jay.

I've already cut down some Schumacher ball studs and also found some stiff AE springs that are a bit shorter (1.66" instead of 2")

I'll let you know how it goes!

[DerbyDan]

Hi Luke, Having seen your car running at Stotfold, from momory I would say that your car firstly looked both under-damped & under-sprung - it handled the undulations quite nicely but at you say was not good over the jumps & seemed to roll alot in the bends.

However probably the most obvious thing was that your tyres were pretty worn - probably the same ones as in the pictures above?? Causing the car to spin round easily. Are you now using nice fresh tyres? - green compound in the wet/damp & yellows for the dry?

I would be inclined to change (at least temporarily) your shocks & springs for some Bosscat Vari-shocks & run the base set-up recommended in the manual - I would also add some weight around/under the batteries to bring it up to approx the weight of the car if it had a pack of Nicad cells in it.

[kaszal]

Thanks for the detailed advice. Yep, I've got some nice new mini-spikes on now.

The shorter ball cups really help too. I'll also change the front pistons. I've got Tamiya No 2 in at the moment (two 1.2mm holes each) but will try two 1mm holes (I'll drill some blanks) unless there is an alternative?

Ideally I'd like to keep using the dirt shields with the wider Losi springs... but all the front springs are 2" long. Are there shorter ones with a high spring rate e.g. 4 or more?

AE ones are on order from Wheelspin Models

[Jay Dub]

I use associated front springs on most of my cars. I always ended up cutting a few coils off of the other manufacturers (schumacher, Losi, etc.) fronts, so I figured why not use something easily replaceable and repeatable. I do however use one Losi spring on occasion that often works well (given the right track conditions ). It is a silver Rally Car spring. It is 3 pounds, is an excellent length and is made for Losi shocks. BTW, When going to a shorter front spring, you don't necessarily need to use a stiffer spring. A 3lb spring it still a 3lb spring -for 1 inch, it is just more progressive. You will just usually have a little more "preload" (for lack of a better and much longer explanation). As far as the oil is concerned, start with 35wt in the front, and 30wt in the rear. These are good all around oils to start with, and will allow you to get your pistons dialed in. If the car feels too light, put finer pistons in the car. If it feels to heavy, do the opposite. These weight oils are a good static constant for a 4wd car, and you should not change them untill you have a better understanding of how your shocks are reacting on your car. Once the car is acting properly on the track, then you can make finer piston/oil adjustments. -Jeff

[dangermouse]

Yea shorten those front shocks so they can be moved in to allow the front swaybar to be refitted. Should help with body roll a lot, and smoothen steering.

Some other things you could try are, at the back, shims between the inner wishbone mount and gearbox on the rear screws, gives a bit more rear toe-in. At the front, shims between the upper wishbone mounting to shock upright for less camber. Both help to really tame the Cats and make them much easier, and more consistent to drive.

BTW Lazer ZX-5 shocks are pretty much identical in length to the original shocks.

[kaszal]

Cheers! I'm making progress with the refitted sway bar, shorter ball cups, AE springs and drilled pistons. Got an important question though...

Does anyone know the spring rate on the old CAT or Procat springs? Those old Schumacher front springs had few coils didn't they, almost like a touring car spring.

[Jay Dub]

I may have a spring chart around somewhere for the old springs, but if I remember right they are not rated in inch/pounds though . Also, the schumacher front springs are long like a losi front spring. A long front spring is good in certain conditions, namelly when you need a car to dive and pivot more quickly with the front end (e.g. a tight 180 degree turn). Rarely is there more than one or two of these type of turns on any given track though. So, it wouldnt be prudent to set up your car for one turn on the track, and suffer on the rest. I am currently running a Lazer ZX5 FS, and reallly like the AE silvers on the front. I change between them and the Kyosho Yellow, or Yellow/orange (which are slightly longer) depending on the track layout.-Jeff

[kaszal]

Thanks. I've fitted AE blue springs to the front. They are fairly stiff (spring rate 4.20) and the length seems better too (1.66") The Losi springs turned out to be too long (2") but I'm very curious what the stiffness of the old springs was. Cheers.

[Jay Dub]

Well, I just looked at my old spring chart for the colored Schumacher springs, and low and behold there is no rating info. Just the colors, and the length in order form lightest to stiffest. I guess I will just have to setup a spring "dyno" at some point. You may be able to find out what the ratings are from schumachers web site however. -Jeff

[Jay Dub]

Well, I just looked at Schumachers web site, and checked out the CAT 3000 exploded view. It looks as though it gives a spring chart for their various springs including a "short" front sping set. I would imagine by the info given, that the ratings are in lb./inch. Good luck, hope this helps. -Jeff