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Old 02-18-2003, 08:58 PM   #3871
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Looking at the Snowbird setup from Paul it states that the bulkheads were raised 1 mm. Is this the same as the roll mod or simply another tunning tool? Want to put the setup on the car and wanted to do it correct...lol

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Old 02-19-2003, 01:17 AM   #3872
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Jeff:
At least what Teemu (and I) are running is that you place thin shim plates under the upper bulkheads. The diffs are not raised, but the upper wishbone mounting locations and the shock towers are raised.

My latest mod:
I've machined a 19t pulley as the 20t pulley made the rear belt so tight. It's running super free now! I haven't track tested it yet as the pulley needs to be anodized before that. I don't know if it will take the torque of a mod motor, but it probably is a hot ticket at least in the 19turn spec class. By holding the wheels and turning the spur it is very difficult though to make the belt skip. The diameter of the pulley is 16.36 mm kaming it 0.89 mm smaller than the 20t aluminum one in diameter which is 17.27 mm when new.
I wonder how much is it possible to make a 20t pulley smaller or a 19t pulley larger without running into problems with noise or efficiency. I remember when the first Cat 2000 prototype came for JukkaS it had three different tightness rear belts supplied with it all with the same tooth count, so some playing around is possible.
Adjustable layshaft mounts are also under consideration if anyone has a clever idea how to make them.
BR/ JesseT
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Old 02-19-2003, 04:27 AM   #3873
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Default Layshaft Backset

On my custom built chassis I have moved the layshaft back 0.5mm for this reason.

Here's a few ideas.

You could drill out the 8mm bearing holes to 9mm and carefuly wedge the bearing so it sits back in the bigger hole. The belt will be free with the 20T pulley.

Or you could lower the bearing center height by sanding down the layshaft mounts until you belt is at the desired tension and then shim the top, the down side is that the maximum spur gear size could be (will be) reduced.

The first one is fairly easy to try with the plastic pieces.
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Old 02-19-2003, 06:25 AM   #3874
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Yes, I noticed you had moved the layshat mounts. Shimming the mounts up with the 19t pulley or down with the 20t pulley seems like a good idea. Not too thrilled about drilling the bearing holes longer. Your right, I can try it with the plastic mounts.

Another mod:
The ball cup of the upper wishbone creates much play quite rapidly causing weaker anti-roll bar operation. RPM ballcups are of good quality and thick enough to be drilled for a 4 mm turnbucle. Someone also reported of a suitable Losi ballcup somewhere. Being longer, these can also be used with the inline steering with the original bulkhead (as opposite to the Fusion bulkhead).
BR/ JesseT
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Old 02-19-2003, 09:00 AM   #3875
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Default Ball cups

Yes we have notice the same thing with the upper arms.

We have tried both RPM and Losi ball cups. I prefer the RPM long shank, I have re-threaded the 4mm link to 5-40 LH on the ball cup side. Now that I have dulled the thread s(taken the sharp knike edge off the thread) I hope to eliminate the breakage we experienced at the Snowbirds. We simply cut the ball cup a little and use the inline position.

If you try the plastic part trix you will have to be careful about the bit you use to oversize the hole and figure out a way to seat the bearing flange.

Paul
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Old 02-19-2003, 11:32 AM   #3876
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Shimming up the bulkheads was something that we did to reduce the camber change in the car and free it up through the corners. Its not really needed in average to low bite tracks. I ran mine with 2mm shim but its a lot more on edge.
The roll center mod is a totally diffrent change it effects how the car gets in and out of the corners.
Be careful to make sure all the shims stay in place while tightening the bulkheads down

andrew
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Old 02-19-2003, 03:18 PM   #3877
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Hi Jesse, I too have been playing with bulkhead shimming, I have fabricated various plates of Carbon, to sit under the bulkheads, they are in thicknesses of 1.5mm, and 2.5mm.

the 2.5mm plate gives me an upper link mounting position exactly inbetween the 2 standard bulkhead points. Nice tuning option, but the downside is that it also raises the shock tower, can be a problem to obtain correct ride height if using shorter than kit springs such as Ae.

Each plate is cut to the same shape as the base of the bulkhead, with rounded edges, and 4 holes drilled larger than the standard 3mm holes to prevent the plates tweaking or binding the diff halves when tightened down.

I have tested in doors using these mods, and found it had the desired effect in freeing up the car, without too much roll.
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Old 02-20-2003, 06:54 PM   #3878
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Now have you tried that adjustment on only one end at a time? Would raising the rear only, free up a car that has a push feel? Going to do some testing this weekend and just wanted to find out what I can kinda expect from that adjustment.

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Old 02-20-2003, 08:05 PM   #3879
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sure, you can try raising the rear bulkhead only, in small increments until it feels like it is pivoting to your liking.

I made a few of the thinner plates to allow me to do just one end in a small amount.
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Old 02-21-2003, 10:02 AM   #3880
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...just stopping by to say HI. The sun is out and the asphalt is heating up. Time to get racing!
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Old 02-21-2003, 03:18 PM   #3881
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Where you been man? Yeah, cant wait until asphalt ahhhh so fun
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Old 02-21-2003, 03:39 PM   #3882
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Quote:
Originally posted by Racer X
...just stopping by to say HI. The sun is out and the asphalt is heating up. Time to get racing!
Are you running tomorrow? If so email me and maybe I'll break the car out. It's all ready for the Norrca state champs next week in Bakersfield.
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Old 02-22-2003, 12:19 AM   #3883
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Paul.... I noticed that the team drivers have went back to the kit roll center in the front. Can you explain the plus and minus of each roll center and when you would use each and maybe tell us why you went back to the origanal roll center?
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Old 02-22-2003, 10:06 PM   #3884
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Well just got back from racing. One of those nights where some good and some head scratching happend. First of all I did TQ Pro Stock with my Mission tonight. But the car was just never dead on. The layout of the track has not changed in over 2 years...so sometimes a person can spend more time racing the track then the other cars there that night. I was .2 to .3 tenths off what I had run there with a different sedan. I am still learning the car and wanted to know if any piston/oil info could be shared here....

I ran the car with 2 hole pistons with 40 wt oil. The track is a smooth concrete with medium traction. The car looked to be rolling over a bit early in the night so I put Red springs up front Up from Blue. I also ended up with Red springs in the rear. As the night went on the car got real loose in any off power areas or in the middle of a high speed sweeper. I stood the front shocks up to the 4th hole out and layed the rear shocks in to the second hole. THe car just did not feel right. With my other sedan I ran 56 pistons and 50 wt oil and was very successful. Any help would be great in terms of what tips on shock pistons and oil to try (I know the exact one to pick would be tuff over the net but am looking for a process of steps people are using to hook up the mission).

Jeff
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Old 02-23-2003, 09:21 AM   #3885
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Jeff- try the 56 pistons w/ 50weight oil in the mission shocks...... it seems that no matter what sedan is used the piston/oil combo usually is close......
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