BMI's DB12R

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01-09-2009, 08:15 PM

#6706

darnold

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Quote:

Originally Posted by Clegg

My setup: (editing Jasons setup)

Front:
5 degree block w/ 4 degree castor
.020 linear springs and 30K on the kingpins
3.5mm ride height
servo flat w/ medium ballstuds on the steering blocks
Lilac front tires (Jacon Prism stock height)
.25mm droop (I think this is how much droop, but not exactly sure - I was in a rush when I was testing this)
Servo mounted forward with the ball studs on the back of the servo saver
-1.5 Deg Camber
Neutral Toe

Rear:
Gold center shock spring
Silva shock w/ 60 wt Trinity oil
Medium ballstud on shock mount w/ 1.5mm worth of spacers
batteries in the middle
30K in the tubes
Stock flex plates mounted in short position
no tweak screws
Yellow rear tires (at full Jaco Prism size)
172mm rear width
1mm pod droop
Pod Level at ride height
4.0mm ride height

Novak 17.5 BL
Pinion: 45
Spur: 78

Body - Protoform Speed 12

I have 10K and I have 30K silicone, and the hobby store says they cant order 20K cause they cant find it. They also dont know know where to get Sure lube from. Not entirely sure I am going to start experimenting and mixing 10 and 30K to get 20K.

I found that while running thinner lube helps rear traction some it also allows the car to transition faster and turn-in a little better. So far I like 10K in the tubes but traction differences could change this.

Losi makes 20K diff lube so you can ask your shop to try them as it sounds like Jason and the gang have you just about dialed.

Just curious, have you tried the longer position on the flex plates (no tweak screws) with the batteries back? If so what did you think?

01-09-2009, 08:21 PM

#6707

Clegg

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I used to run the long flex plates and the batteries a bit further back, but I also had the servo different up front, and no king pin lub on the front, and 10K in the rear. So I am not really sure if I can compare the setups at all. The more run time I get on this setup the more I can experiement a bit.

I noticed a bit of pitching and excessive chassis roll with the plates in the long config. Where on high bite areas of the track I would get the car to lift a rear wheel and diff out on some tight corners. Stiffening up the damper tubes and going to the short plates with the rest of the changes I made fixed that entirely it seems.

01-10-2009, 03:08 AM

#6708

tellan

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Lower suspension arms WEAK LINK ??????

Any reported problems using the kit lower suspension arms.How do you over come the ball slop.
Also doesnt seem to to be much meat on the screw fixings .Has any one replaced these with the IRS AE lower arms.
The one good advantage of the BMI arms is theya are not handed

01-10-2009, 04:53 AM

#6709

SMOKESHOW86

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I have two questions:

1) How do you set degree's of caster

and

2) How do you set droop on the front

THanks

01-10-2009, 05:58 AM

#6710

SteveL

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Quote:

Originally Posted by tellan

An old trick for front lower arm ball slop is to pop the ball in the arm and then take a pair of slip jaw pliers and pinch the arm on the sides of ball socket. Usually only takes one pinch, but don't go over board, you can always pinch it again until the slop is gone. If you go to far the ball will bind.

01-10-2009, 07:22 AM

#6711

xtrememadness

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Quote:

Originally Posted by tellan

the new irs arms are weak. you can minimize breakage by first tapping the arms with an 8/32 tap before you screw them in. also use either titanium or steel front screws. the aluminum bends like prezels and breaks the arms.

01-10-2009, 07:28 AM

#6712

xtrememadness

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Quote:

Originally Posted by SMOKESHOW86

I have two questions:

1) How do you set degree's of caster

and

2) How do you set droop on the front

THanks

smokeshow86. you change reactive caster by changing the caster blocks. they come in 0,5,10 degrees. this is how much camber gain you have as the suspension travels. your static caster is adjusted with the upper arm shims. both shims in front is 2 degrees, 1 in front and 1 in back is 4 degrees, and both shims in back is 6 degrees. front droop is adjusted with your king pin shims. the less shims the more droop. if your running the linear springs run 1 gold shim on top of knuckle and 2 on top of arm. this is with standard king pins

01-10-2009, 10:34 AM

#6713

tellan

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shock length ?????

Just built my BMI 12RR Following instructions to the letter.If you make the shock 66m as suggested it is far too short.
So what is the recommended lenght from cup to cup.
Also are you running pod and chassis level off .

Also does any one use locktite on the screws holding the L-Plates to the chassis.
Also what do the Alan screws on top of the ball pivot do.??????

Also strange no anti roll mast and only one servo mount.Not a problem but inconvient.

01-10-2009, 10:47 AM

#6714

xtrememadness

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Quote:

Originally Posted by tellan

depending on what holes in the chassis you use will determine your length. i run mine in the hole farthest back on chassis. with the silva bladder shock i cut my ball cups to achieve 1mm of droop. this short setup gives alot of steering. there is no need to use loctite. and the alan screw on the pivot ball is to adjust the tension on the side plates. you want them to be tight but fall on their own weight when you let them go

01-10-2009, 10:47 AM

#6715

Uga

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66 mm was probably length for the old car. What I am using on the RR conversion is ~83.5mm long shock with 2nd and 3rd antena post mounting points when looking from front.

01-10-2009, 11:32 AM

#6716

Clegg

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Quote:

Originally Posted by xtrememadness

I switched to the older style IRS lowered arms (AE arms milled to be .06 lower I think). BMI sells them as the 1/10th scale lowered arms on their site.

Much more meat for the screws and you can still lower down to run the wheels on the rims if you wanted. You also dont need to use nearly as many shims for ride height.

01-10-2009, 03:42 PM

#6717

Clegg

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Oh and BTW I got in the Shure Lube today and switched form 30K to the #4 Red. It feels very similar, but we shal see how it goes tomorrow. I got a bottle of #3 and #4.

01-10-2009, 10:21 PM

#6718

kobiwan

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I have the new silva center shock, and I am having problems with it. First I couldn't seem to build it without it getting air in it or sounding squishy. I mentioned that on this thread and got some building tips that seemed to work. But after a day of racing it makes that squishy noise until I rebuild it again, and then it is fine until I race again. Any help would be appreciated. I am currently looking to replace it with another shock. Will the nickel teflon macro shock (part #DB3060) work on the DB12RR or is that for the 1/10th scale pan car?

01-10-2009, 11:44 PM

#6719

SpraydbySprague

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Quote:

Originally Posted by xtrememadness

I spoke to Dave Irrgang abut the breakage issue with the lower arms. From our conversation, I learned the titanium screws may be slightly larger in diameter compared to the aluminum screws supplied with the arms. I am running on the original IRS arms supplied with my DB12RR since October and have tested the durability thoroughly.

I also pre tapped the holes, I believe this is a big help. I also run the aluminum screws in the front end. Yes I do tweak a screw at least one a week, but they're cheap and act as a stress point.

01-11-2009, 12:06 AM

#6720

InspGadgt

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Makes sense...I ran the original aluminum screws that came with the IRS arms...That with the BMI spacers is what I think stopped my breakage issues when I was still running those arms