BMI's DB12R

[Clegg]

Originally Posted by InspGadgt

The other nice thing about the IRS arms is they are universal left to right. So when you break an arm your spares will fit on either side.

They are a bit more prone to bending the screws and stripping out than the older IRS shaved AE arms of the past (which I have 2 sets of), but they are nice for getting the right ride height on worn tires.

I run the .060 shaved IRS arms normally and only go to the new IRS arms when the ride height is too low on the car with no spacers or shims under the older AE arms.

[PartTime]

Ok Thanks.

I was just wondering cause with my luck I break a part before I can get spares and if sombody had the AE arms I now know I can run those too.

How about the old L-plate, it has one hole, is that the short setting for the new L-plates? I have the old car and its gonna be a few before I can update or pass this one onto my son and get a new one.

Tonight will be my second race with the new car. Got it pretty close last week. Made a few changes to settle it down. Cant wait to get out of work and get to the track. Will post my findings.

DK

[protc3]

Originally Posted by PartTime

Ok Thanks.

I was just wondering cause with my luck I break a part before I can get spares and if sombody had the AE arms I now know I can run those too.

How about the old L-plate, it has one hole, is that the short setting for the new L-plates? I have the old car and its gonna be a few before I can update or pass this one onto my son and get a new one.

Tonight will be my second race with the new car. Got it pretty close last week. Made a few changes to settle it down. Cant wait to get out of work and get to the track. Will post my findings.

DK

The standard mounting holes on the flex plates on the DB12R are the same as the short mount on the DB12RR.

[Clegg]

Just some fun facts.

I have a CRC front end built up and am going to test it at some point here (as soon as the right bearings get delivered... the front Al Axels on this front end suck... who uses 3/16x5/16 bearings?!)

But I weighted the two to see how they compare:

BMI AE Dynamic front end - 34gm

CRC Pro-Strut front end - 40gm

So just adding on the CRC front end could add 6gm or more to the front of the car. Not a whole lot, but its something! I plan on getting the CRC front end built up to test on different track layouts and be able to swap the BMI front end with only swaping the turnbuckles and arm assy's themselves. Should be interesting to compare the two. I am pondering getting the long arm setup for the CRC to see how that feels.

Another thing of interest is that the BMI/AE main sterring block screws barely thread into the CRC arms... they went in very easy... but I notice that after taking them out that they barely cut a grove into the arms. This means they could strip quite easily. And you CANT use the CRC spec steering block screws, or Ti option ones they have. I bought a set of those and found out the hard way you cant use them on the BMI chassis. The reason is - the BMI screws have about 2.5mm of taper or cone on the head that seats in the chassis. This matches perfectly to the counter sinking on the chassis. The CRC screws have less than 2mm and are quite acute on how they taper in from the outside of the head. This means they woble in the chassis, damage the chassis, and dont screw in straight every time. I have 2 ovaled holes on my 4cell chassis for one of my steering blocks because they wobbled when I tapped the boards and ended up just eating the edge of the hole in the chassis. That was with the CRC Ti screws. All flat head screws are not made equal!

[protc3]

Originally Posted by Clegg

Just some fun facts.

I have a CRC front end built up and am going to test it at some point here (as soon as the right bearings get delivered... the front Al Axels on this front end suck... who uses 3/16x5/16 bearings?!)

But I weighted the two to see how they compare:

BMI AE Dynamic front end - 34gm

CRC Pro-Strut front end - 40gm

So just adding on the CRC front end could add 6gm or more to the front of the car. Not a whole lot, but its something! I plan on getting the CRC front end built up to test on different track layouts and be able to swap the BMI front end with only swaping the turnbuckles and arm assy's themselves. Should be interesting to compare the two. I am pondering getting the long arm setup for the CRC to see how that feels.

Another thing of interest is that the BMI/AE main sterring block screws barely thread into the CRC arms... they went in very easy... but I notice that after taking them out that they barely cut a grove into the arms. This means they could strip quite easily. And you CANT use the CRC spec steering block screws, or Ti option ones they have. I bought a set of those and found out the hard way you cant use them on the BMI chassis. The reason is - the BMI screws have about 2.5mm of taper or cone on the head that seats in the chassis. This matches perfectly to the counter sinking on the chassis. The CRC screws have less than 2mm and are quite acute on how they taper in from the outside of the head. This means they woble in the chassis, damage the chassis, and dont screw in straight every time. I have 2 ovaled holes on my 4cell chassis for one of my steering blocks because they wobbled when I tapped the boards and ended up just eating the edge of the hole in the chassis. That was with the CRC Ti screws. All flat head screws are not made equal!

General rule is imperail screw heads are 82 degrees and metric are 90 degrees. You can get different head angles but those are standard and are what our holes are countersunk to.

[InspGadgt]

Originally Posted by Clegg

They are a bit more prone to bending the screws and stripping out than the older IRS shaved AE arms of the past (which I have 2 sets of), but they are nice for getting the right ride height on worn tires.

I run the .060 shaved IRS arms normally and only go to the new IRS arms when the ride height is too low on the car with no spacers or shims under the older AE arms.

I haven't had any bent screws yet with mine but I think that is largely because I am also using the BMI front spacers as well which seem to brace the screw a lot better.

As for the CRC screws...I don't know about the titanium ones but I've been using the Aluminum ones on mine for a long time with no problem. The IRS screws that come with the IRS front end are just a bit more narrow though.

[PartTime]

Last night was pretty wild. For the first time they had a tight technical layout. The elite guys could get into the 9 sec lap range but mostly low 10's. 9.7 was the fastest lap of the night.......

I tried the servo behind the linkage last night and think its better upfront. My tie rods were striaght and like that much better than any kind of angle. I still have to run the red shock spring with 2deg of caster to get the onpower steering the way I like. I think that when I move the servo forward I might be able to get the gold spring to work witch might help settle the car down some.

I also tried the thin L-plate last night. Very nice. Smoother and like the feel of the chassis with a little bit of roll to it. About half way threw the second round my car looked and drove awsome. Chassis was working great. Still really responsive around center though. Started with Jack the gripper. I got some Paragon to try and it smoothed the car out nicely. Ripped a 9.6 in that run also. My next test is with some other tires. Gona try my trusty Black/grey combo to really settle the car down. If it works like it does on the other cars I have tried......its dialed!!

I did have one problem last night. Like I said, tight track and a overly responsive car dont mix. Managed to smack a board pretty hard in the end of the second round. The car took a tweak. I reset the L-plates for the main and thought I got the tweak out but it still had some in the main and ended up pulling it after 3 mins to save the car. I was gona break it in half if I kept on driving it. uggg. Maybe I bent a front screw?

What would cause the rear to tweak? After resetting the L-plates I looked at the pod to chassis seam and it was off just a touch. Maybe the thin plates bend? Or the boss digs in to the end and holds it on an angle? I will dig in to the car this weekend and let you know what I found if anything.

My setup is pretty much the same as I listed before but theres 35 wt in the shock and thin L-plates for changes.

DK

[Clegg]

Originally Posted by InspGadgt

I haven't had any bent screws yet with mine but I think that is largely because I am also using the BMI front spacers as well which seem to brace the screw a lot better.

As for the CRC screws...I don't know about the titanium ones but I've been using the Aluminum ones on mine for a long time with no problem. The IRS screws that come with the IRS front end are just a bit more narrow though.

The CRC Aluminum ones are the same specs as the Ti ones. The screws only seat on the very edges of the head due to their more agressive head angle. Look at a comparison pic below, and the damage they did to the 4 cell chassis I just retired. This caused me some serious headaches as the front end would move on minor wall taps and tweak the car badly.

[Clegg]

Originally Posted by PartTime

Last night was pretty wild. For the first time they had a tight technical layout. The elite guys could get into the 9 sec lap range but mostly low 10's. 9.7 was the fastest lap of the night.......

I tried the servo behind the linkage last night and think its better upfront. My tie rods were striaght and like that much better than any kind of angle. I still have to run the red shock spring with 2deg of caster to get the onpower steering the way I like. I think that when I move the servo forward I might be able to get the gold spring to work witch might help settle the car down some.

I also tried the thin L-plate last night. Very nice. Smoother and like the feel of the chassis with a little bit of roll to it. About half way threw the second round my car looked and drove awsome. Chassis was working great. Still really responsive around center though. Started with Jack the gripper. I got some Paragon to try and it smoothed the car out nicely. Ripped a 9.6 in that run also. My next test is with some other tires. Gona try my trusty Black/grey combo to really settle the car down. If it works like it does on the other cars I have tried......its dialed!!

I did have one problem last night. Like I said, tight track and a overly responsive car dont mix. Managed to smack a board pretty hard in the end of the second round. The car took a tweak. I reset the L-plates for the main and thought I got the tweak out but it still had some in the main and ended up pulling it after 3 mins to save the car. I was gona break it in half if I kept on driving it. uggg. Maybe I bent a front screw?

What would cause the rear to tweak? After resetting the L-plates I looked at the pod to chassis seam and it was off just a touch. Maybe the thin plates bend? Or the boss digs in to the end and holds it on an angle? I will dig in to the car this weekend and let you know what I found if anything.

My setup is pretty much the same as I listed before but theres 35 wt in the shock and thin L-plates for changes.

DK

I've found the thin plates sometimes dont fully center the pod on their own, it doesnt affect handling when driving but if you hold the car in the air and move the pod side to side I find the weaker the flex plates the less centering I get. As long as its equal side to side I dont think there is much of an issue with it.

[protc3]

Originally Posted by Clegg

The CRC Aluminum ones are the same specs as the Ti ones. The screws only seat on the very edges of the head due to their more agressive head angle. Look at a comparison pic below, and the damage they did to the 4 cell chassis I just retired. This caused me some serious headacges as the front end would move on minor wall taps and tweak the car badly.

Those are 100 degree heads. Similar to the AE bulkhead screws for the B4 and T4

[PartTime]

Originally Posted by Clegg

I've found the thin plates sometimes dont fully center the pod on their own, it doesnt affect handling when driving but if you hold the car in the air and move the pod side to side I find the weaker the flex plates the less centering I get. As long as its equal side to side I dont think there is much of an issue with it.

Ya looks like it leans to one side only. I will tear the car down in the next night or two and check everything. Not sure if its the back or the front thats doing it.

Thanks
DK

[luic]

I start to mount the DB12RR, when i mounted the front i see, with the shims how say the manual, i note more spring preload, and i don´t like it, i mount only 1 shim up, and have sligty preload.
For the low arms, i have a screw, for make strip in it, before mount with normal screws, and is fine.
In rear, the pod is not than free i like, when mount the L plates, i working in this part now.

In other hand, the carbon pieces and IRS parts, have a very good feeling.
My big problem, is with Imperial units, i have a caliper with both units, and have to use constantly.

Greetings, Luis C.

[Clegg]

Originally Posted by PartTime

Ya looks like it leans to one side only. I will tear the car down in the next night or two and check everything. Not sure if its the back or the front thats doing it.

Thanks
DK

If you find whats doing it, please post. I just looked at mine and noticed also that it doesnt perfectly re-center more to the side with the diff on it. I remains dropped down about .5mm or so vs the other side which remains .25 or less. I have taken off the dampening tubes, and wires from the motor and it still does it. I may just go and clean out/rebuild the pivot balls on the flex plates, maybe there is some crud in there binding it up.

[Clegg]

Originally Posted by protc3

Those are 100 degree heads. Similar to the AE bulkhead screws for the B4 and T4

The smaller CRC screws you are talking about? the big one on the end is the BMI alloy screw, the two smaller ones are the Al and the Ti CRC screws. now if I can find some Ti flat head screws that use hex drivers that have the proper 82 deg head angle and head length, I'd be in business I hate using big phillips screw drivers on a car that everything else is Hex.

[InspGadgt]

Yeah I can see the difference...though I still haven't noticed any issue with them. Possibly because the aluminum ones are softer then the titanium and might conform some.

As for proper angled Ti screws...maybe the Lunsford ones?