CRT.5 Big Bore Shocks done easy & cheap

now i will have to do this.........


really looks great

[lincpimp]

I have all the parts to do this, and will have to give it a try!

[Finnster]

I like how this mod turned out. I was a bit skeptical at first, but seems like it fits really well.

I wonder if there is a business opportunity for Mike to make a new F shock tower to accomodate the GTR shocks, and provide a few mounting holes for adjustability. Perhaps a bit of work on the body mount as well. Considering its just a flat plate, it should be a piece of cake for him, and there are tons of .5 drivers that would go for the mod vs the very expensive DM-1 shocks.

[GO-RIDE.com]

Skeptical, how dare you sir. I originally made a front shock tower that had mounting holes about 12mm above the original ones, but I did not like the way the body was lifted up. However, it would be nice to have a tower that had two or three holes inboard near the body post holes we are using for mounting the GTR shocks. I'd like to be able to get more up travel and reduce the amount of droop.

[Finnster]

I have the rear LXOne shocks installed in the back, but have not cut any coils. 30wt oil. Still waiting for the F springs to come in to finish it.

Ran it a bit in some rough sandy areas, and the back seems pretty good so far. It does sit a bit high, and I noticed it tended to roll on asphalt were it would hold or slide before. Its def got to come down a bit.

Otherwise I was looking at getting some lighter springs as well. My .5 has the OFNA Ex chassis and small 3S 2500 batts, and @ ~2000g+, may be lighter than some RCM ext chassis conv. Anyway...

I couldn't find a rate for the std yellow LX1 springs. So I tested it and came up with a value of 76 gF/mm (or 4.26lb/in, 0.75 N/mm (trx style).)


Spring rate converter FTW

I also found an HPI Spring that fits well. Now the package rates that as 71 gF/mm (3.96lb/in, 0.70N/mm) but I tested that as well and came up with 59 gF/mm (3.3lb/in, 0.58 N/mm.) IDK why I came up with such lower values than HPI did. My method was slightly crude, but was very reproducible.

Shouldn't matter too much, as I just wanted to get a relative rating to the other springs in that series for the Hellfire. The blue spring I used was softest, while the OFNA yellow spring seems closest to the HPI silver (soft) spring FWIW. The springs are long @ 80mm vs ~72mm for the OFNA's, but both need to be cut down anyway.

GO-Ride: How do you determine what length to cut the springs too? Why wouldn't you cut them short enough to use the stock shock mounting holes? LMK, as I don't want to trim any springs until I am sure on what I am doing. Thanks

[Finnster]

So I tested the CRT.5 springs using the same method as above. I used the rear grey springs as well as the blues.

Grey: 59 gF/mm
Blue: 63 gF/mm

The blue HPI hellfire springs are almost the same rate as the stock grey springs on the CRT.5. The yellow OFNA 1/8th springs are quite a bit tighter, and the blue crt.5s are in the middle.

I would guess the silver HPI hellfire springs are ~74gF/mm by my method, heaiver than the .5 blues, but still less than the yellow LX1 springs.

[GO-RIDE.com]

Originally Posted by Finnster

GO-Ride: How do you determine what length to cut the springs too? Why wouldn't you cut them short enough to use the stock shock mounting holes? LMK, as I don't want to trim any springs until I am sure on what I am doing. Thanks

Just from watching the car on the track it seemed that the yellows were pretty close in rate to what I wanted, but they were so long that I could not get the right ride height (bones level w/ 2.2 truck tires). So, I cut 1 coil off and tested them, the car still sat too high. I cut a second coil off and now the car needed a bit of preload to get bones level.

I don't have the crt.5 here with me, but if I remember right with the shocks mounted in the standard shock tower holes it was going to be very difficult to get the right ride height and the wheels would be very limited on up travel. From my experience with the car on the track mounting both the front and rear upper shock mounts inward gives the car good handling in the corners, lots of up travel for rough sections, and enough droop for big jumps.