I was originally planning to run DM-1 shock towers in my Jammin conversion since they both use the same bulkhead, but then decided to use modified X2 towers. After kicking that around for awhile and also changing my shock choice (from 1/8 buggy fronts to Revo shocks) I finally found the perfect towers, which are from the IGT.

The IGT towers bolt right up to the Jammin bulkheads, since they are almost identical. There are only two small mods that had to be done. One was adding a tiny amount of clearance on both the front and rear towers, and was about 30 seconds of filing, VERY tiny amount of material removed (see pic 1, highlighted in yellow)

The second change was that the hingepin holes in the IGT front tower didn't line up quite right with the Jammin upper hingepin holder. I just decided to get rid of the front upper arms and hingepins altogether, and use a turnbuckle setup instead. Already had the parts in my spares bin. (see pic 2)

So now the towers are all set, and seem just about perfect for the Revo shocks with all mounting holes usable for plenty of adjustment. And the body mounts can be placed on the stock IGT tower locations rather than me guessing with the modded X2 towers, so I know the bodies will go on right. I'm going to run the plastic towers for now, but I'll definitely be saving up for a set of CF IGT towers.

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I like how you built up those diffs with a bunch of different brand parts, sounds like they are bomb proof. Any issues at all with fitment, anything not lining up/clearance issues and needing machining?

Awesome build though man, I'm not really a fan of onroad cars but this is top shelf, great work. I missed it somewhere in this thread, but what chassis are you using?

I am using a Moos Racing chassis, there is a thread about them in the "Product Reviews" section: http://www.rc-monster.com/forum/showthread.php?t=27360

The diffs all came together perfectly believe it or not, I call them Frankenstein diffs LOL! The only part I was unsure of was the Sportwerks TiNi ring gears, but they bolted up just fine. I had to shim them a bit inside the diff bulks, but you'd need to do that even with the stock diffs.

I am waiting on some CF ackerman plates to show up, and now also need to save up for CF IGT towers. Another thing is finding the right spring rate for the Revo shocks. For Jato and Revo springs there is anywhere between like 5 lb/in all the way to 30 lb/in. I emailed Nitrohouse to see if they know what the Ultra GTP and DM-1 use, just to give me an idea of where to start. Still waiting to hear back.

I don't mind it going a bit slow, I want to take my time and do everything perfectly to how I want it. No compromises! Plus I still have quite awhile left until the snow melts and I can actually drive it.

Very nice build, definitely interesting with a the mix of parts. FYI the manuals and parts listing for the GTP and DM-1 are availible on nitrohouse. E-GTP2 uses 1.8 springs all around, DM-1 didn't have a litsting for just the springs, but I might have missed it.

I did notice the GTP2e springs. The problem is that they are giving the spring in wire diameter and # of coils, and I need to find lb/in or N/mm. The good news is I found a few charts listing 1/8 on-road spring rates, and also a formula to convert wire diameter and # of turns (plus a few other values) into lb/in. So I should be good to go on the springs, at least a good starting point.

I have just about enough cash saved up for a body. Would love to hear opinions from you guys. I know in the end it comes down to what I like best, but always like to hear suggestions.

Here are the bodies I am choosing from: http://www.igthobbies.com/category_s/41.htm

EDIT: For anyone else looking for a good starting point for 1/8 on-road spring rate, here is the chart someone gave me. Seems like 20-60 lb/in is the average range.

I knew about the turns, didn't know they were giving the diameter instead of the rate though. Good to know. I like the 80's 911 body alot, it's different and looks proportional too.

It's nice that Bill from IGT Hobbies started bringing in the Deltaplastik bodies. They aren't cheap, but shipping is free. And you would pay the same or more ordering from Italy with the ridiculous shipping cost, and then you have to worry about it getting lost, delayed, etc. Bill said right now he gets the bodies on an order-by-order basis, and it's about 2 week wait. He said once he gets an idea of demand, popularity, etc. he might start having some in stock.

Got my CF ackerman plates in yesterday and mounted one up. Along with them I got a few small pieces of 3mm CF just to have on hand for any custom parts I might want to make. Mainly I am going to make a center diff top plate that extends out as a rack to mount the ESC.

Should have some more pics soon of the whole thing actually assembled.

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Would you mind posting the formula and where you got it? I'd like to add it to the calc pages, but want to give proper credit for the original location, if applicable.

Good idea Brian, I would really like if it was available on your site. It was posted on RC Tech a few different places, not exactly sure the original poster, or where they got it from. I added a few changes/notes also.

The formula for calculating the spring rate of a compression spring is the following:

K = (G*d^4)/(8*D^3*n) (remember your order of operations guys! :wink:)

where:

K = Constant (spring rate), pounds per inch of deflection, (lb/in)

G = Modulus of rigidity (shear modulus, approx. 11 million psi for steel)

d = wire diameter (in inches)

D = mean coil diameter: outer diameter of spring minus wire diameter (in inches)

n = number of active coils (the very last top and bottom parts where the spring is closed and ground are not considered as active coils)

Here is a calc at Engineer's Edge: http://www.engineersedge.com/calcula...ring_k_pop.htm

I tested out the formula and calc using a Revo spring of known rate, and it came out just about perfect using 11 million psi for modulus of rigidity. You can convert lb/in to N/mm (common metric unit for spring rate, used by Traxxas for Revo/Jato springs) by dividing by 5.7, and then of course N/mm to lb/in by multiplying by 5.7. Studying the formula you can see how a "progressive rate" springs are made, by either changing the spacing between coils at various parts of the spring, or the mean spring diameter at various points. It could also be accomplished by having a wire diameter that varied in thickness, but that's not very practical compared to the former 2 methods.

Believe me, in the search for the right springs for my 1/8 on-road conversion I learned more about springs than I ever thought I'd want to know!

When I still planned on using the 1/8 buggy fronts (Hyper 17mm Big Bores) I learned I would need to order springs from a spring manufacturer, since none of the available stock springs were firm enough. I found quite a few options, but they ranged anywhere from $10-30 a piece (most places required an order of 100+ to get anywhere near a reasonable price per spring.) That was one of the main deciding factors that made me switch to Revo shocks, which I'm glad of now as they seem perfect for the job.

Today I used one of my pieces of scrap CF to make a center diff brace with an extended shelf for the ESC. It will extend out towards the front of the car, so I can use the stock length MMP wires without cutting them or adding extensions. With the ESC and motor mounted to the center diff, and servo and RX mounted to the servo mount I'll be able to remove the electronics from the vehicle with 7 screws, and won't need to disconnect any wires. This brace also allows much easier Slipperential adjustment with the lipos still in the vehicle, with a wide opening directly over the adjustment ring.

I also purchased a body today. It was actually an auction on Ebay, when I saw the body I had to have it. Paid a little more than I wanted to win it, but I'm typically very frugal with my RC purchases, and for once I decided just to splurge (if it wasn't for one guy bidding 5 times in the last hours it would have been way cheaper! :grrrrrr:). I will leave you guys in suspense until it arrives... :wink:

The only thing I am waiting on to finish assembling the vehicle are some stand-offs to mount the shocks. Those should be here in the next few days, then it's all systems go!

http://i47.photobucket.com/albums/f1...3/P1030240.jpg

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Man, you been splurging with all that carbon fiber.

LOL! I guess all the money spent isn't as easily apparent to me since I've had a lot of it sitting here for awhile. The CF chassis was the main thing at $100, but that's not much more than what I would have paid for a brand new 7075 alloy chassis. The other stuff was either very cheap (ackerman plate, scrap pieces) or I already had it (servo mount, front brace, shock towers). Bill from IGT Hobbies gave me the plastic IGT towers for free just to learn if they'd fit. I'm putting the CF IGT towers on hold for now since I just spent my RC money on a body, but they'll come eventually. Those are really the last pieces of CF that will be going on the vehicle.

I am going to have to sell some motors and a pan car to fund some carbon fiber myself. Your ride inspired me to go carbon on one of my gtp.
Waiting for Ipanema to sell the speedrun body that is in the works.

Oh yeah, I saw you guys posting about that. Pretty cool to see a 1/8 body made exclusively for speed runs, sounds right up your alley. I chatted with Jspeed a few times on RC Tech, very nice and knowledgeable guy, answered a few questions for me when I first decided to do a GT conversion. I just kind of wish he wouldn't push his products in every single post. I mean I have no doubt it's good quality stuff, and nothing wrong with a little promotion, but it seems a little overboard to me. The wide rear tires are a good idea. If they ever got them in radial I would definitely try some.

So you going to do your own chassis out of CF sheet? It's nice that the GTP chassis is flat. If I knew I was going to do an on-road at the time I bought my Jammin chassis I would have had him leave out the kick-up. But at least if/when I decide I want to make my own CF chassis (probably after this one dies) I can just use sheet CF and not bother with kick-up. I've seen where people heat and bend CF, but I'd rather not deal with it at all.

Anyway, can't wait to see what kind of CF goodness you have in store!