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revo 2.5R to 3.3 chassis conversion... Any info?

Discussion in 'Traxxas Revo' started by olds97_lss, Jan 20, 2007.

  1. olds97_lss

    olds97_lss RCNT VIP Supporter

    Anyone know what you need to convert a 2.5R revo chassis to a 3.3 revo chassis? I wasn't thinking clearly when I just bought a 3.3 chassis for my revo. I found a crack in my engine bay and figured since I'm running a true BB that going with the 3.3 chassis may help make it more controllable... but I didn't think of what would be needed for the change.

    I'm guessing steering linkage, front center shaft and front skid. Is there anything else? Isn't the 3.3 just longer between the front of the trans to the front of the chassis? Nothing from the trans back is moved is it? And basically, isn't just the front shock mount moved forward, front center axle longer and steering linkage longer?

    I did a few searches and came up empty... Although, I didn't check traxxas's site to see if they had a comparable swap list like HPI has with the savage and savage x.

    Sorry for being dense guys. I'm guessing a few of you have done the swap though and I'd appreciate any input.

  2. SMaxxin

    SMaxxin SLAP YA MAMA Staff Member

    You guessed correct!
  3. olds97_lss

    olds97_lss RCNT VIP Supporter

    So, you know for a fact that those are the only chassis differences?

    I'm in the process of taking both the 3.3 parts list (as text) and the 2.5 parts list (as text) to create a database of bot sets of part numbers to find the differences... If you know it for a fact though, then it will save me about a half hours worth of work.
  4. SMaxxin

    SMaxxin SLAP YA MAMA Staff Member

    Yep, I actually put everything from my 3.3 onto a 2.5 chassis for a while...IMO the 2.5 chassis is a lot funner for a basher. The only advantage I found with the 3.3 chassis was the handling and the engine support. Let us know what you think when your done.
  5. olds97_lss

    olds97_lss RCNT VIP Supporter

    Cool. Thanks.

    While waiting, I had already converted the 3.3 chassis list to a usable format for diff'ing the two lists for differences. Now I can stop.

    Considering I'm running a NE BB kit with an OS 21 RG in my revo, it's wheely happy and I don't really want to gear much taller as it's about as fast as I can control. But, if I'm at 1/4 throttle and I punch it, it flips onto it's roof. Half the time, when in the grass, it flips onto it's roof when it hits second if I'm leaning on the gas. Tons of fun, but makes it prone to high speed damage... I just feel that a little longer chassis might help tame it a bit so I don't have to gear it to the moon and have a truck that is too fast for the areas I bash. And just too fast for me in general.

    Engine support? I don't see how having the 3.3 chassis changes the engines you can run. The rear of the truck is the same as the 2.5 as far as shoehorning goes... or am I wrong?
  6. SMaxxin

    SMaxxin SLAP YA MAMA Staff Member

    Sorry, I was referring to the chassis brace that comes with the 3.3, it helps stiffen the chassis around the engine. I can definitely see the longer chassis being a benefit with a BB.

    If you had to cut around the chassis to fit the BB you might have to trim the chassis brace??? Here is what it looks like

    Last edited: Jan 21, 2007
  7. TalonOne

    TalonOne Hardcore RCNT User

    I agree with you there Smaxxin, as I have both 3.3 and 2.5 rigs and I enjoy the 2.5 "feel" when bashing.

    The 3.3 should be tighter on the track....but I dont know as I have not raced yet...this coming season for sure. With A BB though I think Olds you will se a handling dofference you will like.
  8. olds97_lss

    olds97_lss RCNT VIP Supporter

    Oh. No, I have the chassis brace. I think the crack is from before I had the BB in it. The BB fits without modifying the chassis, but I can't use an 1/8 scale clutch/flywheel. I have to modify the chassis to move the trans forward about 1/4" so I can use the 1/8 clutch. But I would have to do that regardless of BB kit or not. I won't even bother with the stock traxxas or any other 2 shoe/3 shoe 1/10 type clutch.
  9. TalonOne

    TalonOne Hardcore RCNT User

    Olds which clutches are you using? I have tendancy to burn them upo alot. I have used the Mc3 alumium ones , Stock ones, integy crap.....whats your secret ?
  10. Bryson

    Bryson Hardcore RCNT User

    I was thinking about converting my 2.5 but now I'm just saving up for a new3.3 revo for racing this summers racing season. I think the 2.5 is too good of a basher. But for a BB the 3.3 chasie would deffinatly keep the front wheels on the ground a little better i think.
  11. olds97_lss

    olds97_lss RCNT VIP Supporter

    HPI Savage 3 shoe flywheel with HPI savage Teflon shoes/springs. I also run OFNA CB's.

    To get a BB clutch/flywheel to fit the revo, you have to move the trans forward about 1/4 inch or so. I ground off the the corners on the chassis by the brake disk, elongated the 4 trans mount holes. After getting it lined up and cinching the trans bolts down, I made two new holes in the chassis and trans screw flange. Then I ran 3mm bolts through it to "pin" the trans into place so it won't slide.

    I've been running with this setup since last spring. I had to make a shim to elongate the crankshaft on the 2.5R and OS 18TM so I could mount the clutch bell properly as well.

    Unfortunately, I'll have to re-do the chassis again when it shows up as the NE BB engine mount doesn't allow for the necessary space of a 1/8 scale clutch either. It was designed to use the stock flywheel/clutch/bell as I believe most after market BB kits are.

    I went through all this effort due to my ownership of a t-maxx a few years back. The clutch was too weak and broke springs/melted shoes often. Also, with the 18TM, the power wasn't getting to the ground off the line with the stock clutch. It had a tendency to slip and overheat which caused more slipping.

    This is how the alignment looked with the 2.5R or the 18TM prior to sliding the trans forward:

    Stupid me didn't take the same shot after getting the alignment correct. I have this photo which doesn't show the alignment very well so you can see the difference of the before and after:

    Even when running the 2.5R, I noticed an improvement off the line. I was running the 2.5R engine later in the fall last year so I didn't damage my 18TM in the cooler temps. That said, with the BB kit, I have a 2.5R with 3-4 gallons through it and a 18TM with 2-3 gallons through it. Both run like a top... but they are lubed up and in baggies and I'll probably never use them again.
    Last edited: Jan 21, 2007
  12. wickiit

    wickiit RC Newbie

    the Answer with part numbers

    So.. i know that this posting is old but i just got done with the conversion and when i was in the process i was trying to find out what was needed to be done and there was nothing that had any of the part numbers or what needed to be done. Here you go.....


    5322x is the 3.3 chassis
    5456 is the front drive line
    5341 is the steering linkage
    5387 is the body

    and that would get you to the finish but if you want to go platinum....

    5414 is the Center diff.
    5417 is the rear brake kit
    5446 is the wing and the mount
    5361 is the chassis brace
    some Proline velocity wheels and crimefighter tires
    and you're good to go besides the engine

    If you bought all of this new it would cost around $200, i got all this stuff on ebay for about $50 shipped so look around before you buy new

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