Race maxx trans

[hulkmaxx]

Okay guys got a trans question. I am wanting to run the #4907 trans in my project truck. The center CVD's that came with the chassis is for the older style 2.5 max truck. The chassis is the same length as the #4907 Maxx. what center CVD setup would work for this. I believe I seen on this forum someone was running hpi dog bones with 6mm drive cups is this correct. I have a #4907 maxx trans on the way with a full RRP gear set installed. So I hope it is possible to use this trans. :\ Also what is the diff between the #4907, #4908 #4909 transmissions.

 

[Snook Man]

Is the chassis an extended BB chassis? If so the measurements will be different than a stock short or long chassis.
The stock 4908/7 extended chassis is extended in the front mostly and can use the 77mm HPI Dog Bone for the rear center, an aftermarket BB extended chassis will be extended in the rear and will need a longer rear center shaft.
You will probably need to mock up the chassis with the tranny you will use and measure between the diff and tranny to determine what Bone or cvd will work.

The 4909 transmission came with reverse and uses a 5mm output shaft and the hex style brake setup. The 4908/7 tranny is forward only with a 6mm output shaft and uses the pin style brake setup.

 

[chickenman242]

Need to know what chassis your using
I'm running an ice chassis and that came with a rear dogbone, to use a 4907 tranny you would need to use the flm front dogbone kit that can be had on ebay

 

[hulkmaxx]

The chassis I am running is an RD Logics .21 BB chassis. It is setup to run either a BB or SB. I measured both My RD chassis, and the #4907 chassis they are the same length. What is the diff in drive cups. I see 8mm, 5mm, 6mm listed on egay. What makes them different. I have a couple sets up UE supermaxx cups I have tried one set I think might work. And the chassis I am using uses the stock length skid plates don't know if that would matter or not.

 

[nikko508]

Let me chime in on this.. I'm using the FLM ice chassis as well, i have the gray 3.3 trans and using the emaxx diffs, with that set up you will not be able to use the FLM front drive shaft, it is to long, and it binds up. The best thing to do is what snook said, set up the rig and measure to get the correct length you need. The emaxx diffs and the 3 3 trans use 6 mm shafts and the tmaxx and the 2.5 black trans use the 5 mm, if i remember correctly.

 

[Snook Man]

Drive cup size is determined by the size of the shaft they fit. 5mm fits a 5mm shaft, 8mm an 8mm shaft etc. You also need to use a bone that the ball end diameter matches the inside of the cup bore. An example would be a HPI HD bone will not fit inside the UE drive cups but the standard 77mm HPI bone will.

The overall chassis length can have nothing to do with the length of the rear center shaft. The RD logics chassis may be the same overall length as the 4907 chassis but is the transmission mounting the same distance to the rear bulkhead? When comparing chassis lengths for fitting center shafts you must measure/compare front to rear using the transmission mount locations as the base line.

 

[Kyleb]

The overall chassis length can have nothing to do with the length of the rear center shaft. The RD logics chassis may be the same overall length as the 4907 chassis but is the transmission mounting the same distance to the rear bulkhead? When comparing chassis lengths for fitting center shafts you must measure/compare front to rear using the transmission mount locations as the base line.

X1. Some BB chassis are not actually longer/extended. Some gain the room for a BB by mounting the transmission further ahead. The UE thunder chassi is only 2mm longer than a stock chassis

 

[hulkmaxx]

How can I tell what drive cups I have. I have several different cups. Also what can I do with the brake setup. Di I just convert it to a hex style.

 

[Snook Man]

Post pics of the cups. I'm sure some of us can identify some/most of them.
I would go with the hex brake, that way you can use a standard or extended cup with more options for the center shaft.

 

[hulkmaxx]

I will post pics of the Drive cups tonite. I think I have figured it out. I had a set of UE drive cups that fit the transmission I mocked everything up and the center CVD's worked perfrect, I had to use a hpi savage o ring inside the rear cup to take up some play but it worked nice. As far as the brake setup I had a set of 42mm brake disk I think that were a factory traxxas brake upgrade not sure but the newer style pads fit on the disk nicely. As long as the #4097 trans is the same as the #4908 trans I should be good to go. I believe the trans I used as a mock up is a #4908 it looks the same as the #4907 but has the reverse.

 

[Snook Man]

The 4908 and 4907 transmissions are identical (both forward only) the only grey transmissions that came with reverse are the 4909 (and the old 4902 2.5R Maxx)
The 4909 uses a 5mm output shaft so the cups you’re using are probably 5mm cups, the diffs use 6mm cups on input and output pinions so you can check that easily by seeing if the cups you have on the tranny will fit the diffs.
I am almost positive that the RRP FOC gears for the grey transmission require it to use the 5mm output shaft so you should be good to go as for as that’s concerned. You would just need the brake hex that fits the outer diameter of the UE 5mm cup to use the hex style brake disk and then modify the hex to use 2 long grub screws to mount it and the cup to the tranny output shaft. Its not nearly as difficult as I just made it sound.

 

[Kyleb]

The finished product of what snook is talking about will look like this
I'll be able to Le you know in the next few days if the RRP gears require a 5mm output shaft

 

[hulkmaxx]

The finished product of what snook is talking about will look like this
I'll be able to Le you know in the next few days if the RRP gears require a 5mm output shaft

Ok thanks. I have the 6mm cups and the 5mm cups so I am good either way. I mocked it all up tonite and everything fit really nice. I will be using the 42mm brake disc though. I found out the trans I was using for mock up is a new #4909 trans. But like I said I have the 6mm drive cups also so I should be good to go. The trans I have coming has the RRP gears already installed. Guysaid it was from a #4907 truck and was only ran once or twice. I don't figure the plastic gears would survive very long with that LRP .30 runnin hard.

 

[hulkmaxx]

quick question guys are the 3.3 diffs 6mm just wondering. Because I have a set of diffs that the 5mm cups don't fit. But my 6mm cups I am pretty sure that's what they are fit the diffs, and not the older style 5mm trans shafts.

 

[Snook Man]

Yep, all stock TMaxx diffs (all models) use 6mm cups on the input and output.

 

[Kyleb]

With the 4907/4908 transmission you will defintly need to order output shaft part #5184 if you plan to use the RRP gears

 

[hulkmaxx]

With the 4907/4908 transmission you will defintly need to order output shaft part #5184 if you plan to use the RRP gears

Actually I had some excess play in the center cvd's so I am hoping the longer shafts take up the play. From what I measured it should work out about right. Plus I already have the shaft from the 4909 trans plus one on the way I purchased just in case.

 

[Kyleb]

Actually I had some excess play in the center cvd's so I am hoping the longer shafts take up the play. From what I measured it should work out about right. Plus I already have the shaft from the 4909 trans plus one on the way I purchased just in case.

Its not the stock shaft length that was the problem its the diameter

 

[hulkmaxx]

Its not the stock shaft length that was the problem its the diameter

Yah I know They use 6mm drive cups, same as all tmaxx and emaxx diffs use 6mm drive cups I have also worked this out. You just need 6mm drive cups mounted on the 4907 transmission output shaft. The 4909 trans uses 5mm same as the old black transmission. I got lucky I had some extra 6mm drive cups laying around, they are getting harder to come by. The trans I bought already had the RRP gear set installed guy never ran it had it on a show truck. I have not got the trans yet waiting for it to come in. But as I said I am covered either way If I need the 5mm drive cups I have them also with the correct brake hex that fits my 6mm cup or my 5mm cup. Guess buying up all those UE drive line parts was a good call.