bradjones

Hi I have a unlimited engineering thunder chassis, i'm looking to buy a UE small block engine mount for it, any advice on where to get this would be very helpful, or anyone who has one for sale or knows the right guy, I'd be very grateful to buy it off you.

Thanks Brad

jkdv8

My Feedback: (1)

Have you tried to email them. Any particular reason you want to run a small block.

Maxximize

I agree there, I'd email them and see if they can get your one. It's listed on their site for $25, though it says it's out of stock. Even if it says that it's out of stock, they may make them as requested. Otherwise your only bet is going to be Ebay, really. Do you have the big block mount for the chassis? If so, I'd just get a big block and forget the small blocks. If you need that mount, it's listed on their site for $10, and is in stock. I recently was able to run my big block Maxx with it's new .28 engine for the first time, and it is definitely worth stepping up to, though it did require some modifications for everything to fit right the way I configured it. It used to be a big block chassis with a 2.5R on it before, I finally completed the build recently and updated the truck's drive train fully to 3.3 specs with E Maxx diffs.

bradjones

Hey thanks for advice I have it pretty much ready for a big block, mip outter cvds, ti ue centre drive shafts, stock 4907 tranny with foc, hcr alloy diff cups with rrp in the rear diff and stock up front. Both have been shimmed so not really any play, and no binding.

the reason I want the small block mount is I have the trx3.3 not even a gallon on it and would have liked to just have it running there and then,.

i am going to buy the bb mount as you've said they have some for sale still, I was thinking along the lines of a lrp.28 spec, the 30x is abit out of my league money wise, considering I'd need to buy a pipe header and all the clutch assembly too,

maximize, quick question. Your running a bb tmaxx, can I use the stock flywheel etc on a bb or would I need a 1/8th scale flywheel and clutch? And if so any kits avaliable which are still around?

here is a pic of my build so far, need to put my arms back on (UE ext) just easier to work on with them off 


thanks brad

jkdv8

My Feedback: (1)

Hmm. That's cool. Bulkheads look like they are from New Era. However they were both very similar in that aspect.

As as for the clutch you can use the stock setup but it is recommended to run a 1/8th scale setup to get the most out of the engine. I run an ofna on mine but just about any 1/8th clutch/flywheel will work but, you have to keep in mind that you have to change the spur gear as well because they run a different gear pitch.

bradjones

There acncm bulks hcr diff cases . Just looked and UE website sell a 38mm fly wheel and clutch kit which is in stock,,$33 & $10x2 for engine mount, I have emailed him asking about the sb mount before, it's just nice to have the 3.3 still as a back up & till I can buy a decent mill (lrp)

Maxximize

Yes as jkd said you can use the stock clutch, but 1/8 scale is the way to go. I had issues burning the stock clutch out with my 2.5R when it was on this chassis, usually it would last 5 tanks or so and the spring would break. I'm currently running a stock HPI Savage flywheel and 3 shoe clutch with a 17 tooth Savage clutch bell. I think the whole set up was $15 or so from an Ebay chop shop, it came off an RTR Savage. For the spur you'll need to match the mod 1 1/8 scale clutch gear, I went with a stock 40 tooth Revo spur gear. I'm running a stock 4907 FOC tranny too, and with my LRP Z.28R Spec 3 that gear combo seems perfect for bashing. You can also try and gear it up with a bigger clutch bell, HPI makes 18 and 19 tooth bells, too. I love that engine, by the way! Mine's got about a quart through it so far, almost done with break in, and it is great so far. I haven't been able to cut it loose yet, but even at 1/2 throttle the power is very noticeable. I've just begun to lean it out after each tank, and it's very receptive to tuning, and runs cool as well. I used a THS hardened Savage pipe and a Reedy buggy header on mine and it seems to like that combo. Great engine for the price! I am going to try a 19 tooth clutch bell when my truck is fully broken in. I'm going to leave the pipe, though. A Savage pipe with a buggy header is usually pretty cheap, too. I did have to get some engine mount shims to make the gears mesh well on my chassis, but those are cheap and easy to find. You may have to change the output shaft from the tranny to match your center shafts if your chassis was set up to use the 2.5 Maxx tranny. You may also have to trim your crank down, mine had to be trimmed because the 4907 tranny has a round hump sticking out right where the crank is, which the 2.5 black tranny didn't have and my crank would hit it otherwise. This is an easy mod, I had to do it for mine, which is an ACNCM mega chassis. I just used a Dremel and trimmed about 1/16" off the end, and used an Ofna clutch shim kit to get the clutch bell where I wanted it. By the way, that is one killer looking chassis you've got there! Can't wait to see that all put together!

One thing you could do is try and sell that 3.3 on Ebay if you can't find the mounts, that will get you closer to the big block. You should be able to get about $80 or so for it if it's new looking.

jkdv8

My Feedback: (1)

Yea what Maxx said. He went into much more detail.

Is the mount adjustable on there. Need to keep that in mind. Some mounts allow you to move the engine forward, back, left, and right. Others just allow you to move it left and right and there are some that are fixed. If it's fixed it might require you to use all UE components.

Reason I mentioned it, those bulkheads look just like mine. It is a nice looking rig btw.

bradjones

Thanks for the advice

I think the savage clutch and flywheel is a good Idea with the REVO spur gear, easy for me because I'm in the uk And alternative parts are hard to find her, these will be easy to find. Do I need a diffrent slipper clutch or can I use the stock?

with the tranny, I bought 2.5 trx5195 foc instead of cutting mine down, and needed the old brake hex and disc, 4907 output shaft was too long and made the front UE cvd bind, wouldn't work so this was a no mods way. As I think you said the tranny is diffrent, will come to that stage when I need to with the bobbly thing off the side ha, mAy need to buy a dremel,

and nd yes I may sell the Trx engine to buy a big block because it would be rendered useless otherwise

bradjones

One more question, on the UE site they sell 34mm and 38mm flywheel kits, I seen someone say you can't use the 38mm kit, which is the one they have in stock so that wouldn't be worth buying? As I'm guna buy a mount and some drive cups off them soon. Other wise I'll go the savage route seems affordable and they run bb so must be up to scratch for bashing the .28

jkdv8

My Feedback: (1)

Yes you will need a Revo slipper if switching to Revo spur.

I'm assuming that's outside diameter. Usually when companies do that its for use with a bump start. However, didn't think any of the MT's were bump start compatible. Could be used on a buggy however. It's possible but, would probably require mods. Engine would probably have to be raised to clear the chassis. That could lead to mesh issues if you're limited on engine mount adjustments. On a positive note 4 shoes are better than 3.

bradjones

I see, that's why there is two diameters then, I don't think bump start would be very easy, pull start or roto start for me,

ok ok so im guna need, when I get round too it. Savage 25 flywheel and clutch, hpi pinion gear, revo spur gear 40t and REVO slipper clutch, newest model Revo or the old 2.5 spec?

Let me know if I've missed anything and I will get pictures and update when I'm at that point

Maxximize

Mine had the same issue with the 4907 tranny shaft being too long. This is very easy to overcome, though. All you need to do is buy a FOC kit for a 4909 T Maxx and install the shaft into the 4907 tranny. It then uses the 4909 brakes, which are a metal disc with composite shoes like the 4907, but mount on the same blue hex the 2.5 composite brake disc does. The 4909 shaft also uses the old style 5mm center shafts unlike the standard 4907 tranny, which uses larger 6mm outputs. The 4909 T Maxx was a reverse equipped short chassis T Maxx with a 3.3, so the tranny output shaft is shorter than the 4907. The tranny case and internal layout is identical to the 4907, just the brakes and the output shaft were different. This mod is what I did to get the 4907 tranny mounted in mine, which was designed to use the black tranny originally. The 4907 tranny uses any toque control slipper unit for nitro trucks, just get the one for the T Maxx 3.3. To run the gray tranny with the 4909 shaft, you'll need the complete 4909 brake system, the brake arm, the disc, the pads, and the screws that hold it all to the tranny. The arm is #4967, disc is #5164, shoes are #5365, and the screws are #4978. If you have a blue hex for the 2.5 brakes, it can be re used, otherwise it is #4966X.

Unfortunately, with the black tranny a Revo spur will not work. I originally tried this and the engine is quite far away from the Revo spur. It is because the black tranny sits higher than the gray one does and it's also geared higher internally than the gray one, so a 40/17 combo would be waaay too high. There is a way to get mod 1 1/8 scale gears with the black tranny too, though. You can use the slipper set up and spur for an Associated Monster GT on that tranny. It is the peg style slipper, so you'll need to have the original style input shaft that accepts the T Maxx 2.5 stock slipper, not the newer torque control one. The MGT spur literally bolts right onto the black tranny. With that set up, a 17 tooth Savage clutch would work well with a 47 or 48 tooth MGT spur. I went the 4907 tranny way because I hate the peg slipper, and it has different second gear ratios that can be swapped into it for more top end or more torque in second gear. Not to mention the metal brake disc is way better than the old fiber one the 2.5 uses.

The Savage clutch is holding just fine on my truck so far. I've got about 1.5 quarts through the truck (1.4 L) and it's working as intended yet. The only down side is the stock carbon shoes spit black dust out as they wear, but some aluminum shoes for a Savage would alleviate that issue. I'm not sure if there's a difference form the older .25 version, but I got the flywheel and clutch for the Savage X 4.6. It came with the 17 tooth clutch bell as well.

Here's a link to the 4907 tranny mod I was talking about in case you still want to go that route. Click Me! Either tranny should hold up just fine in FOC form with a .28-.32 engine onboard, it just comes down to what you want to run for the slipper and brakes.

jkdv8

My Feedback: (1)

Maxx you're the AAMCO man for traxxas trans.

On a separate note from experience is to use a good hardware set (preferably titanium; turnbuckles, hinge pins, and screw set) and lightly thread lock screws for the main components.

Also a Dremel is your friend with this hobby. One of the things I've been meaning to do is cut a line across the inside of the front skid plate at the bend. Not all the way through but enough where it would bend and snap in half in the event of a collision. I've had the unpleasant experience of extracting thread locked screws out of the bulkheads. Stronger the skid plate the more likely it is to pop the screw heads off. Just something to think about if you are bashing.

bradjones

Ok so I just write up a long ass reply and it suddenly errored me out now I have to write it again

i got the 5195 foc and the hex brake and disc for the brake and tranny output,

im Guna order the savage flywheel and clutch and cb,

if I under stand right the slipper I have on my 4907 will work with the revo spur gear?

Foc is is backorder so will be here next week, just need a few parts from ue and a Lrp mill after I get all this right,

btw thanks for all the advice been much appreciated, sorry so the long wait lost my phone only had it back today,

Maxximize

Hahaha I do know entirely too much about the T Maxx tranny, that's for sure Luckily I literally just finished my big block truck up so all this is still fresh in my mind. Brad, that is the correct part number FOC, and yes the slipper you have will work with the Revo gears. After that mod the only issues you may run into is the height of the engine on it's mount, and compatibility with the newer style Maxx diffs if you upgrade to those. They can be made to fit too, though. And the engine can be raised up by using some engine mount shims if it's needed to get a proper gear mesh. I have 3908 Brushless E Maxx diffs in mine, your aluminum ones should hold up fine if you shim the gears well. Definitely get some steel center shafts as well as the outer shafts, you'll need the UE extended one for the rear of course, and a 4910 or 4909 T Maxx one for the front. I'm running THS Racing CVD's on the corners and a lengthened dogbone for the center rear, my front center one was plastic. The front one has broken twice now in just 5 tanks after break in, so I'm ordering a Traxxas center CVD kit for the 4909 Maxx to use in the front. That engine is an absolute power monster now that I'm getting it tuned in, I'm very glad I upgraded my diffs or they would be gone by now! It actually pulls the front wheels off the ground in second gear even The power is simply insane and nearly uncontrollable under full throttle. This truck is nearly untouchable when I run against my friends' Maxxes and Savages. You won't be disappointed with the Z.28 mill!

uihsongshi

I finally completed the build recently and updated the truck's drive train fully to 3.3 specs with E Maxx diffs.

bradjones

Yo yo, so talking about drive train I have mip outer cvds (shiny ones) and I got the centre cvds with the thunder chassis, which are made from titanium, I'll get a picture with arms on, I have a few bent hinge pins so going to buy the Lunsford hinge pin and turnbuckle kit 4801, I think it is.

with the diffs originally they where 4907 stock diffs (revo spec) and I have bought hcr diff cases and shimmed them to have the littlest play without binding, are they different to the 3908 e maxx diffs? And if so what's diffrent? I'm Guna try out my diffs for now and when they are eaten up I'll get some 1:8th scale diffs in there or these maxx ones,

with shimming of of the engine mount do you mean using shins to raise the engine up a little between the chassis and the mount/ mount and engine?

jkdv8

My Feedback: (1)

In this case I would shim inbetween the engine and mount. Longer screws maybe needed if it needs to be raised to much.

mauolaidom

I was thinking along the lines of a lrp.28 spec, the 30x is abit out of my league money wise

Maxximize

Yea your axles should be just fine. I recently changed my last plastic one to steel and none are breaking now even though my slipper is slightly too tight. My center front was plastic before and didn't hold up at all. I went with the Lunsford hinge pins for mine, too. I had heard they are the only ones that fit with aluminum bulks and RPM arms. Mine fit with room to spare and are holding well.

The 4907 diffs are almost identical to the 3908 ones. They are both sealed type, and use the same gear ratio, pinion, and case. The only difference is the 3908 diffs have an I shaped brace inside the diff cup to better hold the spider gears in place and the cup has metal guide pins to take some strain off the screws that hold the ring gear to the diff cup. I would think 4907 diffs shimmed well and with an aluminum case would be strong enough. You can always get the 3908 diff cup and spider gears and upgrade the diff later on if you need to, the 3908 internal assembly will drop into the 4907 case if I remember correctly. The only thing stronger that the 3908 diffs that is affordable is the Losi LST diff, which requires modification to fit in the Maxx bulks.

For engine shimming you shim between the engine and the mount. Ofna makes some engine shims as do most other 1/8 scale buggy manufacturers like Kyosho and Mugen. I went with the Ofna #30482 shims. They are about 1/8" (3mm) or so thick so I only needed one set of them for the 40/17 gears. I used 3x16mm stainless cap screws to hold it all together. Without them on there the gears would not quite mesh enough. Here's a pic of them on mine.

jkdv8

My Feedback: (1)

The Lunsford stuff is solid. Use the hinge pins and turnbuckles from them.

I have the original Maxx diffs, shimmed, in aluminum cases. I am however only running a force .21. They seem pretty solid though.

Maxximize

Very true, I have a set of their T Maxx springs on my rig, too. Them in combination with Associated MGT copper springs are the only thing that will hold my truck up and it still needs pre load spacers! Wow, you have the originals and they're good yet? Those things are stronger than I thought they were. Although the aluminum case does do away with the flex the old cases had. Smaller big block or not I'd say that's conclusive evidence that the 4907 diffs will hold out just fine, and 3908 diffs are probably overkill.

jkdv8

My Feedback: (1)

Yea I think the flex from the plastic cases had more to do with them failing than the gears themselves. Guess I will find out how strong they are when I move up to a .28 or .30.

As for the springs I don't remember what brand however, I think I found them on eBay. Always like the dual spring setup but couldn't ever find a set. Those prolines were not out long before they were discontinued. Truck bottoms out at times with really high jumps.

Maxximize

Very true, only 2 screws holding them together is not really optimal haha. Yea the LRP .28 is a really good test for drive train reliablitly, I had several people tell me my front plastic drive shaft would not break easily referencing older big blocks, yet it did. I can't imagine the power from the ZR.30 or the ZR.32 for that matter. When my .28 dies I might move up to the ZR.32, that thing would probably be too much for my truck to handle though!

Hmmm I bet you have the dual rate RC Raven springs, they came in chrome or red I think and sold in packages of all 8. Always heard good reviews on those, though they are becoming harder to find these days.