TRX 3.3 EZ start delete - bump box conversion

[Beer_Goggles_RC]

Ditching the EZ start and converting my 3.3 to bump box. My concern is that with the EZ start, the drive kind of acts as a spacer between the rod and the plate

The new plate does not provide any type of spacer between the rod and the backplate where the little pin that comes off the crank meets the backplate

Am I missing something or is this how it should be?

Also I’ve read that a 40mm flywheel is helpful with the bump box

As always, any and all input is appreciated!

 

[tudordewolf]

Ditching the EZ start and converting my 3.3 to bump box. My concern is that with the EZ start, the drive kind of acts as a spacer between the rod and the plateView attachment 199233
View attachment 199234
The new plate does not provide any type of spacer between the rod and the backplate where the little pin that comes off the crank meets the backplate
View attachment 199236
Am I missing something or is this how it should be?

Also I’ve read that a 40mm flywheel is helpful with the bump boxView attachment 199238

As always, any and all input is appreciated!

View attachment 199235

View attachment 199237

To do that mod you'll need the crankshaft without that pin, part # tra 5288, or you'll need to grind the pin off yours without marring the crankpin underneath.

Edit: now that I look for it, it appears quite rare. I remember seeing them listed for $40 just a year or 2 ago. Maybe the only source for them is whole engines being broken down to resell for markup on the parts. There's one overseas

 

[Beer_Goggles_RC]

To do that mod you'll need the crankshaft without that pin, part # trx5288r, or you'll need to grind the pin off yours without marring the crankpin underneath.

Thanks for the input. I was able to find a TRA 5289R. Possibly the same part with an updated number?

 

[tudordewolf]

Thanks for the input. I was able to find a TRA 5289R. Possibly the same part with an updated number?

That's the 'multi-shaft' version which lets you swap that engine into non-Traxxas vehicles (super neat of them to offer that, really, I used one in mine) you'll want the one that's "IPS shaft w/o starter"

There is TRA-5219, the TRX-2.5 version, which is physically identical except for a smaller intake passage through the center, which would probably cost more performance than it adds. Swapping a 3.3 crank into a 2.5 is an upgrade to the latter for this reason.

 

[Chubaka]

That's the 'multi-shaft' version which lets you swap that engine into non-Traxxas vehicles (super neat of them to offer that, really, I used one in mine) you'll want the one that's "IPS shaft w/o starter"

There is TRA-5219, the TRX-2.5 version, which is physically identical except for a smaller intake passage through the center, which would probably cost more performance than it adds. Swapping a 3.3 crank into a 2.5 is an upgrade to the latter for this reason.

Thanks for posting. Since 2005 I've always wandered the ips crank. Make sense now.

 

[Beer_Goggles_RC]

That's the 'multi-shaft' version which lets you swap that engine into non-Traxxas vehicles (super neat of them to offer that, really, I used one in mine) you'll want the one that's "IPS shaft w/o starter"

There is TRA-5219, the TRX-2.5 version, which is physically identical except for a smaller intake passage through the center, which would probably cost more performance than it adds. Swapping a 3.3 crank into a 2.5 is an upgrade to the latter for this reason.

Thanks for the input, you really know your trx engines. Maybe I'll just throw a dyna .19 in it!

Edit: sheesh looks like the .19 doesn't have a pull start eliminator backplate

 

[Chubaka]

Thanks for the input, you really know your trx engines. Maybe I'll just throw a dyna .19 in it!

If you have problems cracking that motor mount...... strc has a machined aluminum one.

 

[tudordewolf]

Thanks for the input, you really know your trx engines. Maybe I'll just throw a dyna .19 in it!

Edit: sheesh looks like the .19 doesn't have a pull start eliminator backplate

This isn't a perfect solution, but you could swap the backplate to the one from an Sh.18, and then put on a roto-start backplate with the gears taken out and the opening sealed up, which would delete the one-way-bearing while leaving the starter stub axle in place.

I have a spare TRX 3.3 IPS crankshaft lying around, never run, the one I pulled when I swapped in a multi-shaft. I'll grind off the pin and send it to you if you want. Since you're going to have to pull the crankshaft anyway, I highly suggest putting in a ceramic/hybrid rear bearing while you're at it, I had the stock one on mine fail pretty early but the $30 budget ceramic bearing from Boca is still going strong.

 

[Beer_Goggles_RC]

I have a spare TRX 3.3 IPS crankshaft lying around, never run, the one I pulled when I swapped in a multi-shaft. I'll grind off the pin and send it to you if you want.

No problem man! I'll do a teardown in the morning and grind mine down. Shouldn't be a problem! If I marr it I guess I can just order a new one lol

Thanks for all the help, it's very much appreciated. This would've turned into a big headache without you lol.

I'll keep you updated!

 

[Beer_Goggles_RC]

I have a spare TRX 3.3 IPS crankshaft lying around, never run, the one I pulled when I swapped in a multi-shaft. I'll grind off the pin and send it to you if you want.

Success

How does this sleeve look to you? I’ve only done 1 tear down before and can’t remember what the sleeve looked like but there’s a little bit of wear on the inside. Not noticeable to the touch just to the eye. Engine still has good compression either way.

 

[tudordewolf]

Success
View attachment 199255
View attachment 199256

How does this sleeve look to you? I’ve only done 1 tear down before and can’t remember what the sleeve looked like but there’s a little bit of wear on the inside. Not noticeable to the touch just to the eye. Engine still has good compression either way.
View attachment 199257

Nice work! I don't have much experience identifying sleeve wear by eye, it looks pretty good to me.

 

[Beer_Goggles_RC]

Everything feels nice and smooth!