3 speed transmission blown :( help please

[Savagebeast93]

Hi all,

I recently fixed my 3 speed transmission, it was working fine up until last night when I heard the gearbox grinding as I was driving along. The whole car stopped moving. I took the gear box apart to check what had happened and the small idler gear was completely shattered, the teeth had also gotten in between other gears and smashed teeth off of several other gears including the plastic spur gear.

I found a grub screw that had been sheared off and I think this might be what has caused it.

Stupidly I forgot to put loctite on the grub screw that holds the longer grub screw in the clutch shoe/housing.

Am I right in thinking that this screw has backed itself out and gotten caught in the gear and caused the transmission to blow? I have purchased another transmission box from eBay as it was cheaper and easier than buying all of the individual parts. I felt that it was better to replace anyway as idler shaft seemed slightly bent from the force of whatever happened inside there.

What am I doing wrong? Did that tiny bit of loctite that I forgot to put on the grub screw really cause this or is it something else?

Cheers

 

[Jam Racing 1]

Most likely that is what caused your trouble... you need to use blue locktite any screw/bolt that goes into metal...

 

[Savagebeast93]

Most likely that is what caused your trouble... you need to use blue locktite any screw/bolt that goes into metal...

Cheers, I've noticed that the engine mount is very slightly bent, by a few MM at most. Could this also cause something like this to happen? Cheers

 

[Jam Racing 1]

do you mean the plate?? the cast mount rarely bends it just cracks and breaks.... a couple of clear pics will help alot......

 

[Savagebeast93]

Hey, I can't get a photo right now but I have drawn a diagram. The area drawn in red is the engine mount, it's a single piece mount. If I take it and lay it on a completely flat surface there is a slight bit of play in it where there shouldn't be. The diagram I've drawn actually makes it look more bent than it really is. It is probably no more bent out of shape than 0.5 - 1mm. 1.5mm max.

Would it be worth straightening out? Get a new one or just leave it?

I had some bearing go a couple of months back but I think that was because the car had been sat for literally years before this guy sold it to me, who knows how long those bearings hadn't been changed in. I got some ceramic ones and it hasn't given me any problems since. But I was just wondering if this could have contributed to the exploding transmission. I've just replaced it so I don't want anything happening again any time soon as they aren't exactly easy to some by.

 

[jssouthtx]

This is purely a guess but if that bent engine mount happened at the same time as the transmission damage then it is entirely possible that something got between the clutch bell and spurgear causing the damage to both. At high speeds it doesn’t take much to upset that trans. I would definitely replace that engine mount and likely the motor plate too before I ran the new transmission. Good luck. Post up if you find the cause.