I am not having much luck with my TT46PRO engines. The first one dropped the rear bearing cage at 3 hours. The second one has a stripped thread in the crankcase in one of the backplate retaining cap screw receptacles. I've used Darrol Cady's torque driver everytime I've tighted those threads to 13 inch pounds - so I am sure that they have not been over tightened.

The worst bit of this back luck story is that I've been getting my engines from Tower Hobbies - and have discovered that Thunder Tiger don't have any international warranty and neither Tower, the USA distributor or the Australian distributor want to know about it. I've had a complete run around from Tower, Ace Hobbies (USA distributor) and Thunder Tiger in Taiwan. I've had to actaully call people as no one will return emails when you start asking about warranty. All in all, not a good look.

A lesson here for anyone buying TT engines internationally, you have no warranty!

Enough of my problems - what I would appreciate some advice on is what people do when they strip threads in the crankcase - as I've got here with my backplate retaining screw receptacle.

can you drill and tap to next larger size? Maybe install a stud and tighten a thin nut. JB weld. These little bolts need only just to be seated, not nearly 13 inch pounds.

Hi Joe
Simple options would be fit a slightly longer screw or drill and tap a little deeper.
Or being a back plate use a little Loctite retaining compound on the flange of the back plate and just use 3 screws.
I do agree that they dont need to be that tight for a back plate as the screws are typically so short half that torque should be heaps
Terry

For many of the backplate mounts we use with TT, you need to use longer screws than stock in order to have sufficient thread depth.

Dan

I checked the factory set torque on two new TT46PRO engines tonight. The head bolts were all in the 12 to 14 "lb range and the backplate bolts were around 6 to 7 "lbs. I've had a head bolt strip at these settings.

At least I'm getting adept at installing Helicoil thread inserts with all the threads I've stripped lately.

I am now using 10mm cap screws with Dave Shadell's backplate mount on the TT. The factory bolts are only 7.5mm long.

I have 8 TT 40's. Two of them have been returned to ACE for problems when they were newer. The first had a rear bearing failure. It was retooled to remove crankcase damage, the bearing replaced and the piston and sleeve replaced. You could see mill marks inside the case where they removed scoring from the bearing damage. So some machinist spent a lot of time on that engine. The engine was returned, no charge, in about three weeks. More than fair, in my opinion, considering I was running it at 16,900 RPM on a 9x6 APC.

The second had ingested the coil spring from the carb when the retainer screw fell out. That engine was replaced with a brand new one, also no charge. So my experience with ACE has been first class!

I would suggest to you that you call them on the phone, because I don't believe they ignore their customers. Remember, You can catch more flies with honey than with vinegar.

As for the back plate screw, if it's a lower one, you might be able to drill on through, thread the additional length with a tap and use a longer screw. Also as noted in a post above, if you use a rear mount you need to replace the back plate screws with longer ones.

Stan

It is nice to see the service is so good! IMO.... it is best to ready the engine for racing prior to it's first run rather than waiting for the inevitable failures from our torture test....


1) - take the carb spring out... you will swallow it when the barrel falls off... clean the carb real good and use a little blue loctite on the barrel set screw

2) - Replace the rear brearing with a quality bearing such as those that Shadel sells for Nelsons... cheap insurance IMO as using the stock bearing is a crap shoot even though some claim they will not fail if broken in just right....

3) - Pull the piston/rod out and remove the wristpin.... clean all very well with denatued alcohol... and replace the wrist pin while using red-loctite to prevent the pin from floating around(it is a loose fit) and eventually egging out the hole and ruining the piston. Wipe off the excess loctite let dry and reassemble motor.


None of these changes will increase the RPM at all... they will only ensure the engine will run well as long as possible... which... these TT PRO40's are quite surprising how well they will run well for a $70 motor!


Dan