Info on old frogshots diff fix

[smiffffy 0]

Hey guys, I am suffering from the clacking gearbox on my Blackfoot and have always been intrigued by old frogshots fix which shows drilling one side of the diff cups to 2.5mm and tapping the other diff cup to receive a 2.5 mm screw to maintain a width on the side plates.

https://www.tamiyaclub.com/showroom_model.asp?cid=24674&sid=3142

my question is ? When this fix is done am I right in saying that one cup is fixed hard and fast to the screw. Whilst the other cup is free to spin on the shaft of the screw passing through it.

if this is the case, is the hole that is increased from 2mm to 2.5mm actually large enough for the screw to freely spin.

 

has anyone tried the 5mm shims to obtain a fix , and if so do you think it is a good enough fix.

I do know that MIP now do a ball diff, but am a little shocked at the cost of it. It seems to be so much more expensive than many of their other ball diffs that look to be pretty much the same but in slightly different sizes.

So with 4 ORV bashers I am looking for a less costly solution than 4 MIP diffs.

cheers 

Smiffffy

 

 

[Saito2 6676]

I actually tried a variation on this fix. I was able to locate a tiny machine screw and nut that I put in place of the pressed-in diff cup shaft. This way the machine screw spins freely within the cups but still prevents separation. I've seen others do it with a bit of old threaded tie rod material (the thin stuff the old buggies used) and nuts on both ends. I've stacked the lower half of some old diff side plates (with the top halves cut off) over top the existing plates also and this has worked. Others here have done a similar trick with large washers. Cheap and does the job.

 

[MAD RACER 566]

My Re re frog was starting click away a little and was just about to investigate this Frogshot mod till a remembered some guy told me a few yrs ago that he just gets a large pair of adj multigrips and gently squeeze the side plates in a little.

I did it near the drive cups and a little just under the spur gear shaft.

Did the fix and no more slipping for now and took 1 min. No doubt the plates will spread apart again but was a quick fix . Untimely the Frogshot mod will be a permeant fix but this was quick.  As for bigger tyred ORV's this may not work due to the extra stress placed on the drive train.

[Backlash 481]

Back in the day, we would just lay the aluminium gearbox side plates on the plastic gearbox casing, place a socket or piece of pipe over the outdrive hole, and give the socket it a hit with a hammer to slightly bend the side plate in so it put more pressure on the diff gears ..  I have even seen some people bend the side plates with a pair of multigrip type pliers..

 

[smiffffy 0]

Well the quickest fix, was definitely the squeezing of the two diff plates with a pair of grips. 

Instantly fixing my clacking box, bit as said above , not sure how long this will last.

I also took an old pair of frog dog bone drive cups and attempted "old frogshots mod".

Well I can't believe how quick and easy it was when I had found a suitable tap to create the thread for the new machine screw.

after using a Dremel to take off the long locating pin, a quick centre punch on the end gave me a bit of confidence at keeping a vertical hole dead centre as I drilled through the narrow drive cup.

this hardly took any time, with the remainder of the pin just falling out after a few turns of the drill bit.

now to do the same on my other Orv's.

also saw a gearbox online that had had a similar machine screw through the centre of the higher drive gear in the box.