This looks like THE mod. Could you tell me the drill size to order for the gearbox sides ie the part that needs tapping? I assume you go 4mm in the pivots that they pass through? Cheers. This is a good solution I think.

A 3.3mm drill will be perfect.

Of course:thumbsup: and a 3.9mm drill will be more than enough ;)

I could look at putting a kit of bits required together if anyone is interested? :confused:

G

As above, and yes I used 4.0mm on the pivot blocks.

http://www.modelfixings.co.uk/

They sell M4 taps and the correct sized drill bit together I think. They also sell M4 high tensile screws. Ran my car all day today at Newbury, took some stupid crashes and not even slightly bent :)

Of course if Northy could do it all as a bundle would be ideal. If you are going to do it, 10mm and 12mm bolts are needed for front. I've not bothered with my back, not really needed I don't think. If I bend one, then I will.

I was looking at completing this mod, but wanted to ask some questions. I appologise if someone has asked them before.

1. Tapping a M3 to M4. so do you first redrill the hole, then use the starter M4 Tap, the the finishing M4 tap? Or can you just go straight in the with the starter M4 Tap?
2. Are people re-tapping the front and back holes of the front gearbox?
3. Do you need a cutting fluid of some kind?

Thanks

Paul

1. First you have to re-drill the existing holes with a 3.3mm drill bit. Then I recommend you to use the starter M4 tap, because it's easier to place tap normal to diff housing and you will do a better tap job.
2. Yes both
3. I usually do tap job with cutting fluid, but in aluminum material it's quite useless

As above, but you need to remember to enlarge the pivot blocks too so the screws can go right through.

And you never need cooling fluid to drill a small hole is basically any material! Cooling fluid is for machining jobs.

doesnt it weaken the pivot blocks as i am seriously thinking of doing this mod as i dont think i can afford the upkeep replacing the bent screws :lol:

How often are you bending them Neil? Ive slightly bent my front screws once, and the rear ones only after a huge crash, and the car has had a lot of use now.

If they come loose during a race then they become more prone to bendages, so do use thread lock and keep checking them. i check mine after each race, its quick to do with an L shaped allen key - no need to take wheels off.

Chris

Did 2 yesterday and 2 at york indoor series, i do threadlock them in and they dont seem to be coming loose maybe i am just a crap driver and hit everything :blush: i bent one side so bad a few weeks ago it broke the outdrive.

Are you guys using M3.5 or M4 screws?

I can look at putting a kit together if you want, never got round to it :cry:

G

chris i now paul c is bending them after every run nearly

High tensile m4, and its much better for it.

Im bending mine nearly every run. I would like to get a kit together to do it. This fricking car has cost me fortunes.:cry:

Hey mate, please pay attention on the difference between cutting fluid and cooling fluid. Cutting fluid may be not only a cooling fluid, it also could be design to lubricate the tool, and it's very useful (especially with low cost tools) for tapping or drilling jobs in many material. Mineral oil is basically a good start ;)

Run my car with the M4 screw mod on the front today, and broke one of the rear wishbone hangers.. Just a thought, but by beefing up the screws are we just transferring the force of impact?
If this is the case usrely it would be better to bend an M3 screw than snap a w/bone hanger?

I have completed the M4 Mod on my Cat SX and have had no problems at all since doing it. Does anyone know where I can get M4 washers in 0.5mm & 1mm thicknesses?

The M4 washers sold by Schumacher for the wheels are 1mm (from memory).

Perhaps Nortech can source 0.5mm? Que G.

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Think microtech does these as well

m4 washers & loads of different screws here http://www.stagonset.co.uk/fasteners...mit=M4|Washers