Final Drive Helicoil tapping issue

[fb9]

Hey all.

Recently was a bozo and did a righty-tighty to drain the final drive on the 850g.
The threads of the final drive body stripped out, the screw is good to go.

Threads are indeed the metric spark plug size, and I picked up a Helicoil kit that uses the solid body inserts.

Running the tapping tool up the hole results in a problem -- there is some metal material about an inch from the outside opening that gets in the way from the tap bit from getting deep enough in there to finish the cuts.

The front of the bit has the small size threads to help feed and guide the bit for the larger new threads.

This metal appears to just be either just semi-structural and to only perhaps help funnel the oil towards the drain hole.

Has anyone ran into this before or have any tips?

Taking the final drive apart seems very ugly, and the Clymer manual made it sound 'impossible' and with out guidance.

Possible I may be able to get a different tap, but I like this one that is helps keep the process straight as the first threads are cut because of that entra length that it has.

Can anyone confirm that the metal in my way is irreverent?
Perhaps I could send a drill bit up there and carefully drill it out...

Finding a good +1 screw might be difficult or not possible since I already started cutting the metal.

Thanks for any thought or words of wisdom before I get too cowboy on it.


Disclaimer:
No offense to cowboys.
My interpretation of you is that you are awesome and just jump-to-it.
My jump-to-it abilities result in bad thing happening.

[Nessism]

What about getting one of those self tapping oversized drain bolts? Take your old one to a good auto parts store like a Napa and get the next oversized. The plug is tapered to get it started and then you just torque it in to cut it's own threads.

[rustybronco]

You would need to find a bottoming tap to finish making the threads for your heli-coil (time-sert?), or take apart the final drive to complete the repair.
the pinion gear would remove as a unit, all the pre-load shims for the ring gear would stay the same, so it can't be that difficult...

what about getting a used final drive? it can't be more than 50 usd.

***edit*** Ed, I like your thinking.

[Nessism]

Speaking of used final drive units...I have one gathering dust. If all else fails fb9, drop me a PM - I'll let it go for cheap although shipping won't be since it's pretty heavy.

[fb9]

M14 x 1.25 is the current threading.
I'll check around some more, but so far I think it was just M14 x 1.5 oversize being the availible around.

I'm assuming that wouldn't work quite the same since the oversize just digs deeper into the pre-exiting thread holes.
Guessing 1.5 would cause cross threading like behavior and make leaking possibilty worse.

I may need to look closely at how much metal has been removed already, I'm concerned that the tap did enough metal removal that perhaps the new bolt might not seal nice; but uncertain as well because I'm not sure how big said replacement bolt head would be for sealing that up.

Perhaps finding a bottoming tap is a nice plan, but I swear somehow I'll send it though not being square and be really sad.

Sounds like an adventure. Worse case, part replacement I guess..

We will see. Thank for input thus far

All of the above probably beats sending a drill bit through a nd clearing out random metal that is in my way.

[Nessism]

The OS drain plugs are tapered and make their own threads. This is not a matter of just going larger on the thread pitch.

Good luck

[fb9]

FYI-

Took my a few days to track down the info:

I am using Helicoil kit #5408-14.
Kit includes the piloted tap (tip M14x1.25, body M15x1.25 STI threads) #5329-14.

[EDIT]alternate slight taper tap is #1030-14[EDIT]
Part came in and it has the same taper and pilot specs as the original.
The threads on this alternate tap are just longer, so you could tap a very deep hole is desired.
Still useless to me. Sale person and I not communicating on the same page...


I have this other one on order and hopefully that can fishing the job that the piloted tap started before 'bottoming' out.

[rustybronco]

Still useless to me. Sale person and I not communicating on the same page...


I have this other one on order and hopefully that can fishing the job that the piloted tap started before 'bottoming' out.

There are 4 choices as I see it.
(1) keep going the same route you are on.

(2) P.M. Nessisim on the used 3rd member

(3) e-bay http://cgi.ebay.com/ebaymotors/ws/eB...3AIT&viewitem=

(4) pull the rear wheel, get an o-ring for the two halves of the third member. remove the ten bolts and remove the ring gear/ gear housing cover (with two 6mm bolts) as an assembly. then you can run the tap into the housing w/o the ring gear in the way!

it might be wiser if you bought the two housing seals. but I suspect if you are careful you won't need them.

I'll be happy to walk you through it if need be.

[fb9]

Progress

I called up Helicoil (Emhart) and after some phone bouncing I was online with someone from the actual engineering staff.

Apparently the 2 previously mentioned tap are still yet of actual different sizes. I haven't hit them up with the calipers to make measurements, but they are just a little different.

One is for the spring inserts, one is for the solid metal bodied inserts. Apparently the sizing is just a bit different. So... even then I was barking up the wrong tree some more.


I ended up taking my original tap into a steel fabricating/etc place to see what they thought. One of their guys took the tap to the back and said grab a seat, he'd go see what could be done. About 10 minutes later he returned with the tip chopped off. I couldn't pay or tip him even no matter what, he just said go give it a whirl and come back if it's not good enough. Not sure what exact tool he used, but they had all sorts of the plasma/laser/water cutting stuff available.

I used the modified tap and was able to finished the threading all the way though.
I'm now finishing up the cleanup of oil residue and will place the sealant/insert into tonight. I'll let it sit for a while and then do leak tests.

I'll let you know how it turns out.

[rustybronco]

Sounds like a plan. (crosses fingers...)

. One of their guys took the tap to the back and said grab a seat, he'd go see what could be done. About 10 minutes later he returned with the tip chopped off. I couldn't pay or tip him even no matter what, he just said go give it a whirl and come back if it's not good enough.

Drop off a pizza, that will take care of them.

[fb9]

Update --

Helicoil insert was previously installed and then was out of town for the holiday weekend and such. Red loctite had plenty of time to set up and then I tested it out. Wanted to give thing af ew additional days after that to see how things went.

I put the drain bolt in and it appears my threading job is just ever so out of alignment, even after using that piloted tap to get it going 'square'.

It's just enough out of spec, that I didn't trust the [even new] crush washer to fully seal. I do have a replacement crushwasher, but getting the old one off the current bolt seems to be trouble. I may pickup a new drain bolt at some point and then try a new crush washer to test for sure.

In the meantime, I rigged up a different solution using an oversized metal washer and one of the 'free' garden hose gaskets from Real Gaskets.

Initally I just trid the Real Gasket, but the drain screw head is much smaller than it, and the gasket started to 'fold up' as the drain screw 'peeled though' when tightened down.

I picked up the big metal washer from the hardware store for 15 cents; it extends larger than the gasket, so it pushes down evently and with with out the drain bolt 'peeling through' the hose gasket.

The external metal work of the final drive worked really well for this because there is a rounded cutout area for this RealGasket and oversized washer action to perfectly align up with. HArd to explain, but makes sense when you look at it.

I let it sit for a few days to make sure no leaks.
First try there was a drip, but I had kept torque very low for testing purposes. Tightened it up and good to go.

I did loose half of the drain screw threads to the thickness of the gasket and washer, but otherwise I don't currently have any concerns over the performance of it all.

I didn't fully fill the final drive, going to drain it out again to remove any metal shaving that might still be present and then top it off once and for all.

Thanks.

Now don't be stupid and perform this same screw up as me.