914/6 oil leak, Case stud question Options

[gereed75]

I had the same thing. I cleaned out the stripped threads with brake clean and a wicked long Q-Tip. (not a real Q-Tip, but one of those medical ones with material that doesn't fray...)

I bought a 150mm long tap and was able to tap about 10mm further with more threads. I found a longer stud, reinstalled it with locktite and it hasn't leaked a drop.

-bob

This is encouraging! Where did you find the 150mm long tap and longer stud? How long has it been since the repair or how many miles?

That stud was also leaking on the T motor that is in my car. I currently have the motor out and the cases are split. I will look at what is "behind" that stud. It might give you a better idea of what you can get away with as far as "in the car" repairs.

I will try to check tonight.

Also please check your PM's.

[bob]

I forget where I found the tap. (maybe McMasterCarr?) I had a longer stud in my stash, but I'm sure you can find them at the usual places. (McMasters, Bel-Metric, etc.)
I fixed it earlier this year and the 914 is only used on the track, so maybe 10 hours? since I was able to tap it almost as long as the original thread-length, I don't expect it to fail.
-bob

[bcheney]

I had the same thing. I cleaned out the stripped threads with brake clean and a wicked long Q-Tip. (not a real Q-Tip, but one of those medical ones with material that doesn't fray...)

I bought a 150mm long tap and was able to tap about 10mm further with more threads. I found a longer stud, reinstalled it with locktite and it hasn't leaked a drop.

-bob

This is encouraging! Where did you find the 150mm long tap and longer stud? How long has it been since the repair or how many miles?

That stud was also leaking on the T motor that is in my car. I currently have the motor out and the cases are split. I will look at what is "behind" that stud. It might give you a better idea of what you can get away with as far as "in the car" repairs.

I will try to check tonight.

Also please check your PM's.

Thanks for checking on that. I replied to your PM.

[bcheney]

I forget where I found the tap. (maybe McMasterCarr?) I had a longer stud in my stash, but I'm sure you can find them at the usual places. (McMasters, Bel-Metric, etc.)
I fixed it earlier this year and the 914 is only used on the track, so maybe 10 hours? since I was able to tap it almost as long as the original thread-length, I don't expect it to fail.
-bob

So you just turned in the tap...no need to bore a hole deeper first?

[bob]

yeah. I measured the original stud and the hole. the hole was significantly deeper than the stud, etc.. I dont think the factory tapped it to the end, so I lucked out. (3R case if that matters...)
I used a bottoming-tap and the stud I used was threaded 'longer' on one end, so I inserted that end.

-bob

[gereed75]

sorry I did not post sooner. Just got to the shop yesterday Pics of the stud in question I think. I have not pulled it yet so not sure how deep the hole is. I am sure there is plenty of meat left to lengthen the threads.

Do not see how you could do this "in car" or without splitting cases - if this is the stud you are talking about.

[bcheney]

sorry I did not post sooner. Just got to the shop yesterday Pics of the stud in question I think. I have not pulled it yet so not sure how deep the hole is. I am sure there is plenty of meat left to lengthen the threads.

Do not see how you could do this "in car" or without splitting cases - if this is the stud you are talking about.

That is the one. Keep me posted if you pull the stud. It does look like there is plenty of meet behind there...maybe the Germans threaded that sucker much deeper and I'll get lucky...I plan to run a coat hanger down the hole tomorrow to see how deep it is as well.

[gereed75]

Never thought that the threads might go deeper. It's a possibility. I might have a chance to pull the stud tomorrow. For now, Halloween partee!!

[wndsnd]

Not sure the threads are deeper but I do think the factory overdrilled it. Also you can get different timecert lengths if you are looking for more grip. Belmetrics has many sizes.

Other than headstuds, that one is the one that strips and pulls. I also did the transmission mount studs behind flywheel.

John

[bcheney]

yeah. I measured the original stud and the hole. the hole was significantly deeper than the stud, etc.. I dont think the factory tapped it to the end, so I lucked out. (3R case if that matters...)
I used a bottoming-tap and the stud I used was threaded 'longer' on one end, so I inserted that end.

-bob

When ordering a replacement stud what spec does it need to be? I found this on McMasterCarr...

Also known as setup and driver studs, these studs are typically used in clamping applications. Inch sizes have a Class 2A thread fit; metric have a Class 6g thread fit.

Black-oxide steel studs are made of C1541 steel. The black-oxide finish provides lubricity and mild rust resistance. Studs have a min. Rockwell hardness of C27 and min. tensile strength of 125,000 psi. Those marked with a star have flat areas on the shank that facilitate installation with a wrench. For matching hex nuts in inch sizes see 95479A; for metric sizes see metric hex nuts.

[sixnotfour]

http://www.mcmaster.com/#99067A248

you cut to cut to length..

double nut to install, then trim to length

[sixnotfour]

darn double post (IMG:style_emoticons/default/beerchug.gif)

[bcheney]

yeah. I measured the original stud and the hole. the hole was significantly deeper than the stud, etc.. I dont think the factory tapped it to the end, so I lucked out. (3R case if that matters...)
I used a bottoming-tap and the stud I used was threaded 'longer' on one end, so I inserted that end.

-bob

I measured the depth yesterday and it appears to be the same length as the stud (125mm). My case is a 3R as well. Was hoping that the threads were a little deeper than the stud and I could just clean up what has pulled and run a longer stud down in there and grab the extra threads (a well respected 911 engine builder - Mike Bruns was in agreement with this approach). Running a bit down in there to bore out enough material to allow for the tap to do it's thing may be a show stopper.

[bob]

that sux... sorry to hear that the depth is different then mine. (for whatever it's worth, I have 2 more engine cases, an OEM -6 case and a 7R case.. both of them measured the same as the 3R case in my car... the 'hole' is about 10mm deeper than the factory threads)

at this point, unless you want to risk drilling the case.. ugh! full tear down.

-bob

[mepstein]

Get a pro to time sert. See what Joe O'brien can do for you.

[bcheney]

that sux... sorry to hear that the depth is different then mine. (for whatever it's worth, I have 2 more engine cases, an OEM -6 case and a 7R case.. both of them measured the same as the 3R case in my car... the 'hole' is about 10mm deeper than the factory threads)

at this point, unless you want to risk drilling the case.. ugh! full tear down.

-bob

Maybe I need to do more recon and see if there is something obstructing my measurement...maybe some case material that has pulled..Will check on that.

[gereed75]

I had a chance to pull this stud yesterday. The depth of the hole is about .835" and the threaded portion on the stud is nearly .6"

Interestingly, my cases are 4R/5R that show no signs of abuse. All of the studs (including this one) felt very tight. Removing the head studs was extremely difficult - they are very tight. But this stud came out very easily and brought the mag threads out with it. It appears that this stud see a lot of tension/stress even compared to the head studs.

Looks like no quick fix to me. Mine is off for some professional attention.

[bcheney]

I had a chance to pull this stud yesterday. The depth of the hole is about .835" and the threaded portion on the stud is nearly .6"

Interestingly, my cases are 4R/5R that show no signs of abuse. All of the studs (including this one) felt very tight. Removing the head studs was extremely difficult - they are very tight. But this stud came out very easily and brought the mag threads out with it. It appears that this stud see a lot of tension/stress even compared to the head studs.

Looks like no quick fix to me. Mine is off for some professional attention.

Where are you sending the case to have the time certs installed? Let me know if you are having all the case stud threads taken care of in this way and what the bill is if you dont mind.

Thanks,

[Luke M]

I had a chance to pull this stud yesterday. The depth of the hole is about .835" and the threaded portion on the stud is nearly .6"

Interestingly, my cases are 4R/5R that show no signs of abuse. All of the studs (including this one) felt very tight. Removing the head studs was extremely difficult - they are very tight. But this stud came out very easily and brought the mag threads out with it. It appears that this stud see a lot of tension/stress even compared to the head studs.

Looks like no quick fix to me. Mine is off for some professional attention.

Where are you sending the case to have the time certs installed? Let me know if you are having all the case stud threads taken care of in this way and what the bill is if you dont mind.

Thanks,

Try Ollie's Machine ... Check the price list on the main page.

http://www.olliesmachine.com

[gereed75]

I have a couple of Ideas depending on what all I decide to have done. I should know tomorrow or the next day. I will keep you posted (IMG:style_emoticons/default/smile.gif)