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Thu Aug 08, 2019 2:35 am

I have a stock 1600 block with 10mm head studs and no case savers. Which is better: Drill/tap case for 10mm ID case savers and reuse 10mm studs OR install 8mm ID case savers and switch to 8mm head studs (and will this require drilling/tapping the case)? Thanks all.

Thu Aug 08, 2019 7:05 am

I would just stay with the 10mm studs since you already have them.
Are you staying 1600? Make sure you recess the case savers slightly in the case also.

Thu Aug 08, 2019 9:30 am

Thanks. I'll be sticking w stock 1600. A few follow up Q's...

-Anyone know if the 8mm ID case savers (time sert) will thread into the existing 10mm stud holes, or does this still require retapping?

-What prevents the case savers from pulling out of the case? If the answer is "Locktite" then why not just Locktite the studs into the case?

-Is there any advantage to having 8mm studs, (why the factory went to 8mm studs with case savers instead of enlarging the stud holes for 10mm ID case savers) is this stronger?

Cheers

Thu Aug 08, 2019 12:10 pm

10mm? Hell no!!! VW changed because 10mm studs cracked cases in a hot running engine. The heads became too tight and the studs pulled the case apart. 8mm studs stretch allowing even tension when hot. Check the case carefully for cracks inside the bore at the end of where the stud stops, that is where the problem starts. Get OE 8mm studs from GBE. Get 12mm OD inserts. Dan

Thu Aug 08, 2019 1:43 pm

Well, VW changed to 8mm AND installed case savers. The 10mm studs loostned and pulled out of their threads because the magnesium case is softer than the steel stud. Why not do case savers w the 10mm...why offer case savers w 10mm ID for sale on vw supply stores?

Thu Aug 08, 2019 1:44 pm

I’ll agree with Dan here.
Yes you’ll need to drill and tap but you will never have a stud problem after that. They all them “Case Savers” for a reason.
The thread pitch is coarser so it grabs the case better and won’t pull.
The torque is what actually holds everything together. I use a thread sealant on the open holes but mainly to hold them in place while installing the head studs. Sometimes they will start turning themselves into the case especially if the case is clearanced for stroke.

Thu Aug 08, 2019 3:07 pm

Yea, it makes sense to follow suit w what the factory did, I'm only curious to know the reasons "why" behind these type of things. The Gene Berg kit looks like the way to go.

It also looks like there's not a whole lot of material in parts of the case to accommodate a 10mm stud+case saver.

Thu Aug 08, 2019 3:13 pm

The reason why is because a problem became evident.
As the engine tries to expand, the head studs did not. Since the steel of the stud is harder than the magnesium alloy of the case the studs would pull themselves out taking the magnesium alloy threads along with them.

Believe it or not, if you stay with 85.5 barrels a 10 mm case saver will fit without compromising the barrel spigot or mouth or hole whatever it’s called.

Thu Aug 08, 2019 5:28 pm

Sorry if I wasn't clear, I understand the reasons for needing this fix. I meant to understand which solution was better and why. Good to know that case savers for the 10mm are still an option. Thanks.

Thu Aug 08, 2019 7:03 pm

Ok I redact my previous statement.
I believe the 8mm studs would be the better choice in your situation.
My “AE” case came with 10mm studs. I opted to do the 10mm studs with case savers installed on the advice of the vw machinist that inspected my case etc.
Tons of people have run 8mm stock studs and case savers with zero problems.

Thu Aug 08, 2019 7:38 pm

Oh, cool, mine's an AE as well. So I assume that you have not had any problems with your setup using the 10mm stud+case saver?

Thu Aug 08, 2019 8:25 pm

3de wrote: Oh, cool, mine's an AE as well. So I assume that you have not had any problems with your setup using the 10mm stud+case saver?
It can work with 10’s but you have to be very careful to avoid ping and overheating.

10’s with case savers make the problem even worse, now you have a solid anchor for the stud and threads are less likely to strip out, something has to give and the case cracks and becomes junk.
Dan

Fri Aug 09, 2019 5:49 am

if you go to the 8mm setup ( which i would do on a street engine) be aware that a lot of aftermarket 8mm stud kits are pure junk and made from much softer steel than the real ones..so they wont stretch and come back....and these have been around for over 30 years and were supplied with brand new cases so just grabbing the studs out of an old motor vs buying new ones doesnt guarantee they're real...i'll clamp the threads in aluminium soft jaws in a vice and pull on the end of the stud....the real ones will flex and spring right back, the fake ones will bend and stay bent

Fri Aug 09, 2019 10:29 am

Think of the head stud as a very stiff spring. 10mm is much stiffer than 8mm. 10mm is so stiff, as the engine expands (hot cylinders), and the studs don't (they are cooler), the stud torque goes WAY up. So much so that they often pull (strip) the case.

8mm are much more forgiving about this, they are stretchable enough (softer spring) they stretch before they do case damage. I always recommend 8mm head studs for street cars.

Fri Aug 09, 2019 3:11 pm

I kept the 10mm with case savers and have not finished my motor yet. (Probably never will) but I would listen to John’s Advice if I were you.

Sat Aug 10, 2019 12:38 am

Many thanks all... Much clearer to me now.

Wed Sep 25, 2019 6:57 am

[email protected] wrote: Think of the head stud as a very stiff spring. 10mm is much stiffer than 8mm. 10mm is so stiff, as the engine expands (hot cylinders), and the studs don't (they are cooler), the stud torque goes WAY up. So much so that they often pull (strip) the case.

8mm are much more forgiving about this, they are stretchable enough (softer spring) they stretch before they do case damage. I always recommend 8mm head studs for street cars.

John- Question; i believe i am having this issue here as well my question is can i go down from 10mm stud to 8mm ? i am running 94mm cylinders with a turbo application. i think the extreme pressures have cause one or couple studs to come loose although i am only running 12lbs with methanol injection for cooling purposes. Should i stay with the 10 or go down and is this possible>