ptuomov

Just thinking about it with my logic, PKT is the most valuable upgrade for engines with custom cams, stiffer valve springs, and intentionally shaved heads. It's not at all clear what tension the stock tensioner should be set after those modifications that change the belt tension side tension and therefore the required slack side tension, and what the impact of those changes will be on the required service intervals. The stock tensioner will probably be ok with those modifications, but who knows?

Because I think that the PKT system is most valuable for systems with a lot of modifications, then I think the kit should have clear instructions about how to modify the system to match alternative geometries of modified engines. This would add value to the kit when installed to (expensively) modified engines.

Cosmo Kramer

Here is another tidbit. The piston extension is different depending on where the engine stops. I found my varied from 6.6 - 7.4 mm during my measurements. It seemed to measure longer at 0T and 45 then at other spots where the engine stopped after cranking.

ptuomov

Logically, that level of variation is perfectly within the range at which the engine can safely start.

The engine will want to stop at approximately 45 degree angles when the cylinder in compression stroke is at 45 BTDC and the cylinder is power stroke (unburned) is at 45 ATDC. That's where the gas pressures are at minimum potential energy level. Then, when the cylinder pressure leaks slowly thru the ring gaps, valve springs and block thermal contraction become more meaningfully forces. As long as the PKT system is within the adjustment range, the crank gear stays wrapped with belt and life is not only good but great.

PorKen

Sounds like you are doing this but for other's benefit:

Extension should be checked after spinning the engine with the starter to settle the belt, then waiting a few minutes (more when cold).

Hot readings will be smaller than cold. (Usually about 2mm from dead cold to hot.)

The Audi system is dynamic. It will not show a true reading by hand cranking.

Cosmo Kramer

WTF Ken!

I just spent FOUR hours of my time messing with this f'in tensioner to get it into spec and all you can do is be cheeky?? For the record I was spinning with the starter just like you say in your instructions. I noticed different measurements at different points on the crank rotation and posted it as a data point for others.

I have always defended your products on this forum and your attitude about this is very disappointing. You haven't answered my earlier post as to why I was at 9 mm installed with a new belt with 6 mm holes in the t/d. Exactly like the fellow in the other thread. This product should NOT have to be modified to be safe on any 928 engine, period. It should have enough range designed into it.

If I didn't have an early water pump it would have been tossed in the garbage and put back to stock.

PorKen

Sorry for the misunderstanding but I realized that others reading may not be as knowledgeable as you. I absolutely did not mean to diminish your work.

Different amounts of valve spring tension at different crank angles and the temperature of the components will change the reading as you indicated.

I do not know why the reading is higher on your engine.


In designing the final bracket I experimented with many forms of the bracket and different methods of making it adjustable, including slotting the upper holes but it did not help. Modifying the tensioner/damper (to a size that already exists on the T/D) was the simplest and best option that works without making a whole range of brackets.

j.kenzie@sbcglobal.net

I agree. I didn't think Ken sounded cheeky, though.
Dave

Cosmo Kramer

How about sourcing a t/d with a longer range and adapting your bracket for it?

Once my belt stretches I will be at 8 mm cold. If my tensioner slips back in the elongated holes bolts it will be past 11 mm. Don't think it will happen but it's not the best solution don't you agree?

PorKen

The T/D, lever, and pulley are a system.

That is the procedure I was able to come up with. Can you propose a better solution that can be applied to existing brackets?

j.kenzie@sbcglobal.net

Overbore or slot the T/D holes and supply eccentric bushings?
Dave

PorKen

That would be a good option but I am not sure if there is enough material to work with.

If you are concerned with the hole size, how about filling the holes with some material?

Yamabond? Epoxy? (Coat the bolt with oil before insertion to stop adhesion?)

j.kenzie@sbcglobal.net

Yes, or glue in a 8-9mm crescent with JB Weld. You also could possibly supply offset studs and nuts?
D

Lizard928

Offset bolts/ studs would cost a great deal of strength.

If you don't find a solution that you like, ship me your lever, or have Roger send me one. I will modify it to fix the problem you're having.

Cosmo Kramer

How about redesign the bracket so the TD is 2 mm closer to the lever? Then if it's too tight to get the belt on have instructions to elongate the holes and move it back. It's better to have to move in that direction then to drill, push up and depend on friction to keep it at minimum spec.

j.kenzie@sbcglobal.net

Hi Colin,
Why not share your solution?
BTW offset studs combined with partially over-bored T/D hole would not need to cost strength.
Dave