PorKen

Duh!

After a flash of inspiration (followed by a feeling of 'gosh yer dum'), I checked the manual on how exactly the 32V cam gears are adjustable.

The gear keyway is just oversized! (The gear is one-piece; the extra slotted holes are for locking the gear to the rear cover while loosening or tightening the bolt.) The parallel (woodruff) key is the same, 4x4x16mm (longer in '87+, 22mm).


16V flat teeth vs. '85+ 32V HTD

So, can/should I put in 32V gears, or just oversize the keyway in my 16V gears?

*Original Thread*
~thread~start~
Post 900!

Zandramus

works on the 32v cars dont it?


seems easier than moving the belt tension around.


Z

DR

Hi Ken,

I have been biting my lip wondering how long it would be before you realized this. I guess I should have said something sooner but I was curious watching you with your development of adjustable cam sprockets for 16v cars and didn't want to stifle your creativity.

All you need to use the later style cam sprockets on a 16v is the "spiders", part #928.105.459.00 , cost is $23.22 each.

Lucky Ekman has been doing this for many many years and he used to bug me all the time for used 32v Sprockets and spiders. He had me on a standing order for them and took all I ever got my hands on.

PorKen

DR,

If gas ever gets cheaper, I'm gunna drive down there and kick yer ***!

So the 'Timing Gear Hub' (spider) fits on the back (also in the bore?) of the cam sprocket (gear) and bolts to the back of the sprocket? I was trying to figure a way to do this with the 16V gear...

Note to 16V'ers - we have to upgrade to all HTD (round tooth) gears to make the switch.

DR

Hi Ken,

>If gas ever gets cheaper, I'm gunna drive down there and kick yer ***!

But Ken, you were coming up with some really neat ideas, no kidding !!!

>So the 'Timing Gear Hub' (spider) fits on the back (also in the bore?) of >the cam sprocket (gear)

Yes.

> and bolts to the back of the sprocket? I was >trying to figure a way to >do this with the 16V gear...

It seems to be more a friction fit, except when you are doing adjustments and then bolts are used. See page 15-132 of the FSM for details of how it is used for adjustment on the 32v cars.

I had been toying around with the idea of making some nice degree wheels for the 16v cars using this setup, but alas time seems to slip away with me...... I will toss that torch to you now.

TeufelHei

Holy crap that's great!

DR do you have such an installation on your car at this point?
I'm looking forward to seeing this develope, I've got a penchant for the old style and absolute precision at the same time. Tough combo.

DR

Hi Tim,

>DR do you have such an installation on your car at this point?

Not yet, it has been on my "to do" list for a long time, unfortunately my list keeps getting longer and time shorter. After I finish up the current resto I am planning to schedule some "fun time" for MY 928s :-)

>I'm looking forward to seeing this develope, I've got a penchant for the >old style and absolute precision at the same time. Tough combo.

Me too, I am hoping that by the time I can schedule my play time that Ken will have some nice pretty timing dials for the sprockets ready to send me.. right Ken ?? :-)

PorKen

DR,

"some really neat ideas" - somthing akin to reinventing the wheel, in order to learn why it rolls.

Do you (or someone reading) have a picture of the timing gear hub (spider)? I cannot find a picture of it (don't have PET).

Perhaps the spider can be used along with machined/laser cut modified factory flat tooth timing belt gears (with laser etched degree marks) so that syncing the cams would not involve the whole HTD swap.

DR

Hi Ken,

I am out of the office now, heading into the deep mountains camping for the weekend on the off chance that gas prices drop tomorrow :-)

I will send you a photo Monday, and/or give me a call and I will send you a pair of the spiders to experiment with.

Have a great 928 weekend,

PorKen

DR,

Thanks for the (belated) insight, and the offer.

Have a good weekend!

PorKen

After taking another look at the WorldPAC pics, I understand how the timing gear hub works.



The back side of the 32V gear is machined flat and the keyway is oversized. The hub fits snuggly on the key, and has bolt holes for the cam to bolt to when adjusting the cam position, otherwise the ignition rotor to bolts to it.

I'm thinking that a 16V flat gear could be similarly machined, combined with an aluminum plate on the front side to clamp the gear to the hub.

toofast928

PorKen, I'm right with ya. So what do we need to buy? 32v cams gears and spider assembly?

PorKen

toofast928,

The easiest path to precision would be too upgrade to '85-up gear set.

Gear hubs (spiders)
HTD 32V cam gears
HTD oil pump gear (bonus?: aluminum for HTD vs. steel for early)
HTD crank gear

I already have a used HTD 16V set I got off eBay, plus a new belt (unfortunately, compared to the originals, the cam gears were a bit worn so I just put an early belt back on my recent belt change).

The other way to do it would be to have the early 16V gears machined to work with the factory spiders. I have another idea too; machine the front of the early gear flat and have a steel plate made to work like the 32V spiders.

I'm not quite sure if it would be worth the trouble making the early style work though.

Normy

The Rabbit people [as in early VW Golf] are all into cam gears. You can buy an adjustable model, with screws....or you can even buy one with weights that centrifugaly move the cams based upon RPM.

Funny, their Gilmer-belt gears look extremely similar to ours. I don't know the diameter at all of a Golf cam gear, but I am certain that this system at least could be modified to fit an M28-

I have no idea what a "spider" is...other than that I kill dozens in my house each time I come home.

N!
'85 S2 5 Speed

jpitman2

Porken, interesting possibilties here....one question arises - how would you do the timing setting? difficult to check valve lift on a 16V, with anything! You would need to compare the 32v wheel with a 16v wheel and work out what setting gave normal timing (for a 16v), and what timing the extremes of the adjustment gave .......If this was reliable, you could mark the wheels accordingly?
jp 83 Euro S AT 47k