Seeking advice for my engine build.

[Piledriver]

There are a few threads here on the subject, will see if I can dig up links for you when I get home.

Heres a starter via Google:
http://www.etischer.com/914cableshift.html

[Clatter]

This is how it starts...

If you are going to get a proper exhaust,
vs. chopped heater boxes, or..?
And a real counterweighted crank,
vs. a stock crank..

You really are pushing yourself right up into a big 2270..

Once you get the heads done -- 44x38 costs the same as 42x36.
The bigger exhaust costs the same as the smaller one.
The 86b/86c costs the same as the 163/86b..

Since you are there... You end up building quite a motor...

IMHO, while there are many who do not like to rebuild stock heads.
(metallurgy/heat-treatment issues, welding, etc..)
The stock castings do have a fine detail that today's AMC castings don't.

If you start with good cores (which yours appear to be from looking at one pic),
You are likely to have better luck with rebuilding.
Have seen far more plug cracks on these heads before..

Check really carefully inside the exhaust ports - along the inside radius of the turn the port makes.
A really clever hidden spot for cracks is between the port and the combustion chamber.
It can often run away from the seat.. into the port.
Those cracks are pretty common, and can hide VERY well.

If you don't have these cracks, you are very likely to have good luck with rebuilding..

And, if they haven't been flycut too much...

Looks like fun!

[Piledriver]

Jake Raby always used to swear counterweights were not needed or even desired on a T4 crank... Even strokers.
DPR can make them either way, and aircooled.net sells them in both configs.

The stock T1 transmission becomes an expensive paperweight before you hit 150 HP.
The 901 is rated to around 250 lb/ft torque, except for first gear, its a granny gear for crawling in traffic.
A 7K clutch drop has been known to shear it off the end of the mainshaft.
Its a solid transmission for normal driving and can tolerate a mild V8, but drag starts not suggested in first.
(with a big enough motor you don't need first, the v8 guys frequently have it locked out or removed entirely)

[Type 4 Unleashed]

The 914 trans is set up for mid-engine, so to use it in a bug, you will have 5 gears in reverse and one forward, or go and have the expense $$$ of having the ring gear flipped or you could possibly run it up-side down ? The early 911 901's or is it 902's are rear engine, and have the ring gear on the correct side to use the trans in the bug location, and they also have a hockey puck to hook a shifter up to in some form, but those tranny's are also expensive.

[vwbaker83]

I think I read something a while back that said the differential can be flipped

[Type 4 Unleashed]

The ring gear is attached to the differential, so it's the ring gears position that determines which way the tranny faces to operate in the correct application. Which runs anywheres between $600 to $800 dollars done correctly.

When the ring gear is flipped, you can't just flip the different thickness shims from side to side and think all is good. The depth of the pinion has now changed and also requires to be re-set which is determined by the thickness of the gaskets for the gear stack.

[vwbaker83]

Is there not a way to determine the pinion depth in a garage? I know it is an ignorant question, but it would be a great learning experience.

[Piledriver]

Is there not a way to determine the pinion depth in a garage? I know it is an ignorant question, but it would be a great learning experience.

Yes it can be done in your garage, and anyone getting $600-$800 for ~an hours work is an amazingly talented thief.
I don't even make that.

Are you perhaps adding the cost of a refresh i.e. replacing a few synchros etc "while you are in there"?
A 901 is not like a VW trans, it doesn't require a dozen ridiculously expensive special tools and the sacrifice of a goat.

If you can score an earlyish 911 901 reasonably it saves some work, and the shifter setup is better beaten, although not necessarily better. The 914 trans is probably geared better for most uses.

Anything you buy probably has worn synchros etc, and if you start jacking with replacing everything just because you are in there you might as well just keep your wallet out...

[vwbaker83]

The 914 transaxle I have already is same one used with the engine. Is there any recommended reading for this besides 914 factory manual?

[Type 4 Unleashed]

An hours work, to flip the ring gear, your kidding right...

Here's a link from: http://forums.pelicanparts.com/porsche- ... ted-2.html

Another: http://forums.pelicanparts.com/porsche- ... rning.html


This is a write up from the 911 Registry, and it's just replacing bearings not flipping the ring gear

Chip,

If you are replacing “several” bearings, I would go for all six. The marginal additional cost isn’t that great.

You will probably find the differential bearing pre-load way below spec with the old bearings and still not in spec (bearing torque or backlash) with a new pair. That is your starting point. It isn’t difficult to make the tools necessary for setting the running torque and backlash. A Pelican search will show them.

There should be someone local to your parts that has P258 and the other little accessories. Once you have the pinion depth set correctly, you can then set the backlash to what is indicated on the ring gear.

I am not very skilled investigating the contact pattern. That said, I’m increasingly leaning to adding that technique whenever setting a R&P (particularly a used one).

My recent procedure is:
Remove the differential and measure the undisturbed pinion depth.
Reinstall the differential, remove the nose piece (keeping the seal at the shim gaskets) and measure the backlash.
Clean the gears and investigate contact pattern.
Remove the pinion and axle flange seals and measure the differential bearing running torque.
Install six (eight on 915) new bearings, setting the differential bearing preload.
Measure/set the pinion depth.
Reinstall differential and measure/set the backlash.
Investigate the contact pattern.

The serious question comes if/when the contact pattern has changed (particularly for the worse).

As you can see, this is very time intensive.

There are three issues here (some times they are mutually exclusive): First is insuring the R&P is set to the original numbers (done for quiet running).
Next is having the R&P running as it was before the bearing change ( to minimize the “disturbance” to previous running wear patterns.
Third is improving the running contact, possibly to extend the R&P life (also possibly with increased noise).

It is easy to rebuild a transmission with all new parts. It is not so easy to rebuild one trying to extend the life of 40-year-old good used parts. One reason you find many pros (with all the tools) shying away from this is it may take several iterations (of the entire rebuild process) to find the best compromise. The Forums can help with this.



BTW, I am collecting marginally rebuildable transmissions (901/911/915) in order to document some of these issues. Please let me know if you have something sitting around – nothing really good. I may even pay some money. Even 4-speed and Sportomatics will help. Eventually I hope to brow-beat Wayne Dempsey into authoring a really good and comprehensive Porsche Transmission Book. I’ll provide the 901/911/914 and 915 chapters. If this stuff doesn’t get written down, in another generation or two the information will be lost. Porsche doesn’t have it any longer.

[Piledriver]

I have helped once and seen it done twice more, was done exclusively via contact pattern, as that is the actual final test even if you use all the "special" tools.
Took ~3 iterations to get it right, where goal is ~same contact pattern as it was to start with ring gear on other side.
No bearings were replaced as they were known good low mile transmissions.

Those trans went in daily drivers years ago, and they were not noisy.

If you need to replace all the bearings and synchos, its not just flipping the diff, and that will suck some time and drain your wallet like a new hot girlfriend.

...but its still entirely possible to do without $5K in special factory tooling.

[Type 4 Unleashed]

I have helped build several of my trannies, one has a flipped ZD fifth as the third gear forth is a Q gear and fifth is a flipped O gear making it taller than the original ZD, but shorter than an H or HB that are what are usually used for V-8 914's. So I know the time it takes to work on these trannies, and what it costs.

Here's the link to where anyone can purchase a rebuild video: http://www.914world.com/bbs2/index.php? ... 587&st=100

I had attended a couple of his rebuilding classes when he lived out here in CA, that he did for our members of our 914 community.

[Clatter]

FWIW, IMO,

If you are going through all of the gyrations to put in a P-car 5-speed,

Might as well just go with a 915 vs. the 901.

It'll end up costing about the same in the end.

http://www.bugat5speed.de/en/beetle-co/ ... ission-915

[vwbaker83]

I'll do some research, in the end I'll probably not use it. I have a family member that has been working on Porsche's and other German cars for decades and has been doing it for a living with his own business here in Omaha. Never thought of contacting him till my brother mentioned him tonight. He would have the tools and the knowledge to help me rebuild and flip ring gear. I'll talk to him and see if I can gain a learning experience from him and possibly a suitable transaxle.

[Piledriver]

Sounds like a good plan.

914 guys sometimes need transmissions too!