914 flywheel vs a bus flywheel, any differences? Options

[malcolm2]

I sure can’t see any.

Building a 2.0 from a 1.8 from a 914 for my 72 bus that came with a 1.7. Have both flywheels. I did not label either. The 914 was running when removed so it must be the shinier one. The bus sat in a field for 10 years. So much moisture under there that the magnesium bell housing deteriorated.

Anyway, both are 210 mm. Some vendors say their 914 FW won’t work on a bus and visa-versa.

Anyone have more details?

[GregAmy]

One thing I see is that the one on the left does not have the step for the pilot bearing "seal" (a round piece of basically felt that you oil.) Do both have the inside groove for the o-ring?

Measure the flange thicknesses and offsets, see if there's a difference.

Edit: also, check the offset of the ring gear versus its inner base flange (where it mates to the crankshaft.) I seem to recall a prior discussion that this offset was slightly different due to the difference in transaxles used. If so, the 901 trans starter gear may improperly engage with the flywheel ring gear.

[rgalla9146]

In the Porsche parts manual the part number is 022 105 273 A
That is a bus part number.
Look interchangeable to me.

[malcolm2]

One thing I see is that the one on the left does not have the step for the pilot bearing "seal" (a round piece of basically flannel.) Do both have the inside groove for the o-ring?

Measure the flange thicknesses and offsets, see if there's a difference.

doesn't the "step" come from the fact that the pilot bearing is slightly smaller (shorter) than the thickness of the hole?

The FW on the right still has the pilot bearing installed. FW on the left has the Pilot bearing removed.

And Yes, both have an o-ring groove, even still have the o-rings installed.

[GregAmy]

doesn't the "step" come from the fact that the pilot bearing is slightly smaller (shorter) than the thickness of the hole?

Shouldn't matter; after all, that "step" is covered by the plate that goes under the bolts. As I understand it - and how I did it on my engine last month - that step is to make space for the oiled felt seal.

And in case you missed my edit above, measure the offset from the backface to the ring gear.

[malcolm2]

In the Porsche parts manual the part number is 022 105 273 A
That is a bus part number.
Look interchangeable to me.

I found lots of part #s yesterday....
211 105 275
311 105 271
021 105 271 C

Best I can determine in a small amount of research is that the 72 bus with a TIV came with a 210mm FW. In mid-74 they may have changed to 215mm, I think. Then to 228mm and used that one on the Vanagon. all with 130 teeth. I believe the Type 1 engine used a 200mm FW.

Clutch and pressure plate need to match, and it seemed that the 228 FW had different teeth and needed a different starter...... The 74 bell housing would handle a 228 but a 72 and older TIV would not.

But I read no differences between 914 and Bus.

[Bleyseng]

On a bus the pilot shaft bearing is in the crankshaft not the flywheel. On the 914 engine you pull out that spacer and install the bearing. I'd get a rebuilt 210 bus flywheel that is resurfaced and ready to run vs those rusty pos ones.

[malcolm2]

OK. That is what I see. With that difference in accessory assembly or attachment, it still appears that the FWs are the same.

If I may ask, does it matter, why the difference? I guess the input shaft is different? More evidence that the rusty one, with no pilot bearing is from the bus.

I have several 914 tranz cores etc...under the house along with my rebuilt 3-rib Bus Tranz. So I will check.

1.7 BUS engine sitting on the floor... Pilot Bearing in the crank


Donor 2.0 Crank from another 914

[Krieger]

My car had a 228mm flywheel when I bought it. Idk at the time, but I found out when I went to do the clutch. If my memory is correct the 228 mm flywheel is lighter than the stock 914. By the way, that donor crank you have looks like the flywheel came loose when it was in service.

[Mark Henry]

Bus came with a 210, 215 and the 228mm.
I know for sure the bus flywheels have a small pilot hole.

[Krieger]

Bus came with a 210, 215 and the 228mm.
I know for sure the bus flywheels have a small pilot hole.

When I figured out whaI flywheel I had I noticed I had no pilot bearing. I had to have a machinist enlarge the hole for the correct pilot bearing. I also determined that the lack of a pilot bearing was the cause for oil leaking around the trans input shaft. The input shaft was moving around enough that it had worn a slight groove on its tip from contacting the flywheel. This excess movement created enough of a gap at the trans input shaft seal that it leaked...

[Bleyseng]

That 2.0l crank is shot but it does show you the 914 spacer you must remove. Any bus 2.0l crank is the same as a 2.0l 914 crank.

[malcolm2]

Bus came with a 210, 215 and the 228mm.
I know for sure the bus flywheels have a small pilot hole.

OK. I removed the pilot bearing of the above pictured FW and got the same diameter as the rusty on in the pic. I am pretty sure the bus engine had been out at some point.... 1. they painted the tins and valve covers. 2. looks like this rusty flywheel was re-installed without the thin 5 hole washer and the serrated bolts dug in. So maybe the PO put a 914 FW in with no FW pilot bearing or spacer.

Am I right about the years and the sizes of the FW? I did read where folks could not fit a 228 in a 72 bell housing.

[Bleyseng]

You have to install a 091 bell housing on it. The gearing on the 72 tranny is setup for a high reving 1.7L vs the 2.0L so you end up running higher than the sweet spot of the 2.0L which is 4200 rpms at 70 miles per hour. (max cooling)

[porschetub]

They aren't the same,the bus flywheel has a different ring gear offset incase someone hasn't mentioned it already.
I've never checked but I think the pressure plate position is different also from one to the other.

[malcolm2]

http://www.type2.com/

Flywheel section has some info.