L20 flywheel

[jovial_cynic]

I believe that I've got a flat-spot on my 6-bolt flywheel; I've swapped out the starter, thinking that it might have been free-spinning because the shaft didn't kick out, but after swapping it out, I'm pretty sure that the flywheel is the problem.

 

Has anybody re-rung their flywheel, or do they just grab another one? Are all 6-bolt flywheels the same for Datsuns? 280z flywheel work?

[datzenmike]

All 6 bolt L and Z will interchange but some are different weights. I have seen a 29 and a 21 lb 225mm wheel. Identical otherwise.

[jovial_cynic]

Interesting. Any thoughts about the aluminum 10lb 6-bolt flywheels that are on eBay?

[jovial_cynic]

wait wait. That can't be accurate. I had two 6-bolt flywheels, and only one of them mated correctly to the roadster pressure plate that I bought.

[slodat]

The pressure plate mounting hole bolt circle is 200mm on the roadster clutch and 225 on the Z/620 clutch.

[jovial_cynic]

So... which flywheels work? From what vehicles? My flywheels both came from boxes of misc. datsun parts, so I don't know where they came from. If I'm going to hunt for a flywheel that'll mate up to the roadster clutch, which flywheel do I need? (aside from the seemingly obvious roadster flywheel).

[datzenmike]

Sorry, they will all interchange and physically bolt up to any L/Z motor. As for clutches, only cars with the matching 200mm clutch/flywheel are the '80-'81 200sx with the Z20E motor (possibly the '82-'83 with the Z22E) and any other L20B powered car. All 620/720 trucks are either 225mm or 240mm.

[hang_510]

which flywheel do I need? (aside from the seemingly obvious roadster flywheel).

 

... the matching 200mm clutch/flywheel.

 

match the FW to the PP(roadster=200mm)

[jovial_cynic]

thanks. i guess it's time to go parts fishing again.

[jovial_cynic]

In the event that I can't find another good flywheel any time soon, is this a reasonable option? Has anybody ever re-rung a flywheel before?

 

http://cgi.ebay.com/ebaymotors/Datsun-Fairlady-Roadster-Flywheel-Ring-Gear_W0QQitemZ280201823156QQcmdZViewItem?_trksid=p4506.m20.l1116

 

It's the roadster flywheel ring-gear. It seems that it's the minimal approach to getting what I need done. Any clues on what it costs to get a flywheel re-rung?

[datzenmike]

I have my doubts as to weather the roadster flywheel or starter ring will fit an L or Z flywheel. As far as I know the only thing in common is the 200mm pressure plate and clutch assy.

 

The old ring can be cut with a saw and removed. To put the new one on, cool the flywheel in the freezer while heating the ring in a 400 degree oven. Quickly place the hot ring over the cold flywheel and tap quickly into place.

[jovial_cynic]

Didn't the roadster fairlady have the L16 and L20 in it?

[ppeters914]

Didn't the roadster fairlady have the L16 and L20 in it?

 

Nope. R16 (pushrod) and U20 (SOHC).

[jovial_cynic]

ah. Good to know.

 

So... this is the right ring-gear, correct?

 

http://cgi.ebay.com/ebaymotors/FRG634-Ring-Gear-Nissan-75-77-78-79-80-81-82-83-84-85_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116QQitemZ310004939316

[banzai510(hainz)]

YOu have a 200 mm 6 bolt from a car. like a 77-79 200sx and any maybe 610s and 710 that had L20 in there.Truck L20s use the bigger 225mm or maybe a 240mm

 

I believe Napa, Rockauto or maybe others might have new ring gears if you think its bad and a machine shop will put it on. So you can sgtill use you roadster set up or maybe Ted has one in Yelm.

Fidanza has aluminum ones for about 380$

[datzenmike]

You can replace the ring gear at home. Place the flywheel in the freezer and heat the ring gear in the oven (with your wife's permission) at 350-425 degrees. Quickly slip the hot gear over the cold flywheel and tap into place... easy.

 

To remove the old damaged one just grind away metal until it splits.

[jovial_cynic]

thanks, folks. I've got a new ring gear now, and a near future plan is to swap it on.

[datzenmike]

My FSMs all say when working with the flywheel never to drop it. I always thought... Duh. But they never say this about equally heavy parts like the crank or head. Dropping could cause the flywheel to flex like a rubber ball and the ring could pop off.

[jovial_cynic]

Old flywheel ring gear.

 

New flywheel ring gear.

 

Old flywheel ring gear.

 

New flywheel ring gear.

 

Holy smokes, that old ring gear has seen better days. I should get the one new pressed on in the next day or so.

[ppeters914]

Holy smokes, that old ring gear has seen better days. I should get the one new pressed on in the next day or so.

 

T'would appear to be a good idea. :D

[jovial_cynic]

Based on the way the ring gear sits against the flywheel, there will be no hack-sawing of the old ring gear -- there's no way for the hacksaw to go across the ring gear without cutting into the flywheel itself.

 

I've read that using a torch and a metal chisel is an alternative solution. I've got a torch. I've got a chisel...

 

 

As for a new starter, any thoughts to the value of a reduction gear starter? The stock compression ratio on the L16 is something like 8.6:1. Mine is upwards of 9.58:1. Is that so high that a reduction gear starter is a good option? Or will the stock starter suffice?

[slodat]

I have the Z car gear reduction starter on my car. I like it.

[mklotz70]

If you're looking to split the old gear off.....can you drill an 1/8" hole or two across the width of the gear....that would make splitting it much easier.

[jovial_cynic]

mklotz70 - that's what I had in mind. :) The less metal I have to chisel through, the better.

[Farmer Joe]

All 6 bolt L and Z will interchange but some are different weights. I have seen a 29 and a 21 lb 225mm wheel. Identical otherwise.

 

sorry to hijack, but thats absolutely true? i can put an Z24 flywheel on an L20? if so then i dont have to worry about gettin the last L series flywheel at the yard.