How's it going guys? Thanks for taking a look. I'm new to the whole bug building process but I've been bitten by the bug for sure, so please bare with me because my question is probably simple and dumb.
Anyway I have a 66 bug, with an AS41 block with a new cam, jugs, and pistons. Standard jugs/pistons made it a 1600, now its at 1776. I put the original transaxle in it, with new boots and all that happy stuff.
The problem I am having is when switching from 1st to 2nd gear, when I let off the gas and clutch the engine keeps revving up higher and higher. I dropped the engine a few hours ago and checked the clutch and clutch plate. No bolts were sheared off, nor was the clutch looking or showing any signs of it going out. typical standard test I've heard from guys at my local bug shop is to stand on it with my heel and see if the clutch has force when letting off of it(it did). I did however end up changing out the flywheel because it was visibly shaved down so to speak in one place.
This seems like a no brainer to me that it would be the clutch, but why wouldn't it happen in any other gear than 2nd?
Sorry again if I seem stupid but this is my first bug I've built so far.
66 bug issue(have some questions)
- Marc
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Re: 66 bug issue(have some questions)
That does seem a bit odd, one would expect a slipping clutch to be worse in the higher gears as well - but the "split" between the gear ratios is wider from 1st to 2nd than it is from 2nd to 3rd or 3rd to 4th, so it may just be that you're noticing it first on the 1-2 upshift because the engine is higher up on its power curve when you release the clutch there. I'm also going to assume that it's clutch slippage you're experiencing...15 seconds in the driver's seat would've let me know for sure, but that opportunity doesn't exist when attempting a long-distance diagnosis - I can only go by what you report. Probably not the best forum for the topic, but it'll have to do.mdlamerica wrote:...This seems like a no brainer to me that it would be the clutch, but why wouldn't it happen in any other gear than 2nd?...
All US-market `66 Beetles came with a 1300, equipped with a 180mm clutch. Although fine for a 1200 or 1300, it's inadequate for anything bigger. You can get 180mm pressure plates with stronger springs, intended for an old Porsche or Bus, but even with the stiffer pedal (harder on you and the cable) they don't offer the torque capacity of a standard 200mm clutch. The first thing I'd do is upgrade to a 200mm flywheel & clutch.
If this has already been done, there's still a possibility that it wasn't done correctly so engine oil is getting on the clutch...or the flywheel could've been resurfaced improperly (the surface that the clutch cover bolts to has to be machined an equal amount to that removed from the friction surface.)
`66 was the transition year for the change from sealing the flywheel to the crankshaft with a gasket, to the vastly better O-ring setup - and the last year (in the US) for the 6V electrical system and 109-tooth flywheel. `67-up are 12V, with 130-tooth flywheels which are approximately ⅛" larger in diameter than the 109-tooth - they won't fit into the bellhousing of a "6V" transaxle without some clearance-grinding to the four bosses where the engine-to-trans bolts/studs pass through and to the boss which supports the starter bushing. The pinion teeth and shaft diameters of the 12V starter are smaller; to run the 130-tooth flywheel you must use a 12V starter with a thick-walled adapter bushing or one from an automatic/AutoStick that's self-supporting and doesn't require a bushing.
Changing a flywheel on an ACVW is a critical operation since the crankshaft endplay must be set properly (using shims of varying thickness) - the "gland nut" which secures it to the crankshaft needs to be torqued adequately (a mininum of 217 lb-ft) or it'll come loose which ruins both parts in no time flat. Because of the two different styles of crankshaft snout one may encounter on a `66 there are some other "gotchas" lurking - the presence or absence of the gasket between crank & flywheel makes a difference of ~.008-.012" in the endplay (and you only get about a .002" margin of error), and the I.D. of the early shims is larger than that of the late ones - if used on an O-ring crank, early shims will slice a nasty groove right through the end of it.
There is such a thing as a 109-tooth, 200mm flywheel (from a pre`67 1500 Bus or Type III engine) which uses the gasket setup, but they are rare indeed - at least with serviceable starter teeth, since they aren't induction-hardened like the 130-tooth version it's only a matter of time before they wear out even on 6V, and if the 6V starter is spinning on 12V that can be a very short time. What's typically done when the crank is gasket-style is to machine the I.D. of an O-ring, 130-tooth 'wheel out so it'll fit (and run a gasket, since there's nowhere for the O-ring to live on the crank). Replacement 109-tooth ring gears are available which can be shrunk/welded around either style of 200mm 'wheel after its existing teeth are milled off, probably the best approach if retaining the 6V electrical system (but that's not cheap - personally I'd spend the money towards a 12V conversion instead).
The 1600 gland nut is beefier than the ones used on earlier engines and should be considered mandatory for this application. IMO anything bigger than a mild 1641 should also be fitted with 8 crank-to-flywheel dowel pins and a larger-diameter glandnut washer (its added thickness may require that the head of the glandnut be undercut to prevent contact with the clutch disk center as the friction material wears) - run the stock 4-dowel setup with a healthy clutch and you're asking for trouble...big trouble - it may be a blessing that the clutch is slipping and preventing you from shucking the flywheel.
The point I'm trying to get across here is that you may be in a little beyond your depth. It's how we learn, but this area can have some pretty heartbreaking (and spendy) learning experiences...I strongly recommend that you enlist the aid of someone who knows what they're doing - and IMO whoever told you to test a clutch cover by stomping on it is probably not the guy
To close with an actual transaxle-related comment: once you get the clutch hooking up, it probably won't be long before you break the differential in the `66 trans with a healthy 1775. 15/1600-equipped Beetle transaxles have more bolts holding the ring gear to the diff and a 6% taller final drive ratio that's more appropriate for the larger engine - and they're already clearanced for the 130-tooth flywheel. In the US all Beetles went to the 4-joint "IRS" rear suspension in `69 so there are only two years' production of the better trans (fortunately `68 was a banner year though). `67 uses the same brakes as `66 but the axles & tubes are longer for a wider track width; `68 also has longer axles/tubes - although NOT the same as `67 - but uses bigger brakes and 4x130 lugbolt pattern, so you'd probably swap those parts from your existing transaxle. Although somewhat stronger, the stock `67/`68 trans still isn't really up to the job if you'll be flogging it and a custom-made gearbox using later/aftermarket internals may be called for eventually.
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Re: 66 bug issue(have some questions)
Thanks for the reply man, turns out my assumptions were right, and yours as well. I replaced the clutch and it runs great again.