1500 swing axle box mods

[GARRICK.CLARK]

Hi guys.
I have a type 4 turbo in my bug.
The box and axles are standard .
Only mod ive done to the box is put an uprated cross shaft kit on it.
I'm only going to be using it for street use. With preloaded take offs
I need to be able to go over 70 mph on the motorway.
I want both rear wheels to get power.
So LSD OR SPOOL.
3.88 OR 4.125.
What shall I have done to it.
thanks.

[Casting Timmy]

You might want to list a budget for this as well. This will be an interesting one to follow and see the responses. I have seen some neat gearing using the 3.44 as well when using all aftermarket gears.

First can be moved up and the gear spacing or drop can stay the same or get smaller between gears and still give you a pinch more top speed. This does mean all aftermarket gears though so the price goes up a lot, but you get the extra strength which you definitely have the power for as well.

If your budget was stock, I would suggest looking into not only bug ratios but bus as well as I think the bus had a 1.22 3rd....not 100% for sure so that the drop to fourth wouldn't be so bad. I mention this as if you move up fourth you can shift up third as well to even out the spacing.

[GARRICK.CLARK]

Hi Timmy. My budget is about 1500.I want to get it right 1st time SO if I need to put a bit more into it then so be it. Hopefully this will get me a strong box and some good ratios. What I don't want is to be stuck in the 1st lane on the motorway.
What I wont be doing is side stepping the clutch.
By the way the clutch is a standard 210mm so that shouldn't be to fierce.
I have had a bug with a GT box fitted. That was quite good to be fare. still a bit too many revs in 4th tho.

[gkeeton]

A swing axle with a LSD diff, 3.88/3.44 r&p, aftermarket 1-4 gears, and axles that aren't going to snap the first time you get frisky is going to run upwards of $3500.00. You need to up your budget, or lessen your requirements. $1500 might get you a 3.88 r&p with stock 1-4, and a super diff.

[GARRICK.CLARK]

AHH right. Yeh its a fair few quid. What about if I was to fit a type 2 box. I think it would be better and make more sense to put the money into a type 2 box which is a stronger box from the start. I can get hold of a CE code type 2 box. Think its called an early 002. Would this be a good box to put some money into.
Thanks for advice

[gkeeton]

If $1500 was your budget, start contacting builders to see what is available for that. A Type 2, 002 trans is going to be IRS with the CV joints. They also have very low ring & pinion ratios compared to a Type 1 trans. There is a conversion axle set up to mount a Type 2 IRS trans into a swing axle car, but it is quite expensive. As for any sort of LSD, Quaife makes a diff most advertise as a LSD, but it is actually a Torque Biasing Gear diff that is still technically open. GT used to make true LSD Disc diffs for Swing Axles, and there are the older ZF versions around. Anyway you look at it, you may have $1000 in a used ZF, $1500 in a new Quaife, or $2200 in a new GT diff if you can source one. Swing Axle Spools are available from Weddle for around $385. Although I know some that have driven race cars on the street with Spools, it will be EXTREMELY dangerous to drive with the tiniest bit of moisture on the road surface, so I don't consider a Spool to be a streetable item. I personally would look into a Swing with a 3.88 r&p with a 3.78/2.06/1.26/.89 gear stack with a 4 spider diff, and a set of axles from someone like Weddle. That's going to give you the most trans per dollar spent. Once you start adding close ratio gears, LSD diffs, or Swing converted Type 2 trans, the price starts jumping up 200-300%.

[GARRICK.CLARK]

Thanks Gkeeton . I'll look into upgrading the box I have. I rang cog box yesterday and his price was £2200 and for that price I would get a decent fairly strong box. He also said I would have to be careful with it as its still only a bug box and not indestructible.

[gkeeton]

The above mentioned combo, with the exception of a shorter 3rd/4th, was used in a friends normally aspirated 1900lb drag car running around 12.00 for a few years. But yes, it is not indestructible, and needs to be driven/taken care of with that in mind. I would get some sort of heavier axle. I've seen more than a few stock axles get broken with much smaller engines than yours.

[GARRICK.CLARK]

Hi Guys. My idea now is to get the 1500 box I have now modified. A local gearbox guy who has recently fixed a vanagon box for me can rebuild and fit some uprated parts for me. Gunna get this done over the winter. Could you me a parts list of what to buy to uprate this box. Its only a street box really with some preloaded traffic light starts.
box is an AC 1500. Is there a 3.88 ring and pinion I can fit to this EARLY box.
I will get some sway away axles. I can get these from cool air in UK.
So 3.88 if can.
super diff.
what else can be bought off the shelf and given to the box guy to fit
Thanks.

[Marc]

I'd look for an "AO" box from a swingaxle 'Ghia post-8/70.

That'll get you the 3.875 R&P already set up in the swingaxle case.
An alternative choice would be its IRS brother, the "AN" - but you'd need a donor 8-bolt swingaxle trans to give up its final drive guts/sideplates/axle tubes.

Arguably better than a 4-spider "SuperDiff" using the early spider & sidegears would be to update those to the `73-up setup which uses the 10-tooth spiders (like late IRS) and 15-tooth sidegears. The carrier itself needn't be changed (unless you're converting an AN of course) but since you probably want to fit an HD sideplate on the ring-gear side the backlash & preload will require attention anyway so the labor's about the same if you do.

Late 'Ghia boxes also retained the .88 4th ratio - `73-up Beetle transmissions with the 3.875 got a shorter .93 4th which almost totally compensates for it so the highway RPM remains almost the same as it would be with a 4.125 box. With the .88, your RPM in 4th will drop 6% from what it is with the stock 4.125 box ... ~170 less at cruise.

If you really want to bring down the RPM on the highway, you can fit a Bus .82 4th. I'm using a 3.875 AN and .82 in my trike, and with 26½" tires it goes 97 MPH @ 4000 RPM - so it takes less than 2900 to loaf along at 70. With stock-diameter (~25.4") tires that combo would yield 70 MPH @ 3010 RPM...too tall IMO for a stock Type I engine in a full-weight Beetle, but should be fine with the Type IV. The downside is the wider spread between 3rd & 4th but that's not a problem if the engine has a broad power curve - works well if you have good torque at ~2500 and can rev freely to 4000+, but 45 MPH zones can still be annoying

[gkeeton]

Not sure what's available in the way of stock gearing in transaxles for you locally. There are a lot of things from late transaxles that can be retrofitted to an earlier ones, but like mentioned it may be less expensive to find a core that may be closer to what your end goal is in stock form. My choices would be a 3.78 1st gear, the 3.88 r&p you are looking for to lower rpm's, and HD side cover. I'm still for the 4 gear 17/11 tooth combo super diff. The cost/finding the 15 tooth side gears is more than likely going to be more than the 4 gear super diff with the extra spider gears. I don't have any first hand experience with the 15 tooth swing axle gears since they were never offered in the US, but I have seen the 15/10 tooth IRS combos fail with only 2 spiders. I know some feel the diff housings available don't mesh up a 4 spider gears equally as they should, but I have never seen one fail with either the 11 tooth spiders in a swing, or the 10 tooth ones of an IRS diff when replacing a 2 gear setup that has failed. The 4th gear ratio is up to you depending on driving habits. With the added cooling capacity of the type 4 heads you shouldn't have any issues using an .82 4th.

[Marc]

Be aware that SuperDiffs are notorious for being badly made so that their lateral runout exceeds the stock spec limits for backlash adjustment - I wouldn't use one without first having it chucked in a lathe and checked (may as well just get it cut true at that point). There are also two styles, one that uses snaprings (or double snaprings) and one that uses threaded retainers which are pinned in place once installed. The former are easier to dismantle but the latter are less likely to fail (and cost more).
These liabilities are why I'm not a big fan of SuperDiffs - the 15/10 swingaxle sidegears are virtually nonexistent in the US but you shouldn't have any trouble finding some there, if you do they'll give you nearly the same strength for far less expense than a "corrected" threaded SuperDiff will cost you. If you don't upgrade to the late mainshaft w/3.78 First, it could end up being wiser in the long run to have the diff be the weak link - it'll be a lot easier/cheaper to fix if it does scatter compared to replacing a mainshaft
The same argument could be applied to the axle selection - better to break one of those than something deeper inside the trans - but stock axles just break TOO easily in my experience so personally I'd go with the SAW axles and just be sure to "preload" the trans when doing a hard launch. With the smallish clutch and careful technique you should be able to make it live at your budget level (I'm assuming street tires, not slicks).

[gkeeton]

Marc, what did you pay for the last set of 15 tooth swing axle side gears you got? It's my understanding that the non US markets switched over to them when the US market IRS transaxles went to 15 tooth side gears. It's also my understanding that VW switched back over to the 17 tooth swing axle side gears when the US market Aircooled Beetle was discontinued. Not sure what the production figures were, but that only makes about a 7 year span going on 36+ years ago for the 15 gear swing side gears. The last set I got about 8 years ago were $200 not including shipping, and I haven't seen any for sale since on any of the forums. If they are readily available in the UK/Europe, I'd be interested in some more sets...

[Marc]

Yep, going rate is ~$200 around here....but they should be relatively easy to find in Europe, if you know what you're after I'd expect to get some for the price of a core trans.

[GARRICK.CLARK]

Right. Been doing a lot of thinking about what to do. Again.
I've put some miles on this bug to get a feel as to how it drives and how I'm going to drive it. Its only ever going to be a street car.
Only issue I have is the motorway cruise speeds / RPM.
This motor has a low static comp, so trying to launch fast doesn't work to well. Power comes on good and hard in the MID to WOT range. So with this I think I can do without the sway away axles. With this style of driving what could happen.
I'll put a stronger side plate on.
would I need to fit one on both sides.
3rd and 4th gear are too low.
I will get 3rd and 4th welded.
Silly not to when its in bits.
could I not change these gears to something better and leave the 4.125 as it is.
What ratios would work.
Do I really need a super diff.