Weak points on an IRS Gearbox - Info needed

[Andy]

I will be uprating my IRS Gearbox, and I want it to be as strong as posible (within my budget). I do not intend to go the Porsche 5 speed route, but probably order one from www.VWSpeedShop.co.uk who supply Rancho transmissions.

Has anyone uprated their IRS box, as I have heard that the CV joints are something which needs to be replaced.

I am not sure I will be getting a Quaiffe, so will 930 CV joints fit straight on, or will I have to change anything else.

Also, what are the other weak points (apart from mainshaft etc) on the IRS box, any recomendations would be appreciated. Any cheaper but stronger alternatives (if they exist), apparently the CV joints on late type 2s are stronger, but are they compatible.

The gearbox will be used on a large torquey motor(type 1) with occasional drag strip use.

Any info would be appreciated.

[MattKab]

Hi Andy,

I believe the inner CV joint bolts are the weakest point outside the trans. As for inside- I'm not sure.

The T2 CV's have the same diameter spline as the Bug, and the mounting flange PCD is bigger, the same as all the Porsches (?). The axles from a steel armed 944 are bigger in diameter and the same length as the Bug. The problem is the smaller PCD on the T1 trans. output flanges. The T2 trans has a bigger diff. and output flanges that will not fit in the T1 case. The Trekker/T181 trans is IRS T1 with T2 PCD output flanges. 'probably for the extra abuse the military vehicles had to cope with (?). I don't know the dia./length of the T181 axles.

Maybe you could specify T181 output flanges for your 'built' trans' and use the early 944 axles. This would make a much stronger set-up.

I too want to drag my '03- as well as drive it everyday! I'm going Porsche5- :silly: for the challenge!

I'm also looking into a 'built' T2 trans' with more appropriate 'ratios. I've got the Ally 'arms- nice, shiny and light. Bigger PCD CV's and longer, stronger axles.

Also worth mentioning is that most T181/182's had LSD! As do some '03 trans, I'm surprised that no-one raves on about these tranny's for IRS drag applications. 'Must be a reliability reason for this. 'Onewheel' burn-outs were common at Bug Jam RWYB :mad:

I've not seen the insides of a 'chewed-up' T1 IRS trans'- not yet anyway!

One thing's for sure, I'm gonna need a better trans too. My trans' doesn't have 2 side plates so mods are probably worthless in the long run.

Matt

[Andy]

Thanks for that, you have obviously done your homework, and it has given me something to ask about. cheers.

I have heard that the Trekker have strong CV joints. I may go for a quaiffe, cos the Porsche 930 CVs will fit on them, but its the cost.

Never heard of any IRS trans having LSDs as standard.

So you have ally 'arms, what swing arms? Are they any good, and where did you get them from?

I want close ratios, proably lower about 1.14 final drive on a 3.88 but that will mean going everywhere at 50, to keep the revs down. Compromise!!

So you are hard on the heals of Ritchie in his yellow cab. Two fast cabs racing, that would be a site, specially if you can lift the wheels like he does...

[Alex]

MattKab,

if you have a single sided IRS tranny...keep it. It is supposed to be the best IRS case. It has extra ribs there and should be stronger. When I was planning my tranny I was told to find such a case by Bruce Tweddle who knows trannies pretty well and he is the one that sells the ZFs to everyone I know in the US/Canada. The only better option for a case would be the Autocraft case.
Another week point with all trannies is the R&P. I believe that you can only get an aftermarket 4.125 new somewhere. All the others are used and you have to find a good one.

Alex

[MattKab]

Originally posted by Andy


So you are hard on the heals of Ritchie in his yellow cab. Two fast cabs racing, that would be a site, specially if you can lift the wheels like he does...

I'd be up for that! Lift the wheels? I cannot hardly break traction on wet grass!

Only 1 year gone, daily driver at the mo', Australia (VW holiday) trip before the prime mover mission happens. Then we're putting on something never seen at the 'Pod :cool: 'oldskool T1 against something rare! That paler yellow Karmann was stunning. Germanlook in the UK is much bigger than was evident at Bug Jam this year. 'Could count 'em on one hand, couldn't yer? 'Action was different. :D

www.porschapart.co.uk in Ramsbottom, Lancs. supplied the lot, '86 944T Ally arms to Brembo's and front 944T stub axles to Brembo's, all mint, £650. Very competitive.


Alex, thanks- I thought it might be junk!- Where could I find more info? Now I have atleast 3 different transy's to choose between!

My original trans' has a whining input shaft, 'sounds quietly awful in neutral and seems louder in second than any other gear. I think the diff. is untrue also, I am expecting a rebuild to be costly due to obscurity. It's brimming with EP90. It softley screams in reverse. 'More than just the normal straight-cut whine.

The forth contender has to be a more modern 996 Tiptro'6/7 - but lets not fly before we can run.

Is it true that some later 911's have a 'hot oil' trans? surely this would have the same advantages in a Bug?

[Steve C]

Hi MattKab

When you come down under on your trip to Oz let me know, I can show you around the VW shops in Sydney.

Im using a Quaiffe and Im quiet happy with it, it will still allow some slip and the car drives just like it had an open diff.

Steve C

[MattKab]

Steve, I'm going to Adelaide via Sydney, just to change plane. Thanks anyway it would be awesome, I'm sure.

I've seen the 1303 LSD dif' on the Quaife website and I'm seriously considering rebuilding my 4speed trans for future monster motors. Have you different gear ratios? What sort of speed can you cruise at?


Andy, how much roughly are they in the UK?

I'm only assuming that it will fit!

[Steve C]

Hi MattKab

The VW scene in Adelaide is pretty strong, there is a guy down there doing a Quaiffe copy for about half the price. See if you can contact Adam Debiasi, Im pretty sure he knows who is doing them. He owns the Beetle that you can partially read a bit about here http://www.autospeed.com/A_0908/page1.html

Im using 3.88 final drive with 235/40 x 17 tyres, 3.55 1st (taller), 2.00 2nd (taller), 1.30 3rd (lower) and 4th is the standard .93 ratio. All gears are semi straight cut and are reasonable quiet. They were made in Australia by Albins.

Steve C

[Andy]

Originally posted by MattKab

Andy, how much roughly are they in the UK?

I'm only assuming that it will fit!
Quaife component is £750 www.vwspeedshop.co.uk I was told that it may be cheaper for an IRS box. Ring Paul and tell him that I recommended you.

I am going for a 4 speed IRS with Gusseted case, with super diff, chromoly mainshaft etc with Super Spline conversion allowing me to use type 2 CV joints and uprated drive shafts.

Not sure about ratios, I want it to be quick acceleration, but cannot decide on
3.78 1st 2.31 2nd (or 2.36) 1.48 3rd 1.04 4th. OR
3.89 1st 2.36 2nd, 1.58 3rd 1.19 4th

I am not going to use it all the time, only at weekends in the summer, and even then, not long distances.

Cruising at 3000 RPM will give me 55 or 48 with my 17s,

Why can't everything be a simple choice!
:confused:

[Steve C]

Hi

Andy, ask anyone that has big motor in a bug and they always say 1st is a waste of time, thats why I went to a taller 1st & 2nd.

I was out on the motorway near my house today and I checked my speed v rpm (my gear ratios are in a post a few above this one) in 4th. 3,000 rpm gave me 100 kph and 4,000 gave me 130 kph. According to my tyre calculator with my gearing and 24.4 inch tyres (235/40x17) I should get 126 kph @ 3,000 rpm, but my rear tyres are almost worn out, so that may explain the difference. Im going to fit some 255/40x17s (25 inch) soon, this should lift my kph to 143 kph @ 4,000 rpm.

Steve C

[Andy]

I understand about 1st gear, but car is heavy...

This is what I am going for:
3.89
2.36
1.58
1.12

Hopefully there will not be too much of a jump between 3rd and 4th.

So it looks as though I will have to cruise slowly on long jouneys, but the good point is that everybody will be able to see the car better!!!:)

[vujade]

Andy are you going to use a type 4 motor in that car?
If you are, the taller gears will porbably work better with the torqueier type 4 motor.

[Andy]

Originally posted by vujade
Andy are you going to use a type 4 motor in that car?
If you are, the taller gears will porbably work better with the torqueier type 4 motor.

No Type 4(not mentioning Boat Anchors :D) would love to have one, but would cost more to do what I have done to a type 4, its going to be a very large stroker Type 1, but I will be using it on the strip. Thats why I went for a closely grouped set of ratios. The cam WebCam 226 has a small power band as well.

[vujade]

I understand :)

[MattKab]

Have any of you guys heard of a 5speed Skoda trans in a Bug?

I noticed one at a local breakers, and it would be cheap. It has very similar dimensions, somewhere between a T1 and a T2 trans. Probably a daft suggestion but still just an idea.

I remember an old skoda estelle built here in Warrington years ago (Mr Blobby paintjob!) that pulled wheelies! 'don't know what was done to it but it must have handled the torque neccessary to wheelstand. I may try all the local Skoda mechanics (if there is any) to see if this is feasable.

Andy, do you think you'll be VWDRCing next year? I'm very tempted, with arguably the heaviest Bug at the 'Pod. 'Looks damned addictive!

I simply just want to krooz in the fast lane with all the modern cars, without going near 5krpm.

[Andy]

Originally posted by MattKab

Andy, do you think you'll be VWDRCing next year? I'm very tempted, with arguably the heaviest Bug at the 'Pod. 'Looks damned addictive!


Yeah, I did think about it, as the chap who bought my old engine runs "The Hustler" buggy in the VWDRC, and he practically sold me the idea. I know that the regulations can be a bit of a pain. Main plan is to get my car sorted, and will see where I go from there.

[Chris Percival]

Originally posted by MattKab
Have any of you guys heard of a 5speed Skoda trans in a Bug?

I have never heard of it being done, though I have heard many people say that they are roughly the same size. Probobly too much work involved, when you can do porsche for less hassle..

I think the reason people don't use ZFs is: they would if they could find one!

Keep us posted on your progress Matt..

[Andy]

Apparently some IRS boxes have the LSD, I have found some ID on my old IRS 1303S gearbox, but this is the part number of the trans case, does anyone know where the ID of the trans is?

The Ids are in the appendix in Keith Suemes Performance handbook. It could be that there are lots of cars out there with ZFs in, and the owners do not realise.

I assume that it must have been an optional extra!!!
:silly:

[Alex]

As far as I know the Thing was the only car that had the option of getting a LSD. It was not a standard feature I believe. ZF LSDs are rare and not that cheap either. Bruce Tweddle in British Columbia, Canada supplies North America with good used ZFs. He is also the one that said that the single sided IRS tranny case it the best VW case.

Alex

[Chris Percival]

Andy, the ID is near the bottom, between the drive shafts and the nose. Its on a flat peice that faces about 45% to the ground I think...