Swing Axle vs IRS Technical Topic

Post by **Dipsy** » Tue Oct 18, 2005 12:24 pm

As there seems to be a lot of interest and discussion on the relatve merits of SA v IRS at the mo, I thought I'd put a sticky up for a while, to try to collect a bunch of expert opinion all in one place. If it goes well, i'd like to make it a regular thing, with different topics all being archived, to help those that come along later asking the questions that get asked time and time again.

Feel free to put your thoughts, both positve and negative for each option, but keep it friendly, and in the interest of posterity, we could even try to stay on topic for a change

Over to you................

Post by **Doc** » Tue Oct 18, 2005 12:58 pm

Very good idea.
I'd suggested a Tech FAQ before (http://www.ssvc.ukshells.co.uk/phpbb/vi ... hlight=faq), This seems like a great idea to pull together all the thoughts.

Once enough subjects have been pulled togther it could even be possible to collate the information into a little book may be?

filby · Post by **filby** » Tue Oct 18, 2005 1:22 pm

Have been working on my setup for the last couple of weekends after finally gathering all the bits together, will be chucking a write up into the rides and projects section once all is installed this weekend.... watch this space, will post a link on here when its up on my rides thread!

Couple of sources of info i'd like to put up are the ever superb Bus-Boys type 2 suspension conversions pages found here http://www.bus-boys.com/bbsusp.htm
and also the book How to Modify Volkswagen Bus Suspension, Brakes and Chassis for High Performance By James Hale

which can be got here:
http://www.amazon.co.uk/exec/obidos/ASI ... 55-7901460

dubbus56 · Post by **dubbus56** » Tue Oct 18, 2005 2:11 pm

IMHO
I can not tell the difference in ride quality between SA or IRS both great as far as I'm concerned. My pick up is SA'd the 13 window is IRS'd both are quiet and quick. I don't think one holds a major advantage over the other in all honesty.
Hope that helps.

Ben

SteveW · Post by **SteveW** » Tue Oct 18, 2005 6:37 pm

Isn't straight axling more 'easier' than an IRS conversion? I've seen loads of articles on IRS conversion but nothing much on straight axle conversions!

silversteve · Post by **silversteve** » Tue Oct 18, 2005 8:52 pm

dubbus56 wrote:IMHO
I can not tell the difference in ride quality between SA or IRS both great as far as I'm concerned. My pick up is SA'd the 13 window is IRS'd both are quiet and quick. I don't think one holds a major advantage over the other in all honesty.
Hope that helps.
Ben

biggest difference is price, S/A is far cheaper to do, with SA you have to go low (2 splines) over wise you get "positive chamber" and you dont want that!!

IRS keeps the wheels nice and striaght however low you want to go.

In my old bus I had SA, doing my new one now I have IRS'd it so will soon be able to compare.

cheers Steve

dubbus56 · Post by **dubbus56** » Tue Oct 18, 2005 11:24 pm

silversteve wrote:
dubbus56 wrote:IMHO
I can not tell the difference in ride quality between SA or IRS both great as far as I'm concerned. My pick up is SA'd the 13 window is IRS'd both are quiet and quick. I don't think one holds a major advantage over the other in all honesty.
Hope that helps.
Ben
biggest difference is price, S/A is far cheaper to do, with SA you have to go low (2 splines) over wise you get "positive chamber" and you dont want that!!

IRS keeps the wheels nice and striaght however low you want to go.

In my old bus I had SA, doing my new one now I have IRS'd it so will soon be able to compare.

cheers Steve

You do have to go lower with SA, that was why I IRS'd the camper, I didn't want to go that low. But most people want to slam them anyway.
Ben

Post by **vwJim** » Wed Oct 19, 2005 9:47 am

silversteve wrote: biggest difference is price, S/A is far cheaper to do, with SA you have to go low (2 splines) over wise you get "positive chamber" and you dont want that!!

Even in stock strength format, SA has always been cheaper, but with the increasing interest, prices of parts has risen. Noticed how many people have started selling SA kits....?

And in performance strength setup, it is FAR cheaper than IRS.

Mick Annick · Post by **Mick Annick** » Mon Oct 24, 2005 8:19 am

I'm new to VW's so please pardon my ignorance, but why move away from the original set-up in the first place?

Mick

Sim · Post by **Sim** » Mon Oct 24, 2005 12:32 pm

Mick Annick wrote:I'm new to VW's so please pardon my ignorance, but why move away from the original set-up in the first place?

Mick

both SA and IRS lose the stock reduction boxes on the rear wheels, allowing for better top end speed when used with an engine with more grunt.

IRS also has better suspension geometry for lowered busses as wheels travel more like a conventional swing arm ( i.e camber dosent change as much)

Cheers

Sim

Mick Annick · Post by **Mick Annick** » Mon Oct 24, 2005 3:40 pm

Sim

Thanks. I'm planning to keep mine as stock as possible for insurance reasons, so lowering is out but am going for a 1600 lump. A bit more on the cruising speed would be noce for touring - though if I'm stuck with the hub reduction set up is this a non-starter?

Presumably this also limits my gearbox choice?

Mick

Post by **vwJim** » Mon Oct 24, 2005 3:57 pm

You can get 'freeway flyer' gearboxes that work with 'stock' setups. Basically gives you a slightly quicker cruising speed for the same rev's

Bootsy · Post by **Bootsy** » Mon Oct 24, 2005 4:23 pm

vwjim wrote:You can get 'freeway flyer' gearboxes that work with 'stock' setups. Basically gives you a slightly quicker cruising speed for the same rev's

This is the set up I have - coupled to a 1776 is cruises at 60 at about 3300-3400 revs.

ronmidg · Post by **ronmidg** » Mon Oct 24, 2005 4:25 pm

Excellent thread but confess I have no experience of either, I have till next spring to deliver a more reasonable cruising speed though hence my interest. I've just laid a tape measure against the wheel gearbox and it looks like 4 inches between axle and wheel centres, this is about the same as the clearance above the front tyre at its outside edge. If the front track was narrowed a bit there looks to be another inch. I dont know how much of this is suspension travel. So if go for straight axle does it follow that for a level van and neutral camber the front suspension has about an inch of travel at most? I think the ride is already harsh (not a critisism as is what I would expect for a one ton truck), surely x times stiffer is not an option for a family van?

I havnt seen a reference to a freeway flier gearbox before is there more info somewhere?

radish · Post by **radish** » Mon Oct 24, 2005 7:24 pm

Any chance anyone could put up a photo or two of the rear of their vans that have been straight axled. just want to know how low its going to be. obviously wheel n tyre choice will change that but just want to get some idea. cheers