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Solid to Independent Rear axle

robiewing

VolvoRacr
Joined
Nov 14, 2005
Location
386
I searched and found no references to swapping a solid to independent axle. My car is a 94 940.

Anyone have any experiences.

Thanks
 
Why would you want to? seems like alot of $$$ and work, not to mention iirc parts are harder to find for the IRS setup
 
dasvolvo said:
Why would you want to? seems like alot of $$$ and work, not to mention iirc parts are harder to find for the IRS setup


Same reason that it was offered in the first place. Better performance and handling. :)
I don't plan on using Novimats.
 
The hassle outweighs the advantages as far as cost goes, really not worth it unless you have a lot of money and then you might as well swap what you have into a 960..
 
A dutch member? Welcome to the club!

Adding IRS can be dione, It requires some modifications to the bodywork but not really difficult. There is a thread about someone who is going to convert his 940 to IRS.
 
If you are in europe you can outsource shocks and springs from a 740 16 valve turbo car. They had IRS setup. Also get a rear sway bar. It's not hard to lower IRS cars. It just whether you want to do the research. Its about 500 bucks to lower the rear end of a IRS car.
 
I am the one with an IRS who is planning on swapping it into their car. It looks to be a really simple job, about the same difficulty-wise as converting an 850 to awd, but without any of the drivetrain worries. The only thing holding me back is a lack of a lift anf the confidence in my welding abilities to attach the spring seats and IRS subframe mounts. The other thing holding me back is my engine build project and the 500 wheel horsepower that I'm gunning for, and right now it seems like it's alot easier (read: proven) to route that kind of power through a volvo live axle. From what johnlane said, the halfshafts and CV joints seem to be the big weakpoint, along with the rearmost lower control arms. I want to look some more into halfshaft swapping on the IRS, and find a set of stronger halfshafts in a length that would fit the IRS. I also want to see what the strongest diff I can fit in the mk. 1 IRS housing is. With thanksgiving break coming up, I'm going to try to bring the IRS back out to school with me so I can get to work taking measurements of the rearmost lower control arms and getting newer stronger ones made in the machine shops.

If you aren't planning on putting large amounts of power through one, the IRS is definately something I'd try to do, as it shouldn't take more than a weekend to do the swap if you have the right equipment. I just don't have the lift that I feel I'd need to properly do the project. Another fun project which I plan on doing to the front end of the car is swapping the lower control arms and crossmember from an s90 and mounting them to 240 ABS hubs with the 940 strut tubes. That should give me the ability to mount R brakes while increasing front track width, decreasing my turning radius even more, and eliminating my need to use 25mm spacers in the front to run my peggies.
 
acbarnett said:
I am the one with an IRS who is planning on swapping it into their car. It looks to be a really simple job, about the same difficulty-wise as converting an 850 to awd, but without any of the drivetrain worries. The only thing holding me back is a lack of a lift anf the confidence in my welding abilities to attach the spring seats and IRS subframe mounts. The other thing holding me back is my engine build project and the 500 wheel horsepower that I'm gunning for, and right now it seems like it's alot easier (read: proven) to route that kind of power through a volvo live axle. From what johnlane said, the halfshafts and CV joints seem to be the big weakpoint, along with the rearmost lower control arms. I want to look some more into halfshaft swapping on the IRS, and find a set of stronger halfshafts in a length that would fit the IRS. I also want to see what the strongest diff I can fit in the mk. 1 IRS housing is. With thanksgiving break coming up, I'm going to try to bring the IRS back out to school with me so I can get to work taking measurements of the rearmost lower control arms and getting newer stronger ones made in the machine shops.

If you aren't planning on putting large amounts of power through one, the IRS is definately something I'd try to do, as it shouldn't take more than a weekend to do the swap if you have the right equipment. I just don't have the lift that I feel I'd need to properly do the project. Another fun project which I plan on doing to the front end of the car is swapping the lower control arms and crossmember from an s90 and mounting them to 240 ABS hubs with the 940 strut tubes. That should give me the ability to mount R brakes while increasing front track width, decreasing my turning radius even more, and eliminating my need to use 25mm spacers in the front to run my peggies.

Dude if you are going to lower the car then dont mount the spring seats just put coilover shocks on the car. It will make it alot easier. Just weld on the half of the mount so you can mount the IRS setup on.
 
Boosted2003 said:
Dude if you are going to lower the car then dont mount the spring seats just put coilover shocks on the car. It will make it alot easier. Just weld on the half of the mount so you can mount the IRS setup on.

quite right. this is the only thing that makes any good sense.... A proper coilover shock will save you LOTS of trouble.
 
You can make your car handle as well as any street car should be expected to handle with your solid rear end. That's how Saleen got started. I had a 91 5.0L LX that was pretty competant in roadholding ability, considering.

It just seems you'd be spending SO much more to get an extra 5% potential from an IRS setup. How often will you drive the car to 100% of it's limits?
 
I don't like axle hop, the IRS will always give a better ride and more ajustable handling than a solid axle will, especially a setup as ajustable as the mk. 1 IRS. Why do you think all the serious racing classes use IRS cars?
 
I think this is a worthy proposition. Of course the easy way would be to nab a 760/780/940SE/960 rear end...yadda blah blah...but in my humble opinion the rear end out of a 3 5 or 6 series Bimmer would be perfect-IRS, LSD, and take as much power as you and yo momma can throw at it.
 
V8 supercars don't use IRS

Neither do Porsches for the most part and they seem to do OK.

Why do you think all the serious racing classes use IRS cars?

Because they are serious race teams with serious race cars and seriously deep wallets...not daily driven/weekend warrior Volvos with a couple of bolt-on parts.

You can probably go faster than you think with what's already under the car! If it were me, I'd make 100% certain I was completely out-driving the stock setup (with good tires/shocks/springs/swaybars/bushings installed) before attempting a conversion.

IRS = Nice to have in certain situations, but over-rated, IMHO.
 
SwedishFish said:
I think this is a worthy proposition. Of course the easy way would be to nab a 760/780/940SE/960 rear end...yadda blah blah...but in my humble opinion the rear end out of a 3 5 or 6 series Bimmer would be perfect-IRS, LSD, and take as much power as you and yo momma can throw at it.
The diffs, CVs and half shafts out of the 3 and 5 series Bowel Movement Wonders are tiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiny, esceially the woefully undersize 3 series crap, way smaller that what Volvo used in the IRS set up and Volvo's stuff is stoooopid small.

Also, limited range of stock ratios and no aftermarket final drives, bad all round.

Solid rear can work just as well as typical IRS, if you don't have it, don't sweat it.

Most OEM IRS, including the much (overhypped) bally-hoohooed
Bayerisch Mänlischkeit Verlänger stuff is junk, (especially the 3 series) and especially if you change the designed right height and don't compensate or correct.
 
MACH FYV said:
Neither do Porsches for the most part and they seem to do OK.



Because they are serious race teams with serious race cars and seriously deep wallets...not daily driven/weekend warrior Volvos with a couple of bolt-on parts.

You can probably go faster than you think with what's already under the car! If it were me, I'd make 100% certain I was completely out-driving the stock setup (with good tires/shocks/springs/swaybars/bushings installed) before attempting a conversion.

IRS = Nice to have in certain situations, but over-rated, IMHO.

with new england's combination of awesome twisties and horrible roads with deep potholes and frost heaves, I'll take the extra benefits of having the rear wheels seperate. A good solid axle is no worse in a perfect world or on the race track, but day-to-day up here I have way too much axle hop for my liking and I'd like every little extra bit of rough-road handling that I can get.

and john, how hard would it be to replace the dinky volvo CV joints/shafts with something beefier, and where might I find that beefier setup? I have access to what it would take to modify the splines, etc if necessary.

and iirc porsche ditched the swing-axles for an IRS setup back in the mid 60's and have stayed IRS ever since.

Now the one that has ME interested is the de dion rear suspension, as it's always seemed like a great potential cross between the two, as well as seeming like it would be easier to make a proper setup from scratch with. I would go with a 4-link de dion setup with a watts linkage.
 
MACH FYV said:
IRS = Nice to have in certain situations, but over-rated, IMHO.
It really depends on the circumstances. Australian roads aren't generally particularly racetrack-like in terms of smoothness, and what IRS does best is iron-out the mid-corner bumps so you're not hopping uncontrollably around corners.

Whether it was worth it would kinda depend on where your priorities were. From what I can tell, there's a fair bit of weight involved in the standard Volvo setup, and the components don't seem to be as strong; meaning I guess you'd be bolting a lot of non-standard stuff in there, which starts to get expensive. I think I'd want to have spent a lot of money on the motivating force for the car, before I started forking-out IRS-conversion money on the rear end ... if (and here's the big if) I only had performance in mind.

Seriously guys, we're talking about making Volvos go faster here! :) Outright performance isn't necessarily the goal, if that was all I wanted I could've visited the used section of the local Subaru dealer & forked over a few less readies than Project Big Red Car has cost. :)
 
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