Homemade IRS

[rb70383]

I have an idea on a IRS and want some ideas. Would it be possible to use an existing rear end, narrow it enough then make some brackets to solid mount the pumpkin? On a project I'm thinking of, I might need an IRS due to the driveshaft ending up too short. Under 12". Hoping I can use one of the rear ends I have and not have to get an IRS specific pumkin.

[MrQuick]

sounds pretty small. Datsun?

What kinda wheel base are you running with?

[Lowend]

Like so








Ok admit it you're scared

[Lowend]

Its C4 Vette stuff BTW

[Beige]

What axles do you have laying around?
You can probably whip something up using 4x4 front axle parts.
You'll probably be better off just getting an IRS, though.

[rb70383]

Scared yea! I'd still drive it though! I was thinking of 4x4 axels too. The wheelbase is 109".

However, it is a shortwheel base van, with the idea of relocating the engine to behind the front seats, like the old A100 vans/ pickups. Doing rough estimates the "standard" driveshaft with a live rear end with make one short driveshaft. Basically the tranny would almost bolt directly to the pinion, hence the need for IRS. With the engine back there turbos can take the place under the hood. All the mid engine van conversions have been on the 127" wheelbase except for this shortened one. Mid engine Van

This is the subframe he used and it looks like it pivots at the front with the rear solidly attached to it. Not too fond of the whole engine being on a moving suspension member. I would airbag the van as well.

[kmcanally]

This VW bus was in Hot Rod a while back...has the same engine mounted rear suspension. Also was a Hot Rod mag Top10 in 2006.
http://www.hotrod.com/featuredvehicl...3_1962_vw_bus/

[HILROD]

Get a newer Vette transaxle, mounted to the motor. Not as cheap, but still do-able. The setback could even be more with one of those.

[deuce_454]

i would recomend jaguar.... its basically a dana 44, and it is real easy to install... here are some pics of what i did..

[rb70383]

What is the track/width on the Jag rear? I like that idea. I completely forgot about them.

IF I was to do the whole engine cradle/rear suspension setup wouldn't it have to be triangulated? With just the 2 pivot points I imagine the rear tires, during a turn, would have a lot of leverage on those points.

[astroracer]

Look into the T'bird/Cougar IRS's. Pretty cheap in a 'yard.
Mark

[Twin_Turbo]

The C4 IRS is easily narrowed, all you need is some shorter halfshafts adn then you jsut have to order shorter camber sleeves and some poly ends or rod ends if you want to use those. There's nothing to it and has been done lots of times (for instance when fitting it to a C3 wityhout wanting to use the pos. offset wheels and keeping it tucked in the fenders) The biggest problem is the transverse leaf, better option would be to go to coil overs and custom mount them. It's practically impossible to narrow the spring without it failing

[deuce_454]

as you can see i shortened the track-width my self... its just a question of shorter halfshafts, and cutting and re-welding the LCA to the desired length.. i am not sure about what you mean by triangulating... but if you look at my setup, the crossmember is rubbermounted, and there are mounts for longitudinal controll arms that transfer the forces to he frame... if uoy solid moubt the pumpkin, the attachmentpoints of those arem sill have to be in line with the inner shaft the LCA rotates arround... but if the pumpkin is rubber mounted tou have some play as to where the horizontal location of the front mount for the longitudinal controll arm (which is equal to the instant center if a 4 link by the way... so the jag offers the possibility of tuning the weight transfer, unlike a corvette IRS...

the halfshafts are OEM ones i drilled out on a lathe and pressed/welded to a 40mm solid chrome/vanadium center shaft.. the alloy was weldable with a special electrode... cant find specs..

another added bonus of the jag, other than being a dana44 (albeit with a 10 splinecount) and thus almost undestructible is that the halfshaft doubles as an UCA and toy can then lower the car substantially more than with other IRS setups WITHOUT modifying theframe

[Twin_Turbo]

if you get a 85-96 C4 IRS from a manual it will be a super Dana44 using a Dana 60 sized pinion, same guts as a viper diff (only a different case, although very similar) On the C4 (and also C2 and C3) IRS the halfshaft too is the UCA.


Here's a Super Dana 44 in my 82 C3 (it's not narrowed, it's wider and it's a double a arm IRS now). Easy to mount, all you need is brackets for the batwing and 1 for the c beam mounting pad (since these don't have a pinion mount/snubber)

[rb70383]

When I was thinking of triangulated I was refering if I used long truck arms style that also double as an engine cradle. Some of the upper pics of the vw bus. Would a double A arm IRS stronger that the jag style in relations to side loading? It is going in a van mind you.

Twin_Turbo: Do you have any pics of the "c beam mounting pad" area?

astroracer: What style is the T-bird/Cougar style IRS? Were you ging to use an IRS in your project?

What keeps the spindles on the jag rearend from twisting from brak forces or accel forces. It looks like just the 2 lower mounting points do that. I'm I right, or is something not shown in the pic?

[Twin_Turbo]

Yeah, here: the one on the left is the C4 super dana 44, the right one is an 80-82 dana 44

[KagA152]

i believe the irs in the mid 90s thunderbirds is 8.8" ring gear, pretty stout setup. if you need any help making some custom cv joints, pm me

[Beige]

Twin Turbo, when you added the upper control arm to your C3 IRS, was there any problem with the axleshafts binding?

[Twin_Turbo]

No, because right now the stub is floating. If I wanted to built it all with the pivots and lengths in compliance with the halfhsaft the geometry would be less than desired. Floating the stubs is just for mockup, I still have to order some telescopic shafts like the vipers and the panteras have, then I'll put the clip back in the diff. I needed new shafts anyway since the rear susp. is significantly wider than stock so I figures, why stick with that geometry. This way I have more room above the outboard upper arm mount also.

[ragtopdodge]

BTW folks, don't mean to hijack the thread, but I have a C4 Dana 44 IRS ('88-'96 style) in the Classifieds. Can easily ship this in several boxes.