Just thought I'd post a few photos of what has been done at VMC regarding IRS in a Spyder with a VW and Suby engine and what my frame looks like. My frame has the lower tubes moved in closer to the transaxle to allow "A" arms to be used. It will not have the tubing type "spring plates" as shown in the photo of the car with the Suby engine with VW Trans.......Bruce
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Very cool Bruce!
Awesome Bruce! Keep the updates coming when you get them.
Yes, keep it coming, Bruce.
I was going to do a rear IRS suspension like an early Corvette, sans the transverse leaf spring. It appears the "upper links" are indeed half-shafts with U-joints
Single trailing arm(already have that with the swing axle) with a VW Beetle IRS bearing carrier welded to it. Then 2 simple lateral links parallel to the CV shafts. Easy peasy, just fabricate inner mounting points and clear the exhaust system. You don't even need to change the main chassis lower rear rails to do it. You of course retain the existing coilover shocks.
Danny.......Interesting how they have the third member securely bolted to the frame on top, bottom and front. It's frightening to think of how much torque that component sends to the frame in a "launch" ! The transverse leaf spring sort of serves to help hold everything in place too ! In addition to supporting the car ! I've always admired that suspension system and never thought of trying it in a Spyder...Interesting idea.......Bruce
Bruce, do you think Greg is going to try upper A arm and lower H arm and loose the trailing arm, like a Thunderbird?
Danny, I’m not sure if the current exhaust will clear, it might hit on the lower link. You might have to change to an over the top style, a la GT40.
Rick.....Yes.......Bruce
Rick, the suspension I have designed fits with the current type1 exhaust. The lateral links go behind the axles and away from the cylinder 1-3 360 degree primary tubes. But they're also above the exhaust even with wheels at full droop/extension.
Ooh, I like the T-Bird SC suspension!
@DannyP posted:Rick, the suspension I have designed fits with the current type1 exhaust. The lateral links go behind the axles and away from the cylinder 1-3 360 degree primary tubes. But they're also above the exhaust even with wheels at full droop/extension.
Ooh, I like the T-Bird SC suspension!
You won't like the weight. It was known to be very heavy.
@Lane Anderson posted:You won't like the weight. It was known to be very heavy.
The T-bird or the suspension? We are just looking at the design, not advocating transplanting a suspension direct from the Ford.
Both. Road tests back in the day praised the T-Bird for being one of the first American cars with IRS (besides the Corvette) but said the IRS setup was needlessly weighty, contributing to the car missing its targeted weight by hundreds of pounds.
As with Lotus, the suspension arms could be much lighter in a sub-1800 pound car. I'm quite sure the Bird was about twice that.
These T-bird IRS are used in many Cobra replica cars, I’m sure they make aftermarket tubular arms. Like Danny said, I was just discussing the design.
More than twice that. Pam had one and it was ~4k, possibly more. I do agree that lighter control arms are probably now available.
"What we've got here is failure to communicate!"
But the weight!
Bruce,
Wouldn't it be nice if the bent crossbar was gone and replaced with a removeable strut (with heims on each end). Then the complete engine and trans can be hoisted straight up by simply removing the strut (actually just unbolt one side).
You never need to jack the car up to remove the engine/trans. And once the drivetrain is hanging on the hoist you can push the car (still on its wheels) off to the side (or outside) while it waits for the process to reverse.
IRS axles make this possible and it is a costs-nothing upgrade. The benefit should be obvious.
It's funny you should say that, Mark. Last summer I worked on a 2001 Vintage Spyder that someone had cut the cross bar from.
I did a lot: built a new 2276cc(82 x 94) instead of the old and seized 2213(86 x 90.5). Installed a CB dry sump pump, tank, cooler, thermostat, filter, and made all the lines. Removed the very clunky Fibersteel shifter, then installed a VMC cable shifter and fabbed the Spyder e-brake bracketry. Re-mounted the passenger seat 2.5" lower, it was on wood blocks. Re-wired the engine compartment too. I had to fabricate/weld the mount for the new nosecone/cable shift housing. You can just see the new breather on the left side of the firewall. I think it came out great.
The early Vintage cars had a 1" chassis cross bar. Somebody had cut it and made kind of a spare tire mount. I replaced it with some 1.25" 0.120" wall and some connectors I got from an off-road shop. No need for heim joints. The connectors come in different sizes depending on tubing wall size and tube O.D.
That’s a structural member, I wouldn’t use heim joints in this application. I think a flange system would work much better, either a 2 bolt or maybe a 3 bolt triangular flange.
Danny, Ll-Rick,
On the IRS chassis I did, I flanged the crossbar (4-bolt) like mentioned by Ll-Rick. It is a fixed dimension so the flanges (and Danny's connectors) work. And, when I was doing it, it was simple to make flanges and weld everything together to fit.
After-the-fact, I wish I'd used a couple of 1/2" Heims and made a strut. It would have made for a cleaner fabrication and even easier for application. I had plenty of 1/2" Heims, there were 18 of them in the rear suspension linkage. I just didn't think of doing it that way at the time.
As far as structure; the crossbar is stressed in compression and tension, there are no significant sheer forces on the Heim joint on each end of the crossbar strut.
In real life, I lifted the engine/trans in and out of the spyder I don't know how many times during the build and over the next 20 years, thanking myself every time for having the foresight to make the rear crossbar removeable.
PS: Yes Danny, that's a very clean looking spyder. And, the option to hang the oil cooler on the crossbar is not as likely if the crossbar had Heim swivels on each end. So in this case your solution wins. Again. 
But I think Vintage mounts the oil cooler somewhere else?
Edit: I just noticed the dpp decal on the fan shroud. Cute! 
The removable crossbar with IRS is an awesome combination.
Yeah, Greg mounts them low between the two rear lowest crossmembers. I prefer to keep the oil lines on the upper frame rail, away from the exhaust. Thermostat is right at the cooler on this one. Oil filter is in front of the engine on the firewall.
And thanks, it was a lot of work, but I really enjoyed it.
@DannyP posted:Yes, keep it coming, Bruce.
I was going to do a rear IRS suspension like an early Corvette, sans the transverse leaf spring. It appears the "upper links" are indeed half-shafts with U-joints
Single trailing arm(already have that with the swing axle) with a VW Beetle IRS bearing carrier welded to it. Then 2 simple lateral links parallel to the CV shafts. Easy peasy, just fabricate inner mounting points and clear the exhaust system. You don't even need to change the main chassis lower rear rails to do it. You of course retain the existing coilover shocks.
Danny, the mid-year ('63-'67) through 1982 Corvette all used that basic design, and yes, the half shafts with u-joints are the upper link member. The lower links being a basic bar with rubber bushings and cam washers for camber adjustment. The rear cover of the diff mounted the center section to the cross member, and also holds the leaf spring on the bottom side. The leaf spring to trailing arm link was a pretty much a bolt with washers and rubber doughnut bushings. Toe is set with the shims at the front of the control arms, with the pocket in the frame allowing a handful of shims to be moved from side to side to set toe individually on each side. It's been a couple minutes since I played with one of those....
Just re-read your easy peasy rear arms...I would think regular spring plate would be way too flimsy to hold the hub, unless I'm thinking incorrectly about what you are referring to as trailing arms on a swing axle. You would also loose toe adjustment if the hub were welded. You might get away with a lower link similar in concept to what Beck uses on their 904's, a "Y" arrangement with the inner pivot adjustable fore -aft for toe if you wanted to forego heims at the hub side connection.
Steve
@SteveinAZ, @DannyP. Here is a Beck 904 suspension. I think this is similar to what Danny has in mind.
The trailing arm would NOT be a spring plate. It is a fabricated tubular affair on Vintage Spyders. There is a heim joint at the front pivot point in lieu of the torsion bar and spring plate.
With the proper gusseting to mount the hub bearing carrier the fabricated trailing arm would be plenty strong.
Toe-in can be adjusted easily by adjusting the length of the trailing arm with the threaded heim joint up front, as it is now in swingaxle configuration. From what I remember, you get about 1/16" of toe-in for each half-turn on the heim joint.
I can post a photo of a trailing arm later, set up for swing axle. It would require some fabrication to strengthen it and mount a bearing carrier plus pickup points for the lateral arms.
Similar, but not identical to the Coupe's rear suspension. As a probably cost-saving measure the Coupe utilizes a Miata rear upright rather than the fancy machined one shown above, and the trailing links are setup a bit differently. You're more than welcome to climb under the Coup at Carlisle if you want to see, assuming someone brings a jack and stands or someone RaceRamps.
I could try to get some pics but the angles might be a little tough unless I can get it up on a rack. I do have RaceRamps, which would help.
@DannyP posted:The trailing arm would NOT be a spring plate. It is a fabricated tubular affair on Vintage Spyders. There is a heim joint at the front pivot point in lieu of the torsion bar and spring plate.
With the proper gusseting to mount the hub bearing carrier the fabricated trailing arm would be plenty strong.
Toe-in can be adjusted easily by adjusting the length of the trailing arm with the threaded heim joint up front, as it is now in swingaxle configuration. From what I remember, you get about 1/16" of toe-in for each half-turn on the heim joint.
I can post a photo of a trailing arm later, set up for swing axle. It would require some fabrication to strengthen it and mount a bearing carrier plus pickup points for the lateral arms.
Danny, Makes way more sense now. I recall the coil over-tubular comment but didn’t put it together before. I know you can buy T1 bearing carriers somewhere, way easier than cutting old ones out, and they’ll look a lot cleaner when done.
@SteveinAZ posted:... I know you can buy T1 bearing carriers somewhere, way easier than cutting old ones out, and they’ll look a lot cleaner when done.
Try Sway A Way or McKenzie's. Any place that specializes in VW offroad stuff should know who makes them.
BAM! $85 each.
@DannyP, $69 here, and free shipping.
@LI-Rick posted:@DannyP, $69 here, and free shipping.
That's also where I got 'um, decades ago. That's what I used for the core when fabricating the suspension uprights. The flanges welded right on to the bearing housing.
A couple of things though, I wish I had drilled them for grease zerts, and I wish I had cut a keyway for a punch to remove the bearing races. As it turned out, I never needed either, but if I did it would have been nice, and easy to do at the time.
My suspension layout was fabricated pretty much like the 904 pictured above, sans the refinement of German production. It is not much of a challenge to move some tubing around on the rear of a 550 chassis to accommodate it. Almost a no-brainer.
@RS-60 mark posted:My suspension layout was fabricated pretty much like the 904 pictured above, sans the refinement of German production. It is not much of a challenge to move some tubing around on the rear of a 550 chassis to accommodate it. Almost a no-brainer.
Dude you're way too modest.
It should be mentioned that this thread started a discussion of possible IRS concepts for "production" chassis. Conversely, a hobbyist doing an IRS as a one-off is not the same method that is conducive to "production".
I don't know, I am still REALLY impressed with your entire car: chassis, suspension, and execution.
😊 Thanks
