Rear torsion bars

AL - You putting on a little weight and need to fix Butt sag???

Aren't we a funny boy!   anybody with some useful information?

Sooo........  nobody's running larger than stock (21 or 22 mm- depending on the year) rear torsion bars?????

I've never seen such things advertised.

I believe mine are stock in both the MG and the Spyder. I recall hearing about a fellow MGTD replica owner having his rear torsion bars turned down a few thousandths to soften the ride,* and I know that Dale Schumacher (@schu I believe) has run coilovers all around on his TD since he finished it--lifting it a couple inches to clear the wider wheels and tires he runs.

I will say on the front beam, my TD runs only the large leaves, both top and bottom, and the Spyder runs a full bottom complement of torsion leaves but only the four large leaves in the top tube, which is as delivered from TR, I assume.

In my decade in the hobby, on this site, TDReplica.com and the Spyderclub.com I have never once read or heard of anyone running larger or heavier-duty rear torsion bars for any reason in a Speedster, Spyder or TD, and in fact I was not aware of their existence.

==

*Which I would expect would also be the right way to go if I had spent the past three decades drilling holes and otherwise lightening the chassis of my prospective clown car.

@edsnova posted:

In my decade in the hobby, on this site, TDReplica.com and the Spyderclub.com I have never once read or heard of anyone running larger or heavier-duty rear torsion bars for any reason in a Speedster, Spyder or TD, and in fact I was not aware of their existence.

I'm running 24mm rear torsion bars with IRS, along with 19 mm front and rear sway bars. Now Ed has heard of somebody running them, and as far as their existence - Sway-Away makes them.

I used to know my corner weights, Al - but my inability to remember things any more is something I commented on in another thread.

I did this at the suggestion of Henry Reisner, who also put Koni shocks on all 4 corners. I believe this was the best handling setup available from Intermeccanica in 2005 that didn't involve a 911 front end. Regarding how it handles, I'd say that I've never wanted to change a single thing in the back, but I've often thought of something better up front. It is an order of magnitude better than the swing axle car I started with in 2000.

Well, again, I sit corrected.

The rear torsion on mine is stock (22mm '69 IRS). Like Stan, I'm running 19 mm front and rear sway bars. I'm just running standard oil shocks and took a couple of leaves out of the top tube in the front. The ride is firm enough, I wouldn't want it any harder. No info on the weight.

It's really all about weight. Stan's IM Speedster weighs the same or more than a stock Beetle, so a higher spring rate for better handling makes sense.

TDs and Spyders are ALWAYS lighter than a stock Bug, so less rate is needed. Or stock rate on a lighter car, which is equivalent to a higher rate on a stock Beetle.

Greg runs 250 in.lb. springs on his Spyders with Bilstein coilovers on the rear of his cars. Lenny and I run 275 springs and are very happy with the ride and handling. We also use QA1 adjustable coilovers. Mine are set at 9 or 10 from full soft for compression and rebound out of 18 clicks.

@DannyP posted:

It's really all about weight. Stan's IM Speedster weighs the same or more than a stock Beetle, so a higher spring rate for better handling makes sense....

Of course, Danny, that was my next question for @Stan Galat-  Stan- do you consider your Speedster to be heavy, middle of the road, or a little light compared to other Speedsters?

@ALB posted:

Of course, Danny, that was my next question for @Stan Galat-  Stan- do you consider your Speedster to be heavy, middle of the road, or a little light compared to other Speedsters?

The tube-frame IM is not lighter than the pan cars, but I know I'm under 2000 lbs as I sit. I've got a mag case with the engine slid forward (as IMs do), but I've also got at least an extra 40 lbs of exhaust plumbing and dry-sump whatnot. I'm not especially light in the back end.

Knowing that you are targeting a 1500 lb car, I'd run 22 mm torsion bars with a big (3/4") sway bar.

Here is a spring rate chart to give everyone an idea how much diameter and length effect spring rates.

Thanks for the info, @Stan Galat; I thought I'd remembered you mentioning this once upon a time.  I don't think it'll hit the 1500 club with the addition of a kafer bar (with tubing to the frame horns and torsion housing) and maybe a roll bar with the back supports attaching to said kafer bar, although that would be fantastic if the car did end up being that light.  Maybe I should be building the kafer bar in aluminum....

To refresh all you's Poopieheads' memories- it's irs but I'm using shorter swingaxle torsion bars (21¾ vs 26 9/16"- almost a pound saved per side going to the shorter bars) with modified swingaxle spring plates- mine weigh in at just under a kilo each vs almost 1800 g for a stock irs single, over 2500 g for stock double and 50 or 75 grams heavier again for a Sway a Way adjustable plate.                                                                       

I have a pair of 24 or 25 mm short torsion bars, but even gun drilled 12 mm (which will only lower the spring rate by 8-9%) they will still be far too stiff.  I also have some short, late ('67 and newer?) 22 mm bars that if I can get gun drilled (a machinist friend thinks he knows of a shop near him that owns the equipment, and I think he said he knows someone there) should be about right.  If I find them still too much, earlier swingaxle torsion bars are 21mm- maybe I should be looking for a set now- hmmm....  While a little heavier torsion bar in the back is good, too much does induce oversteer, and the whole idea is to get a little closer to neutral handling.

That's a great chart, @LI-Rick; thanks for posting it.  I've been using this as a reference-   https://swayaway.com/tech-room...e-torsion-bar-rates/

Sooo..... nobody else???

@ALB, do you really think you can get the weight that low? Most Beetle’s are in the 1800-1900 lbs region.  I don’t know what the average speedster weighs, but I would think they are almost the same as a Bug.  I ran a tube chassis drag bug, aluminum floors, interior, light weight glass nose and fenders, Lexan windows. It still weighed just over 1300 lbs.

I believe you are right, @LI-Rick, that most Speedsters weigh about the same as an early to mid '60's Beetle.  While (as I said above) I don't think cracking the 1500 lb club is possible (without spending a lot of money on titanium and such, especially with a 4 point rollbar- wait- can the roll bar be aluminum?), I'm pretty sure I remember reading that the first series IM's (which is what I have- one of the first 608) weighed under 1700 (1680?) lbs completed and that was with steel wheels and heater boxes.  Jack Crosby once wrote his Speedster weighed 1654 lbs and Lane's red Speedster was 1698 lbs, so I think somewhere around 1650 lbs is possible.  Right now I have the shift selector rods from the Berg 5 with a machinist friend so we'll see how much he can hollow them out (and how many boxes of Tim Horton's donuts it will cost me).  I've done a bunch of weight removal stuff (for a little while I had access to a lathe and knee mill) so the goal is to get the trans to 4 speed weight.                       

I've done other stuff as well- hollowed out the throwout bearing shaft, drilled and contoured the clutch cable arm (that went from 150 or 160 grams to 93 grams- a pity I didn't weigh it before I started!) and others.  Some good reading on weight loss, drilling holes, making things out of carbon fiber, titanium and other such nonsense-  http://cal-look.no/lounge/index.php/topic,5293.0.html                                                          Some of these guys are pretty serious- and a (just over) 1300 lb drag bug ranks right up there!  I come from the VW world as well and know that's pretty bad@ss!  Personal best? what size engine? gearing?

PS-  my profile page has a few more pics of things with holes if anyone is interested...

Scott Hansen from Milwaukee (who never posed here, but was a friend through Rich Drewek) hit 1500 lbs with a CMC running a 2332 and a Berg-5. It took a custom sub-frame and a lexan windshield (which he had made for the frame using the original as a mold), and a lot of attention to details, but he got it done.

Sadly, he passed away far too soon.

I remember you and Rich talking about him when he was working on Rich's Ghia, @Stan Galat.  I was impressed with the couple of pics I saw of his Speedster and yeah, it was unfortunate he died so young.  I didn't know his car was so light.  Do you have any pics it?  If I could totally redo my Speedster body I'd have the subframe done in aluminum- that's 100 lbs gone right there (I can't begin to comprehend how many holes with the accompanying piles of swarf that is- it's gotta be bucket loads! ).  And a lexan windshield- brilliant.

@ALB posted:

I believe you are right, @LI-Rick, that most Speedsters weigh about the same as an early to mid '60's Beetle.  While (as I said above) I don't think cracking the 1500 lb club is possible (without spending a lot of money on titanium and such, especially with a 4 point rollbar- wait- can the roll bar be aluminum?), I'm pretty sure I remember reading that the first series IM's (which is what I have- one of the first 608) weighed under 1700 (1680?) lbs completed and that was with steel wheels and heater boxes.  Jack Crosby once wrote his Speedster weighed 1654 lbs and Lane's red Speedster was 1698 lbs, so I think somewhere around 1650 lbs is possible.  Right now I have the shift selector rods from the Berg 5 with a machinist friend so we'll see how much he can hollow them out (and how many boxes of Tim Horton's donuts it will cost me).  I've done a bunch of weight removal stuff (for a little while I had access to a lathe and knee mill) so the goal is to get the trans to 4 speed weight.                       

I've done other stuff as well- hollowed out the throwout bearing shaft, drilled and contoured the clutch cable arm (that went from 150 or 160 grams to 93 grams- a pity I didn't weigh it before I started!) and others.  Some good reading on weight loss, drilling holes, making things out of carbon fiber, titanium and other such nonsense-  http://cal-look.no/lounge/index.php/topic,5293.0.html                                                          Some of these guys are pretty serious- and a (just over) 1300 lb drag bug ranks right up there!  I come from the VW world as well and know that's pretty bad@ss!  Personal best? what size engine? gearing?

PS-  my profile page has a few more pics of things with holes if anyone is interested...

@ALB, you are definitely the king of drilling holes!  I ran a 002 box with Folts swingaxle conversion.  3.78 2.06 1.48 1.04   4.57 r&p. 1915, T03 turbo, street eliminator heads. Ran low 11’s at 18lbs of boost. No race tracks left around here anymore.

Even painted it in my garage. Al, look at the holes in the door jamb! lol

And to bring it full circle to Torsion Bars, 27mm short bars.

@LI-Rick posted:

@ALB, you are definitely the king of drilling holes!  I ran a 002 box with Folts swingaxle conversion.  3.78 2.06 1.48 1.04   4.57 r&p. 1915, T03 turbo, street eliminator heads. Ran low 11’s at 18lbs of boost. No race tracks left around here anymore.

Very cool car, Rick!  Too bad there's no tracks around any more.  Where are you and how long were you racing for?  And it looks like you tried to post 2 pics above my quote in your post above, although they don't show here.  Al

@ALB posted:

Very cool car, Rick!  Too bad there's no tracks around any more.  Where are you and how long were you racing for?  And it looks like you tried to post 2 pics above my quote in your post above, although they don't show here.  Al

I edited the post to move the pictures down.

I live on Long Island, NY.  I only ran that car for 2 years, 2000-2001, before the local track closed. I ran a pan based Ghia for a couple of seasons in the mid 1990's.

Alright, you fixed it- your oval looks really cool green.  I'm a house painter, have done a lot of spraying (everything from catalyzed furniture lacquer to coal tar epoxy) and have painted 3 offroad tube frame race buggies (multi colored), my baja bug, a VW van, an '81 Toyota 4wd pick up and 2? 3? fiberglass buggies over the years, all in garages or warehouses.  My brother and I are for hire (we're expensive- lunch and beer!) when the bulk of the body work is done and it's ready for a final prime and sand- I did this 1 June 2020-

Gerry is one of my best friends and an amazing mechanic/fabricator (he built the tube frame to fit around a 3.5 liter Honda V6 and Mendeola 4speed, designed/built the 15" travel suspension) but a photographer he is not- not 1 pic of me working where you can see my face.  Here (I think) I'm just starting the 2nd of 3 coats of 3 component polyurethane.  I really like spraying it but boy, is the stuff deadly if you're not wearing a respirator with fresh cartridges.  Us on our July trip up in the mountains near Lillooet, BC 1 month later-                                  And this 1 just 'cause I like it so much (that's my FJ in the background)-                                                                                                                                                                                      The most recent for another friend last summer- that's my brother in the background-                                                                    I don't know why he picked that particular shade of sh*t brown- it doesn't even match his new Dodge truck.  I just put it on.  Despite not liking the color, I actually think it's my best work yet.  Even when you've been spraying off and on for almost 50 years, when doing something like this you learn something every time out.  For 3rd coat I thinned it a little more with 1 step slower solvent- it flowed almost like glass!  Too bad it's brown...                                                                                                   

While we’re on the subject: has anyone ever found a source for <22mm rear bars?

My Spyder rides like a “Hard Tail” with (what I assume is) a stock 22mm bar. I’d like to try an 18 or 20.

I’ve heard of machining/re-heat treating a stock bar, but I’d like to forgo that hassle/cost.

As far as weight is concerned, Speedsters run from 1700 pounds(I think that was Lane's tube-frame Beck) to 2400 plus(Bob's IM6) with most under 2000 pounds. I believe that Lane's car had almost 70% of the weight on the rear, so over 1100 pounds. So figure 550 on each rear tire or thereabouts.

Spyders are lighter though, by a bunch. Mike's Spyder came us at 344 pounds on each front wheel and 399 on each rear tire. That makes 1486 pounds total. My first Spyder was 1450 with an empty gas tank, about 1500 or so full. I think Beck Spyders are a little lighter, but I've never weighed on.

Dave, if your car "rides like a hardtail" I'd suggest maybe rear shocks or maybe really stiff bushings, along with dropping the tire pressure to 25 in back, which is the pressure I run.

dealers call that color"stick around brown"

@dlearl476 posted:

While we’re on the subject: has anyone ever found a source for <22mm rear bars?

My Spyder rides like a “Hard Tail” with (what I assume is) a stock 22mm bar. I’d like to try an 18 or 20.

I’ve heard of machining/re-heat treating a stock bar, but I’d like to forgo that hassle/cost.

David,  see if you can find a machine shop with a cylindrical grinder.

@LI-Rick-

Oh, I forgot to mention that I liked the holes in the doors- they just need more!

@DannyP posted:

Dave, if your car "rides like a hardtail" I'd suggest maybe rear shocks or maybe really stiff bushings, along with dropping the tire pressure to 25 in back, which is the pressure I run.

BTDT. I replaced the Bilsteins with the soft KYB’s and run 22/24 (started with 18/22 when I got the new tires)

My buddy Rick suggested it’s bottomed out with my whale carcass aboard, which may be. Raising the whole car an inch or so is in my long-term plans. I’ve been holding off thinking I could find a couple of 18mm rear bars.

@LI-Rick posted:

David,  see if you can find a machine shop with a cylindrical grinder.

Got one Rick. The shop that balanced those brakes does a lot of Hot Rod work. They said they’d do it, but didn’t have a clue about heat treating them. Apparently they have to be in a jig or they can warp.

Once I found all that out, I realized I’d wait until I was ready to re-do the rear end and see if I could whine to SwayAway to build me some 20’s to go with the adjustable spring plates I’m going to buy from them.

@dlearl476 posted:

While we’re on the subject: has anyone ever found a source for <22mm rear bars?

My Spyder rides like a “Hard Tail” with (what I assume is) a stock 22mm bar. I’d like to try an 18 or 20.

I’ve heard of machining/re-heat treating a stock bar, but I’d like to forgo that hassle/cost.

Have you tried Sway a Way, Dave?  I'm guessing your car has short (21¾") bars.  In that chart I gave the link to there are spring rate figures for smaller diameters.

I'd put my money on riding on the stops. Raise the car and stop dicking around with it.

I don't know of any Becks that ride hard in the back, and I've driven a few, and ridden in more than a few.

What stops?

Either the shocks are bottoming or the spring plates are hitting the stops from LOW ride height.

Shocks could be but there are no spring stops on the Beck frame to my knowledge. Unless they're in the front part of the trailing arm/spring plate housing?

As you know, @DannyP, I made limiting straps for mine that mimic what you did on yours, but those "stops" only work when the car is lifting up, to prevent tuck-under, not when it's squatting down as in "bottoming out."

Is there anything that could bottom out other than the shock?

@DannyP posted:

Either the shocks are bottoming or the spring plates are hitting the stops from LOW ride height.

Good call Danny! I hadn't even considered it...

@ALB posted:

Good call Danny! I hadn't even considered it...

Actually, David's friend suggested it. I'm unsure why David thinks softer torsion bars would help if he's bottomed out. If it's bottomed out, that would suggest that perhaps stiffer springs are needed, but what do I know?

@Stan Galat posted:

Actually, David's friend suggested it. I'm unsure why David thinks softer torsion bars would help if he's bottomed out. If it's bottomed out, that would suggest that perhaps stiffer springs are needed, but what do I know?

Makes sense to me Stan...

@edsnova posted:

Shocks could be but there are no spring stops on the Beck frame to my knowledge. Unless they're in the front part of the trailing arm/spring plate housing?

As you know, @DannyP, I made limiting straps for mine that mimic what you did on yours, but those "stops" only work when the car is lifting up, to prevent tuck-under, not when it's squatting down as in "bottoming out."

Is there anything that could bottom out other than the shock?

Maybe. Can't really tell without looking at the car, but the torsion bar housing has stops just inside the cover for the spring plate, no?

FYI, those straps are to limit rebound or "droop" in Formula Vee parlance. Keeps positive rear camber in check to alleviate "jacking" or "wheel tuck". (I know you know this, Ed, this is for others that may not know these terms)

@Stan Galat posted:

Actually, David's friend suggested it. I'm unsure why David thinks softer torsion bars would help if he's bottomed out. If it's bottomed out, that would suggest that perhaps stiffer springs are needed, but what do I know?

I don’t think it’s bottoming out. I’ll have to inspect. It does ride very low. And it most definitely has travel without me in it. But it’s at least 50% stiffer than the front end according to my calibrated “push-downers.”