Shocks and sway bars for MG TD replica

[KentT]

I'm resurrecting an old FiberFab MG TD kit car on a '69 IRS pan. As best I can figure out, the running gear has 53k original miles, but it sat in a barn for about 15 years before I bought it. Just finishing up an engine build for it, and want to address the suspension and brakes before putting it on the road.

It was originally lowered about 2" in front when built (early 80s is my guess) by cutting and rotating the lower torsion bar tubesin the front. Rear was lowered about 1" by rotating the swing arms by likely one notch. That's what the factory build manuals called for then...

I'm building a new-to-me used front beam with Sway-Away adjusters, and plan to remove all the short leaves in both top and bottom stacks, to soften the suspension. Adding a bolt-on disk brake kit at the same time. I'll also add camber shims to bottom tube.

Anyone have suggestions for shocks and swaybars to run on this light car, with an even lighter front end?

I've heard/read that used oil (non-gas) work well on the front, due to the very light weight up there, but have seen very little discussion for the rear shocks. I'm considering either KYB Gas-Adjust or KYB GR2s on the rear. I understand the stiffer Gas-Adjust my raise my rear about 1/2" to 3/4" of an inch and certainly would give a firmer ride. Raising it a hair wouldn't be a necessarily bad thing, to provide added clearance for my 1.5qt sump and single quiet pack. How harsh would that ride be, compared to oil shocks?

How about sway-bars? All I have now is the stock front one. I've seen VERY little discussion of swaybars for these kinds of kits that will be entirely road-driven... Not sure that recommendations for a heavy bug sedan really apply to a much-lighter 1300 lb car with a totally different weight and balance. Similarly, not sure how usage on the shorter wheelbase of a dune buggy might be different from this full-length pan that's now driven from the back seat...

BTW, the new engine is a bit old-school:

• 88x69, using Berg's machine-in jugs & forgeed pistons, rebuilt stock crank and rods
  Big valve (40x35) heads, with SS valves and HD single springs
  Set up for 8.0:1 (or close) compression
  Engle 110 cam and lifters
  Dual 40 HPMX carbs on CB space-saver manifolds, CB linkage
  Scat solid rocker shafts and 1:1 swivel foot rockers, stock pushrods
  CB Maxi filter pump and Scat 1.5 deep sump
  Extractor and quiet pack
  Scat fresh-air 36HP doghouse shroud with venturi ring, thermostat flaps, and thermostat for cooling
  Rev-limited to 5400 RPM to avoid crank and valvetrain problems

Looking to turn this into a fun lightweight 75-80 HP (or so) sports car for cruising the winding roads in the hills/mountains of East Tennessee...

[Piledriver]

Sounds like fun!
Make sure to add a real cage or it's a drive-through for anything larger than a 10 speed in an accident.

Monroe makes oil shocks for a T1 that are quite soft, as does EMPI.

Anything softer than those is going to be custom, as in buying a set of Bilsteins or QA1as and having them custom valved, possibly even going to coil overs.

The good news is due to the light weight going to coil overs will not require much reinforcement.

Given the cost I'd give the cheap shocks a try first.

[FJCamper]

Hi KentT,

Usually, lightweight kit cars or buggies do not need even a stock swaybar.

Get your fuel up front (custom tank, likely) and battery way up front, to at least try and win the weight bias game.

See if it's possible to hide your spare tire in the "engine" compartment, standing upright.

FJC

[KentT]

Thanks! Most of that has been done. Fuel tank and battery are already up front. It uses a stock VW tank, rotated 180 degrees and mounted basically the same as stock -- over the foot-well, but that is moved back 24" or so.

Battery box is just in front of the gas tank, in the center on top of the tunnel -- about where the stock footwell was. There's no room for a full-size spare without cutting and shifting some of those things around -- this thing has a NARROW nose. I'm carrying a can of Fix-A-Flat that I hope I'll never have to use... [:)]

[Steve Arndt]

It is easy to drill oil shocks for a small pipe plug. Then you dump the stock shock oil and measure its quantity. Replace with same amount of oil but use 7wt or so motorcycle/bike shock oil. Or go lighter. Anything is possible.

[Ol'fogasaurus]

Marc made an interesting point the other day when he said that the load is biased more towards the lower torsion tube; I had wondered about that myself. I would be cautious about taking too much out of the spring stacks at one time as you could over do it and go to an extreme in the other direction. One thing that has been proposed is that by using the adjusters and setting the two spring stacks differently you can get the upper stack to come in full at a later time.

Since you have a ball-joint (BJ) front beam be careful with the instructions you get for the adjusters. The instructions cover both BJ and king & link (K&L) beams and you can get lost/confused with the instructions. http://www.swayaway.net/joomla/images/I ... USTERS.pdf This is the online instructions for the sway a way adjusters which I think I a bit better (and larger print) than what comes in the kit. Which ever instructions you use, go though the instructions and mark out the instructions that apply to only K&L; this is so you don't get confused... I and several others I have talked to sure did. Remember that the K&L and the BJ springs are pinned in/rotated differently which can cause much #$&%*ing when you find out you made a mistake.

As far as the shocks go, I would not go with cheap shocks! I also would not modify the shocks unless you really know what you are doing and know a lot about the valving inside the shocks (adding thicker oil/STP was an old trick when I was young and it wasn't a good idea then either). What we call "shocks" the rest of the world pretty much calls "dampeners" which is what the "shocks" really do. They are there to help keep the tires in contact with the ground and absorb spring/dampen action. Also remember: if you lower the car as a result of manipulating the adjusters/changing when the upper torsion stack comes in, you might have to go with shorter shocks.

Sway bars: unless you are going to use your kit car in competition then I would stay with the stock sway bar. A lot of stock VW bugs did not come from the factory with them but the VW engineers must have thought they were a good idea or they would not have changed over the front end to install them. I think there are stock equivalent sway bars available plus competition quality bars available too.

My two-bits on this. My opinion is worth slightly less than you paid for it.

Lee

[FJCamper]

Hi Fog,

Porsche, et. al. always knew about front sway bars, but made the engineering assumption the very design of the beam axle made extra roll stiffness unnecessary.

They had to give in, of course, in 1954 with the Speeders getting the first front sway bar, followed by the Ghia and then the Bug.

In the case of this MG kit car type, of which I am actually familiar, KentT has his handling work cut out for him. KentT, this is where we talk about you in the third person.

Those MG kits built by the instructions, were evil handlers because of the stiff suspensions and short wheelbase, and bassackward weight distribution. The driver sits wayy back in the chassis, and weight compensation is nonexistant. But, they were attractive little spin-out traps.

KentT has the option of no front sway bar, and to remove the top torsion leaves altogether and hold the arms on with a "pass-thru" rod. That will relieve most of the ultra-stiff springing, and the car will be manageable.

The quick fix for the MG's, back in the day, was sand bags in the front.

I have the feeling KentT is not going to cage himself in, because the very persona of the MG-TD and TD sports cars is ruined by that.

FJC

[Ol'fogasaurus]

I was aware that they knew about sway bars and they chose not to use them for the same reason you said. What they ended up with is different that other cars as the middle of the sway bar done not attach to the frame stubs as the torsion tube /ere assumed to act similar to a beam axle in some ways... it is attached to the frame so to speak. Even beam cars finally joined the sway bar club.

The few kit cars of this source that I have seen (not that many) had a fuel tank up front and granted it was not a large one either.
'
I asked the same question about using a through bar on the upper beam on my short wheelbase glass buggy and was advised not to. I was passing that same advice along assuming it was correct.

I appreciate the clarification.

Lee

[KentT]

Thanks for all the dialogue, guys, as I try to get my head around my options...

I've spent several hours on the Speedster forums, looking at posts about what they've done for the their replicas regarding handling. It runs the gamut. It seems all of them (or at least, almost all) have softened their front suspension by removing some of the short leaves. Almost all are running sway bars. Some are running just the small factory front swaybar, while others are using as large as 7/8" front and 3/4" rear bars. It seems that all are running some type of sway bar (either a front one, or both) -- if they're willing to deal with clearance issues that the front bumper mounts on their kits might have. It seems the consensus -- if there is any such thing -- is that adding both front and rear bars is a major handling improvement. Note that some of them are running swing-axle rears (for authenticity) and running a camber compensator instead.

Similarly, I asked a similar question on Samba -- but didn't get a lot of meaningful help. It seems the buggy guys are building either Sunday-afternoon cruisers to the beach and drive-ins, they're going totally radical (i.e. expensive) with totally custom front suspensions and huge engines, or they're building them for dual on-road/off-road use. Few are trying to make them "sports street cars" with the VW suspension. Similarly, most of the guys in the TD Replica forums (where I'm a member) most are building cars for car shows or around-town Sunday-afternoon cruisers. One valuable bit of advice from Samba, though, was from a guy who's running gas shocks front and rear on his buggy -- but he adjusted his spring rate and ride height to accommodate those stiffer shocks. He said he likes the fast rebound of the gas shocks, and would trade off the firmer rider for the increased handling.

Mine will never be a "show car" -- it's a "20-footer" at best -- and as evidenced by my engine build, I'm doing it on a limited budget. But I am trying to build, a safe, sporty car for winding roads that will be reliable AND streetable -- I'm not looking to impress folks at the local drive-in, the beach, nor a car show. I don't mind a FIRM ride, I rather enjoy it -- but I want it to be predictable, and not so harsh that I can't keep the wheels on the ground and under control. I'd love to be able to have a totally custom front suspension, or fully adjustable swaybars, just like I'd love to be able to afford adjustable Koni or Fox shocks, but that's not my reality as a retired guy on a fixed income.

The thought of adjusting the top and bottom front beam adjusters to give more progressive handling is intriguing -- especially since I am thinking of adding the inexpensive 7/8" front/rear 3/4" Bug sway bars like the Sportster guys are using. Can I use that "adjustable progression" to help tune out any negative side effects of the large 3/4" rear sway bar?

My choices seem very limited for what might work -- most aftermarket stuff is for heavier, steel bodied cars -- and "custom stuff" or "racing stuff" is largely outside my budget.

And, I'm not opposed to adding a sand bag or two of weight to the front, if that is what it takes...

Thanks again, for helping me think of alternative ways to do what I'm trying to do...

[Ol'fogasaurus]

DaleM, who occasionally still posts here but is on TOS ("The Other Site"... what The Samba is usually referred to here) a lot was doing auto-crossing with his glass dune buggy. He might be able to give you some personal experiences with larger than stock sway bars as I seem to remember he had upgraded his buggy at one point.

There are a lot of sites that STF members are also on so it is not a bad thing. Doc has given us a very good place to hang out and there is a lot of information and opinions freely traded here.

You are asking some very good questions. Thanks.

Lee

[KentT]

Thanks, Lee. This is certainly THE best place that I've seen to find out proven info on what works for street and track handling, instead of drag strip ETs or opinions.

One thing I did do, as I'm trying to wrap my head around this -- I ordered a set of bolt-on frame stiffeners from EVH this morning:

http://evhcompany.com/stiffeners.html

I thought they couldn't hurt, only help, and if nothing else would be the equivalent of steel "sand bags" way down low, below the center of gravity...

Mine has a solid pan, but no reinforcements of any kind were added. Having owned both Bug and Ghia convertibles in the past, I knew that you needed to stiffen the frame when you don't have a full metal hard-top over your head. If nothing else those should help reduce flex and dampen shakes and shimmies from a stiff suspension in a light car... while helping to keep the rubber on the road.

[Ol'fogasaurus]

Eyeball engineering sells this the EVH part.

I built my own out of square tubing. I kerfed it to make the bends.



This was the first attempt and we did it by heating bending it with a torch. Fit was OK but not good enough.



This is the kerfing bend. I also added tubes for the bolts to go though. Over kill but looks good and is strong.



This is the front end and I ended up welding it to the front beam lower piece. Seems to be strong enough.

You need to have the body off to do this though.

Lee

[KentT]

Nicely done! I'll bet that really stiffened it up -- and should almost totally eliminate twisting...

[Ol'fogasaurus]

The pan is still in process but it did stiffen things up. On my other buggy I built a 3" body lift the same way. Not something you will do but it really did stiffen up the pan. Just getting into the buggy the first time I could immediately feel it, the car did not have to move to make the feeling obvious. I am sure that just adding the one you talked about is going to make a big difference.

I have also heard of people removing the body mount tunnel and welding the floor to a 1 X 1 or larger perimeter tube to end up with similar results. The outer body mount tube requires the body to be in place but I have heard that the additional support makes a difference also.

Have fun as I have looked hard at those same bodied toys myself but they are asking way too much for my budget.

Lee

[FJCamper]

Hi KentT,

I set up VW's to race, from slalom to road courses. I've even done a few kit cars for friends. Handling as applied to the VW, 356, and 911 chassis is something I know.

I apologize for being blunt, but to save you time and money, the handling experience of most kit car people (the Speedsters being the latest batch) is a sad story. Ever more sad is handling is subjective, and relative to application ... plus most drivers wouldn't know a well sorted out car from a slapdash one.

Your MG is one of the most extreme of the kit car designs for light noses and really heavy tail ends. Even the Speedster people have better weight distribution.

However, your MG can be made to handle well if you'll begin with the "thru-bar" replacing one whole torsion leaves stack, and (at first) no front sway bar of any kind. All of this is reversible. You can put the leaves back in later if it comes to that.

After that, it comes to suspension tuning to balance front and rear tire adhesion breakaway ... but we're getting ahead of ourselves.

FJC