- This topic has 197 replies, 36 voices, and was last updated 7 years, 9 months ago by
.
-
Posts
-
Roy, I think you’re correct in general, but I’m trying to get my head around the issue of the 150-180 lbs of preload applied to the bottom torsion tube. The upper torsion bar is now carrying the majority of load on the front suspension, in its normal operation.
But, a shorter shock would also serve as a limit on the extension of the suspension, similar to the old days when people would install limiting straps (in addition to sway bars) on rear solid axle suspensions. (My ’62 Vette with it’s 327ci-340HP and optional performance suspension package came with both axle straps and front/rear sway bars from the factory).A shorter shock would limit overall suspension travel, but most of the available travel now is down and not up, with the front lowered, which isn’t necessarily a good thing… A shorter shock would then also limit the extension of the inside wheel on a sharp turn, similar to how a sway bar works, reducing plowing. That is, if I’m correctly visualizing how this suspension works, now lowered…KentT2013-05-30 17:37:48
Early FF TDr on 69 VW pan
Slowly coming back from the ashes...When the suspension botoms you have no suspension. That’s not good. In the VW case, in front, that will tend to make it plow.
A bottomed-out shock is not acting like a sway bar. Sway bar limits body roll.
Not following you on the “preload applied to the bottom tube.” You’re not trying to run a beam with the center grub screws other than parallel, are you? ‘Cause that might not work, or it might…but it’s going to be mighty hard to figure out along the way.
Ed,
As I understand it, the shorter shock should help prevent bottoming out, not contribute to it. The shorter shock, when fully compressed, is shorter than the long shock when fully compressed… Using original length shocks on a lowered car means that the shocks are not starting at their neutral position — they’re compressed by however much the car has been lowered…Let me use this example, though my numbers are hypothetical, and not real VW numbers. Let’s say the stock suspension provides for 6″ of total travel, and sits at the mid-point when on the ground, loaded. The stock shock length provides for this travel. That’s 3″ of upward movement and 3″ of downward movement. Then, by whatever means you lower the car 2″ without changing the shock mounting points. That 2″ of lowering is subtracted from the 3″ of original upward travel, leaving only 1″ of upward travel before the shock bottoms out. But, that 2″ is added to the downward travel, now allowing 5″ of downward travel before that tire gets lifted off the ground because the shock is fully extended…Now, lets run those numbers with a shock that is 2″ shorter, when fully compressed, even if it only provides 4″ or perhaps 5″ of total travel. However, it’s starting position, under level load, now more closely matches the 2″ that the car has been lowered. So, it provides at least 2″ (perhaps a full 3″) of upward travel before the shock bottoms out. Conversely, the wheel travel downward is limited by the extended length of the shorter shock — at least two inches less than the original shock, or something akin to 3″ instead of 5″ of downward travel that the stock shock provides. That two inch shorter shock is acting more like the original shock did in its original position before lowering…So, it will tend to limit downward movement of the inside wheel in a turn, similar to how the sway bar operates… This limiting of extension is what I was talking about in another thread when discussing the “Sway Away” or “Sway Adjust” coil-over springs that used to be available for VWs. They clamped onto the shock top and bottom (not like the common “overload” coil-overs where only one end of the spring is fixed), and their spring tension limited the extension of the shock the same way that it added to force needed to compress it…The lowering is done by cutting and allowing the center section of the lower torsion tube housing to move (grub screw and all), when the 150-180 lbs is temporarily added to the front end, then it is welded back into place — so the grub screws top and bottom are in a different relationship (as are the torsion bar center leaves) that when you began. Perhaps “preload” is not a good term to describe what has been done…I may be using poor terminology or not communicating well, AND I may be missing something here, but I don’t think I’m all-wrong in this thinking. The top shock mount has not been moved, though the car is lowered. The lower shock mount has moved closer to this top mount by the distance the car has been lowered. Consequently a longer shock will bottom out more quickly than a shorter shock…KentT2013-05-30 23:34:20
Early FF TDr on 69 VW pan
Slowly coming back from the ashes...Kent, your second paragraph is wrong. You lower the car and that takes away downward travel. That means the stock shock will tend to bottom out. I know this because it does on my car. With the shorty shock it didn’t bottom, but the tire would rub–driver’s side (I should have bought a narrowed beam). And with the shorty I had less than an inch of “upward” travel in the suspension.
Much of the rest of what you say is right. Your thinking about how to match the length of the shock to the suspension you have is spot on. Bill in Parts (Ascheman) can help you find a shock with the travel characteristics you’re (we’re) looking for. Weak, oil-only shocks tend to work best in our cars, because of the light weight.
But lowering these cars by cutting and welding the torsion tube is not ideal. Why not buy an adjustable beam or–as long as you’re welding–cut the centers out of your beam (one at a time!) and weld in adjusters? (Get both for under $30). Then you’ll be able to set the ride height at will.
And you can also remove leaves to get a better ride, independent of the ride height.
The VW guys who actually race tend not to set the beam with the upper and lower torsion packs working against each other. You might get a ride height that looks cool that way, but the spring rate will be weird, and will tend to progress in a way that is, if not unpredictable, not easily predictable. And not optimal. (I know there are tricks people have tried–disable the lower tube…or the upper..etc. And these tricks have their evangelists. But think about the design of the beam, the intension of the engineers who built it. Or just think about the loads and stresses that had been distributed over four ball joints now being directed mainly at just two of them. I think you’ll see why, in the long run, setting up the beam parallel in the early going is a long-term win.)
There is probably no one “best” way to make these cars acceptable for street driving. But the consensus is that the cut-and-turn method specified by most kit makers is one of the worst.
Thanks for the ongoing feedback and dialogue, Ed.
I agree that removing leaves to soften the front suspension is very desirable due to lower front end weight of the fiberglass body and the new seating position — and combining that with beam adjusters would be the best solution. I also agree that my car’s lowering technique (cutting and rewelding) is not the best way to do it.My limitation right now is simply $$. I’ve checked with the local VW suspension guru about a new, adjustable beam. Bottom line is that he wants over $600 for a new beam, new bushings/bearings, and new ball joints — he won’t build one without those components, and insists on Brazilian or OEM German quality parts. That quote was for me to remove my beam and take it to him, and he assembles a new one for me with as many leaves as I want in either tube, reusing as much as possible from my beam, pressing in new ball joints, etc. Cost could increase should he find any broken leaves, damaged knuckles, etc.I think our “disagreement” may be terminology and semantics. When I say downward travel, I’m talking about travel of the suspension component (in this case the front wheel hub) and not the travel of the car’s body. If you lower the car’s body, you decrease the potential upward travel of the wheel hub, wheel and tire, due to the tire hitting the fender, etc., but increase the potential downward travel as the the tire drops down out of that fender…Similarly, to clarify, sway-bars work by using the weight of the opposite axle, wheel and tire to discourage movement of the wheel in question. As long as both wheels are moving in the same direction at the same time, such as a speed bump or expansion strip, they have little if any impact. But when one wheel is trying to move up (such as the outside wheel in a curve), the weight of opposite, inside wheel tries to pull it back down. Sway bars do NOT function like a torsion bar, because the center is not locked in place by a grub screw. (The center of a sway bar is in almost constant movement.) Instead, they function more like a see-saw, where the weight (or force) on one end offsets the weight on the other. The thickness of the sway-bar only determines the amount of “give” or “flex” in this relationship – picture a see-saw using a 1″x10″ board compared to a 2″x 10″ board. Axle straps or shock lengths (when compressed or extended) serve as stops that are a hard limit on that travel.Meanwhile, on a somewhat related note, I resurrected an old thread on shoptalkforum that discusses the unusual old shock/spring combination that I’ve referenced here a couple times. The product’s name was 4-Way Adjustable Shocks. (I couldn’t remember the name before – danged CRS syndrome.) They were made by an Australian company, now out of business, and someone dug this out of the “way-back” machine:
As you can see, the spring on the shock is fixed on both ends – resisting both upward (compression) and downward (extension) of the shock. They were uniquely designed to push or pull the car back flat regardless of the direction of travel. The advantage they had was that they did not tie two wheels of an otherwise fully independent suspension together, like sway-bars do… the impact of a pothole or bump was dealt with simply by the wheel in question, and the other wheels continued to function as intended. They reduced body lean in curves, nose-dive in braking, and nose-lifting in acceleration. IMO,these would be great for these kit cars, if they were still available…Early FF TDr on 69 VW pan
Slowly coming back from the ashes...Ah! I get it now.
Ball joints complicate the matter, but the whole job may not cost as much as you’ve been quoted. I will probably need new ball joints too at some point, and the press-in thing means I’ll be getting the job done by someone with a press and some knowledge, rather than DIY. I would be interested to hear your guy’s quote on that job. I’m thinking it should be about $100 to take the old ones out and press new ones in. They sell for about $15-$20 each, I believe.
I think I paid $300 for my adjustable beam. Might have been $200. It came with the seals, bearings inside, adjusters welded in, etc.. I just had to rattle can the new one (the paint they do isn’t so great), disassemble the old one, slide the leaves in the new one, grease it up and re attach the trailing arms. It was not that bad a job. My complication was a bit of rust on the frame head, which I didn’t really fix. If you don’t have that, you could consider doing the beam swap yourself.
I have enjoyed the repartee on suspensions. I am considering buying a narrow adjustable beam for my MiGi as a winter 2014 install. I think that despite having removed all the small leaves from both beams, it is still about 2″ too tall in front. But my wheels sit almost at the outer edge of my fenders and I do not like the hot rod look.
My questions are three:Should I buy the narrow adjustable beam and take care of all the problems? orGo with drop spindles? (I understand that these increase your stance about 1″.)Does my standard VW tow bar still hook up normally if I were to get a narrow front beam?
http://www.monroe.com/assets/downloads/english/08_MountingLengthSheet.pdfHere’s a rather simple but complete listing of available shocks.
Pick your mounting style then find the shock with those mounts with the desired extended and compressed length.
Happy hunting.
edsnova2013-09-25 20:59:58Bill Ascheman
Fiberfab Ford
Modified 5.0, 5sp., 4:11
Autocross & Hillclimb
"Drive Happy"Roy, your car doesn’t look to me like it sits too high. Dropping the nose 2.5 inches would be a bit much, imho. To your questions:
The off-the-shelf narrowed beam is only 2 inches narrow. I think that would tuck the wheels under the fender OK but would not be as narrow as a stock TD.
I think the drop spindles put the track out a little, but not an inch. More like 3/8-inch per side. So the narrowed beam would still bring the tires under by about 5/8 per side. Two-plus inches down, though, might be trouble.
The tow bar should work. What messes up tow bar functionality is the bolt-on beam stiffeners.
on my car the original owner did not take out any leaves top or bottom. How many of these should I take out ? probably won’t get done till next weekend I’m waiting on seals& ball joint boots
I took out all the small leaves. This should be 12 small leaves. It leaves 4 large leaves in each beam. I know it sounds drastic. Just do it. The front end on my car went down about 1-1/2 to 2″ and the ride was dramatically improved. All aspects. Softer. Much better control in gusty cross winds. All’s well.
Crash. I did the same on my TD. Check the MGTD Gallery. My Photos are in 4806.
Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackOops!! I didn’t post those. They are in http://www.fotki.com/Allen1209 I’ll have to add them a little later.
Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackI’m not saying that my photos are better than Allen’s but mine are #18705 in the TD photo gallery.
Hi!
I have a MIGI on a 1970 vw chassis. My question on suspension is: When you remove leaves from the VW front beam is it really necessary as many claim, to glue, weld or otherwise insert short pieces of spring to compensate for the leaves you have removed? I have looked into the center support and the spindle arms and as far as I can see they are not necessary.
Thanks!, didn’t think so! I have removed all the small leaves and installed shorter shocks and the difference is unbelievable! I also put a 1/8 shim in to increase the caster, makes the car feel really stable on the road. still a little squirrelly in gusty crosswinds but no worse than my Toyota Echo.
I wish I had seen this post when I was modifying my VW (69 VW bug, Daytona Migi TD replica), except that it was about 33 years ago. The lowering instruction were so that it “looked” right, with apparently no consideration for the ride. I added some concrete in the front for weight, and cut and rotated both tubes, rather than just one.
I don’t really consider the ride or handling too terrible, it’s just that I know it could be better, and I would rather have not put in any additional weight.
I am left with a camber adjustment issue. After I lowered the front I took it in for alignment. They said they moved the adjusters to the full max position, but it still has too much camber. People notice it when they’re standing in front, but not from the side, of course. The tires wear too much on the outside.
Does anyone know a solution for this? It seems that just a different set of adjusters could take care of this. Is there any problem when you by an adjustable front end, or can you adjust it for zero camber?
With all this talk about adjusting the torsion bars does anyone know what the length of the front shocks should be? I have the KYB GR2 shocks and they seem like they are too long. I haven’t measured them, just eyeballing.
capnmike wrote:With all this talk about adjusting the torsion bars does anyone know what the length of the front shocks should be? I have the KYB GR2 shocks and they seem like they are too long. I haven’t measured them, just eyeballing.Well, I tried the 2″ shorter shocks on my TDr with a cut/rotated lower torsion beam, and they’re too short. I couldn’t jack the lower shock mount up high enough with my floor jack to bolt them in, without adding additional weight to push the top mount down — so I’m back to using stock length shocks…Early FF TDr on 69 VW pan
Slowly coming back from the ashes...That makes sense to me…that you;d need stock length shocks.
Most of the TD kits were designed to fit with the stock height VW suspension.
What has been described as “lowering instructions” is necessary because the front end lifts up because there is less weight on it.
By “lowering it” per assembly manuals instructions, you are actually bringing it back to the stock ride height.
Of course more variables come into play if you remove torsion bars from the front tube.
But at the end of the day, the front suspension ends up back at a stock ride height.
Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica RoadsterIf you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)
How can I identify whether I have an adjustable front axle and can the leaves be removed without removing the axle from the car? Hints and tips are welcome.
Look for ratchet teeth behind the grub screws in the middle of each tube. The adjusters are easy to find pictures of on the web. You’ll know them when you see them.
If you don’t have them, there will be plain grub screws and they will (at least one of them) be aiming down instead of straight at you. That’ll be because the beam was cut and turned, changing the grub screws’ (and the spring anchor mechanism’s) orientation.And yes, you can take the torsion springs out with the beam still bolted up.
- You must be logged in to reply to this topic.