Why does my buggy rear end keep sagging

[DBUG Nist]

hello all i have a tube frame buggy with a sohc subaru motor in it (only about 60lbs more than vw) it sags in the rear or at least seems like it. i adjusted the torsion bars correctly. when i looked at the bars the left bar which had a big L on it was on the passenger side while the right R was on the driver side. assuming that you sit in the car and left is left and right is passenger side (LHD car ) and not L and R facing the front either way i set it to 20 degrees and some odd minutes not sure off the top of my head but it was the spec posted. when i lowered the car both times after doing it, it seemed perfect it raised the car up to the perfect height i wanted it after the day came to an end i went out the next day and it was back to where it originally was and sagging. I don't know if this is the torsion bars just weak after all the years or not. It didn't stay at the height i wanted it to be at. it keeps going back to sagging or at least it seems like it. also is there a specific direction i need to install them? please forgive me as i'm still a big novice to old vw parts and procedures.

thank you!

[Marc]

...when i looked at the bars the left bar which had a big L on it was on the passenger side while the right R was on the driver side...

"L" means driver's side (LHD car). If you have them crossed they're going to sag - may even break I've heard. I'd recommend replacing them and tossing these ones.

This'd be a great time to upgrade to slightly stiffer bars...do you know the vintage of the bars? Or the overall length and diameter in the middle?

[DBUG Nist]

...when i looked at the bars the left bar which had a big L on it was on the passenger side while the right R was on the driver side...

"L" means driver's side (LHD car). If you have them crossed they're going to sag - may even break I've heard. I'd recommend replacing them and tossing these ones.

This'd be a great time to upgrade to slightly stiffer bars...do you know the vintage of the bars? Or the overall length and diameter in the middle?

yeah when i took them apart the first time the idiot before me had them switched like they were looking at the front of the car instead of sitting in it but i fixed that hoping it would solve it but it didnt. i belive they are the shortest bars 28" inches or something like that. its a late IRS set up. thats what one of the local vw shops was saying was replacing them they had some really thick blue ones that looked real nice. they are not thick bars by any means they are a darker shade of red.

heres the sag just scroll down youll be able to tell in the rear.
http://www.shoptalkforums.com/viewtopic ... 4&start=45

the bars right now look like this (not actual pictures there just to give you an idea):
http://images.thesamba.com/vw/gallery/pix/649341.jpg

Do the stiffer ones help with a street setup? or whats best with the street setup?

[Ol'fogasaurus]

As has been said: the torsion bars do take a set which is why you don't want to switch them. I also have heard that they can break more easily after the switch. It might be a good time to move up to a larger diameter torsion bar. Sway-a-way used to have a weight to torsion bar calculator but they have been working on their site and the VW stuff was missing the other day when I was looking for it. You used to be able to call and get one on one help on what size torsion bars you will need for the engine swap and I doubt that has changed.

It is the same with rear axles. Some feel just the normal driving can cause a set in the axles while others think that hard use such as racing or quick starts around town can be the cause of the axles taking a set.

Also make sure that there are no scratches to the paint (scratches in the outer painted surfaces of the torsion bars could indicate scratches to the outer surfaces of the torsion bar which can cause loss in strength of the torsion bar) or bruises (like dropping it) to the torsion bar either.

Lee

[Marc]

IRS rear torsion bars (Bug/'Ghia, Type III, and Thing) are all 676mm (26.614") long - actually the longest there is.
Beetle are 22mm diameter, Type III is 23.5mm...don't recall what Things and 924/944 Porsches have.

Because the spring rate is proportional to the 4th power of the diameter, a small change makes a big difference. (compared to the stock Type I IRS 22mm bar) 23.5=> 30% stiffer, 24=> 41%, 24.5=> 54%, and 25.5=> 80%

22mm (healthy ones) may be just fine for your application, but in deference to the higher engine weight I think I'd be inclined to give the 23.5mm bars a try if you can find some.

[gtmdriver]

In my experience after any adjustment the car will take a day or so to settle to its final ride height but I suspect the main problem is the extra weight of the watercooled Subaru engine. If you can't find a set of uprated torsion bars you could try spring/damper units with helper springs.

[Marc]

Shock absorber mounting points were never engineered to carry the weight of the vehicle, it's never a good plan to rely upon them for suspension. Yes, it can work - but better to use the appropriate rate torsion bar, carrying 100% of the load. That said, it's common to lower the ride height with the torsion bars slightly on race cars so that coil-overs can carry some of the weight, just because it's more convenient to make fine adjustments on them when it's necessary to jack a little weight to optimize the handling...but for normal use there's no reason to add Band-Aids (they're unnecessary weight, too, half of which is unsprung).
The "settling" in this case is obviously due to the torsion bars being installed on the wrong sides so that their initial "set" is unwinding (never a good thing on torsion bars or drive axles)...under normal circumstances it's only due to the rubber bushings finding "home" and shouldn't take more than a run or two around the block - the torsion bars don't have brains, it's not as though they somehow realized that they'd been reset provided that their direction isn't reversed.

[Ol'fogasaurus]

I completely agree with what Marc said. The coil over shocks that are readily available and quite often used for for additional support are basically overload shock not for replacing the (failing) torsion bars. The shock absorbers(dampeners) inside them probably are a minimum style of shock and most of them I have seen do not really do the job they are thought to be able to do.

There are also the cheap "air-shocks" the ones that you can fill with air. So many people use them for things they shouldn't; basically they do not really belong on a car and more so a truck (air bags can be abused also). Without going into a diatribe about the ways they can be abused it is just best not to even think about installing them.

[Dale M.]

If you find the settling problem continues, you might consider a stiffer (competition style) bar, believe Sway a Way Suspension has them... IF bars are really fatigued at this point they are just going to get worse as time goes on...

https://swayaway.com/product-category/t ... olkswagen/

Dale

[Marc]

If I only needed a bar in the rate range that's covered by stock parts I'd be disinclined to spend $800 on a pair

The odds of a set of used bars being fine (assuming they weren't installed on the wrong side too) are in your favor. Reject any with rusty spots any worse than can be sanded off and repainted.

[Chip Birks]

If I only needed a bar in the rate range that's covered by stock parts I'd be disinclined to spend $800 on a pair

The odds of a set of used bars being fine (assuming they weren't installed on the wrong side too) are in your favor. Reject any with rusty spots any worse than can be sanded off and repainted.

Go to page 3 and 4 and the torsions get much cheaper. 250-400 for a set.

[Ol'fogasaurus]

If I only needed a bar in the rate range that's covered by stock parts I'd be disinclined to spend $800 on a pair

The odds of a set of used bars being fine (assuming they weren't installed on the wrong side too) are in your favor. Reject any with rusty spots any worse than can be sanded off and repainted.

Marc, are you sure about sanding on the surface of the torsion bars. I was told when I looked into it years ago that any scratches (and sanding does put scratches on the surface), nick, bruises, dings, dents, flaws, et al could negate the strength of the torsion bar. The coating on the bar should be perfect to ensure that the bar is OK.

Just asking as this is way different than I am use to seeing.

Thnx. Lee

[Fiatdude]

just maybe???!?!?!??



Sorry, I was just in a silly mood

[Marc]

Marc, are you sure about sanding on the surface of the torsion bars. I was told when I looked into it years ago that any scratches (and sanding does put scratches on the surface), nick, bruises, dings, dents, flaws, et al could negate the strength of the torsion bar. The coating on the bar should be perfect to ensure that the bar is OK... Lee

Certainly it's true that any significant defect will cause a stress riser, and if the bar breaks it'll most likely be at that point. I'm only talking about miniscule scratches from sanding/wire-brushing in preparation for painting any spots in the coating that're compromised and could let moisture in. Done it many times, never had one break. Same thing goes for coil springs, which are actually also torsion bars, just wound into a helix. Coilovers on racecars are susceptible to getting their paint/coating/chrome-plating marred in wrecks, doesn't mean they have to be scrapped for minor flaws - just smooth the affected area to remove any stress riser and seal against corrosion.

[Ol'fogasaurus]

I agree with the stress riser bit. back in the '90s, when I first started playing with Dune Buggies (glass buggies) I was told not to do anything with the painted area on the torsion bars and to reject anything that looks like it could have been messed with which is why I asked. Not bickering just trying to find the answer.

Lee