Crazy wiggle on accelleration

[dbrick]

I just finished changing the upper arms to even ones and new HD spindles and HD balljoints. While I was there, noticed the entire front suspension unit was held on with 6 loose 5/16 bolts.Not a very good design. Took time out to repair that, now it has 6 tight 1/2" stainless bolts.
After finishing I ran it down the paved street, at night, same one I test drove on with bent spindles and really bad ball joints before the repair. As I accellerated through about 10-15 mph the whole buggy was wiggling, like a trailer doing the death wobble. and a bit of a rumble from the drivetrain. It's bad enough I wouldm't try to drive through it, feels very unstable.
Didn't happen on the before test ride. Front alignment isn't great, might be toed out. Rear wheels spin straight, I couldn't see any shake in the front. I know at least one of the rear swing arm bushings are bad, waiting for those to arrive. still steers like crap, takes 40+ ft to turn around but that's design

Any suggestions would be great, I'm checking the belt tomrrow, and will test drive in daylight with someone watching.

Stuff that is different between drives:
While I was waiting for the font end parts to arrive, twice, once wrong and then the right ones, I replaced the coil with an orange one, (because orange stuff is faster ) and a CDI box.
Rear wheel hub nuts were loose, tightened them

[ckau]

Originally Posted by dbrick

After finishing I ran it down the paved street, at night, same one I test drove on with bent spindles and really bad ball joints before the repair. As I accellerated through about 10-15 mph the whole buggy was wiggling, like a trailer doing the death wobble. and a bit of a rumble from the drivetrain. It's bad enough I wouldm't try to drive through it, feels very unstable.

A book could be written on this subject. There is a multitude of issues can attribute to this problem. In essence it's all about alignment, front and rear. Correct tracking with the least amount of resistance. The rear axle is a "live axle meaning power is put down equally by both rear wheels. If the axle is not positioned dead square with the frame. front to back, side to side it will not push the frame in a straight line. It's the crabbing effect, the buggy appears to roll at a slight angle. The front wants to roll in one direction while the rear wants to go in another creating a scary wobble at speeds.
For me, I found the best way to check total alignment is to get a full sheet of 3/4plywood, Draw a line down the center lengthways, remove all wheels and shocks then position the frame, measuring so the line is down the dead center of the frame, front to back. Then screw blocks around the rails to hold the frame in place. This line is the reference mark to check alignment front and back.
Use a framing square off this center line check rear swing arm for square, centering and play off the frame. If not, fix it, other wise all else will be in vain. Then go to the axle and do the same, square and center. Once the axle is positioned correctly you have a reference point for the front. Pulling measurement off the ends of the axle you can check for square. Using the center line you can check for A-arm center. Your checking for correct tracking here . The idea is to get the four corners of the chassis square and equal. you'll most likely find the frame tweaked out of square slightly but using the center line as reference you can get the four corners straight square and parallel. In most case it's a simple matter of loosening mounting bolts, tapping components into square and then retightening. but if the mounting holes have been beat out due to loose bolts it won't hold long.
The BD ball joints are high quality best direct replacement for OEM stuff. These joints will give strength and dependability. What they won't do is hold alignment. Just by the design of a ball joint system there's too much play to hold alignment. In dirt it's of no issue, on pavement it's everything! The only way I found to totally and permanently cure the problem is to do the heim conversion.
The BD spindles are the best that can be had. Though I would like to see them incorporate 3/4 axles rather than the 5/8 that's just my personal preference. I have never had or heard the first complaint about those spindles what so ever.
Front tires are everything! If your still using the OEM front wheels and tires, forget about it! The kenda Front Max are the best I found to steer with. Setting toe at approximately 1/8 inch in will keep tension on the tie rods and reduce sloppy steering. Again, the spindle end ball joint on the tie rod has enough slop to change alignment with every rotation of the front tire. A heim connection to the spindle fixes this.
The turning radius can be improved by cutting some extra teeth into each end the steering rack to give more travel.

[dbrick]

Thanks, I see it's a struggle. Precision from low price low tech. I put it up on jackstands and ran it in gear. Right rear wheel was wobbling alot, add that to the bushings and we have a wiggle. Thought it was an axle, but it's a bent hub. 2 of the 4 arms the whheel bols to are bent back 1/8"-3/16". Multiply that up to a 22" tire and it's a big wobble. the hub was a little loose, and I had tightened the nut, probably the slop was letting it align better and once tight it squared up to the axle and really shook. Probably try 2 thin washers for now, and will order a hub asap
I'm pretty OK with the spindles, finish was sloppy and with stock wheels and the stock spacer the nut only goes on halfway, not up to the nylon locking ring. Tire is very close to the spindle, so it needs the spacer. Either way, worlds better than what was on there. Still has too much camber, but Heims will fix it.
I redrilled the holes for the tierod forward and inboard a bit to increase the amount of steering, helps get more angle . Once they have racks in stock, I'll order one with the extra teeth, my tierods are beat, boots torn and one inner tierod bent, so may as well get the whole rack.
I did get this on Ebay to play with see below, for $23.00 brand new worth it for fun. Small, 11 " but well built. A few friends are bored old guys with a shop. If I leave it with them for the winter, they'll probably do the Heims and redesign the whole thing and give it back with a Hemi and 4wd in it.
http://i.ebayimg.com/images/g/gSUAAO...Jd/s-l1600.jpg
Of course, just found another yerfdog buggy for sale and considering it. Nobody said I'm bright. Build that one to sell with the parts I don't use on the first.
Got the Wife a minibike to make her a co-conspirator so she can't complain.

[dbrick]

A little bit redneck, but two of the 4 "arms" of the rear hub were bent in 1/8" far enough the lug bolts didn't want to go through the wheel, so it's tweaked. A few hard smacks with a dead blow didn't move it, so it's not cracked. Made spacers from hard nylon washers and it's about 90% true with the wheel bolted on. Good enough to run around the driveway. Have to decide between new hubs for $60.00 or the whole axle upgrade for approx $250.00. Hate to get new hubs then snap an axle.

[tkeagle]

If I had to do it all over again. Id do the axle upgrade first. The upgrade uses a different bolt pattern, and recommended 10" rims. Going from 8" to 10" is very min. if any price different at all. And doesn't cost any different on bolt pattern. In long run, think you be happier, and save money going to the upgraded axle first.

[dbrick]

I replaced the rear swing arm bushings, not horrible, but not fun. The rear is now not wobbling. Discovered one rear shock bushing is shot. On the road it's better, but steering wander is random and pretty violent, really don't want to exceed 25 mph. It feels like bump steer, but can't see the front wheels doing anything odd. Gravelly road, and asphalt are unstable, on grass/dirt not as bad. I need to get a rack anyway, so I'll get that in and the tierod extensions and see if anything improves. The bigger front wheels and tires seem to help. Bonus.. I think the old front wheels will fit my lawn tractor!

Oh, Even though I red a warning here in another forum, I made a too fast right turn without a passenger and backed off on the gas and caught traction. It lifted the front right wheel 2 feet and damn near rolled. That was enlightening.

[tkeagle]

yes, they are easy to roll. Their center of gravity sucks!!!!!! And they are really light.