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  View original topic: wider king pin front end vs A-arm front end
21golden007 Fri Dec 25, 2020 1:37 pm

Iím in the middle of my fiberglass buggy build and Iím about to drop way too much money on suspension. Currently building the cage. Will be running 3x3ís in the rear with coil overs up to the cage. Still not sure what Iím doing with the front and want some input. Itís the ball joint front. Iím thinking my two options are

1. 6Ē wider king pin front end with coil overs as sold by pacific customs (link below.) I understand this means cutting the head off and fabbing it into the cage as the king pin beam is different width than ball joint. $3500

2. Looking at the a-arm.com conversion kit that bolts right on to the ball joint style frame head. I would still weld in supports from the cage Iím building. $4300

What would you go with? A arm kit would probably be easier honestly since it would bolt on and Iíd just weld suppprts in place. Plus a better ride i would think?

https://www.pacificcustoms.com/mm5/merchant.mvc?Sc...axle-beams

https://a-arm.com/

richardcraineum Fri Dec 25, 2020 2:44 pm

i looked into my crystal ball and it predicted the future of your thread will be people asking what you plan to use your buggy for, type of terrain, how you drive, etc etc.

21golden007 Fri Dec 25, 2020 3:01 pm

richardcraineum wrote: i looked into my crystal ball and it predicted the future of your thread will be people asking what you plan to use your buggy for, type of terrain, how you drive, etc etc.

Thatís probably accurate.Iím in Michigan so itís quite a variety: silver lake sand dunes a few times of year, rough wooded trails and sand trails on public land up north, down the road to the brewery etc.... so mostly trails, some dunes, but itís also titled so it would be fun to take it into town every once in a while.

cbeck Fri Dec 25, 2020 6:57 pm

I got 12" travel out of my 6" beam and 2.5"x1"arms with 8" shocks. I always thought a beam would ride better because the arms move back and up when compressing. All of the competitive woods buggies in the you tube videos have beams.

dustymojave Fri Dec 25, 2020 7:09 pm

Richard got it right on. Exactly what I would have asked. And the answer is a good one.

As to which is the better...

That's going to be up to the car owner.

The a-arm kit page does not indicate whether the kit is designed to bolt on to a link pin frame head or to a ball joint frame head.

The up front price is 1/3 more for the a-arms.

One thing they don't show very well and do not mention at all, is that in the pictures of the Baja Bug with it installed, it appears the rack and pinion is installed through holes bored through the forward part of the tunnel. And they do not anywhere show the steering column connected to the rack. It looks from that same picture of it in the Baja that the angle of the steering column is substantial and would require a shaft support bearing at the firewall, and a short shaft with a pair of u-joints.

They act as though the entire deal will bolt right into the car with no modifications. But do not address the above issues.

The +6 link pin beam will have at least as much issue with connecting the steering shaft.

Both will need support from the roll cage to prevent structural failure the 1st time you drive it off road.

21golden007 Fri Dec 25, 2020 9:35 pm

dustymojave wrote: Richard got it right on. Exactly what I would have asked. And the answer is a good one.

As to which is the better...

That's going to be up to the car owner.

The a-arm kit page does not indicate whether the kit is designed to bolt on to a link pin frame head or to a ball joint frame head.

The up front price is 1/3 more for the a-arms.

One thing they don't show very well and do not mention at all, is that in the pictures of the Baja Bug with it installed, it appears the rack and pinion is installed through holes bored through the forward part of the tunnel. And they do not anywhere show the steering column connected to the rack. It looks from that same picture of it in the Baja that the angle of the steering column is substantial and would require a shaft support bearing at the firewall, and a short shaft with a pair of u-joints.

They act as though the entire deal will bolt right into the car with no modifications. But do not address the above issues.

The +6 link pin beam will have at least as much issue with connecting the steering shaft.

Both will need support from the roll cage to prevent structural failure the 1st time you drive it off road.

It actually does say that itís bolt on for the ball joint style, which would be nice as that would give me a starting point and I could support it into the cage from there. Nice catching the steering shaft. I did not see that. I havenít gotten to the point of figuring that part out yet.

Iím going to try and get a hold of the a arm guy to pick his brain. For a thousand bucks more I need to determine if itís a better enough ride to go with it and the ease of it bolting up to the frame (instead of cutting it out for the king pin) is worth it.

Any other a arm kits out there?

As far as 6Ē wider beam kits go, there was another guy that was on here building beam kits like this with coil overs and everything but I donít remember his name. Any ideas?

manxvair Sat Dec 26, 2020 11:27 am

Just by going to a coil over suspension as opposed to stock torsion is going to improve the ride tremendously. On my Manx it runs a 5" wider beam and 4" Foddrill arms & Fox 2.5 shocks. We've logged over 38,000 miles on & off road including 3 NORRA Mexican 1000 races, 2 trips from So-Cal to OBX, NC and back and it rides like a dream, 70 mph on the highways or 70 mph on dirt roads it's very comfortable.

dustymojave Sat Dec 26, 2020 5:13 pm

A VW trailing arm front suspension has a ride advantage over a-arm in that the wheel moves back and up around the pivot points, which smooths the ride.

An a-arm front end pushes the wheel outboard as it compresses, then pulls it back in. And then pushes back as it returns. A long travel a-arm front suspension can push a car sideways as the suspension works, which the VW trailing arm suspension does not do.

You can in theory, get more wheel travel out of an a-arm front end. But, interestingly, this a-arm front end kit offers 12" of wheel travel, while the beam kit with +4" arms you are considering offers 15" of wheel travel at 3/4 of the price.

If you're using it offroad, either needs frame structure built to reinforce the mounting. Which pretty much renders the "bolt-in" aspect of the a-arm kit nearly meaningless.

It's all a question of personal preference. Some people are hard core "beam only" and some are hard core a-arm only. It comes down to Buyer's choice.

baja5 Sat Dec 26, 2020 7:50 pm

Dusty is right on this one. My last car was a beam as are most of my friends cars. Amazing what a set of 4 over arms, coilovers and bypass shocks can handle. And there really isnít much geometry to consider as it it built into the components. Other than steering of course, but setting up the rack to minimize bump steer can be a challenge. A arm front ends are not all created equally. So, finding a set up that maximizes travel while limiting track width change can be tough. I have seen lots of sand cars that have to ratchet strap the front wheels to fit them on a trailer. This is usually ok in the dunes but can get sketchy on hard pack. Also, having your caster built into your set up will help with cycling as well as the steering return and handling so so your research if you plan to go A arm. Keep in mind as well that to get lots of clean travel out of A arms the car tends to get wide. Mine cycles we inches, hits -4 degrees of camber at full droop and bump and track width change is 1 inch overall. But, it is 84 inches wide. It was designed on Solid Works by a good friend of mine. Nice thing about that is, you can see all the geometry changes on the computer before you ever start the actual build. Changes after you build mean more work. Good luck.

richardcraineum Sat Dec 26, 2020 9:11 pm

21golden007 wrote: ...

Any other a arm kits out there?

.....

couple years back i built an A- arm conversion on a buggy similar to the old a-arm.com's style. it was pretty cool really and i planned to work on building and selling some, but got a few little things to work on to make it a universal kit.
it had 16" of travel and wasn't any wider than the rear with 12" wheels. i tried to make it work with a center mounted vw steering box but it really needed to be R&P.
ill probably get back to working on it again before long. always figured id get a couple guys from here to trial test em and give feedback... one of these days.....

21golden007 Sun Dec 27, 2020 7:45 am

Alright, you guys have me leaning towards beam. Any good threads on the process? tying it into cage, determining angle, how far forward, how one guy with 2 hands can hold 12 things in place at the same time, etc?

baja5 Sun Dec 27, 2020 9:55 am

Once again, research. There used to be a thread here with tons of cage work, I would start there. Figure out your budget, then double it. Itís amazing how the little things add up. Hardware alone can cost hundreds. My beam was pushed out 5 inches. 5-8 is usually the norm as after that it can get tough to mount the hood and make it look normal. 6-7 degrees of beam tilt(caster) seems to be the norm as well.. building a jig table to square everything up would be helpful.

dustymojave Sun Dec 27, 2020 10:55 am

Look in the classifieds for the imitation Manx bodies and frames for sale. That should provide some ideas of what is needed. But some of other kit cages are not so well engineered and are more intended for a car show Buggy than one intended to be used. Manxvair is probably a good source of info for this as he should be able to provide pictures of how he built his.

OCB Sat Jan 16, 2021 8:41 am

I have been building beam and A arm cars for years now. I.M.O. A arm is far better when the design is done right. There is much better caster, camber, KPI. that make it much better King pin. Also the shocks are much easy is tune right.

This all comes at A very high cost over the cheap beams they sell now. If you buy chormoly race beam, arms, spindles ect. you will find the cost is not that much more for A arm. If you want the best ride and handling A arm is King!


Vanapplebomb Sat Jan 16, 2021 4:30 pm

21golden007 wrote: richardcraineum wrote: i looked into my crystal ball and it predicted the future of your thread will be people asking what you plan to use your buggy for, type of terrain, how you drive, etc etc.

Thatís probably accurate.Iím in Michigan so itís quite a variety: silver lake sand dunes a few times of year, rough wooded trails and sand trails on public land up north, down the road to the brewery etc.... so mostly trails, some dunes, but itís also titled so it would be fun to take it into town every once in a while.

Most the guys I know who ran A-arms stuck to the dunes. They work fine in the soft sand or gravel, but were not great on the rough trails, especially rocky ones in the north western UP. It does seem that the VW trailing arm system just works better at absorbing the rear shock forces from hitting rocks, holes, etc. the trailing arms swing back and up to absorb bumps.

Now, the one guy I rode with with an A-arm that worked had it set up raked back about 5-10 degrees or so by eye-balling it. That offered some rearward give, and seemed to help soak up the harder hits. It was also a lot more beefy than the light weight a-arm dune going buggies typically have here in Michigan.



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