Anybody running the RMS AlterKation? Was it really worth the cost?
- Thread starter harrisonm
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67autocross
A new iron curtain drawn across the 49th parallel
Strange reply.....
I thought maybe a kid? But hell I looked, he's 67!
loganscuda
This/These
I guess that makes it an A+ 2.0 body then.
JeffisOld
Old, Ugly and generally Disagreeable!
Good read! Thanks
69RRGTX
Well-Known Member
Good read! I have it (AlterKtion) on my 69 road runner. My main reason was weight, weight, and weight, and room! Dry sump pan and large headers on a hemi almost mandate something like it. Mine is not set up for handling, but I am sure that it would be superior. I also have a 69 GTX driver, when rebuilding its suspension I decided to make it as good as I could with original style parts. I am happy with it, but the price for all of the firm feel components, etc get you near a conversion kit pretty fast. I am doing a 69 Dart now, it might get a few upgrades but nothing that fancy.
Ok, so how much lighter is it?
Comparing like to like, ie, comparing a manual rack to manual steering, HemiDenny says his coilover conversion kit saves 29.8 lbs. That doesn't include brakes because you can go aftermarket brakes on either style suspension. I'm sure the RMS kit isn't any lighter than HemiDenny's. From the man himself Early A-body HDK to be released soon
Now, comparing a manual rack to stock power steering the difference is probably more like 60 lbs. But, that's not like-to-like, and comparing a power rack to a new Borgeson power steering box probably puts the difference back in the 30-40 lb range. Sure it's a weight savings, but it's really not all that much.
Yup. That is an advantage of the coilover conversions, and not a bad reason to do a conversion. But that's probably the biggest advantage.
Really? You're sure that Pinto suspension scabbed onto a Mopar chassis would handle better? Why?
Coilovers aren't magic. They are springs and shocks combined into one unit. That's it. Coil springs are not superior to torsion springs, and shocks are shocks. Both the Mustang II coilover design and the torsion bar suspension design are unequal length A-arm suspensions. There are some geometry differences between those two examples obviously, but for the most part they are the same basic style of suspension. With the aftermarket parts now available for the original torsion bar suspensions, you can tune the geometry just as well as you can with a coilover set up.
I've posted an itemized list of everything you need to upgrade a torsion bar suspension for handling several times. The price to rebuild and upgrade the entire torsion bar suspension to something comparable with an RMS conversion (ie, replacing the steering, full tubular control arms etc) is less. In fact, you can rebuild the rear suspension as well and still be less than the cost of the RMS by about a grand. That's like to like (manual steering), with all new parts, and even a bunch of fancy stuff you don't really need for a street car. You can absolutely do it even cheaper than this. Here's the break down...
Frame or chassis options for A bodies
I've got no problem with the RMS, HDK, Gerst or any of the other coilover conversions out there. If you need the space for headers, or just absolutely can't live with the feel of a worm and ball steering box then the conversions offer a nice option. Plus you can get everything shipped from one place and just bolt it all on, and there's something to be said for that.
But don't believe for a second that you can't achieve similar handling with an upgraded torsion bar suspension. Or that you can't make them at least somewhat comparable in weight if you compare like-to-like components. All suspension systems are a compromise, and the RMS is no different. It has its pros and cons, just like an upgraded torsion bar system does. But the coilover set ups are not inherently any better, and they have not proven to be any faster on the track for handling.
69RRGTX
Well-Known Member
Well you know everything, so you must know how much weight I saved. I also know all of these systems are a trade off. I was posting what worked for me in those situations take it for what it's worth.
Ha! I definitely don't know everything, never claimed to, not even on the very limited topic of torsion bar suspension.
As for your weight savings, I asked you. You're the one that made a point of emphasizing what a big difference it was, I figured you actually knew what you were paying for. I'm just going off of what Denny said, he builds the HDK set up, he should know. Even if you went from a stock power steering set up to a manual rack it's probably around 60 lbs or so. Hardly worth paying $5k for, and that's not a like-to-like comparison. I know if I were going to cut a $5k check to save some weight I'd know exactly how much weight I was going to save, down to the ounce. Maybe I'm just a cheap bastard though.
There's no doubt that the RMS works, and I've never disputed that. It does. It's not a bad system at all, and coilover conversions have their place. There are advantages to the conversion, more space, rack and pinion steering, easy tuning, etc. The thing is, you didn't just post what works for you. What you said was that you're sure that the RMS "is superior" for handling, and that the price of upgrading the torsion bar suspension "get(s) you near a conversion kit pretty fast" Both of those claims are false unless you've got evidence I've never seen before. The fastest autoX and road race set up Mopars are still torsion bar cars. And I posted the price break down on the upgrade I did on my car, you can see what costs more and it's not the upgraded torsion bars set up.
You like the RMS? Awesome, a lot of people do. It's a great piece and it absolutely has it's place. But I'm tired of seeing claims made about it that either aren't true, or at best aren't being backed up with any kind of facts/evidence. Let people weigh the actual facts and make a decision.
replicaracer43
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100% agree
67autocross
A new iron curtain drawn across the 49th parallel
This fall when I get back from Drag Week I will put a stock front end and an RMS on the digital scale in the shop. I will include a stock manual box,a stock power box and a borgeson box and give the weight of each.
My guess is the the RMS will be at least 50lbs lighter than a factory setup...
My guess is the the RMS will be at least 50lbs lighter than a factory setup...
People got to look up 20-80 rule.
Basically when put to are cars a few well chosen parts in the suspension (20%) will give you 80% return in performance.
Unless your competitive racing with unlimited like budget. You don't need the best or even close to it. And that's assuming rack and coils are better.
I'm sure in your daily driving you will rarely exceed the stock suspension cornering ability nevermind a $10,000 one.
Like I said before a few well chosen parts will are you need to make high speed cornering feel and be a lot safer.
On the weight issue weight below CG matters a lot less than above but being polar weight will help some.
Basically when put to are cars a few well chosen parts in the suspension (20%) will give you 80% return in performance.
Unless your competitive racing with unlimited like budget. You don't need the best or even close to it. And that's assuming rack and coils are better.
I'm sure in your daily driving you will rarely exceed the stock suspension cornering ability nevermind a $10,000 one.
Like I said before a few well chosen parts will are you need to make high speed cornering feel and be a lot safer.
On the weight issue weight below CG matters a lot less than above but being polar weight will help some.
People are going to defend their choice and in this case it is front suspensions. That is what makes cars different and most money spent is spent where the owner/builder wants to put it. Period.
Alright, time to do some math. Denny already weighed a bunch of this stuff. Here's his post, click to expand. Or to see the original go here Weight comparo: HDK vs Stock
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HDK vs. Stock K-frame weight comparison
All measurements taken with a new digital scale
stock K -frame assembly w/manual box and steering linkage ..................................60.8 lbs
stock A arms without lower ball joint/steering arm...............................................38.2 lbs
stock torsion bars and front shocks..................................................................19.4 lbs
stock total.................................................................................................118.4 lbs
HDK K-frame assembly w/manual rack (includes steering linkage)............................47.6 lbs
HDK control arms, upper shock mount, chromoly support hoop and hardware.............25.8 lbs
Alden Eagle coilovers/ #654 (pair) complete assemblies w/ 450 lb springs.................15.1 lbs
HDK total............................. ......................................................................88.5 lbs
..............................DIFFERENCE...29.9 LBS
*weights do not include the lower ball joint and spindles.
**for a fair comparison I weighed the stock and HDK lower control arms w/ sway bar mounts.
The HDK K-frame has sway bar mounts, but the stock assy did not.
So, starting from where Denny left off, I weighed some things. Now, full disclosure, I just used a cheap digital bathroom scale. I weighed each item a couple of times and took a bit of an average, but really anything within a pound of these measurements wouldn't surprise me. I also used a 73-76 /6 K because thats what I had laying around, but I'd wager a V8 spool K is within a pound or so, only the engine mounts are different and not much really for total metal used.
OE manual steering box:..........................12.4 lbs
OE power steering box, large sector:......... 37.5 lbs
Federal pump/pulley/brackets V8:..............15.4 lbs
73-76 spool mount /6 K frame:..................34.0 lbs
Stock tie rods & ends:...............................4.6 lbs
Stock center link, pitman and idler:.............9.6 lbs
Stock LCA's w/tabs, bushings and pins:.......21.2 lbs
Stock UCA's with ball joints:.......................9.8 lbs
Stock strut rods 73-76 w/bushings:.............4.8 lbs
Just Suspension 1" torsion bars:................ 17.0 lbs
Bilstein RCD's x2:......................................6.2 lbs
So for the stock K, manual box, and steering linkage my numbers give 60.6 lbs, which is real darn close to Denny's 60.8 lbs for the same items. For the control arms (upper, lower and strut rods) I get 35.8 lbs, which is 2.4 lbs lighter than Denny's numbers. I was a little concerned about that until I saw the stiffening plates on Denny's LCA's in the picture. Makes perfect sense, those are close to a pound each, so pretty close again. For the grand stock total, manual steering, I get 119.6 lbs. That's pretty close to Denny's 118.4, and I used 1" torsion bars.
So, now some mathematical gymnastics.
73-76 spool K, OE manual box, steering linkage, UCA's, LCA's, upper ball joints, strut rods, 1" torsion bars and Bilstein RCD's: 119.6 lbs
Same set up but with OE power box, federal pump/brackets/pulley/hoses:...........................................................................160.1 lbs
Same but only with power box (to compare to power rack, which also needs a pump & junk):...............................................144.7 lbs
We also know that the Borgeson box is 15 lbs lighter than the stock power steering set up, at least according to Peter Bergman and I believe him. That would mean a Borgeson power steering box weighs ~22.5 lbs by itself. So,
Same stock everything, Borgeson power steering box, assume same weight for pump& brackets as federal:..............145.1 lbs
Same everything, just the borgeson box, no pump or accessories(to compare to power rack):.................................129.7 lbs
What does is all mean? Well, the HDK and goodies are 88.5 lbs with a manual rack. So.....
The HDK conversion with a manual rack is 31.1 lbs lighter than a stock manual steering set up by my numbers. It's 71.6 lbs lighter than a full on stock power steering set up, but that's comparing stock power steering to a manual rack. If you assume the power steering pump and brackets for the Borgeson weigh the same as the stock stuff (actually not a horrible assumption since it uses a saginaw pump) then the stock K, Borgeson power steering set up to HDK manual rack is a 56.6 lb difference. But again, that's comparing power steering to a manual rack.
The problem is, I don't know what a manual or power rack weighs by itself. So, I can't make the power box to power rack comparison without assuming a power rack weighs the same as a manual rack, plus the pump/pulley/bracket/lines. Not sure if that's a good assumption.
If it is, than an HDK with a power rack is roughly 56.2 lbs lighter than a the stock K and power steering box, and only about 41.1 lbs lighter than a stock K and borgeson set up.
So you can only lose more than 50 lbs if you have stock power steering or a power borgeson set up and convert to a manual rack. If you go manual to manual it's only ~30 lbs, and if you go power borgeson to power rack it's only around 40 lbs. So I was off by 10 lbs on the stock power stuff to manual rack and the Borgeson to power rack is on the high end of what I said.
Now, if we can get power rack, power rack plus it's pump/brackets/pulleys/junk, and more Borgeson box measurements we can narrow it down with more accurate numbers. I would be willing to be the RMS K is pretty close to the same as what the HDK weighs though.
OE manual steering box:..........................12.4 lbs
OE power steering box, large sector:......... 37.5 lbs
Federal pump/pulley/brackets V8:..............15.4 lbs
73-76 spool mount /6 K frame:..................34.0 lbs
Stock tie rods & ends:...............................4.6 lbs
Stock center link, pitman and idler:.............9.6 lbs
Stock LCA's w/tabs, bushings and pins:.......21.2 lbs
Stock UCA's with ball joints:.......................9.8 lbs
Stock strut rods 73-76 w/bushings:.............4.8 lbs
Just Suspension 1" torsion bars:................ 17.0 lbs
Bilstein RCD's x2:......................................6.2 lbs
So for the stock K, manual box, and steering linkage my numbers give 60.6 lbs, which is real darn close to Denny's 60.8 lbs for the same items. For the control arms (upper, lower and strut rods) I get 35.8 lbs, which is 2.4 lbs lighter than Denny's numbers. I was a little concerned about that until I saw the stiffening plates on Denny's LCA's in the picture. Makes perfect sense, those are close to a pound each, so pretty close again. For the grand stock total, manual steering, I get 119.6 lbs. That's pretty close to Denny's 118.4, and I used 1" torsion bars.
So, now some mathematical gymnastics.
73-76 spool K, OE manual box, steering linkage, UCA's, LCA's, upper ball joints, strut rods, 1" torsion bars and Bilstein RCD's: 119.6 lbs
Same set up but with OE power box, federal pump/brackets/pulley/hoses:...........................................................................160.1 lbs
Same but only with power box (to compare to power rack, which also needs a pump & junk):...............................................144.7 lbs
We also know that the Borgeson box is 15 lbs lighter than the stock power steering set up, at least according to Peter Bergman and I believe him. That would mean a Borgeson power steering box weighs ~22.5 lbs by itself. So,
Same stock everything, Borgeson power steering box, assume same weight for pump& brackets as federal:..............145.1 lbs
Same everything, just the borgeson box, no pump or accessories(to compare to power rack):.................................129.7 lbs
What does is all mean? Well, the HDK and goodies are 88.5 lbs with a manual rack. So.....
The HDK conversion with a manual rack is 31.1 lbs lighter than a stock manual steering set up by my numbers. It's 71.6 lbs lighter than a full on stock power steering set up, but that's comparing stock power steering to a manual rack. If you assume the power steering pump and brackets for the Borgeson weigh the same as the stock stuff (actually not a horrible assumption since it uses a saginaw pump) then the stock K, Borgeson power steering set up to HDK manual rack is a 56.6 lb difference. But again, that's comparing power steering to a manual rack.
The problem is, I don't know what a manual or power rack weighs by itself. So, I can't make the power box to power rack comparison without assuming a power rack weighs the same as a manual rack, plus the pump/pulley/bracket/lines. Not sure if that's a good assumption.
If it is, than an HDK with a power rack is roughly 56.2 lbs lighter than a the stock K and power steering box, and only about 41.1 lbs lighter than a stock K and borgeson set up.
So you can only lose more than 50 lbs if you have stock power steering or a power borgeson set up and convert to a manual rack. If you go manual to manual it's only ~30 lbs, and if you go power borgeson to power rack it's only around 40 lbs. So I was off by 10 lbs on the stock power stuff to manual rack and the Borgeson to power rack is on the high end of what I said.
Now, if we can get power rack, power rack plus it's pump/brackets/pulleys/junk, and more Borgeson box measurements we can narrow it down with more accurate numbers. I would be willing to be the RMS K is pretty close to the same as what the HDK weighs though.
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Good info!
That's just that power rack by itself right? Any info on the steering pump/bracket weight for the power rack?
So using those numbers, if you assume the pump/brackets/junk weigh the same for each set up, that would mean the stock K, oe power steering set up would be ~50.2 lbs heavier than a HDK with a power rack. A stock K, power borgeson set up would only be ~35.1 lbs heavier than a HDK with a power rack.
And for those keeping track, that would mean the HDK K frame assembly by itself would weigh in at ~31.6 lbs, or only about 2.4 lbs lighter than a stock, 73-76 spool K frame.
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Good calculations. .... over the years, thru updates, I have added some weight in some areas....and taken off some weight in other areas, but still close.
From feedback I receive, especially the drag racers.....they love the weight loss, the room, the simplicity, but also love the way they can run more caster for higher speed stability. I imagine that applies to other aftermarket coil over /rack and pinion conversion front ends.
On the rear, for a street car and the best dollar for dollar ride, I am still a fan of leaf springs.....unless you are a serious racer, then there are drag race / auto X specific versions of 4 bars /4-links.
From feedback I receive, especially the drag racers.....they love the weight loss, the room, the simplicity, but also love the way they can run more caster for higher speed stability. I imagine that applies to other aftermarket coil over /rack and pinion conversion front ends.
On the rear, for a street car and the best dollar for dollar ride, I am still a fan of leaf springs.....unless you are a serious racer, then there are drag race / auto X specific versions of 4 bars /4-links.
First, none of the big name kits like HDK,RMS or Gerst are "Pinto suspensions" stuffed into a mopar chassis. I know the only thing they share are the base spindle design. Some like the Gerst are using redesigned/improved mustang II forged spindles. But other than being a spindle that has been redesigned to take care of some of the issues with the mustang II factory spindle, there is no other similarities to that of a mustang ii or the pinto for that matter. Lots of cars use a coil over design, pinto's are not unique to this. The geometry of these kits are totally different, materials are different etc. It's not simply cutting the suspension from a Pinto and putting into a Mopar.
As for your weight savings thing, you've got some valid points there. And I will agree, a properly tuned suspension will almost always outperform an untuned one. The aftermarket now a days has grown to where mopar owners can tune torsion bars quite well.
we've had this debate before, we'll have it again.
I think the problem is people over estimate what the need/want. If your never gonna corner faster than .85 of a g no point of building a g machine. Which your not gonna hit too often in your daily driving. Decent tires, heavy duty sway bars and a slight lowering go a long way. But if you got the cash and can't find a better way of spending it go ahead nothing wrong with a tricked out suspension just know it's not absolutely needed to make your car handle.
agreed. and I say that as one who owns 2 mopar cars, one with a full four corner coil over system and the other that's simply has hemi T-bars in it. The biggestest reasons I went with the coil overs on all for corners (All Gerst Suspension stuff) are:
Weight savings, roughly 120 pounds total, roughly half-60% of that in unsprung weight,
Four corner adjustable weight bias, something you can't do with the leaf springs
Adjustable rear roll center, something you can't do with the leaf springs
Adjustable pinion angle, something you can't do with the leaf springs
Adjustable front geometry. something you can't do as much with the factory front
Clearance around the headers, transmission(eventually a t56)
Ditched the big heavy factory power steering box for a rack weighing half as much with better feel (IMO)
and a few other minor reasons including finding more options and cheaper options locally for brakes and such.
But thats in my pro-touring build on my dart. My 64 Polara is gonna retain the factory suspension as its a cruiser.
Thanks Denny! I try to keep things factual/accurate. And I definitely respect what you've done for the community with your products, you make great products and obviously know your stuff. Even if I'm constantly telling people they don't need coilover conversions.
I will say you can achieve plenty of caster with the torsion bar suspension. I have +7* on my Duster at the moment, and I'm not even running adjustable UCA's yet. Just non-adjustable, bushed magnumforce UCA's I bought used. Peter Bergman runs about +7* as well if I remember right, he has the SPC arms I'm going to next. Before I dialed in my current alignment I was near +8* caster on one side and up to like +8.2* on the other, but with 16:1 manual steering and 275's that was more arm workout than I wanted the few times I drove it with the alignment just roughed in. Just going down to +7* made a big difference. That's not all UCA's on my set up though, I know I picked up some + caster with the poly LCA bushings and adjustable strut rods. I basically set the strut rods as short as I can get them without causing a bind condition, but since my cars are lowered I don't have as much suspension travel to deal with so the bind issue is reduced some, so even tuning for no-bind I think I get a little + caster out of them.
The stock power steering is almost an unfair comparison, that set up is such a boat anchor. I mean, you lose 40 lbs just going to a stock manual set up. But fair is fair, you can drop 70 lbs going from stock power to a manual rack, and the manual rack probably feels a bit better than the stock manual boxes so that probably does happen. But a ~30 pound difference manual to manual rack and a ~35 lb difference borgeson power to power rack is pretty decent. Definitely shows that you don't need to go full conversion to drop some weight.
They're all MII based designs, and the Pinto is where that came from. Yes, I admit was being a little dramatic, I realize no one is going out and pulling Pinto parts out the junkyard. But, if your argument against them being called Pinto suspensions is geometry and construction based, I could get snitty about people calling the suspension on my Duster "duster suspension". At the moment the only stock parts on my Dusters suspension are the spindles and modified LCA's. And the modified LCA's are being replaced with tubular pieces. So, the geometry is different, the materials are different, by your logic it's not Duster suspension anymore. Heck, same for my Challenger. It even has Hotchkis UCA's that relocate the forward UCA mount, so, not even the same suspension points on that car.
Point being, you can change just as much geometry and keep the torsion bars.
The Hotchkis Challenger pulled .93g's on the skidpad with torsion bars and leaf springs, and you don't even need all the Hotchkis parts to manage that. But skidpad g's are heavily tied to tire compound. Still, that car is pretty easy to replicate from a suspension standpoint, and you don't have to spend a ton to do it.
All really good points. Seems like most of them are tied to the leaf spring rear, and really those are all known disadvantages of the leaf spring rear. It's a pretty simple, not super adjustable design. That can still get to .93 g's on the skidpad in an E-body. But yeah if I changed anything to coilovers on my cars it would be the rear suspension, just a lot more adjustment to be had.
As for the front, I think the torsion bar based suspension is just as adjustable as the coilovers. With a set of adjustable UCA's and strut rods, and throwing in the changes with ride height you can do pretty much anything you want for geometry. Yes, some of it is tied to ride height changes, so you do have to play with that. But with the adjustable shocks and multiple torsion bar options out there I don't think tuning is really much of a limiting factor anymore.
And header clearance and the steering rack are pretty much the biggest pro's of going coilover. You can obviously work around both, but those are two things you just won't have with a torsion bar set up.
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roylerumble
Well-Known Member
finishing up installing the altekation and street lynx in my 69 valiant. The install went great, great fitting parts, easy to follow instructions, and if you follow Bills suggestions for parts everything fit without a fight. I can't believe how much room there is to work compared to my dart. Bill and his family were great to speak to when I did have questions. I can't wait to fire it up and get some miles on it.
67autocross
A new iron curtain drawn across the 49th parallel
Post some pictures! You will love this set up once you get it on the road.
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