Will Trailing arms work with 700HP ?? Calling all DRAG GUYS!

[smoknbarrels]

I have decided to go bigger then originally thought, I am going to put a 8-71 blower on my '67 lwb 454. but I have never run this project yet and am am trying to decide if the trailing arms will still work good or if i need to go to an expensive 4 link.
I already found mickey street radials that are 17" wide and will fit if I cut the rear end narrow, so I think I have enough meat...but if I simply put coil-over shocks on the trailing arms... will this be good enough to hook up??

any experience would be great!

thanks.

[71Dragtruck]

Yes they will work, you'll still need a slick for drag racing to hook up. Even with 17" wide street tires, if your running 700hp it will roast them. Also plan on doing something with your rear end, tranny and driveshaft if they are stock.

[smoknbarrels]

I am using a Tremec TKO 600 5 speed tranny... drive shaft will be aluminum. you don't think the rear will hold at all? hmm, I have two new stock posi rears for it, perhaps I can sell them and get one bigger one.. is a ford 9" really that much better? anything else I should consider looking at?

[71Dragtruck]

Bad thing with the truck 12 is that 30 spline axels is as big as you can go, nobody makes a carrier for larger axels. With the 9" you can go 35 spline and a locker that's good for 1000hp, even 40 spline and a spool, plus there's aftermarket parts for them coming out the arse. I right now have a 12 with Moser axels, Richmond gears, Eaton posi, LPW brace, Moser retainers, and I'm scared it won't last, going to a Moser 9" next spring. Other than that if you plan on running NHRA don't forget all the safety stuff.

http://members.tripod.com/MY5LTR/NHRArules.html

[smoknbarrels]

I also have a new 9.5" chevy locker that they used in 84-06 3/4tons 14bolt rears. I don't know much about c-lockers, would it be any good use to me? I bought it on ebay for a $60 steal, so i figured i can't go wrong. but all i have is the carrier, those rears must be tough i imagine?
so spline # = toughness? not carrier size?

My weak area is differentials, I'll have to do more research.

[71Dragtruck]

It's both, spools are the strongest, the spider gears are the weak part. A 9" Detroit locker is stronger than a Eaton posi unit. The carrier you bought won't fit your rear end. Weak axles will twist and break, weak spider gears will break also. According to Moser the weak part of my rear end is the posi unit, then the axels. I drive a bit on the street and don't want to run a spool, so that's the main reason for me going to a 9. It also helps to weld the axle tubes on a 12 to keep the center section from spinning upward, mine is done, so the only other thing I could do to make mine stronger is spool it.

It's all a matter of what you intend on doing with the truck, mainly race or just once in a while. What RPM do you plan on dropping the clutch at, and how sticky a tire you going to run, also 700 dyno horses or what it suppose to make? Alot of people plan out a high horse power motor based on cam specs and what they read in a magazine only to be really dissapointed on dyno day. I'd wager to bet that 80% of guy's motors don't make as much power as they think maybe even more. Also how fresh is your rear end, a original 150,000 mile rear is not going to be a good as a fresh one.

[bigjimzlll]

Doubt you will hurt the rear end...you have to hook up to do damage. Trailing arms will be fine. The Tremek however???? Good luck and have some fun. If you run the 12 bolt...at the very least upgrade to 30 spline axels with C clip eliminators. Weld the tubes to the housing(ask me what happens if you don't)

[jhow66]

Here is a axle out of a Ford 9" that was behind a chevy sb. Got Mosers now.
(came out of this)

[RSRXION]

Trailing arms work every weekend on Nascar tracks around the country. Usually there is a great deal more than 700 horsepower in use. I'm confident that they'll be fine but if I were you I'd consider some kind of a pull bar ( or torque arm ) with a 90/10 shock to help control rear end wind up. JMHO, Dean

[roughedup72]

Jhow66, Thats one beutifull 56.

[smoknbarrels]

I figure it should be about 700 dynoed HP, if I run dual 750's with even an under driven 8-71 on my ported heads, I don't think I'm asking too much of the motor.. yea, all of my posi units are brand new. the 9.5 carrier of course would need a different rear, but i have no idea what kinda axels they slip in..
well i guess i'll keep the trailing arms in, but now i'm concered about my rear
I plan to mainly drive the truck on the street and only sometimes take it to the track. mind you it won't be a daily driver either.
I was planning on using the stock rear, since I have 2 complete units, but if it is gonna snap each one quick.. i think i should find something else.

so what do you reccommend? a ford 9" with aftermarket everything?
I wonder if i can get that 3/4 ton 14 bolt rear with 4 3/4 5 bolt pattern studs? I would like to try out that c-clip locker! it looks tough!

[smoknbarrels]

Originally Posted by RSRXION

Trailing arms work every weekend on Nascar tracks around the country. Usually there is a great deal more than 700 horsepower in use. I'm confident that they'll be fine but if I were you I'd consider some kind of a pull bar ( or torque arm ) with a 90/10 shock to help control rear end wind up. JMHO, Dean

whats a torque arm and what do these shock numbers mean?? my rear end knowledge is about as good as my suspension knowledge..!

I'm going to lower the truck about 5", and want to put in coil over shocks in the back but haven't found what kind to use yet either.
what should I be getting?

[71Dragtruck]

For what you are going to use the truck for, I'd just go with the 12, weld the axle tubes and go with some Moser 30 spline with c-clip eliminators. A 90/10 is a drag shock the #'s are the compression and rebound rate. A 90/10 is a front shock that extends really fast to let the front end rise for weight transfer and then compresses slowly to hold it there longer and let it down slower. Not for street use, will cause poor handling. Go with a adjustable rear coil over QA1 makes some nice kit's a bit $$ but that's to be expected with a aluminum adjustable coil over.

[nxtruck]

If you're not opposed to running a spool, then Moser does offer a 33 spline spool for the truck 12-bolts. I would not be opposed to running a spool on the street, as I have been doing so for about 6 years now without any trouble. I'm running 30 spline Moser axles, spool, LPW cover, and 4.88s in my '66 and have street-driven it quite a bit.
As the guys have already said, the trailing arm setup will work fine with the right springs and shocks.
Good luck with it...

[smoknbarrels]

so what kind of shocks should I get for the front? just look for ones that have a different rebound rate.?it would be nice to have some weight transfer, and also a little driveability. hopefully i'm not asking for to much?
I don't think i'll go with a spool, i imagine it might be a little hard to turn with a long box. and i will need to take it on the highway a bit.
the tremec tranny is a 5 speed std, supposed to be guranteed for 600lbs of torque. anyone know of anyothers that have a nice overdrive, which may hold up?

thanks for all this advice so far guys, it really helps me out a lot. i will most definately be using it to get the ponnies to the ground better. have any other recommendations or little tricks for suspension or launch?, other then coil-overs and a 5" drop, my suspension is all stock.

[RSRXION]

About the "torque arm"... It's also referred to as a lift arm , a fifth arm , a spring arm etc... depending on what part of the country you live in and your peers. The function of this arm is pretty simple in that it works very much like a traction bar except that it is MUCH longer and there is only one as opposed to a pair of traction bars. The torque arm uses a bracket welded on to the rear end housing and the arm bolts to this bracket at the rear housing. On the other end is a coil spring ( you choose the rate according to your desired compression, a 150 to 200 works well ) which is attached to the tip of the torque arm at the bottom and to the chassis on the top. Typically the torque arm is about 4 feet long but can be a little longer or shorter as your application warrants. Most people use a coil over eliminator for this mounting since they are so inexpensive.

Under heavy throttle and rear end wind up the torque arm actually lifts up on this spring and tries to pick up the front of the vehicle by compressing the coil spring. Obviously this greatly improves traction and forward bite.

With respect to the question of a 90/10 shock.... the fellow member is correct that you should not run these on the front. To say that your truck would be ill handling would be an understatement. BUT , if you mount that 90/10 shock as intended on the rear end you'll love it. The shock should be mounted in a near horizontal position via a pair of welded brackets. It should mount on top of the rear end at the pinion center and the other end should be bolted to a bracket welded to the chassis. When the vehicle launches against the 10 side of the stroke , the shock will compress easily and allow the torque arm to work by compressing the coil spring. Then when you get out of the throttle and the rear end tries to unwind against the 90 side of the stroke, the shock will control a violent reaction by reducing the unwind rate. Without this shock in place , you'll see a very violent reaction as the coil springs on the rear end and the coil spring on the torque arm unload.

Cozy up to a local dirt track racer with a modified or late model. You can probably purchase one of these setups complete for a couple hundred dollars or less. Used they should sell for about half that. Take a look at their cars and you'll quickly understand how they work and why you'll enjoy it.

Don't forget to tune your rear shocks while you're at it. The engine and trans makes the horsepower and torque, but you can only use what you can plant to the ground. Take the time to learn the intricacies of hooking it up, unless you like really long smoky burnouts.

JMH&WEO , Dean

[smoknbarrels]

RSRXION, i've read that last post about 6 times to try wrap my head around it, it sounds really interesting, i even tried to google it a bit. i am just trying to get the principal straight: so the 90/10 would be a third rear shock but mounted horizontal? does the torque arm go centered as possible under the truck?. I'm going to look that up more, see if i can get a visual.

[RSRXION]

You're right all around. The torque arm typically mounts to the right side of the pinion and near the center of the rear end. The 90/10 lays horizontally and mounts in a linear fashion, front to rear. I'll get you a couple of photos and post them. Dean

[RSRXION]

This ebay item number is the spring and coil over eliminator assembly. The same guy also has a 90-10 shock in used condition. Ebay item number 290012528216 . Look at the pics he posted and you'll get a better understanding. I've also attached a couple other photos. Dean

[57sailplane]

why would he add a torque arm when he has 2 of them already? the drag arms are 4 foot long 4 inch i beams which are bolted to a 5 inch pirches that are welded to the rear axle. one of these arms is near as strong as the one that is shown and he has 2 of them... don't spend the extra money.. if anything you should put in an adjustable panhard bar..

[RSRXION]

Because those trailing arms allow the rear end to wind up. Think about it for a second... have you ever seen a 67-72 Chevy pickup wheel hop under full throttle ? It most assuredly will in stock trim if you've got enough ponies under the hood to blow the tires off. The torque arm DOES NOT PIVOT. It's in a fixed position both front and rear. It may travel up and down but it is intended to prevent rear axle wind up which is EXACTLY what causes wheel hop and loss of traction.

While the trailing arms are in a fixed position at the spring perch, it pivots at the chassis mounting point. As the coil springs flex and the rear end winds up and tries to pick up on the chassis, the front mounts pivot and actually cause the chassis to lift AT THE BACK. Simply put, when your ass gets lifted it's never a good thing.

Trust me on this one guys. I've been around race cars all of my life. The torque arm will certainly assist in forward bite while having no negative effect on driveability. The torque arm works on the same principle as a set of traction bars. It justs uses a chassis point a little farther ahead. That's a good thing.

You'll still need to use your panard ( or panhard ) bar to control lateral movement of the rear end unless you're on leaf springs.

Hope this helps, Dean

[57sailplane]

huh,

you better tell that to this guy.


i emailed the original owner about this truck he told me what he had in it..


the new owner is shooting for the low 9's



heres a pictrure of his rear, huh no tork bar!

[RSRXION]

You're right, no torque arm... just a torsion bar and a pair of what appear to beadjustable length rods to help pre load the rear. Windup is controlled via the assembly. I don't want to argue with you and I certainly don't want to lead anyone astray.

Here's the deal, there is more than one way to skin a cat. My setup is cheaper and easier to install than the set-up you present. Does it really make a difference as long as the truck gets from point A to point B as quickly as possible without damage to man or machine ?

[nxtruck]

Dean, I'm not trying to start an arguement here, but I have to say that I don't quite agree with your theory on trying to add a torque arm to one of these trucks. Not that there's anything wrong with a torque arm suspension, however, as I feel that this is probably the best factory-style suspension out there. I've been around the drag radial scene for a while, and also have a friend that runs a super stock Camaro, and as such, have spent a lot of the time that I go to the track with him looking underneath the stockers that are there. The torque arm setup obviously works very well on these cars.
OK, now that I made somewhat of an arguement in favor of the torque arm, let me add this. I've owned my '66 long wide bed for 21 years, and have spent at least 15 of those racing it. It has progressed from a high 8-second 1/8 mi. ride ( when it was my only vehicle ) to running mid-6s in the 1/8. All the while using the factory trailing arms, a set of Comp. Eng. 90/10 shocks for an early Camaro adapted to the front, the original factory shocks in the rear along with a set of custom made trick springs in the front and a set of used '70 Monte Carlo springs in the rear. The idea behind these springs was two-fold: 1. to lower the rear about 5 or so inches to match the front, and, 2. more importantly, to allow for some rear body separation to aid in planting the rear tires.
With the suspension that I just described, my truck has went as quick as 1.55 in the 60', pulling the left front wheel about 10 "s, and ran a 7.13 @ 96 in the 1/8. I can tell you that I don't have any more than $200.00 in these parts that I just listed, and the only thing that required any fabrication whatsoever was making a couple of brackets to attach the tops of the front shocks to the original holes in the frame.
I guess it all boils down to this: it is my opinion that smokin could use what he already has, change the springs and shocks ( he'll be doing that anyways, since he wants to lower it ), put a sticky tire on it ,and go from there. Like I said earlier, though, that's just my opinion, and I respect your opinion as well.

[RSRXION]

Sounds like you've accomplished the cat skinning in a different manner and the truck is obviously quick enough as you've built it. How do the front shocks effect streetability ? I recall about 30 years ago we would commonly look for 6 cylinder springs to install in whatever we were racing to allow the front end to come up quickly on hard launch. We also looked for worn out shocks for the same reason. The one thing I always hated was the hard nose dive on braking and the incessant bouncing.

With that in mind let me ask you this ? Are you making anywhere near 700 horsepower ? I don't think you can plant that much power and torque on the suspension you just described. That's why the super stockers etc... use more elaborate systems.

Thanks for being open minded and I promise I will as well.

JMHO, Dean