Make it handle

[k5warwagon]

I am new to the site. I love it. It gives us truck guys the resource we need that Pro-Touring.com doesn't.
I do have a question for this thread. I have a '87 c10 short bed stepside. It was a prostreet project for someone else and I got a good deal on it. The PO removed the narrowed 9" rear and 4-link setup so I have nothing in the rear except the (removed) original leafs and shackels. I want to convert to trailing arms with jack bolts. Am I wasting my time looking to swap from a 67-72 and modifying it or should I just save my money and buy a kit from you or HotRods to Hell? I will be going the kit route on the front but money saved now helps.
Thanks,

[NPilot1975]

K5warwagon, I haven't done the mod, but I know you can use 67-72 parts to change your truck to trailing arms. If you are on a budget I would suggest getting a crossmember from Porterbuilt, cpp, ride tech, or early classiscs and use the factory arms. If you have the money you can buy a kit from any of the above that has all the parts.
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[robnolimit]

K5 this is an easy enough swap. I'd use the stock stuff, you'r in nascar country so I'd guess there is plenty avail. Check with Speedway or Motorstate on the spring jacks. - But remember, your frame is not the same as a 67-72, so there will be some mods needed to get the springs where you want them. You may want to consider coil-overs, it could be easier, and cost about the same.

[k5warwagon]

Originally Posted by robnolimit

K5 this is an easy enough swap. I'd use the stock stuff, you'r in nascar country so I'd guess there is plenty avail. Check with Speedway or Motorstate on the spring jacks. - But remember, your frame is not the same as a 67-72, so there will be some mods needed to get the springs where you want them. You may want to consider coil-overs, it could be easier, and cost about the same.

Thanks Rob. Working on a package deal off of a parts truck right now.

[Jonboy]

This may sound out of place, but what will cutting the rear of the springs do to payload capacity? There are 8 or 9 leaves in the rear spring, so cutting a couple shouldn't kill it too much. Scot and I had discussed the rear sway bar; I think he may have forgot to list it. Speaking of, what would be the best way to mount it given the amount of drop (6/8)?

[leftcoast66]

Hey Rob,
Any advice on roll centers? Not sure if my post got missed, I know you're busy. I'm figuring mine out on front suspension geometry pro and it seems off.

Brendan

[NPilot1975]

Rob, I noticed that the trailing arms that you build are straight without the kickup at the end. Is there any disadvantage to this? I assume the kickup is to put that portion level to the ground, but just wondered??? Also, if you used straight trailing arms would there be any advantage to mounting them on top of the axle tubes on a lowered truck? Would this work the geometry at all as far as relation to the front mounts? or would it just completely mess it up. Thanx again.

[robnolimit]

Originally Posted by NPilot1975

Rob, I noticed that the trailing arms that you build are straight without the kickup at the end. Is there any disadvantage to this? I assume the kickup is to put that portion level to the ground, but just wondered??? Also, if you used straight trailing arms would there be any advantage to mounting them on top of the axle tubes on a lowered truck? Would this work the geometry at all as far as relation to the front mounts? or would it just completely mess it up. Thanx again.

We have good luck with straight arms. But you have to set the pinion angle/axle saddles to match with them. (pretty normal) I don't see any gain of top mounting, and a possible loss of clearance. The geometric 'push' is a relation from the tire contact patch, the axle center line, and the front pivit point of the arm. To change the relationship, you can change tire size, make the arms shorter or longer, or move the front pivit point.

[NPilot1975]

Perfect, I am going to build some straight arms and saddles (under mount). Do you think 2.5"x2.5" 1/4" wall tubing would be fine?
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[robnolimit]

Originally Posted by NPilot1975

Perfect, I am going to build some straight arms and saddles (under mount). Do you think 2.5"x2.5" 1/4" wall tubing would be fine?
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I use three pieces, in a step. 2 1/2" tube, 2 1/4" tube, and 2" tube, all with 1/8" wall. This is plenty strong enough. 1/4" wall is a bit heavy. don't forget to try to get the unsprung wieght down.

[NPilot1975]

Rob, how much overlap for each step or does the 2" run all the way from end to end with the additional tubing added? Thanx again, easier to do it right from the start.
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[robnolimit]

Originally Posted by NPilot1975

Rob, how much overlap for each step or does the 2" run all the way from end to end with the additional tubing added? Thanx again, easier to do it right from the start.
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about 3", we drill a 1/2" hole in all sides, 2" back from the end of the larger tube of the overlap to plug weld as well as the end seam. If you need some parts I have inserts for the 2x2 tube with a 1 1/4" thread inside, 18.00 ea. ! 1/4" male thread monster ball pivit knuckles, 39.50 ea. and 3/16" formed steel mounts with hardware (for the monster balls) are 16.00 ea. 147 for all parts needed for the front mount/adjuster assy.

[robnolimit]

Last night we track tested again with the flexi-bar panhard rod. changes are made slowly, one at a time to see any change, and again, most of the changes are driver error. First, we started with the same set up we left off with. The big thing I notice is that in the tight banked 220* turn, the rear is really hooked up, so I'm going a bit faster than normal, then, the flexi-bar hits it's limit (I guess), and the tire slips, the chassis unloads, and the truck 'bucks' to the side a bit, and this repeats through the corner. First change was to tighten up the bushings in the flexi-bar. - better. Next, run 2 psi higher in the left side tires (32ft, 22 rr) - running clockwise. - better. Tighten the bar more - better, Then we added more rebound compression in the rear shocks, - worse. Last, rebound back to the previous setting, added 5 clicks of low speed compression to the rear, - better. On the track, this is al done by feel. We don't get times until we leave the pit area and go the the clubhouse. We got 9 timed laps (3 lost to timing equip error) Our fast lap was 48.45 - pretty fast. average was 49.06 - .58 faster than last week. and the high/low was 1.19 - pretty good for all the changes. My thoughts on the flexi-bar idea? well, the jury's still out. It is helping, but the truck is more challenging to drive. I may need to tighten it a bit more, or try some more shock tuning. But, we are going faster, so, we'll see what's capable from this set-up. More to come, I'm sure.

[CSGAS]

Originally Posted by robnolimit

Last night we track tested again with the flexi-bar panhard rod. changes are made slowly, one at a time to see any change, and again, most of the changes are driver error. First, we started with the same set up we left off with. The big thing I notice is that in the tight banked 220* turn, the rear is really hooked up, so I'm going a bit faster than normal, then, the flexi-bar hits it's limit (I guess), and the tire slips, the chassis unloads, and the truck 'bucks' to the side a bit, and this repeats through the corner. First change was to tighten up the bushings in the flexi-bar. - better. Next, run 2 psi higher in the left side tires (32ft, 22 rr) - running clockwise. - better. Tighten the bar more - better, Then we added more rebound compression in the rear shocks, - worse. Last, rebound back to the previous setting, added 5 clicks of low speed compression to the rear, - better. On the track, this is al done by feel. We don't get times until we leave the pit area and go the the clubhouse. We got 9 timed laps (3 lost to timing equip error) Our fast lap was 48.45 - pretty fast. average was 49.06 - .58 faster than last week. and the high/low was 1.19 - pretty good for all the changes. My thoughts on the flexi-bar idea? well, the jury's still out. It is helping, but the truck is more challenging to drive. I may need to tighten it a bit more, or try some more shock tuning. But, we are going faster, so, we'll see what's capable from this set-up. More to come, I'm sure.

Do you have any way of changing the angle of the flexi-bar while keeping the centers? (or even changing the centers if they aren't in sync with the front ones)

I know the NASCAR guys swapped the mount points long ago left-to-right but that mainly showed an advantage on left-hand oval tracks. Your right-hand sweeper should respond more to a bar angle that plants the tire that's slipping better...any idea on the tire temps across the rears?

My next "seat-of-the-pants" adjustment would want to be raising the left frame anchor point and lower the right axle mount an appropriate amount so the roll center of the flexi-bar remains the same and see the results. This may not jibe with simulations, wish I had Mitchell software to double check my pants with.

I wish I also had more experience to talk from--mainly a hobbyist and learned a lot from other people as well as attending a Mech. Engineering program now. Still I tend to pick a lot of the best people to learn from--you are on that list, now, Rob!

[Jonboy]

Rob, any more ideas on leaf spring tech? Where would the rear leaves need to be cut? I would like to keep a little payload capacity- it is a truck- or would I be money ahead to do a trailing arm rear setup? I do not want to go to air.

[leftcoast66]

That sounds like some great progress. Thanks again for all of the help as well as posting up your methods of testing. Its great to know while I build my truck, I'm sure there will be a lot of testing.

[RANDOMIZM]

http://www.facebook.com/media/set/?s...3277577&type=1

Some cool pics of the No Limit trucks. (and other vehicles)

Hey Rob, that El Camino looks pretty sick. You know anything about it?

[robnolimit]

Originally Posted by RANDOMIZM

http://www.facebook.com/media/set/?s...3277577&type=1

Some cool pics of the No Limit trucks. (and other vehicles)

Hey Rob, that El Camino looks pretty sick. You know anything about it?

The 'Elco is James Crosby of Creative Suspension. His is a long time friend of mine, from Ontatio, ca. He is currently working with Ride Tech doing R&D and some car building. Their new 'True=Turn' steering update is his baby. - He is also the designer of the Shockwave, as well as some of the air ride bikes seen on TV. If you ever get a chance to meet him, ask him 'what the fastest Hot Wheels car is'? (Trash truck or Dump truck is the answer - long story) lol.

[NPilot1975]

Rob,

I will take you up on the offer, that should set me up perfect. I should be able to purchase the above in a couple weeks.

I had planned on 20" rims on the front and 22" rims on the rear, now looking at 18's again. LOL

Thanx again,
Jamison

[stealthy '69]

Glad to see the times slowly getting lower and lower. It just shows all your hard work paying off. Do you happen to have any pics of the exhaust routing through the crossmembers and frame?

[robnolimit]

Originally Posted by stealthy '69

Glad to see the times slowly getting lower and lower. It just shows all your hard work paying off. Do you happen to have any pics of the exhaust routing through the crossmembers and frame?

I'll see what I can do.

[NPilot1975]

Rob, you definitely stand out in that crowd with 2 show worthy trucks next to all the beater looking imports.
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[ItsRandy]

Hey Rob, any chance the rear sway bar for 67 - 72 Chevy truck is available yet? I sure would like one like the one you have on your shop truck.

[robnolimit]

Originally Posted by ItsRandy

Hey Rob, any chance the rear sway bar for 67 - 72 Chevy truck is available yet? I sure would like one like the one you have on your shop truck.

They are finally in production. We have about a 2 week wait for the first batch to be heat treated, and powder coated. I'll post up picts and specs next week. Thanks for the interest.

[robnolimit]

Glad to hear this is helping. Keep Building, It gets a lot more fun when you can drive 'em.