Hooking up a 408 stroker

[pdw5000]

I just completed the install of my new 408 storker. As expected I am having extreme problems with hooking it up. My current setup on my 68 Mustang Coupe is the following:

1. 9", 3:50 gears with open differential (soon to be a Detroit Locker, 4:11)
2. Rancho 9000 series, 9-way adjustable rear shocks
3. 4 1/2 leaf springs from Mustang Plus
4. CalTrac bars
5. Comp Engineering 3-way adjustable front shocks
6. 620 front springs (1" drop) from Mustang Plus
7. 1" font sway bar (unhooked when drag racing)
8. Subframe connectors
9. 6 point cage
10. MT ET Street Radials on rear (275/65/15) running 20 psi
11. 3500 rpm stall

I orginally bought the suspension kit from Mustang Plus when I thought I was going to be running a mild 302. Since them I went with the torque monster 408 that is shreading the tires.

I am thinking about removing the second leaf (second biggest one)from the rear to help loosen it up. I also thought cutting the bands that tie the leafs together behind the rear axle would help the spings separate which would reduce the spring rate. As of now if you jump on the rear it may move an inch or two.

Finally I have some 6 cyclinder front springs that I am going to cut one coil off of to give it the stance I want. This should help transfer the weight. I

Any opinions of my setup...I need help!?? What can I do to improve the setup without spending tons of money (not a 4-link)? How do I "tune" the suspension? Anything would help...it's my first time with this type of setup.

I appreciate all of your help. I am always impressed with the knowledge people have on here. We can all learn a lot from one another.

 

[brianj5600]

I think letting out some air will do wonders. I run 14psi in my 275/50 M/T drag radials. It may be very hard to get them to dead hook on an unpreppared street.

I would not remove a leaf.

Try the 6 cylinder springs before you cut them. Mine put the car very low with the 351w installed. Are they new or 40 year old springs?

 

[pdw5000]

The springs are brand new. If I don't cut them, what kind of drop over stock springs with a 302 can I expect?

 

[blown65]

Ive been waiting to cut my 6 cyl springs, but Ill prob cut them this winter. They sit about 1 1/2" too high for my taste.

I think getting those 620's off and putting the 6 cyl springs is going to make a huge diff, it did on my car. Also, keep lowering the air pressure in the tires. I know its different tires than you, but at 15psi on my 26x8.5 slicks I can only pull a 1.57 60'. Just dropping to 12 I net a 1.51. I haven't tried any lower cause I'm worried of spinning the tire on the rim. (no screws yet)

 

[brianj5600]

My springs are of the 40 yo variety. I have 560 springs on the car now, but switching back is on my list.

 

[Hack]

You could use some Caltracs on the rear - or find plans on the internet to make your own. A lot of people get great performance with leafs and Caltracs.

Don't remove a leaf, that will make any problems with axle wrap and wheel hop even worse.

 

[dodgestang]

What are the current 1/4 times, MPH, trap speed, and what are your 60s?

 

[dennis112]

A properly built 408 will shred those tires at the track. As suggested, try a little less air or get a pair of real drag slicks mounted on a 2nd set of rims just for racing. Go with a tall slick (like a 28") to get a larger contact patch during launch.

I guess I am in the minority here, but I'd try the leafs first as they are and then later try removing one of the leafs. As Dave Zimerman (Team Z) told me, a softer suspension might help the caltracs to work as designed. He even had me running the Rancho's at 2-3 on both sides.

Originally I ran 5 leafs and they worked OK with a similar suspension as you have, but with the 6 cyl springs installed. Times with my stick car were 1.7ish. I removed a leaf and although the car was more springy on the street, I made several 1.6x passes that same week and even a 1.600 even. I ran a few more weeks like that and then put the leaf back in. My times increased again (although the heat of summer may have had something to do with that.) I've since moved to the Caltrac monoleafs and really never seen the same times as I had with the 5 leafs converted to 4--but I also have 50 more hp to contend with this year. I might have to swap to the much more expensive double adjustable rear shocks.

As for what you have, set the Caltracs on the upper hole, and give them 1/4 turn of preload on both sides with someone sitting in the driver's seat. That will plant the rear tires the hardest during launch if you get good front end rise. Try shocks at 3 and if you get spring wrap, move up to 6. Set the CE's to their lightest setting, which is suppose to be 90/10. Get someone to film your launch for you from different sides and from the rear. It is amazing what you can uncover after reviewing a launch video, especially in slow motion.

In the end, since each car is different, be prepared to try different things. There is no "one" formula that works on each and every car.

 

[brianj5600]

I think with an auto that Drag Radials will work. My car has stock 40 year old leafs with an extra main leaf added, worn out shock front and rear, 560 coils, roller perches, rod ends on the strut rods, 1.125" swaybar connected and spherical bearings in the lca's. It has been 1.58 in 60' so far and [email protected] in the 1/8. Here is a 6.94 [email protected] Video

 

[phutch11]

Maybe this is in you sig, but I can't see it on my blackberry - anyway, I haven't done it personally but a lot of guys report good success with battery relocation. All the weight you can get on the rear end will help.

Good Luck.

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[pdw5000]

As of right now I haven't taken it to the track to get any times. It isn't worth it if you go past half throttle and you just spin on the street...you know it isn't going to do that much better at the track. At 65 mph if you floor it, it just spins...kind of dangerous.

I think switching to the detroit locker instead of just spinning one wheel will obviously make a big difference. I have my Caltracs on the bottom hole so maybe I need to put it at the top as dennis112 mentioned. I am going to switch to the 6 cyclinder springs in the front before I do anything to do the rear leafs. But it does worry me that the rear suspension is that tight...should it be that tight, ideally?

Also, I forgot to metion this car is a C4 auto with no trans brake (will leave by footbraking to 3500 rpm).

 

[blown65]

As of right now I haven't taken it to the track to get any times. It isn't worth it if you go past half throttle and you just spin on the street...you know it isn't going to do that much better at the track. At 65 mph if you floor it, it just spins...kind of dangerous.

I think switching to the detroit locker instead of just spinning one wheel will obviously make a big difference. I have my Caltracs on the bottom hole so maybe I need to put it at the top as dennis112 mentioned. I am going to switch to the 6 cyclinder springs in the front before I do anything to do the rear leafs. But it does worry me that the rear suspension is that tight...should it be that tight, ideally?

Also, I forgot to metion this car is a C4 auto with no trans brake (will leave by footbraking to 3500 rpm).

Usually the strip is much much stickier than the street. You'd be surprised how much traction you gain there. (depending on prep of your local track of course)

As for the rear suspension, mine is pretty stiff even with the monoleafs since I run the shocks on 7 in the rear. Way Way stiffer than the stock 4 leafs that were in it prior. (they were real old and worn out) Also, when they set up my caltracs locally they put 50 thousands gap between on the rear bar adjustment, that makes them hit the tires harder, not sure though with drag radials if thats a great idea since they aren't the same thing. Your just going to have to play with it.

 

[66Runt]

Until you get rid of the peg leg, I wouldn't get excited about even trying to hook up. That's way too much torque for one tire to handle without getting some major weight transfer, which certainly won't happen on the street.
Street and track are very different.
(IMO) get the locker in, lower the psi for the track, disconnect your sway bar on one side, then make 3 or so runs at the track (the street is a total waste of your time). Then start making adjustments, one thing at a time with at least a few runs in between changes (unless you find that what you did is totally out of the ball park).
Also this is a perfect time to start a note book. Go to a drag racing forum, and you can see what information you want to start recording. It's pretty easy, and really helps drop your times quickly, while remaining consistent. Plus it's a kick in the pants to look back at 10 years from now.
Good luck, and more importantly... Have Fun! Safe and slow on the street, Safe and fast at the track!

 

[jcode68]

I agree, replacing the peg leg will make the biggest difference first and foremost. I went from open diff to traction loc and was a huge night and day difference in traction on street tires with my 347. Previously would shred the tire with just a touch of the throttle. Now is much better.
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[dodgestang]

Take it to the strip regardless of pegleg and your belief that it won't hook.

Get a baseline so that you can measure your performance improvements.

 

[418mach]

i agree with the others you wont hook up with drive to one wheel and for street and strip i recommend the detroit locker and look to upgrading other parts slip yoke, tailshaft, rear yoke, case and axles beacuse when it does hook the fun begins. mines a manual street car with mark williams slip yoke, chrome moly shaft 1350 yoke, nodular case, detroit locker 4.11 and 31spline axles and spins 1st and 2nd at the track but thats ok cause nothing has broke.

 

[blown65]

Ya, you def want to get that peg leg sorted out. Beginning of the yr I was pulling 2.0 60' because of that and my suspension consisted of 620's, reg front shocks, Lakewood cheap traction bars, and old old worn out rear springs.

Last night got a personal best in Redding with a 1.49 60'. 26x8.5" tires also. Here is a good vid to show ya off the line how mine is working now.

Redding Drag Strip 10/4/2008- Video