Chassis Help: Solved for now!

Posted By: Quicktree

Re: Chassis Help - 06/09/13 01:37 PM

first thing i would do is limit the wheelie, do you really need it to plant the tires?

Posted By: Adrielp

Re: Chassis Help - 06/09/13 03:21 PM

Quote:

When you say "getting loose" are you referring to steering or rear tires unloading?

A good set of front double adjustable shocks set tight on the compression side helps settle the car.

Number 1 thing is to check the toe curve.. you are
probably going toe out... that can cause the car to
dart to the side pretty easy

I can testify to that after getting the bumpsteer fixed on mine, the problem went away.

Its seems to do a little of both honestly. When watching the car from the rear, it lands and wants to move around. The bigger the wheelstand, the more it wants to move around after landing.
As far as the toe, we haven't looked at it in a while but it was set to have a slight toe in although I'm not sure how much the stagger was that we set.

I know there are a lot of ways to skin a cat to fix this situation, just trying to decide on the most efficient approach(cost, benefit, and functionality). Our thoughts right now are, stiffer rear springs, upgrading the front shocks(their ancient), lowering the rear to lower CG, and possibly some taller tires.

I forgot to mention we put a dent in our pan last night. When I say this car was wanting to get after it, it really wanted to get after it. We started out running a 60ft: 1.41 6.44 @ 107 w/manageable wheelstand, made the ladder bar more aggressive 1/4 turns both sides, 60ft: 1.38 6.38 @ 107.86 w/another manageable wheelstand. Went more aggressive, 60ft: 1.36 (getting out of it)w/wheelstand was too high and unsettled to car upon landing. Left it alone but wend up two clicks on the shock to account for the wheelstand, ran again and low a behold the thing went even higher hitting the pan this time and my dad was out of throttle even earlier. Whats amazing is the weather really didn't change much from the first to last runs. 2100ft Density altitude to 1700ft Density altitude on the last past. Only 7 degree change in temperature although the track temperature changed quite a bit. Regardless, we really need to car to react better coming off those wheelstands. Super Stock cars have no issues, we don't want any either.

Posted By: MR_P_BODY

Re: Chassis Help - 06/09/13 03:45 PM

Old junk front shocks arent helping your cause...
start lifting the front weight sooner to help reduce
the wheel stand... if you allow the motion then you
allow it to have momentum... you dont want the vertical
momentum ... so if you can start picking up the weight
sooner(with the shocks being tight) it should help..
if need be strap the front end(limiters)... also on
the rears.. as you seen if you tighten the rear shocks
on a good track it only goes higher... loosen the
rears and allow the rear of the car to lift more to
get the rear up so the CG has to go higher.. then
the front has to go higher to get over the CG...
just dont let the rear shocks top out... put your
ladder bars in the lowest front hole... you may need
to ad more holes down lower(if the cross bar is set
in too high you might not have enough holes)

Posted By: SSDAcuda

Re: Chassis Help - 06/09/13 04:32 PM

Good advice from Mr P!

Limiting the front end travel will also help with the bump steer issue.

Posted By: oldtimer5151

Re: Chassis Help - 06/09/13 04:54 PM

Go to the parts house and buy rubber cone shaped bumpers and put them on the lower control arms. You may have to trim them a little. This will help cushion the frame when it comes down and help the torsion bars control the quick coming down.

Posted By: Thumperdart

Re: Chassis Help - 06/09/13 05:03 PM

I want you problem instead of blowing the tires off............

Posted By: oldtimer5151

Re: Chassis Help - 06/09/13 05:05 PM

Again put 100# in trunk.

Posted By: Thumperdart

Re: Chassis Help - 06/09/13 05:06 PM

I hear ya and will be putting the 2nd batt back then w/new SLICKS try it and see what happens...........

Posted By: loaderpro

Re: Chassis Help - 06/10/13 05:21 AM

You do have a bump steer issue if the car is steering itself on landing, and this MUST be corrected. Another thing to check and make sure the driver is not turning the wheel while in the air, this happens allot more than one would think...just look at some of the cars in these posts. Then a good double adjustable front shock set stiffer on compression and adjust the ext as needed to keep it from bouncing the front tires.

Attached picture 7737192-pomona.jpg

Posted By: gregsdart

Re: Chassis Help - 06/10/13 02:45 PM

two things in addition to what Mike says stand out in my mind. Front shock control for landing, which requires double adjustable shocks if the wheelstands are getting up there. The other is when you limit front travel, make it a "soft" stop like a rubber bumper. If you don't it sends a shockwave through the chassis unloading the rear tires. Kinda like when the other kid slid off the teater totter

Posted By: Adrielp

Re: Chassis Help - 06/10/13 08:58 PM

We've decided to do a few things to help control the car better. We plan to check the bump steer, remove some the suspension travel, and lower the car in the rear for little lower CG. We plan to invest in some shocks later this year. Still don't know if we will get Double or Single Adjustable just yet, we would like to upgrade the rocker arms as well and getting both will nip at the budget a lil bit. Regardless, these few things should help the car quite a bit.

Looks like wheelie bars maybe in our future too as a precautionary measure to prevent excessive wheel stands from happening keep the oil pan off the track.

Posted By: MR_P_BODY

Re: Chassis Help - 06/10/13 09:14 PM

Quote:

We've decided to do a few things to help control the car better. We plan to check the bump steer, remove some the suspension travel, and lower the car in the rear for little lower CG. We plan to invest in some shocks later this year. Still don't know if we will get Double or Single Adjustable just yet, we would like to upgrade the rocker arms as well and getting both will nip at the budget a lil bit. Regardless, these few things should help the car quite a bit.

Looks like wheelie bars maybe in our future too as a precautionary measure to prevent excessive wheel stands from happening keep the oil pan off the track.

If you lower the rear of the car your problems will
get worse till you can control the front lift(limiters)
or better shocks... with the back lower it will be
easier to get the weight up over the CG

Posted By: Cab_Burge

Re: Chassis Help - 06/10/13 09:16 PM

Quote:

We've decided to do a few things to help control the car better. We plan to check the bump steer, remove some the suspension travel, and lower the car in the rear for little lower CG. We plan to invest in some shocks later this year. Still don't know if we will get Double or Single Adjustable just yet, we would like to upgrade the rocker arms as well and getting both will nip at the budget a lil bit. Regardless, these few things should help the car quite a bit.

Looks like wheelie bars maybe in our future too as a precautionary measure to prevent excessive wheel stands from happening keep the oil pan off the track. [/quote ]Wheelie bars are usually bandaid, fix the problem

Posted By: gregsdart

Re: Chassis Help - 06/11/13 03:47 AM

If you are a bracket racer, and run a three speed, your one/two shift is probably close to if not during the landing from a larger wheelstand. This not only affects the way the car tracks (moves around,etc) but the shift timing is affected because you are also busy worrying about the direction the car is going to go when it hits, etc. So taming the wheelstand, eliminating deflection in the front suspension to make it track straight, will go a long way to making you more consistent. A properly prepped front suspension,wheelievbars, and possibly double adjustable shocks will be a big asset.

Posted By: Adrielp

Re: Chassis Help - 06/11/13 03:49 AM

Quote:

Quote:

We've decided to do a few things to help control the car better. We plan to check the bump steer, remove some the suspension travel, and lower the car in the rear for little lower CG. We plan to invest in some shocks later this year. Still don't know if we will get Double or Single Adjustable just yet, we would like to upgrade the rocker arms as well and getting both will nip at the budget a lil bit. Regardless, these few things should help the car quite a bit.

Looks like wheelie bars maybe in our future too as a precautionary measure to prevent excessive wheel stands from happening keep the oil pan off the track.

If you lower the rear of the car your problems will
get worse till you can control the front lift(limiters)
or better shocks... with the back lower it will be
easier to get the weight up over the CG

Thanks for the help! I think I realized that it would be more weight transfer but I guess I had a brain fart moment.

Posted By: Leon441

Re: Chassis Help - 06/12/13 12:55 AM

I can understand and appreciate budget. The cheapest thing I can recommend is what has already been recommended. Only problem is the guys spending someone else's money are too busy chiming in with the more expensive fixes.

But, some traction bar snubbers or suspension bushings. Take the stock bump off the lower control arm. On the snubber you can install fender washers(very large OD washers) to space the snubber up as much as possible. This will not control the wheelie problem. Just keep from tearing up so much when you land. It will also limit bump steer and the car is not allowed to go so deep into the bounce.

Bump steer is easy to check when on a budget. Simply, get someone to stand over in the engine bay and bounce the car up and down. Watch the front tires and see what they do. If they turn in and out well you have bump steer issues. Sometimes just raising or lowering the front end will fix the major problems. Your upper control arm should appear to be level. If the car is too low or high in the front it puts the upper control arm at an angle then the top of the tire is being pulled towards center of the car when the suspension goes in that direction. Don't know whether your car sits low or high so don't know if or in what direction the problem could exist. I have found tons of Mopars that people got happy cranking on torsion bars and seriously screwed up the way the front end works.

Just my 2 cents. Good luck

Leon

Posted By: loaderpro

Re: Chassis Help - 06/12/13 02:55 AM

I was not just chimeing in or trying to spend somebodies money Leon! You put a hot rod engine in that yards the tires 3-4 feet in the air it's going to take more than a handful of steel shims to correct it. Especially if there is bump steer involved...that as you well know is nothing to fool with.

Attached picture 7739841-pomona.jpg

Posted By: Adrielp

Re: Chassis Help - 06/12/13 05:20 AM

https://www.facebook.com/photo.php?v=146...e=2&theater

The link above is a video of the first pass with the car last weekend. We learned a lot this weekend and will make adjustments to correct it. Enjoy the vid! Theres also some pics of the car on the page as well.

Posted By: gregsdart

Re: Chassis Help - 06/12/13 12:51 PM

Quote:

I was not just chimeing in or trying to spend somebodies money Leon! You put a hot rod engine in that yards the tires 3-4 feet in the air it's going to take more than a handful of steel shims to correct it. Especially if there is bump steer involved...that as you well know is nothing to fool with.

Good point. It is probably time to prioritize the moves that most feel are important. IMHO they would be-
1....how good are the front end parts-does the front need a rebuild? If so, determine what type of bushings, rubber or poly
2....set front and rear chassis height and set caster where you will run it. THEN check for bump steer problems through the range the front will travel during a run. Acquire a Mopar chassis manual, and fix the bump steer if needed to get within 1/8 all the way through travel.
3.... set up your travel limmiters, both up and down for cushioned stop to travel. Raising the lower one some should help protect the pan, provided you have some shock control to assist.
4.... Determine what front shocks you want to run IMHO you need some good shock control for landing. I am not up on what is out there for budget shocks that will work for your situation, so that may require a post of its own.
5.... Strongly consider wheeliebars if you can't get it consistent and keep the wheelstand at a reasonable level.
Wheeliebars are costly- but so are oil pans, bent rims, etc. The other factor is consistency. The wheeliebars will make the car more predictable for sure.

Posted By: Adrielp

Re: Chassis Help - 07/01/13 04:02 AM

Problem solved! Car is launching very well and we ran a personal best in the worst air the car has run in all year. Leaves straight as an arrow as well. Anyway, we have some vids up on our facebook page of the runs from this weekend. There is also a few inside car vids as well. Feel free to like our page as well. Follow the link and enjoy!

https://www.facebook.com/pages/Paradise-Racing-Engineering/146044575585862

Career best: 6.34 @ 108.43 in the 1/8th
Conditions: 88deg, 29%, 29.76bar, DA: 2701ft

Posted By: MR_P_BODY

Re: Chassis Help - 07/01/13 04:21 AM

Quote:

Problem solved! Car is launching very well and we ran a personal best in the worst air the car has run in all year. Leaves straight as an arrow as well. Anyway, we have some vids up on our facebook page of the runs from this weekend. There is also a few inside car vids as well. Feel free to like our page as well. Follow the link and enjoy!

https://www.facebook.com/pages/Paradise-Racing-Engineering/146044575585862

Career best: 6.34 @ 108.43 in the 1/8th
Conditions: 88deg, 29%, 29.76bar, DA: 2701ft

So what did you do to correct it

Posted By: Adrielp

Re: Chassis Help - 07/01/13 04:31 AM

Quote:

Quote:

Problem solved! Car is launching very well and we ran a personal best in the worst air the car has run in all year. Leaves straight as an arrow as well. Anyway, we have some vids up on our facebook page of the runs from this weekend. There is also a few inside car vids as well. Feel free to like our page as well. Follow the link and enjoy!

https://www.facebook.com/pages/Paradise-Racing-Engineering/146044575585862

Career best: 6.34 @ 108.43 in the 1/8th
Conditions: 88deg, 29%, 29.76bar, DA: 2701ft

So what did you do to correct it

Limiting the suspension travel up front. Helped a bunch and much more than I thought! I think we took 1 or 2 inches of travel away

Posted By: JoWeTu_6

Re: Chassis Help - 07/01/13 04:34 PM

Nice runs,

I hope to make it to the track soon my self (couple of weeks) Maybe I'll see you all their.

Good racing

John T.

Attached picture 7761463-2013-06-22_13-38-43_523FB.jpg

Chassis Help: Solved for now!