Mastersbilt Crate Questions

[doubleduty]

Running 06 Smackdown with very few nights on it with a 604 crate. Car was very decent for the first night in the car but the setup sheets we received with the car were for a very tight turn short track. Car was very flat and very tight until the track got slicker. Even in the slick the car had a throttle push coming off turn. We lowered compression on the RF shock 2 clicks and seemed to help in the feature as well as took 4 rounds from the RR spring. We do know that our rear percentage was high due to having to add some weight at the track and more fuel. Had some lingering brake issues so we weren't able to adjust much but this is what the car was setup as: Springs RF 400 LF 475 RR 225 LR 225 Shocks RF Afco DA 3-7 LF Afco DA 5-5 LR front Afco 8-2 175lbs pressure LR back Afco DA 6-2 RR 94 Jbar is next to bottom hole on the pinion and is short. Goes to inside of the mount on frame. Forgot measurement on rake. RR bars are trailing 1/4 inch. Drop on the left rear is something we knew was off. It was 12 inches from frame to axle tube but we didnt have any shock extensions to adjust at the time. Ride heights according to their sheets were nearly an inch higher than standard. I guess I am looking for j-bar placement, weight percents, and overall suggestions....not a new driver just new class.

[7uptruckracer]

Can't really assess any of your handling until you get the drop right and brakes right

[doubleduty]

We fixed the brake problem for the feature but unsure where the drop needs to be. I would figure around 14 to 15 inches ? I guess I am looking for general starting points. I was told the Smackdown book settings were very general and more focused towards full blown late models.

[Matt49]

When you say that ride heights were an inch higher than standard, if you mean on the front also, it is no wonder why the car wouldn't turn. You really need to start with your ride heights pretty close to the recommendation (like within 1/4"). Also need to know your scale numbers to see if you are close there (left side%, rear%, LR bite).
Regardless of all this, you need to get rid of the short j-bar in a bad way. You need to be on the 21" j-bar. That short j-bar will get the car way too tight...especially for a crate. As far as j-bar placement, specifying the number of holes up from the bottom on the pinion can be misleading because not all pinion mounts are the same. Think and communicate in terms of j-bar location relative to the pinion. That being said, for a crate motor in a smackdown car, even wight (same height as) the pinion on that side and 8-1/2" from bottom of frame rail to center of the bolt on the frame side is a good place to start.
12" is plenty of LR droop on a smackdown. If you go to 15" and leave that short bar in, I promise you will have something that Scott Bloomquist wouldn't be able to drive.
If you have the baseline setup numbers for a smack car, you are correct, they are "designed" for bigger horsepower. So just do a few things to free yourself up a little: 0.5-1% lower rear weight, softer LR spring, etc.
By the way, by taking 4 turns out of the RR, you significantly added wedge to the car. This will make your throttle push problem even worse.

[doubleduty]

I will look at the scale sheets tonight and post more accurately. I do know that we had roughly 55-56% rear percent, which we knew was high. LR bite was 80 lbs. Front ride heights were correct but former owner suggested that rear heights be 1 inch higher. J-bar on the pinion is roughly 1 inch -1.5 below pinion currently. We had original plans to go to short track but went elsewhere & didn't have time to change everything but we knew that the j-bar would be an issue. Track started to slicken up for feature and it was a 30 lap race....pulled rounds out thinking it would need tightened towards end of race. Thanks for all who have commented

[TheJet-09]

I'm not acutely aware of the specific needs of crate cars, other than assuming they need to be pretty free all the way around. From what you have listed, the 400# RF sticks out to me. I believe a 350# is best in the RF of those cars, unaware of what (if any) issue could arise from changing it. I'd get the back down to the specified ride heights. I believe they still have a lot of rake (front to rear), so no need to add more. I'd also move the pinion side of the J-bar up to even with the pinion to start (especially if you're on the short bar). I am curious, though, how you determined the RR bars are trailing 1/4"? If I'm not mistaken, with the 15.5"/17.5" rear links, the RR wheel is about 3/4" trailed back. Are your RR links longer than the LR?

[doubleduty]

Yes we lengthened the RR bars 1/4 inch. We are planning on starting with moving the j-bar placement as well as going to the longer j-bar itself.

[TheJet-09]

I think you'll see a drastic change/improvement with changing the J-Bar and it's location. Good luck!

[doubleduty]

I just wanted to update the original post with some results and of course more questions....we reset all the ride heights to normal Masters settings. Installed the 21 jbar and moved the the pinion side up til it was a notch above center of yoke. Moved the frame side to 8.5 up and that put our side to side dead on the masters setting. Lowered the RF spring to a 375. Moved weight around and got the rear % down to 53 and trailing the rear 3/4 in. Car is a lot better but it does not want to consistently stay up on the bars (coming our of turn and down straights). Some laps it will jump up and stay rolled over but most the time it stays flat. We even jumped the LR front shock up to a 9-2 with 250lbs of pressure. Am I missing something? Basically took rearend out of the car to check for binding and found nothing.

[Matt49]

I just wanted to update the original post with some results and of course more questions....we reset all the ride heights to normal Masters settings. Installed the 21 jbar and moved the the pinion side up til it was a notch above center of yoke. Moved the frame side to 8.5 up and that put our side to side dead on the masters setting. Lowered the RF spring to a 375. Moved weight around and got the rear % down to 53 and trailing the rear 3/4 in. Car is a lot better but it does not want to consistently stay up on the bars (coming our of turn and down straights). Some laps it will jump up and stay rolled over but most the time it stays flat. We even jumped the LR front shock up to a 9-2 with 250lbs of pressure. Am I missing something? Basically took rearend out of the car to check for binding and found nothing.

When was the last time all of your shocks were checked on a dyno? Inconsistent handling is very often caused by a bad shock.

[doubleduty]

That I am unsure of. They were purchased with the car. The LR front shock is the only gas shock on the car. Matt49 do you have an email I can send some pics too.