lowering blocks and rearend geometry

[sy112]

Just got done installing the good AIM lowering blocks with the built in angle on the blocks. After the install the rear wheels still sat forward in the arches slightly, just enough to know the difference. It is recommended to use them cause then you keep your pinion angle the same. other wise you could just take all the angle out and put straight blocks in and screw up the pinion angle.

was looking up caltracks and slide-a-links........

exact quote from summit website about slide-a-links.......

Competition Engineering claims this Slide-A-Link traction bar will cut half a tenth off your 60 ft. times. The secret is the innovative telescoping design which gives you two inches of adjustability when setting pinion angle and spring preload. That gives you more control over front-end lift and weight transfer,

now with these you are playing with the pinion angle to preload the springs, giving better weight transfer and so on. I thought messing with the pinion angle was bad on driveline parts, if so then why are some installing parts that intentionally mess with the pinion angle from where it came from the factory. possible damaging driveline parts. And is you can do this with springs then why go through the hassle of screwing up the rear axle spacing with the angle on the blocks, why not the the spacing the same with just straight blocks and deal with the pinion angle change.

Or is the pinion angle change from the lowering blocks a step in the wrong perfromance direction compared to the slide-a-links?

 

[sy112]

34 people so far and no one has anything to say, I thought it was a decent question.

 

[canadian]

you won't know anything for sure unless you measure the actual pinion angle. i believe daron has done this. i know there was an article in hot rod or car craft a couple months ago talking about the whole relationship between driveshaft angle, and pinion angle, how to set it up, bla bla bla.

think they said you ultimately want 0* overall (driveshaft angle vs. pinion angle).

http://www.carcraft.com/searchresults/?scope=T&sitename=carcraft&terms=pinion+angle

 

[sy112]

thanks canadian, appreciate the input. anyone else?

Hey myclone, you made the lumpy bars, what do you think?

 

[V]

Re: lowering blocks and rearend geometry

Or is the pinion angle change from the lowering blocks a step in the wrong perfromance direction compared to the slide-a-links?

Not sure if this answers your question, but I'll give it a shot.

Ideally, you want a zero pinion angle, but racers start with a negative pinion angle to transfer more power to the track. Under load, the suspension flexes, the pinion rises and pinion angle gets closer to zero. How much negative pinion angle to start with depends on things like suspension type and horsepower. It's trial and error until you find the sweet spot. CE's Slide-a-Links just adds quick adjustability (pinion angle and spring preload). Basically, you're trading driveline wear and tear for power transfer.

 

[sy112]

perfect V, that's what I was wondering.

So putting some slide-a-links might not be the best idea for a daily driver unless you have it set for 0 pinion then adjust when you get to the track. Cause if you leave it on the track setting then you are adding wear and tear on the driveline.

 

[V]

So putting some slide-a-links might not be the best idea for a daily driver unless you have it set for 0 pinion then adjust when you get to the track.

That's debatable. Click on some of those Car Craft links. Some gurus will recommend 1 to 2 degrees of negative pinion angle (suspension at rest). Others will disagree.

 

[Loeryder]

I was considering using the Caltracs, albeit a little bit different than slide a links I was told by other users that they had lots of suspension noise on the street.

at rest you would probably want a little bit of negative angle to accommodate the regular bumps you encounter daily driving.
A more strictly race setup you could start at zero.

What's fun about our trucks is at launch, the time of the most driveline stress, our rear ends squat HARD dramatically changing the driveline angle.

In my case I used the 3" drop Bell Tech leaf springs and used a 1" block with 2* pinion angle.
I have not been able to get an accurate pinion measurement, and am still waiting for the springs to settle in, but eyeball looks to be at least 2* pinion angle at rest.
No vibration under launch, none of the highway and I've got a good dozen hard launches on them.

The wheel sitting forward in the opening is not always related to the lowering block angled shim theory. Some yes, but I have seen plenty of stock trucks mostly Typhoons that sit forward.
My Ty is one of them, with Flex a forms and no blocks no shims it still sat fwd. not bad but enough to notice.
With the Bell Techs the wheel is located almost exactly the same position.
So 2 different sets of springs cant be wrong, I say its differences in frames, springs, and overall construction.

 

[Bear Dog]

I will be glad to fax some information about pinion angles and how to measure them if anybody needs it.
Eric

 

[Loeryder]

Eric, can you scan it and email it to me @ mrty2u@hotmail.com?

otherwise fax it to
314-773-0555
please use a cover sheet with ATTN to JASON GRANGER
or I will never see it.

Thanx for all your help.