L-body front big brakes w/Spirit R/T knuckles

[Steve in VA]

My Rampage came out of paint yesterday. Time to put it back together. I've read lost of posts on the big brakes setup on L-bodies. Still alittle confused though. I'd like to run Spirit R/T knuckles and front brakes on my rampage. (I've already got the Spirit R/T rear setup on the rampage, will be running 16" pumpers)

Plan A:
In order to do this I have to:
a. machine the R/T knuckle on both sides equal to what the L-body knuckle is
b. I have to slot the two holes on the L-body strut to accept the larger bolts.
c. Tie rod holes on the R/T knuckle stay the same correct?

Plan b:
get minivan brakes, caliper brackets and calipers, 5 lug SC knuckles

Plan C:
single pin K/H 89 Omni front brakes, 5 lug SC knuckles

[turbovanman²]

Plan B.

[Juggy]

you can also use plan A if you have a K bodied strut to use with the r/t knuckle

plan B is the simple and easy way.


but since you already mentioned you have the vented rears, you should do the big 11" vented front...if you go with plan B youd want to switch to solid rear disks

oh yeah, find yourself a 24mm master cylinder. from an all wheel disk 89+ car. i dont know the prop valve ratio on the rampage..u may want to change that as well to help prevent rear lock up. rich bryant has a big thread about that stuff if you do some searching

[Force Fed Mopar]

you can also use plan A if you have a K bodied strut to use with the r/t knuckle

plan B is the simple and easy way.


but since you already mentioned you have the vented rears, you should do the big 11" vented front...if you go with plan B youd want to switch to solid rear disks

oh yeah, find yourself a 24mm master cylinder. from an all wheel disk 89+ car. i dont know the prop valve ratio on the rampage..u may want to change that as well to help prevent rear lock up. rich bryant has a big thread about that stuff if you do some searching

I don't understand, why would he want to switch to the solid rears? Plan B uses the 11" front rotors also.

BTW I vote for Plan B also

[Juggy]

I don't understand, why would he want to switch to the solid rears? Plan B uses the 11" front rotors also.

BTW I vote for Plan B also

plan B im assuming is the 89-90? turbo minivan front brakes with 14" rim, 10.25" rotor and 60mm caliper, as he mentions L body knuckles.

plan A would get him the 60mm caliper with 11" disc up front. which would be best if he has vented rears on the car. will need more stopping power up front to prevent the rear lockup.

[Steve in VA]

I'l be running the 24mm MC and the prop valve from the Sprit R/T for sure on this setup whatever way I go.

Juggy wrote:
>>>you can also use plan A if you have a K bodied strut to use with the r/t knuckle

I thought I did not have to use the K/G/P body strut if I want this route. Just machine the K/G/P knuckle & enlarge the two mounting holes to accept the L-body strut.

I like plan B the best really for ease and cost for now. so which one is it on the minis?
Rob says: Plan B uses the 11" front rotors also
Juggy says: 10.25" rotor

[rbryant]

Plan D is to run a coilover that has the correct strut for the RT brakes. For instance running a Daytona Koni or SRT4 Koni with a camber plate on an lbody.

The real problem with plan A is that the Lbody spindle expects the strut connection to be at ~14 degrees from 90 (76 degrees). The GJHKPA spindle expects the strut connection to be at ~19 degrees from 90 (71 degrees).

This means that if you just drill out the lbody strut to take larger bolts you will have +5 degrees of positive camber which isn't good. The difference is all in the spacing of the holes in the spindle connection on the strut. The bottom hole just sticks out farther on the GJKHPA cars and vans.

I recently drew up some crude diagrams that show this. I can post them if people are interested but they are basically a circle and line diagrams with the angles.

Now if you use an SRT4/GJHKPA strut on the lbody it fixes this problem because the angle of the holes ont he strut compensates for it. Both the lbody and GJHKPA body cars expect the strut shaft to be at around 80-81 degrees. The only issue is that the springs are also different so the best way to deal with it is go to a coilover setup.

-Rich

-

[turbovanman²]

I like plan B the best really for ease and cost for now. so which one is it on the minis?
Rob says: Plan B uses the 11" front rotors also
Juggy says: 10.25" rotor

Well, the parts used for plan b aren't 11" and there is no "bolt on 11 inch brakes" per say, but really, plan B and solid 10" rear discs are plenty.

[Force Fed Mopar]

To me, plan B is brake calipers and brackets off a 90-up minivan w/ the large 11" rotors, then buy new 11" rotors for an R/T or GTC or something which will have the right bolt pattern. You can tell which vans have the big brakes, the caliper will have a "15" cast into it on the outer-facing side, meaning 15" or larger wheels are required. Should also have a "60" cast in it too, as they used a 60mm piston.

[turbovanman²]

To me, plan B is brake calipers and brackets off a 90-up minivan w/ the large 11" rotors, then buy new 11" rotors for an R/T or GTC or something which will have the right bolt pattern. You can tell which vans have the big brakes, the caliper will have a "15" cast into it on the outer-facing side, meaning 15" or larger wheels are required. Should also have a "60" cast in it too, as they used a 60mm piston.

Won't work, unless you use the knuckle. Only the 10" minivan calipers bolt up to the stock L body knuckle.

[rbryant]

Won't work, unless you use the knuckle. Only the 10" minivan calipers bolt up to the stock L body knuckle.

I know Simon meant this and it is implied but...

Slight Corection: Only the Early Year 10" minivan calipers bolt to the stock lbody knuckle.

The 91+ 10" brakes also won't work.

-Rich

[4 l-bodies]

Sounds like maybe you already have the RT knuckles on hand, so I would use those.

I've done plan "a" on quite a few L-bodies. After having the knuckles Bridgeported, I sleeved the knuckle strut holes to bring them back to the same diameter as the L-body knuckles. This allowed me to use the l-body strut mounting bolts and not have to modify the strut holes. This way the alignment guy can align the car properly without having to supervise them

As Rich mentioned you also need to alter the RT knuckle so you can get enough negative camber. This would be on the inboard side of the knuckle that faces the strut mount. Easy to do.

I also have the minivan calipers on another car. The 11" rotors IMO, are a better choice as you have a bigger rotor (more potential stopping power) and a bolt in wheel bearing.
Todd

[turbovanman²]

I know Simon meant this and it is implied but...

Slight Corection: Only the Early Year 10" minivan calipers bolt to the stock lbody knuckle.

The 91+ 10" brakes also won't work.

-Rich

Thank you for clarifying.

Sounds like maybe you already have the RT knuckles on hand, so I would use those.

I've done plan "a" on quite a few L-bodies. After having the knuckles Bridgeported, I sleeved the knuckle strut holes to bring them back to the same diameter as the L-body knuckles. This allowed me to use the l-body strut mounting bolts and not have to modify the strut holes. This way the alignment guy can align the car properly without having to supervise them

What did you see alignment wise or wheel placement wise?

[Steve in VA]

First off I want to thank all you guys for clearing up a few things. Its much apprieciated!! So much knowledge here!!

Simon & Rich, great parts in your signatures by the way!!!!!!! (I want some camber plates if budget allows)

It all comes down to budget for the front brakes. I really like PLAN A, but I do not have the R/T knuckles or the caliper brackets yet (only the R/T rear setup, prop and 24mm). If I cant find a set I may have to go with minivan stuff from the boneyard.

[4 l-bodies]

What did you see alignment wise or wheel placement wise?

Simon, not exactly sure what you are asking me, but I could easily get negative 1.75 camber which is IMO, to much for the street (or at least my tires think so). Settled on around 1/2-5/8 degree negative camber. As Rich states, without modifying the knuckle, you will never get there though. More than likely you will be positive camber without modifying the pad on the knuckle, and we all know that's no good.
Todd

[turbovanman²]

First off I want to thank all you guys for clearing up a few things. Its much apprieciated!! So much knowledge here!!

Simon & Rich, great parts in your signatures by the way!!!!!!! (I want some camber plates if budget allows)

It all comes down to budget for the front brakes. I really like PLAN A, but I do not have the R/T knuckles or the caliper brackets yet (only the R/T rear setup, prop and 24mm). If I cant find a set I may have to go with minivan stuff from the boneyard.

DON'T use van knuckles, you'll find you won't be able to pull a U-turn anymore, the tie rod placement is different BUT you can use any 91+ car as they are all the same, best part is, the caliper bracket simply unbolts to convert from 10-11" brakes and vice versa.

If your stuck, I have caliper brackets but no knuckles.

Simon, not exactly sure what you are asking me, but I could easily get negative 1.75 camber which is IMO, to much for the street (or at least my tires think so). Settled on around 1/2-5/8 degree negative camber. As Rich states, without modifying the knuckle, you will never get there though. More than likely you will be positive camber without modifying the pad on the knuckle, and we all know that's no good.
Todd

More about the changes using a cast control knuckle on stamped arms.

[rbryant]

It all comes down to budget for the front brakes. I really like PLAN A, but I do not have the R/T knuckles or the caliper brackets yet (only the R/T rear setup, prop and 24mm). If I cant find a set I may have to go with minivan stuff from the boneyard.

Don't use the 11" vented rears without the 11" fronts or the system will be very out of balance and probably dangerous.

Just get some 91+ car spindles and then order the calipers and caliper brackets from rockauto. They are something like $20 a side for the calipers and brackets plus a core charge.

-Rich

[rbryant]

More about the changes using a cast control knuckle on stamped arms.

No!

It is difference between the lbody strut/knuckle angles and all of the other cars and vans. Just one of those lingering pre-Kcar things...

On top of the known thinner spindle width, the lbody spindles/struts also have a different angle on the spindle/strut holes than the Kcars.

Stamped vs. Cast has nothing to do with it.

-Rich

[Steve in VA]

Ok, I'm going to try to recap:

Plan A:
a. machine the R/T knuckle or any 91+ knuckle on both sides equal to what the L-body knuckle is
b. sleeve the knuckle strut holes to bring them back to the same diameter as the L-body knuckles and use L-body strut to knuckle bolts
c. Alter the RT knuckle so you can get enough negative camber. This would be on the inboard side of the knuckle that faces the strut mount.

Did I miss anything?

Purchase:
Find R/T knuckles
Find R/T caliper brackets (Simon)
New 11" rotors from 91+ cars
New R/T calipers from rockauto w/core
Hawk pads from (Rich)
Cross fingers on good wheel bearings

Did I miss anything?

[rbryant]

This would be on the inboard side of the knuckle that faces the strut mount. Easy to do.

So you slotted the bottom hole?

There would actually be a little more meat on the top hole as long as it doesn't hit the strut before you can get your desired camber. I calculate that it would take about 1/4" or so of slotting to get back the 5 degrees so I would think that it could be done on the outside of the top hole aswell.

It seems like slotting the top hole would be better when using lbody struts because the strut's are often slotted in the top hole aswell. If you slot the bottom of the spindle then you have slots on both holes and things are more likely to move.... If you slot the top of the spindle then the bottom hole is still tight to the strut body and there is only one point that can pivot.


I ran through the details about this to make sure my BC coilovers would work.

Here are some pictures I drew when thinking about this. I don't have an lbody spindle anymore so I couldn't sketch in the spindle shape. Considering that I can't really draw anything by hand I thought my scan and trace of the spindle outline looked pretty good...

Everything is to scale in these pictures.

Lbody Vs. Gbody Angles:


Slots needed to get back to zero camber:


-Rich