AP LD20 calipers vs Wilwood

[Monte]

Can anyone give me insight as to which you think is better or are they different at all?

I am looking at the AP aluminum LD20 against the Wilwood aluminum model.

Thank you

Chris

[kea]

The AP (LD-20) caliper is a Mono-block, the Wilwood is a traditional multi-piece design.

[DaveW]

The AP (LD-20) caliper is a Mono-block, the Wilwood is a traditional multi-piece design.

From an engineering viewpoint, a properly-designed multi-piece aluminum caliper can be as stiff, or even stiffer, than an aluminum mono-block caliper. The reason it could be stiffer is that the steel bolts have a 3x higher modulus than aluminum and so the multi-piece assembly, properly-designed, could be stiffer.

Proper design depends on the bolt clamping force being high enough so the parts of the multi-piece never separate.

So, IMO, either type could be better, but not because of multi-piece vs mono-block construction.

[kea]

From an engineering viewpoint, a properly-designed multi-piece aluminum caliper can be as stiff, or even stiffer, than an aluminum mono-block caliper. The reason it could be stiffer is that the steel bolts have a 3x higher modulus than aluminum and so the multi-piece assembly, properly-designed, could be stiffer. Proper design depends on the bolt clamping force being high enough so the parts of the multi-piece never separate. So, IMO, either type could be better, but not because of multi-piece vs mono-block construction.

Key here is "could be", "properly-designed". Not sure that a low volume, low end (profit) piece like this would qualify.

[hdsporty1988]

Can anyone give me insight as to which you think is better or are they different at all?

I am looking at the AP aluminum LD20 against the Wilwood aluminum model.

Thank you

Chris

I ran the AP calipers on my 86 Reynard SF and liked them. When I sold it and bought a 94 Van Diemen the Wilwoods had come out. At a savings of $135 per caliper I decided to give the Wilwoods a try and after running them for 4 seasons I've been happy with them.

[BeerBudgetRacing]

Key here is "could be", "properly-designed". Not sure that a low volume, low end (profit) piece like this would qualify.

I suppose I'd hope Wilwood applied the knowledge they have gain in their 45 years of business designing and manufacturing thousands of calipers when they designed and built the WLD20s and didn't simply pull it out of their a.. umm... hat.

[DaveW]

I suppose I'd hope Wilwood applied the knowledge they have gain in their 45 years of business designing and manufacturing thousands of calipers when they designed and built the WLD20s and didn't simply pull it out of their a.. umm... hat.

Also, there was an ApexSpeed thread that commented that Wilwood communicated with a very knowledgeable source (I don't know who) to optimize the design of the WLD20's. As above, I've heard/read nothing but good reports on them. If my Alcon LD20 clones (developed for the Radon and since discontinued) develop issues, I'd buy Wilwoods (~1/3 the price of my Alcons) to replace them.

Link: https://www.apexspeed.com/forums/sho...l=1#post643478

[Lutrell]

From an engineering viewpoint, a properly-designed multi-piece aluminum caliper can be as stiff, or even stiffer, than an aluminum mono-block caliper. The reason it could be stiffer is that the steel bolts have a 3x higher modulus than aluminum and so the multi-piece assembly, properly-designed, could be stiffer.

Proper design depends on the bolt clamping force being high enough so the parts of the multi-piece never separate.

So, IMO, either type could be better, but not because of multi-piece vs mono-block construction.

Years ago my experience with trying both mono block AP LD20 on the rear and Wilwood Dynalite two piece calipers on the front I came to the conclusion that mono block was better (stiffer) because of how much bias would change to the AP's on the rear when hot. I eventually went with AP's all around. However now I really think like you said it depends on the design and materials. I found an article by Caroll Smith that concurs with this opinion. https://www.brakes-shop.com/brakeped...piece-calipers

I did a quick search to see what the price difference would by and Primus has the AP on sale for $375, Wilwood WLD-20 for $232 or with new thermlock pistons for $312 a $64/caliper difference from AP.

For me on my DSR the AP LD20 mono block worked great. I have not tried the Wilwood LD20's.

Lutrell

[DaveW]

Years ago my experience with trying both mono block AP LD20 on the rear and Wilwood Dynalite two piece calipers on the front I came to the conclusion that mono block was better (stiffer) because of how much bias would change to the AP's on the rear when hot...

Bias changing like this has more to do with temperature of the disk and pads front vs rear than flex. Flex would be felt in more travel in the pedal, and w/o knowing which side of the balance bar was moving more you wouldn't know whether it was front or rear or both that caused it.

[problemchild]

The reality is that only the elite of club racers will ever be able to utilize the benefits of stiffer brake calipers. I certainly include myself in that generalization. I would suggest that price, availability, and support should be the determining factors in selecting brake calipers.

[Rick Silver]

I swapped from the ICP LD20s to Wilwood calipers at the beginning of this year. I would say there is a noticeable difference in my pedal firmness. Between the ICP and Wilwoods, the Wilwoods are definitely stiffer.

[Rick Silver]

Also, there was an ApexSpeed thread that commented that Wilwood communicated with a very knowledgeable source (I don't know who) to optimize the design of the WLD20's. As above, I've heard/read nothing but good reports on them. If my Alcon LD20 clones (developed for the Radon and since discontinued) develop issues, I'd buy Wilwoods (~1/3 the price of my Alcons) to replace them.

Link: https://www.apexspeed.com/forums/sho...l=1#post643478

Dave, what are the current thoughts on the master cylinder sizes. My car was a DSTP car and it came with 0.7 front and 0.75 rear. I feel like I have to push too hard and give up some feel as a result early in the braking zone when downforce is high. Is everyone running 5/8 for LD20s front and rear?

[DaveW]

Dave, what are the current thoughts on the master cylinder sizes. My car was a DSTP car and it came with 0.7 front and 0.75 rear. I feel like I have to push too hard and give up some feel as a result early in the braking zone when downforce is high. Is everyone running 5/8 for LD20s front and rear?

I am running 5/8 MC's front and rear, but my caliper pistons are 1.75 front and 1.375 rear. That gives a very close to centered bias bar.

However, your comment on "early in the braking zone" means to me your brake pad compound may not have enough initial bite to allow you full braking ability at the 1st instant of high-speed braking. Many compounds are like that in that they won't give max CF until hot.

I run Carbotech XP20's. Below is a review I've posted several times:

o They have a high CF
o The initial bite is great, allowing high-G braking from initial application
o The CF is constant throughout the braking event, throughout a session/race and from new to almost worn out – Many other pad compounds' CF are not constant and don't work until hot
o The CT release characteristics are super (relates to modulation, below) - brake torque is exactly proportional to pedal force. That was my biggest complaint about most pads I tried - their release characteristics sucked, meaning they still were braking hard as I released the pedal force, causing the rear to step out at the end of the braking zone while turning in and brakes to easily lock up
o Modulation is easy with the CT's because of the release characteristics - I can make the tires be just on the edge of lockup (tires slowing down but not stopping)
o Compared to the lower # CT compounds, the XP20 compound is stiffer (higher modulus) making the pedal action have less springiness – this makes the whole brake system feel stiffer and easier to modulate
o CT's are rotor-friendly

[Rick Silver]

I am running 5/8 MC's front and rear, but my caliper pistons are 1.75 front and 1.375 rear. That gives a very close to centered bias bar.

However, your comment on "early in the braking zone" means to me your brake pad compound may not have enough initial bite to allow you full braking ability at the 1st instant of high-speed braking. Many compounds are like that in that they won't give max CF until hot.

I run Carbotech XP20's. Below is a review I've posted several times:

o They have a high CF
o The initial bite is great, allowing high-G braking from initial application
o The CF is constant throughout the braking event, throughout a session/race and from new to almost worn out – Many other pad compounds' CF are not constant and don't work until hot
o The CT release characteristics are super (relates to modulation, below) - brake torque is exactly proportional to pedal force. That was my biggest complaint about most pads I tried - their release characteristics sucked, meaning they still were braking hard as I released the pedal force, causing the rear to step out at the end of the braking zone while turning in and brakes to easily lock up
o Modulation is easy with the CT's because of the release characteristics - I can make the tires be just on the edge of lockup (tires slowing down but not stopping)
o Compared to the lower # CT compounds, the XP20 compound is stiffer (higher modulus) making the pedal action have less springiness – this makes the whole brake system feel stiffer and easier to modulate
o CT's are rotor-friendly

Based on some of the discussion here and your comments I switched to Carbotech and put on the XP20's last weekend - so only one weekend so far. They were definitely better than the PFC 13, that I thought were terrible and much worse than the old PFC 93 compound that I used for years.

So I want to wait a few more races and see how it goes. I did a careful job of prepping the rotors using Mike at Carbotech's guidance. I was also going to put on front/rear force sensors to be a little more scientific.

[alangbaker]

Also, there was an ApexSpeed thread that commented that Wilwood communicated with a very knowledgeable source (I don't know who) to optimize the design of the WLD20's. As above, I've heard/read nothing but good reports on them. If my Alcon LD20 clones (developed for the Radon and since discontinued) develop issues, I'd buy Wilwoods (~1/3 the price of my Alcons) to replace them.

Link: https://www.apexspeed.com/forums/sho...l=1#post643478

I don't think I'm talking out of turn to let you know that Wilwood worked with Marty Knoll (of MK Technologies, of whom I'm sure many of you know) on the development of the WLD-20 and WLD-19 calipers that were eventually released.

My RF98 currently has LD20s front and rear and if I should ever decide to change, it will be to Wilwood's WLD-20s...

...or WLD-20s front and WLD-19 in the rear (although that would mean changing master cylinder sizes as well).

[EricP]

Am I correct that the Wilwoods are only available in lug mount, no radial mount?

[Lutrell]

Am I correct that the Wilwoods are only available in lug mount, no radial mount?

I was just browsing online for calipers similar to LD20's.

Wilwood has a different two piston caliper with radial mount.
https://www.wilwood.com/Calipers/Cal...no=120-13864-N

Pegasus list these as FF and FC legal.
https://www.pegasusautoracing.com/gr...upID=CALIPERWW

Or you can get a Performance Friction for just $988.99
https://www.pegasusautoracing.com/gr...pID=CALIPERPFC

[alangbaker]

I was just browsing online for calipers similar to LD20's.

Wilwood has a different two piston caliper with radial mount.
https://www.wilwood.com/Calipers/Cal...no=120-13864-N

Pegasus list these as FF and FC legal.
https://www.pegasusautoracing.com/gr...upID=CALIPERWW

Or you can get a Performance Friction for just $988.99
https://www.pegasusautoracing.com/gr...pID=CALIPERPFC

I think you'll find if you do some searching that that particular Wilwood caliper (the PowerLite) has been discussed on ApexSpeed before, and the reviews weren't positive.

[BeerBudgetRacing]

Primus had the best deal on the WLDs. I'm sure Brad will match if you find them cheaper.

[hdsporty1988]

I think you'll find if you do some searching that that particular Wilwood caliper (the PowerLite) has been discussed on ApexSpeed before, and the reviews weren't positive.

This isn't the Powerlite, those are the radial mounted ones.