V1 Add-on brake proportioning valve

[Rauq]

Theoretically if you corner balance the car then you shouldn't lock up one side well before the other unless there's something else contributing like air in the line, a bad alignment, or something causing a difference in traction between sides. But if you haven't corner balanced the car and you're confident there's nothing else major leading to lockup on one side vs the other, extending the shock body a little bit on the side that locks up first can be a useful tool to dial that out.

 

[baustin]

Theoretically if you corner balance the car then you shouldn't lock up one side well before the other unless there's something else contributing like air in the line, a bad alignment, or something causing a difference in traction between sides. But if you haven't corner balanced the car and you're confident there's nothing else major leading to lockup on one side vs the other, extending the shock body a little bit on the side that locks up first can be a useful tool to dial that out.

I need to do this, I hadn't read about corner balancing previously but it could be the best explanation for why I have the possibilty of locking my driver front by itself just before both fronts lockup. I'm fairly sure I don't have air or caliper issues. Good note.

 

[Desert Sasqwatch]

Keep in mind that if you are sitting in the car, the corner balance will be different than doing this without you - or an equivalent weight - in the seat. Could be that your corner balance is okay without you in the seat, but when loaded the balance changes enough to cause the premature lock up of the driver's side tire. @Rauq solution will probably help this.

 

[mike_sno]

Never heard of corner balancing, but just googled it. Very interesting!! Did you guys bought a kit for doing it at home?

 

[Desert Sasqwatch]

The 'kit' to do this is typically a 4-corner weight scales system - not cheap to purchase. Asking around at some of the performance shops in your area, they usually have the 4-corner scales and can do a balance - hopefully at a reasonable fee. Keep in mind that the very light weight of the Goblin will be affected to a greater degree than other heavier cars - your weight as a driver, and if you have a passenger is a much larger percentage of the total weight of the Goblin.

Corner balance can be done through other methods with a pair of scales or even a single scale if the setup is correct. The scale(s) are placed under each tire and the weight of that corner is measured and recorded. The Goblin must be sitting on level ground and spacers are used under the wheels - 2 if using 2 scales, 3 if using 1 scale - to keep everything level. Once each corner weight is measured, it is used in calculations to determine side to side and diagonal weight balance of the Goblin.

If you plan to track your car or just want to be certain of the handling of your Goblin for 'spirited' driving this is highly recommended. And should be done with you or an equal weight in the driver's seat when performed (if going solo).

This calculator may help:
Corner Balance Calculator (robrobinette.com)

This video shows you how the corner balance is done:
How to Corner Balance a Car - The Simple Method - Bing video

 

[Rttoys]

It can be done with cardboard and a jack, the old school way.

everything can be done with bare basic things in your garage. You just have to be creative and realize it’s not precise like high dollar tools of today, but will work. Just like string and levels for an alignment

 

[mike_sno]

Don't kill me.... I never checked the tire pressure when since I bought the car. However for some odd reason I thought the left front tire worked a lot when I drove the car tonight. When I came home I checked the tire pressure and the front left was significant lower then the other tires. Which all were in general low. I will see if that solves the issue.

I was thinking of buying/building a simple kit for corner balance. (Arduino, Display and a few weight sensors.) I wonder if there would be any interest in the forum, I could easily ship that kit, so the rest of the forum could use it too.

 

[Rttoys]

Tire pressure is a very big deal on a goblin (well all vehicles). The norm is about 20 psi give or take a bit. Track settings are different

 

[Sebnuts]

Front pressure should be lower than the rear, and it's going to depend on your tire size as well.

 

[Jareth]

Does anyone have a picture of where the Mount installs that comes in the DFK kit?

.

 

[Desert Sasqwatch]

Which mount?

 

[Ark :D]

 

[Jareth]

That Mount, Thanks

 

[Davidljones88]

Do you guys have 60-0 times? With or without the proportion valve. I plan om testing this week stopping distance with 17 inch an 15 inch rims with different valve settings.

 

[Rttoys]

No hard numbers, but skidding front tires with the rears doing nothing, to locked and stopped all around, is a huge difference.

 

[G Atsma]

No hard numbers, but skidding front tires with the rears doing nothing, to locked and stopped all around, is a huge difference.

That is all the perceived difference needed. Observed data.....

 

[Robinjo]

No hard numbers, but skidding front tires with the rears doing nothing, to locked and stopped all around, is a huge difference.

Sorry, but can you elaborate a bit further. I believe you are saying all 4 locking together is much better but it’s not clear.

 

[Rttoys]

Sorry, but can you elaborate a bit further. I believe you are saying all 4 locking together is much better but it’s not clear.

I was hoping I had an autocross video to show the difference, but I just have spinout videos, not locked up brakes videos. Mostly I meant, with all 4 brakes operating equal and properly, that puppy is stopped, now. If it locks, it’s not for long, because you are now stopped.

Without the prop valve, front can (and will) lock, but the rears won’t, at all. With the prop valve, I have mine adjusted for the fronts to lock, just before rears. You can adjust it for rears to lock first, but that is not recommended due to the uncontrollability when that happens. If it’s going to lock, fronts should always lock first. Remember, we don’t have abs here.

With it set the way I have it and using the tires that I do, I can’t recall really locking all 4 and skidding for any distance, in real world events. Even at autocross I jamb down on them hard, the tires make a ton of noise and I’m stopped, but never locked up. I’m sure I could nail them harder, but I’m fairly in tune with the abilities of the my goblin so I try to keep it on the edge of locking. If all 4 lock, you are now a passenger along for the ride.

I test mine and make adjustments on a road that has a lot of dirt and pea gravel. I can get a good feel on what locks when and how I use my right foot to modulate pressure. Just like the old days.

 

[Robinjo]

Thanks for clearing that all up!

 

[Scott #321]

I have a square setup currently 255's on all four corners. With the proportioning valve set to max rear bias I just barley lock the fronts before the rears. Haven't actually had this occur on dry pavement only on gravel/sand contaminated pavement. Occasionally will momentarily lock one of the fronts at autocross in hard braking on a hard turn-in but not the rear as of yet.