G27 brake mods

stribbeck · Jun 4, 2020

Hi all

Are these any good? Looking at getting the rally version

Brake Pedal MOD “Rally/GT” [Logitech G25, G27, G29, G920] (PC) | 3DRap

This MOD simulates a load cell on the brake pedal. It makes the pedal progressively harder, more realistic. Compatible with Logitech G25 / G27 / G29 / G920. Watch the video that you find at the end of the page. The original spring always opposes the same force to your foot, whether you are...

www.3drap.it

Thanks

GeekyDeaks · Jun 5, 2020

It's a very subjective mod. At that price you are not going to waste much money experimenting to see if it works for you though

The problem with this and other mods of the same principle is that the braking force is still determined by pedal position, not load on the pedal, and the mod is just making it require more force/load to get it to a specific position. i'm no expert on this, but reading around it seemed the general consensus was that it's easier to train 'muscle memory' with load rather than position. As with many of these things though, i suspect this is not the case for everyone and those that adapt easier to pedal position will find the mod hinders this process.

I have the G29 and I personally found the OEM rubber block to be fine, but after a while I noticed the braking force shifted slightly during heavy use. I can only think this is due to the material changing temperature as it was repeatedly compressed, much the same way tyres warm up and soften slightly. This spurred me on to make it more consistent and I ended making a load cell mod instead.

Have you considered the AXC true brake? It's very keenly priced

Locoblade · Jun 5, 2020

The problem I see with any mod that makes the pedal progressively harder is that although the brake might feel more realistic to your foot, you could make it even more tricky to modulate braking effort near the limit in the game because at the point where you're pressing hard and need the most control, the movement of the pedal is now concentrated across a far shorter movement of the potentiometer and won't be linear compared to how much pressure you're exerting. If you can somehow tweak the brake force curve to compensate for that so it amplifies the pot movement at high pedal pressure then it might help but otherwise you could end up needing say 5kg of force on the pedal to go from 0% to 50%, 10kg to go from 50% to 80%, but 20kg to get that last 20% for maximum braking. I believe the G29 has a pre-set curve built in but that will presumably be based on the forces required to compress the default spring/rubbers so it won't adapt to any mods. I'm not sure if the G27 has the same but I know the G25 doesn't, it's completely linear so that would be even worse than a modded G29. I think Truebrake's pot also has a non linear scale matched to their spring design etc but personally I'd be very cautious about buying anything from them as their website is extremely misleading trying to trick customers into believing what they're offering works the same as a load cell by measuring load on the pedal rather than movement, when it categorically can't given that its potentiometer based.

Having tried a couple of DIY spring mods and subsequently used GeekyDeaks' load cell mod design on my trusty old G25 I think the load cell is a brilliant upgrade and well worth investing a bit of time to doing, plus it's cheaper to do than even the Truebrake mod let alone the Ricmotech mod that is a true loadcell upgrade but costs about £130-150 by the time you've imported it from the states.

Paul Glover · Jun 5, 2020

When I was still using my G27 I bought these: http://gteye.com.au/

Warren Dawes · Jun 5, 2020

Paul Glover said:
When I was still using my G27 I bought these: http://gteye.com.au/

That is what I'm currently using, and it is much better. I am planning on getting a load cell brake pedal set at some point though, maybe the Fanatec CSL Elite.

stribbeck · Jun 5, 2020

GeekyDeaks said:
It's a very subjective mod. At that price you are not going to waste much money experimenting to see if it works for you though

The problem with this and other mods of the same principle is that the braking force is still determined by pedal position, not load on the pedal, and the mod is just making it require more force/load to get it to a specific position. i'm no expert on this, but reading around it seemed the general consensus was that it's easier to train 'muscle memory' with load rather than position. As with many of these things though, i suspect this is not the case for everyone and those that adapt easier to pedal position will find the mod hinders this process.

I have the G29 and I personally found the OEM rubber block to be fine, but after a while I noticed the braking force shifted slightly during heavy use. I can only think this is due to the material changing temperature as it was repeatedly compressed, much the same way tyres warm up and soften slightly. This spurred me on to make it more consistent and I ended making a load cell mod instead.

Have you considered the AXC true brake? It's very keenly priced

Do you have a guide to make the load cell mod? Thanks

GeekyDeaks · Jun 5, 2020

GitHub - GeekyDeaks/g29-load-cell: DIY load cell modification for the logitech G29 pedal set

DIY load cell modification for the logitech G29 pedal set - GeekyDeaks/g29-load-cell

github.com

Since you are on PC, you don't have to go through all the hoops to get it to work with the wheel. Take a look at what @Locoblade did https://github.com/GeekyDeaks/g29-load-cell/issues/1 for another option

maelstrom · Jun 5, 2020

Warren Dawes said:
I am planning on getting a load cell brake pedal set at some point though, maybe the Fanatec CSL Elite.

I recently upgraded to LC pedals and looked at the CSL Elite LCs but opted for the TM T-LCM pedals. Better designed loadcell, easier to adjust and with hall-effect sensors on the other pedals rather than potentiometers. Not to mention that they cost less than the Fanatec product. Highly recommended.

tony wright · Jun 5, 2020

I have a hydraulic brake in my old set of G25/27’s (mention both as I have two sets sat in the loft and not sure if there 27’s or 25’s) called the Perfect Pedal. I bought the mod a few years back for £250

. Brake has been faultless over the last 5/6 years and never let me down once, so I suppose it hasn’t turned out to be too bad in terms of value (Man maths

). As a guide, I’ve just paid near on £700 for my new pedals (Meca Cup 1’s) and not improved my times one iota

. Heres a video from Sean

Locoblade · Jun 5, 2020

Jeepers £250

I realise you bought it a long time ago when options were presumably a lot more limited but can't imagine they sell many now, surely just get the Thrustmasters mentioned above for under £200 or throw £100 extra at the problem and get a set of Fanatec Clubsport V3s.

tony wright · Jun 5, 2020

Possibly... although you still wouldn’t have a hydraulic brake. My new MC1’s have a 100kg loadcell brake, but still not as stiff as the PP, you could easily stand on it without fully compressing it. I justified it by telling myself there was no way I could get a set of pedals with a hydraulic brake for under £250, simple man maths again

. I also replaced the springs with stiffer ones, on the clutch and throttle and mounted the pedals separately (out of plastic case) via a Leo Bodnar cable. Once I put my headset on you would be very, very hard pushed to know they were Logitech pedals from the feel.

In fact, it would be interesting to test on a non sim guy to see what his thoughts were once the headset was on and not able to see them.

Locoblade · Jun 6, 2020

Not tried what I'd consider a proper set of load cell pedals or a hydraulic one to compare so not in the best place to judge but a couple of reviews I read on DIY hydraulics suggested the difference in feel to a decently set up load cell was minimal and the hydraulics were more faff to maintain and also generally bulky (although in your case that piston is very neat and compact).

I've gone along a similar path with my G25 pedals bar the external mounting, strengthened up the throttle spring, added the load cell mod above and installed a Leo Bodnar module to make them a separate standalone device. They do feel quite good now so wouldn't be the first thing I upgrade if I find space for a dedicated rig that can handle a better wheel etc

Neilski · Jun 6, 2020

Locoblade said:
and installed a Leo Bodnar module to make them a separate standalone device

What's the benefit of the separate device approach, vs. allowing the Logitech ADC to do the job? Seems like it's more hassle, so I guess there must be some wins to make it worthwhile...

GeekyDeaks · Jun 6, 2020

Neilski said:
What's the benefit of the separate device approach, vs. allowing the Logitech ADC to do the job? Seems like it's more hassle, so I guess there must be some wins to make it worthwhile...

The resolution of the ADC is 8 bit which some consider a little too granular. It also wants the voltage to go high for 0 brake which is fine for a plain old pot, but when you start mucking around with a loadcell amp it means you need some way to reverse the gain.

tony wright · Jun 6, 2020

No faffing with mine. Installed straight out of box and not touched again, no leaking, nothing

Neilski · Jun 6, 2020

GeekyDeaks said:
The resolution of the ADC is 8 bit which some consider a little too granular. It also wants the voltage to go high for 0 brake which is fine for a plain old pot, but when you start mucking around with a loadcell amp it means you need some way to reverse the gain.

Ah, OK. I guess perhaps not all sims allow you to invert a pedal axis.
Personally I doubt I could tell the difference between a 5-bit ADC and a 16-bit one on the brake axis

Probably worth having some extra bits on the throttle, but 8 still seems like plenty for a driver of my limited precision. (Of course, the inputs probably don't always use the entire voltage range of the ADC. I keep meaning to hook up a multimeter when I take my G27 pedals apart to service the godawful pots, but somehow I never remember.)

Locoblade · Jun 6, 2020

Neilski said:
What's the benefit of the separate device approach, vs. allowing the Logitech ADC to do the job? Seems like it's more hassle, so I guess there must be some wins to make it worthwhile...

The main reason was that for me as an electronics baffoon it was easier to do that than make the custom PCB that Scott designed, but yeh the LeoBodnar module does increase resolution for all 3 pedals which in theory should help. The module also has various other inputs you could use for a button box etc if you so wanted, although I've not gone down that route yet.

GeekyDeaks · Sep 13, 2020

stribbeck said:
Do you have a guide to make the load cell mod? Thanks

Did you do any of the mods in the end? If not, I have acquired a 3D printer now and I'll be happy to print a copy of the cell holder I used. You will need a few other bits though!

stribbeck · Sep 13, 2020

Hi Scott, that sounds amazing, what other bits would I need?

Neilski · Sep 13, 2020

GeekyDeaks said:
Did you do any of the mods in the end? If not, I have acquired a 3D printer now and I'll be happy to print a copy of the cell holder I used. You will need a few other bits though!

I'm contemplating the very same thing

Have already bought the load cells (damn, but it's hard to get them to register anything on a multimeter!). Was reviewing your list of bits and trying to work out where I'd acquire them, or at least adequately similar bits. Advice gladly received