Break compensator

[Bobfla]

My 1974 Spider break compensator is bad. I'm seeing conflicting advice on the web. Some say bypass it others say bypassing is not a good idea. Should I bypass the rear brake compensator?

[bradartigue]

The brake compensator is a safety device and is extremely easy to replace. The effort of bypassing the thing is equal to making it work, so why bypass it? When you do replace it also change out the four bushings that go into the rod ends, connecting it to the rear axle carrier. These make it function.

[So Cal Mark]

we've done well over a hundred bypasses without any issues

[GeorgeT]

The brake compensator was an early/crude method for anti-lock rear brakes. When the car would nose dive under hard breaking, when the rear of the body would come up the compensator would reduce brake fluid pressure to the rear wheels so they wouldn't lock-up. It's okay to eliminate it but it's better to have a properly functioning one.

[toplessexpat]

... it's better to have a properly functioning one.

I think this is the point. Sure, you can remove it. 99%* of the time that's going to be just fine and there's no lock up. As Brad said, it's really not that hard to replace, and I believe the parts are readily available from the usual suppliers.

It's my (amateur) belief that for its time it was pretty effective, and was what the car was designed to operate with. Those of us who've lowered the car, and otherwise fiddled with the suspension have caused it's geometry to change, and need to alter it a little anyway (bending the activation arm to match the original profile).

My 2c is to fix it.

A

* this is an illustrative percentage and not intended to indicate an accurate study has been undertaken!

[Odoyle]

I would recommend you replace it, the compensator should be around $30, it's a straight forward job. I did it for my first time a few months ago and had a pretty easy time replacing it. One thing to make sure is to NOT cross thread your fittings, and NOT to strip them. Would be wise to get a really tight 10mm wrench for the job. Here's some pics from my experience.

[So Cal Mark]

if your car has been lowered the compensator is completely ineffective

[zachmac]

BTW, cannot resist the obvious: no factory part compensated for a break, just lots of welding and bondo. Now a brake compensator, yes.

[bradartigue]

if your car has been lowered the compensator is completely ineffective

This isn't true at all, the compensator was used across the right height changes in the Spider; the early cars were considerably lower than the late cars, particularly in the rear end, and all maintained the device. Lowering doesn't eliminate the nose-heavy braking of these cars (neither does a brake upgrade btw, it actually makes it worse). Spiders also functioned properly with wheel height differences and changes in the differential/axle carrier. I can assure you hundreds of Spiders have managed to keep the functionality of this device by understanding what it does and keeping it functioning.

The logic in this thread is that you delete the parts that inconvenience you, or that are unlikely to ever be used. This is like going back to the old style master fluid reservoir, which would cause the entire system to fail if either side was to lose a hose, or deleting the fuel injection relay and direct wiring the pump. The likelihood of failure is near 0, but that's not a good excuse to remove a safety device from a car that has almost none to begin with.

[DieselSpider]

I have had a good number of cars with rear brake compensators and you generally should keep them in place and adjusted to the neutral position of your suspension regardless of ride height. In a hard stop as the rear axle gets unloaded they do help prevent rear wheel lockup and the potential for spinning out which is a good thing. The only time you will usually notice that eliminating it caused a problem unfortunately is once its too late and the rear end is now breaking loose and skidding hopefully not into another car, solid object or worst case pedestrians. If you eliminate the rear bumpers and lightened the rear of the car the device becomes more important while if you have the trunk loaded with 100+ lbs of stuff all the time then it may become less of an issue.

Might a car with the compensator removed appear to stop better than one with a broken one that needs replacing? Yes that could be the case however thats because system is broken and needs repairing not tearing out.

No they are not perfect and the brakes will work like cars from the early days of hydraulic brake systems if you remove them however they do perform a valid function and can make the difference between a controlled stop and a wipe out. Its like insurance, you may never need it however its not a really good thing to go without.

[kmoses]

Or you could remove/bypass the factory brake compensator (proportioning valve) and install a new one that is easy to get to and adjust. And added benefit is that the rear brakes are easier to bleed, just set the proporting valve for full flow and when bleeding is finished, return it to the previous setting.

[So Cal Mark]

I'm always puzzled by naysayers that haven't tried something before they dismiss it. If you take a late Spider and lower it, check the travel of the compensator and you'll find it's now out of it's range of travel. By lowering the car, you've raised the spring rates and the car sits much more level during braking, yes even really hard braking.
So if you're not interested in shorter braking distances, don't upgrade your system

[toplessexpat]

Having lowered our spiders, and run with and without the compensator (indeed right now one has it and one doesn't), my personal preference is to have them. They can be adjusted so that they work just fine when the car has been lowered.

Yes, the car doesn't dip as much, yes the compensator doesn't do quite as much as it does when the car was on stock springs.... But it does work.

I managed to lock up the rear (while pushing it quite hard) in the wet last weekend on the car without it.

It's simple to make them work - so make them work.

A

[Nanonevol]

By lowering the car, you've raised the spring rates and the car sits much more level during braking, yes even really hard braking.

Does that apply to cut spring lowering or only upgraded spring lowering?

[bradartigue]

I'm always puzzled by naysayers that haven't tried something before they dismiss it. If you take a late Spider and lower it, check the travel of the compensator and you'll find it's now out of it's range of travel. By lowering the car, you've raised the spring rates and the car sits much more level during braking, yes even really hard braking.
So if you're not interested in shorter braking distances, don't upgrade your system

I'm equally puzzled by advice to remove safety features of a car or the assumption that those commenting to the contrary haven't done this already.

This isn't an "upgrade" but a "tradeoff" and a foolish one. Your shorter braking distance is achieved by intentionally changing an engineered system to do what it was designed to prevent. It is too easy to do this correctly - and cheap, the part is $35 I think.