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Re: One wheel always locking before the other
Posted: Fri Apr 09, 2021 3:58 am
by emsvitil
Take it out and see what's inside it.
Re: One wheel always locking before the other
Posted: Fri Apr 09, 2021 4:30 am
by AC sports
I thought it was a joiner.....but now you all have me thinking otherwise. It's basically a hex nut shape. No further markings or complications.
Gotta pull half the car apart to get to it.
Car is oem with 4 wheel discs.
Re: One wheel always locking before the other
Posted: Sat Apr 10, 2021 5:13 am
by enigma57
David Redszus wrote: ↑Tue Apr 06, 2021 11:21 am
After pressure testing about a dozen prop valves, I found the knee of the curve point and pressure slope to be very inconsistent. Inconsistent meaning that each model had its own characteristics and readings varied even within a single model. Prop valves must be carefully selected. The lever type were the worst of all and should be carefully pressure tested before use.
Once upon a time, a brake pressure accumulator was installed to dampen and smooth line pressure pulses.
I don't know what happened to them.
Our solution for brake optimization for race cars is to retrofit an ABS system, with all relevant data going into
a data logger.
Yes, I see what you mean, David. Thanks for the info. I had forgotten about the hydraulic pressure accumulators. In the '70s, we removed the originals from an old diesel boat (submarine) hydraulic system, and after 38 Shop aboard the tender reworked them, I brazed the piping joints for the reinstall. It was the Salmon (SS-573).......
Also looked at the photos provided by OP and I believe he does indeed have residual pressure valves in his hydraulic braking system as several posters have alluded to.
That could very well be a contributing factor to his uneven braking issues. Residual pressure valve....... 2 lb. for disc brake applications and 10 lb. for drum brake applications. Could be that either someone installed mis-matched valves or possibly the old ones are just not functioning correctly and need to be replaced.
Here is a general listing. Several pages of them......
https://www.amazon.com/residual-brake-v ... rake+valve
Hope this helps,
Harry
Re: One wheel always locking before the other
Posted: Sun Apr 11, 2021 11:55 am
by AC sports
Residual pressure valve huh? Interesting. If it is, why would it cause a lock up on that side though? It happens in all circumstances when brakes are applied hard. Unfortunately I need to pull the carbies and manifold off to get to it. Pain in the butt right now. When I do I'd be very keen to see.
Like I said. It seems to have evened out with ballast....but am I just compensating for something else?
Re: One wheel always locking before the other
Posted: Sun Apr 11, 2021 1:21 pm
by chimpvalet
I'm confident the X1-9 has an inherent propensity towards uneven locking at the front, as recounted in my earlier posting. Therefore it may be more a matter of what efforts have already been made in attempting to mitigate this, and whether or not they were helpful.
Re: One wheel always locking before the other
Posted: Mon Apr 12, 2021 1:53 pm
by AC sports
chimpvalet wrote: ↑Sun Apr 11, 2021 1:21 pm
I'm confident the X1-9 has an inherent propensity towards uneven locking at the front, as recounted in my earlier posting. Therefore it may be more a matter of what efforts have already been made in attempting to mitigate this, and whether or not they were helpful.
The x1/9 uses the same calipers as these. Its doesnt run a servo as standard either. The main difference between the x and the 124 is weight distribution.
I'll check the brake force first on a brake force machine, then I'll check out that connector/ valve and see what it really is. Last I'll check cross weights .
Re: One wheel always locking before the other
Posted: Tue Apr 13, 2021 12:17 pm
by chimpvalet
Seems I lost the thread somewhere, thought we were discussing an X1-9. I know the 124's ran the same sort of braking kit therefore would correlate with thoughts on the flexing of caliper brackets at least. Same goes for the slider inserts sticking under load.
Re: One wheel always locking before the other
Posted: Fri Apr 23, 2021 1:12 pm
by AC sports
Well, I made it to the test machine. Remember the car is right hand drive. It's the left that's been locking up.
Results below. It seems theres a 4% imbalance at the front and 6% in the rear. The operator said its perfectly normal.
Looking at the shock absorber results I think the imbalance is too great and I also need to tighten up the fronts.
Heres a print out.
Re: One wheel always locking before the other
Posted: Sat Apr 24, 2021 1:16 pm
by chimpvalet
I'd guess that's an MOT test printout. If so, not really up to snuff in terms of optimising for race performance. The Lotus community firmly endorse Northamptonshire Motorsports ( if I recall the name correctly ), are you within reach of them?
Re: One wheel always locking before the other
Posted: Sat Nov 27, 2021 3:36 am
by gruntguru
Is this RHD or LHD vehicle - you refer to "passenger side" and the report refers to L and R?
Are those maximum brake force values? (They usually are for a safety test) If so, the numbers for the fronts will show tractive effort at lock-up, which reflects tyre friction coefficient and corner weight - not L/R brake balance. (The rears are clearly not locked - the Park brake shows higher numbers - but this could be due to a pressure limiting valve on the rear circuit.)
If the fronts were locked for the test, you can still get what you want from this machine by repeating the test a few times with different pedal force and no lockup.