Lola T91/50 front brake rotor challenges

[mikey]

So I'm down to sorting the brakes on my F3000. I've noticed some issues with the setup that was on the car when I bought it.
In the front, the rotor very slightly interferes with the caliper cross bolts and has caused some self-clearancing. Is this an issue?

[tlracer]

Certainly I wouldn't be happy if these were mine. My first step would be to check the specified disc diameter for the calipers and compare this with the ones that are fitted.

Not only is it weakening the crossbolt physically, but it's not going to be doing the discs or correct braking any favours either.

[Garey Guzman]

Yeah, if the rotors are clearencing themselves, they are finding a "home" position and their floating charachteristic will be affected. I would suspect that something is not original and in all likelyhood, it's the rotors. Cutting down the OD by .050 or less should make all the parts play nice.

[J Leonard]

Are these radial mount calipers that need a spacer washer between the upright and caliper to move it further out.

[tlracer]

Are these radial mount calipers that need a spacer washer between the upright and caliper to move it further out.

Did a quick internet search on CP3344 and they do look like they're radial mounted. In which case the 'missing' spacer would solve all the issues, as:

a) The discs wouldn't rub on the crossbolt
b) The pads wouldn't interfere with the disc bell

J Leonard - well called!!!

[mikey]

Yes these are radial mount AP calipers. They have a 3344 cast into the housing and a 4152 stamped on the housing also.
They were shimmed, however it appears a non-standard washer was used which may not be quite thick enough. The washer/shim measures 0.062" thick.
A thicker shim would certainly fix the rotor clearance issue, but then the pad would either be right at the edge or slightly overhanging the edge of the rotor.

I'm beginning to wonder if these calipers are not the right ones for this car originally. everything seems to be off just a hair in the front and rear.

And Garey G is right - the "homing grooves" were preventing rotor float.

[mikey]

After further scrutinizing the calipers, it seems they have a different pad stop tab bolted on the inside than the rear calipers do (which are essentially the same calipers also marked 3344 / 3345.
The pad stop on the front has a raised edge. The pad stops on the rear are flat. If I used flat ones on the front the pad would drop down a little bit to compensate for shimming the caliper out for the rotor clearance. This would keep the pad from overhanging the outer edge of the rotor I think.



I'm wondering if they also make these pad stop tabs with an offset down, to go even further inboard if needed (I think it would help my issue with the rear brake setup as discussed in my other thread.)

[mikey]

Also meant to add that both the front and rear rotors measure 10-13/16" diameter (275mm). I'm having a hard time finding new ones. PF makes 10-15/16" that appear to be otherwise the same. It does not appear that my rotors were cut down to this smaller diameter.

[Garey Guzman]

Also meant to add that both the front and rear rotors measure 10-13/16" diameter (275mm). I'm having a hard time finding new ones. PF makes 10-15/16" that appear to be otherwise the same. It does not appear that my rotors were cut down to this smaller diameter.

No manufacturer name on the hat's?

Were the PF one's the same bolt pattern for the hat? If you got those, then your shim would need to be a little over 0.125 (maybe 0.135?)

Going to a slightly thicker shim as J Leonard said, would likely resolve your issues with the current parts. If you have a proper grinder (I think they were called surface grinders?), you might be good to go with shims at 0.070 or 0.075

[J Leonard]

It would not be uncommon to have custom rotors.

[mikey]

no name on hats.. bolt pattern for the PF discs looks the same in the photo but I didn't see dimensions or spec sheet. If I shim another 0.135 I'll have less than 0.05" wheel clearance.

[mikey]

It would not be uncommon to have custom rotors.

who offers them? are they custom beyond cutting down the overall diameter?

[mikey]

found in an info pack that this car allegedly had 6 piston AP calipers on the front originally. So that might be why the current 4 piston AP3344 (which match the rears) aren't quite working out on the front.. still looking for more tech data, trying to find out what size rotor was original. I confirmed the front rotor hat is the wrong one for the car also.

[mikey]

Updated my rear brake challenges thread as well...
For the fronts, I think I need to start with two stacked 0.062" shim washers on the radial caliper mounting bolts to get the proper rotor to caliper clearances. A brembo engineering drawing calls for 2mm spacing. This should fix the interference issue with the cross bolts and allow the caliper to float freely again.
Then I need to change the pad stop bits from stepped rests to flat, so that the pad will sit back inboard where it was before the caliper was spaced out another 0.062". I may be able to just flip the existing pad stop pieces around. See photo above earlier in this thread.
Then I am hopeful that the PFC 740 size pad matches the size of the custom fit (machined) pads that are on the car now. If that is the case, then only the rotor will be custom going forward, which as was pointed out, isn't a big deal and easy enough to source.


I will be ordering pads this week and will post once everything is all back together with results. Then I can take it back apart again to have new rotors made, matching the size on the car now. I should be able to use the same rotors for front and rear, at least on the same side of the car (directional rotor ventilation vanes).

Cheers,
Mike

[mikey]

Update:

Coleman Racing parts have arrived. They were able to make exact copies of all the features of my original hats and increase the flange thickness on the fronts as I needed to create the proper rotor centering. Also had them make two 0.100" spacer rings so I can use the original front hats with the new zero-offset rotors.

Rotors are now common front and rear, although still left and right handed due to directional vanes.

The Coleman discs have a narrower air gap - website said 0.420" but they measure 0.360". Original rears were 0.55" gap with 24 vanes and cross drilled, weighing 6lbs each. Original fronts were 0.50" gap with 30 vanes, slotted, weighing 7.5lbs each. Coleman have 0.360" gap with 30 vanes and weigh 9lbs each. All rotors are 1" thick, originals are 275mm, Coleman are 276mm.

I was very happy with the price, and now I can easily order discs in the future. Hopefully the increased rotor weight does not make much difference.

[march718]

Have heaps of F3000 discs and pads in stock
disc bells too for the Lola

[mikey]

Have heaps of F3000 discs and pads in stock
disc bells too for the Lola

you tell me this now? LOL

what do you have? Please PM me.

[march718]

you didn't ask the right person!!