Offset brake caliper

[Bobbie]

Hi everyone,

I'm currently upgrading my TR2 front suspension and brakes by fitting a kit from Revington. This involves 3 degree trunnions, upper wishbones from a tr4-6, and an adjustable top fulcrum to set accurate camber. The kit also has alloy hubs, and in general terms installation is fairly straightforward, given I have removed and rebuilt tr suspension and brakes a number of times. The brake upgrade is to go to discs from drums.

However to my surprise when the caliper is bolted up tight to the carrier, the disc is not central within the caliper. It is about 2mm adrift. Also the edge of the caliper, that’s the side nearest the wheel, is within about 2mm of the edge of the hub, this where the wheel seats, to me it’s a little too close. If I could centralise the disc, which ineffect means the caliper would move nearer the centre of the car, this would increase the above gap to around 4mm, which just feels a bit more comfortable. I note from the moss catalogue that adjusting shims are available, and they state to use as required. This would suggest that it is important the disc is central?  Unfortunately moss are out of stock, which I was pleased to learn as theirs are over £11 each, where as rimmers have them at around £7.50 each, both VAT inclusive. I phoned rimmers to ascertain they had stock today, and also to learn how thick they are, so I would know how many to order. To my surprise, once they physically checked stock, they stated each shim was .3mm, yes 0.3! That would mean I need 7 each side, 14 in total! Aside the cost, which as a safety critical item I wouldn’t compromise on anyway, this just doesn’t seem right.

so the question to the learned is, why is the disc not centre? Is it due to bearing seating etc? Is it usual to shim out? If it’s this excessive. Is a simple flat washer a better option than 7 very thin shims?

the callipers as supplied in the kit are “B” type as displayed in the moss catalogue, and fitted to later tr3.

Thanks in advance peeps, I haven’t spoken to revington yet, just wanted to establish why and if any of you have encountered this before.

 

regards Bob.

 

[BlueTR3A-5EKT]

First question.   How much paint have you put on the mating faces of all the parts?   This might be an issue as all those mating faces that are bolted together should be metal to metal.

If your answer is “there is no added paint” then get on the phone to Revington, because that will be the first question they should ask you.   If you do have paint on all those mating faces, strip the assembly, scrape it off and re assemble   The alignment should then have changed.    If not   Get on the phone.

You could use 1 mm thick plain steel washers to prove the alignment requirement before  lashing out on shim stock.   But why should you ?   That kit should be error proofed by the supplier, and if shims might be needed rest assured Revington will have put them in the kit.
 

[Bobbie]

Thanks for the prompt response Peter. The caliper has one coat of gold spray, which I put on. The caliper support bracket looks like it has been powder coated, and quite thickly by them. However if I were to remove the coating where the caliper abuts, this would make the alignment worse, and in effect move the caliper further out.

i will need to speak to revington I know.

[Z320]

Sorry, simple question:

the disc is too much outside or inside?

[Lebro]

Funny you should say that.   I have always had to insert washers (probably around 1mm thick) between the calipers & the mountings for them in order to centralise the disk. Thought it was just me.

This is on original calipers, original vertical links etc - nothing is repro.

Bob

[stuart]

It may well be the new hub thickness is putting the disc out however like Bob says you do often have to shim the calipers anyway, count yourself lucky its not a Jaguar mk2 or XJ series one as you couldnt actually reach to get the shims in due to the shape of the caliper mount.

Stuart.

[Bobbie]

Thanks guys, from the top…

Peter, I keep thinking about the thickness of paint, I painted the vertical links years ago, and didn’t notice if the caliper mounting bracket went over a bit I’d previously painted. Additionally as I may have stated above, I notice the caliper mounts are powder coated, between these two issues there could be 2mm there.

Z320, the disc is either too far towards the centre of the car, which I find impossible to imagine why, or the caliper is too far to the outside of the car. This would back up my/the theory that paint either on the mating surface of the vertical link, and/or paint on the mating surface of the caliper mount is causing this.

Lebro, thanks for that, my gut reaction was simply to put a flat washer in, which I suspect is about the same surface area anyway as the mounts on the caliper surrounding the bolt holes. To know it works ok is encouraging, it just feels wrong to have to do it. These are the original vertical links, with genuine mounts and callipers.

Stuart, my thanks, yes I’ve often looked at jaguar inboard discs, and thought did they put them in the most hard to get to spot out of spite?

Anyhow, I’m awaiting a call back from Neil Revington, but hopefully this evening will strip down one side and examine the relevant mating surfaces, where at the moment I think the issue may lie.

 

regards Bob.

 

[BlueTR3A-5EKT]

When you fit the wheel is there enough clearance between the threaded portion of the outer upper ball joint bolt and the inner surface of the wheel rim?     If not fit the bolt with the nut towards the front of the car on both sides.

 

[Z320]

Hi Bob,

o tell you waht paint causes which direction I must put the wheel of - waht I will not do.

But I an tell you this parts are often painted too much or even powder coated! While ther must not be any paint on a number of surfaces.

The day will come somebody paints the complete brake disc and the brake drums inside......

My previous owner panted the drums outside all around - caused slack whire wheels adapters.

Also the brake discs inside and the hub - causing slack brake discs.

next photo how I found it---

And how I cleaned it. This was only paint, if you ever had to remove powder coat you will never powder coat again...

As told above, the day will come.....

Btw: I not had to shim my calipers on my TR4A

Ciao, Marco

[Bobbie]

Thanks for all responses guys, 

peter, I haven’t got that far yet, but will check and reverse bolt as required.

marco, very interesting about paint, and why it shouldn’t be on these mating surfaces.

i spoke to Neil revington this afternoon who was pretty forthright about how the paint can move, degenerate and therefore in certain circumstances cause the joint so to speak to become loose. Although they supply the calliper mount powder coated, it is expected that the installer would remove surface covering as required to ensure metal on metal contact at the mating faces. I should have applied my engineering head more to this aspect, rather than just installing the kit, but I guess had assumed it was ready to go. Anyhow despite my eagerness to get on, I have a pretty full itinerary for the next week, including a family wedding in Scotland at the weekend, so will have to pause proceedings. Am I the only one, who having built up a full head of steam to get on with a project, find it frustrating when everyday life prevents you getting on with it. Heyho, it’ll be interesting what clearances alter once paint is removed from various faces.

[Trumpy3]

Bob

Re the cost of shims. From my recollection, one shim covers both mounting bolts. Hardened washers should be OK if needed. I have 4 spot aluminum Nissan Skyline calipers with a custom made mount. My original disc was a re drilled Chrysler Voyager unit ( same offset and diam as TR unit). This was fitted back in 2001 but since 2014 re-drilling disc became illegal here so needed to find an option. The only ventilated disc I could find (I need 25mm thickness) was the disc supplied by Moss in there upgrade kit. The only issue was a 3mm difference in offset. That was overcame with 3mm hardened washers.

I have done over 30000km since and no issues. As a matter of interest, there was a loss of braking effort with the new disk (material? they are Chinese). I had to replace my harder TRW pads to a softer road pad.

Brian

[Bobbie]

Thanks for that trumpy3! Very encouraging!

[Nigel C]

A few years ago now I made a large scale model of a caravan wheel bolt for a company. They had proved that most of the accidents where caravans loose there wheels is due to wheel bolts incorrectly torqued (due to drag/resistance/corrosion on the mating surface) and brake drums/wheels being heavily powder coated/lacquered.

The heat created by braking can soften the coating and cause the slightest of gaping/movement which increases with rotational/side loading etc. They were trying to get manufacturers to reduce or stop powder coating.

Their design of wheel bolt was supposed to reduce the torque drag when servicing, hence the cut away/large scale model for exhibitions.

 

.

 

 

[Bobbie]

That’s very interesting Nigel. I owned a caravan for about six months a couple of years ago, I’m usually a motorhome guy, and indeed have a Toyota camper van these days.

Annyhow I was amazed how paranoid caravanners are about wheel nuts coming loose, recommending that nuts are checked before every, yes every journey. What you have said may account for the focus on this area, as I know there are cases where nuts do come loose, and wheels come off!

 

regards Bob.