The Lotus Grand Tourers

Can anyone tell me how the fixed slide Bush is attached to the front caliper.

After removing the single M8 bolt, I can now swing the caliper up away from the pads (top slide was seized but eventually was persuaded to free up).

I then tried pushing the bottom Bush out that the M8 fixing bolt passes through, but it's very tight to move. With a bolt and socket to draw it into, I can move it both ways, but is very tight. It feels like it is intentionally VERY tight press fit into a rubber sleeve. I'm thinking it might be intended to act as a kind of spring return to help pull the caliper back slightly when the brake pressure is removed. In this case, there's nothing wrong.

Or should it be free sliding, metal on metal, with a rubber boot each end?

Both sides are acting the same, so I'm hoping it's the top case.

Tony

Hi Tony

I'm overhauling my front calipers at the moment so I've taken them apart completely. With the bolt removed you should be able to slide the steel bush back and forth easily within the gaiter with finger pressure only.

The rubber gaiter should project an equal amount each side. The steel bush should be a push fit into the gaiter, and each end of the gaiter should engage in the groove in the bush. Copper grease bolt to bush, rubber grease bush to gaiter.

Cheers

John

Thanks John
I was tempted to remove the caliper from the car so I could attack it properly, but whilst there was a possibility it was operating correctly (particularly as both sides were the same) I was hesitant.

Now I know they've got to come off sometime soon.

Have you found a source for spare bushes and or rubber seals?

Tony

Tony

BIGGRED have a good selection

https://www.ebay.co.uk/itm/for-TOYOTA-C ... SwfwdfAbpn

I'd seen that set on Fleabay. It was the picture of what looks like a rubber bush with gator moulded each end that made me think the bottom bush may have been a tight fit in a rubber bush.

Or are the contents of the kit not what they appear in teh picture?

Tony

Hi Tony

I got a caliper rebuild kit from SJ Sportscars, you get a piston seal & dust boot, plus the rubber gaiters for the top pin and bottom bolt, and the steel bush for the bottom bolt. There's one bit that's not included and that's the end cap for the sliide pin. The originals have a little rubber vent in them, SJ do a solid cap like a small core plug.

It all went together great except for the piston dust boot. I tried initially to fit the boot to the piston then feed the retaining ring into place after pushing the piston into place, but the only way in the end was to fit the boot into the caliper body, fit the retaining ring, then pull the top of the boot over the piston - easier said than done, but got there in the end.

John

2 years later and I'm rebuilding calipers and seals whilst redoing the suspension.
The corrosion in the bottom eye on the caliper was so much that it compressed the rubber boot onto the steel pin to such an extent that it was incredibly tight to move. Had to draw it out with a threaded rod and deep socket in the end, but it was mighty tight.
I have a question though.
I bought a seal kit from BigRed and all looks good and correct except that the recess in the piston for the dust boot is 49mm, but the dust boot they've supplied is 37mm ID. That seems a massive stretch to fit and I'm wondering if I have the correct dust boot. The OD of the boot is correct to fit the caliper though.
Tony

A picture showing the stretch needed.

On the left, the piston groove showing 49mm on the caliper gauge, on the right, a 37mm Internal dia of the dust seal.

Additionally, to assemble, the whole piston, with a 57mm OD must pass through the 37mm ID of the dust seal.
It's probably all as it should be, but I'll ring Biggred tomorrow - I need a kit for the rear seeing the state of the fronts in any case.

Tony

Hi Tony

I rebuilt my calipers in the last year or two and from memory the larger diameter is an exact match to the caliper body and the smaller inner diameter that attaches to the piston does appear to be too small and has to be stretched over the piston more than you'd expect. The only way I could get this to work was to fit the larger outer edge to the caliper body first, fit the spring retaining clip, then force the piston through the smaller inner part of the seal. Not easy when there's rubber grease on the parts, and I did split one of the seals in the process, but after a lot of cursing and a few false starts I got there in the end!

I found that by feeding the piston through at an angle you can trap a part of the seal and hold it in place with one hand, then feed the rest of the seal evenly over the full width of the piston - the trick is to do this evenly, otherwise the seal keeps slipping off. Easier said than done!

Good luck

John

Thanks John
I rang BiggRed today and they confirmed by part number moulded in to it that I have the correct part they supply in this kit. He did sound surprised it was going to need stretching so far, but at least I know I have the intended parts.
Yes, I agree the only way to assemble is to fit the seal to the caliper, then force the piston through ( the opposite to how it came apart).
I'll get it together, but my biggest concern is if the boot splits in a few months time due to the tension in it, especially as you say one of your split just trying to get together. I don't suppose you've had reason to look at yours in the last couple of years to know if they are still good ?
Tony

Hi Tony, no I haven't checked them but the brakes are not binding so I guess the dust seals are holding up. I was surprised at how much abuse they can take, as my first effort was an epic! Took a stupid amount of time until I realised that fitting seal to piston first then trying to secure the seal to the caliper body last was a duff plan. There's no way you can get the retaining ring in there properly.

Cheers John

Seal kit fully installed and the dust boot sits lovely.
I always knew it would be seal to caliper, then insert piston, but it's a fiddly exercise as you say John.
Even another pair of hands wasn't delivering success.
In the end, saviour came in the way of an old brass inside letter box plate off an old front door - Never throw anything away, especially if it's made of metal. Most thing find a use eventually.
The cross section was a nice hooked shape, so sliced 2 lengths off about 8 mm wide, then wrapped in tape to protect the rubber a bit.
A wipe of silicon grease from the kit and in they went. Just used the hooks like tyre levers.

I'm expecting the brakes to be transformed when back on the road. Prior, when the brake pedal was applied, I'm certain the relative "sliding" movement came only from the rubber acting like a spring. May have been enough hydraulic force to eventually correct for pad wear, but there was no way they would ever slide by hand. Now with new bushes etc, all slides just beautifully. And with a powder coat at the same time as the other suspension, I've effectively got a new caliper very economically.






Tony

Looking great Tony! Nice work

Pete

You won’t want to drive that through any puddles now.

Nice one Tony, that looks great, useful tip as well for getting the seal over the piston!

Cheers John