IS350 Caliper conversion to IS300h

lexusmoon · February 4, 2018

Been thinking about this for some time as I just dont like the small tiny calipers in the front. Also, for some reason I just can't get used to the sensitivity of the way it brakes...it just doesnt brake gradually to my feel (Just trying to find an excuse to do the conversion).

Anyhow, it does not seem it will be a 1 on 1 conversion considering the bracket mounting points seem to differ. Anyone got any clue?

rayaans · February 4, 2018

4 hours ago, lexusmoon said:

Been thinking about this for some time as I just dont like the small tiny calipers in the front. Also, for some reason I just can't get used to the sensitivity of the way it brakes...it just doesnt brake gradually to my feel (Just trying to find an excuse to do the conversion).

Anyhow, it does not seem it will be a 1 on 1 conversion considering the bracket mounting points seem to differ. Anyone got any clue?

It can probably be done but Id bet nobody has done it in the UK

Additionally, it won't change the brake feel as most of the time, its the regen on the IS300H that is braking, not the physical brakes

lexusmoon · February 4, 2018

Tx Rayaan, not sure I understand this part of the sentence since I am not a native english speaker; but when you say "its the regen on the IS300h", I am assuming you mean this is software related, not any mechanical parts than can adjust the sensitivity of the braking, right?

lexusmoon · February 4, 2018

Been checking on the US forum but they do the conversion from a 200T to 350 conversion, but when checking the bracket mounting points, they appear to be a 1:1 match. I am just trying to figure out if I need to purchase the bracket as well.

Andrew888 · February 4, 2018

The braking 'feel' is different on the IS300H as the gearbox itself is a generator to charge the Battery pack. So when the ECU knows that the car is coasting it will activate a clutch in the gearbox and magnets spin up like a dynamo to produce charge. I am a fan of big brakes as I have fitted Alcon, brembo, Spoon, Endless, Project Mu and AP Racing to cars but however these were 400whp onwards. I personally wouldn't on the IS300H is more of a cruiser/econ model compared the IS350 and IS200T - I would focus the cash for other priorities like saving up to get the thing serviced lol.

lexusmoon · February 4, 2018

35 minutes ago, Andrew888 said:

The braking 'feel' is different on the IS300H as the gearbox itself is a generator to charge the battery pack. So when the ECU knows that the car is coasting it will activate a clutch in the gearbox and magnets spin up like a dynamo to produce charge. I am a fan of big brakes as I have fitted Alcon, Brembo, Spoon, Endless, Project Mu and AP Racing to cars but however these were 400whp onwards. I personally wouldn't on the IS300H is more of a cruiser/econ model compared the IS350 and IS200T - I would focus the cash for other priorities like saving up to get the thing serviced lol.

You got a fair point there. That would likely be the wise choice, but guess I am just not the type to sit still...

Andrew888 · February 4, 2018

10 minutes ago, lexusmoon said:

You got a fair point there. That would likely be the wise choice, but guess I am just not the type to sit still...

To each and their own purely my own opinion. I would use the cash for other bits to enhance the looks personally.

J Henderson · February 5, 2018

If the IS300h has the same front brakes as an IS250 (and I believe it does), then it's a simple bolt-on upgrade. The only modification needed is that the dust shield/backing plate needs to be trimmed slightly to accommodate the larger caliper. Oh, plus 18" wheels are required to clear everything.

lexusmoon · February 9, 2018

When you say IS250, are you referring to 2nd gen or 3rd gen?

J Henderson · February 10, 2018

Either. They have the same brakes.

Thackeray · February 13, 2018

On 04/02/2018 at 3:30 PM, Andrew888 said:

when the ECU knows that the car is coasting it will activate a clutch in the gearbox and magnets spin up like a dynamo to produce charge

I'm guessing that you're talking metaphorically. As far as I understood the mechanics of the IS300h (which admittedly may be not very much) there's no gearbox and no clutch. Please correct me if anyone has better info.

There's no actual gear changing and the drive train is permanently engaged with the drive wheels. (Unlike on most automatics, there's no torque converter.)

From what I've found out on the internet, the IS300h uses the L210 drive train, which is a rear-wheel-drive version of the P310.

Here's a link to a description of the P310, which I assume is much the same apart from driving the rear wheels through a differential rather than the front wheels.

ColinBarber · February 13, 2018

10 minutes ago, Thackeray said:

As far as I understood the mechanics of the IS300h (which admittedly may be not very much) there's no gearbox and no clutch. Please correct me if anyone has better info.

There's no actual gear changing and the drive train is permanently engaged with the drive wheels. (Unlike on most automatics, there's no torque converter.)

From what I've found out on the internet, the IS300h uses the L210 drive train, which is a rear-wheel-drive version of the P310.

Here's a link to a description of the P310, which I assume is much the same apart from driving the rear wheels through a differential rather than the front wheels.

Correct

lexusmoon · March 9, 2018

On 2/6/2018 at 12:30 AM, J Henderson said:

If the IS300h has the same front brakes as an IS250 (and I believe it does), then it's a simple bolt-on upgrade. The only modification needed is that the dust shield/backing plate needs to be trimmed slightly to accommodate the larger caliper. Oh, plus 18" wheels are required to clear everything.

So I ordered a pair of 2nd hand IS350 2008 calipers and received them in the meantime. I just trial fitted them onto the IS300h. Like you said, it is a 1:1 plug and play. No adjustments required from bracket standpoint. Just need the trimm off a bit of the dust shield (bottom part). Now I need to order the rotors and actually do the whole conversion. Looking forward to it.

J Henderson · March 9, 2018

Good for you. I'm planning to do the same upgrade on my IS250 at some point this year.

I've already got the main components in place - the calipers, discs & pads, fluid etc. Plus some high-temp paint to make the calipers look nice. I just need to double-check whether I'll need to buy any small things like clips, shims etc and I'll be good to go.

Farqui · March 9, 2018

So the bigger IS350 calipers also clear the OEM IS300 alloys?

Andrew888 · March 11, 2018

After having a near miss in my IS where I personally found the brakes wasn't there when I needed it. I have decided to experiment with 4 Piston calipers. Yes I know my previous post contradicts myself however (Yes I will eat my hat) I decided to upgrade on a budget. This does not foul under the standard f Sport 18's

I bought the following for this conversion in which some things may not be necessary.

2 x GS300H recon'd calipers. (these are GS/IS250/IS300 (MK2) also)
New IS350 Dust shields as the IS300H are too small to clear the calipers
New bolts - Carrier, Hub
New shims
New Pad plate and pins
brembo pads (18 quid on Amazon)
ATE discs (from Mr Auto)
New IS350 Brake lines *however I think standard IS300H will fit
Techstream to bleed the system
VHT Matte black engine enamel
VHT Laquer
Fleebay Lexus Decals.

All in all with all the genuine parts it costed me around £500 - From a 296mm with 28mm thickness to a 334mm with 32mm thickness I can say the brakes are extremely sharp with less effort from the old setup. Old brakes still was around 27.8mm thick and pads has plenty of 'meat'. Bang for buck for a piece of mind safety aspect I found it well spent in which I am sure other forum members disagree and could spend that elsewhere.

Happy to help with part numbers etc I have this documented. However I did not buy from Lexus UK for any of the parts as they were 30% more expensive.

Andrew888 · March 11, 2018

On a side note: as the old calipers and brakes fit IS220D and IS200 - I'm sure these can be sold to these owners to recoup the initial investment. So the whole setup could be cheaper.

lexusmoon · March 13, 2018

I paid around the same as well. Bang for buck indeed and should be fairly easy to re-sell like you mentioned.

Was it easy to remove the dust shield as when I checked it seemed significant effort was required to get that replaced. Not so much in cost for the parts, but labor cost.

Btw, it looks awesome!!

Andrew888 · March 13, 2018

1 hour ago, lexusmoon said:

I paid around the same as well. Bang for buck indeed and should be fairly easy to re-sell like you mentioned.

Was it easy to remove the dust shield as when I checked it seemed significant effort was required to get that replaced. Not so much in cost for the parts, but labor cost.

Btw, it looks awesome!!

You will need to undo the 4 x 17mm bolts to release the hub bearing assembly. Have to be super careful as the ABS ring is built into the bearing and its kind of pressed into the suspension knuckle. If your mechanic is competent he will be able to figure it out without damaging it. The shield is 'sandwiched' between the hub and suspension knuckle.

lexusmoon · March 13, 2018

4 hours ago, Andrew888 said:

You will need to undo the 4 x 17mm bolts to release the hub bearing assembly. Have to be super careful as the ABS ring is built into the bearing and its kind of pressed into the suspension knuckle. If your mechanic is competent he will be able to figure it out without damaging it. The shield is 'sandwiched' between the hub and suspension knuckle.

Tx bud! very helpful info.

lexusmoon · March 22, 2018

Just got my calipers painted, now waiting for the small items to arrive and we're good to mount them on the car. Excited!

w77 · April 9, 2018

Looks nice. Where did you get your parts from?

lexusmoon · April 10, 2018

14 hours ago, w77 said:

Looks nice. Where did you get your parts from?

eBay

lexusmoon · April 11, 2018

Finally managed to get them installed today.

Loving the looks of it, but more importantly it actually fixed the braking issue I mentioned in my very first comment. Braking is now much more gradually consistent rather than a sudden "break". The bite definitely feels more firm and more aggressive when your fully stepping on the brake.

Really pleased with the upgrade!