es_amixam

iTrader: (9)

After reading through maxmaxima91's J30 brake conversion thread, in which someone mentioned that Q45 calipers were also the same, I decided to try this upgrade myself. I found a set of calipers at a junkyard a few days ago and got a set of rotors today. I did some test fitting earlier this evening and out that there is only one problem which keeps this upgrade from being bolt-on.

Basically, the Q45 caliper bracket is a little shorter in height than the normal bracket. Due to this, the bracket cannot be bolted on, since it hits the rotor. This can probably be solved by machining the rotors down by about 3mm. I am going to send the rotors to a machine shop and see if that solves the problem. There are two other things which need to be done for this upgrade. One is modifying the dust shield, which needs to be bent backwards very slightly where the upper edge of the caliper bracket hits it. The other is adding two washers to the bracket bolts, so that the bolts don't stick out past the hole. You can also possibly use shorter bolts. To see if the caliper clears the factory 15" wheels, I bolted the caliper assembly without the rotor and fitted the wheel on. There was about a fingers' space between the caliper and the wheel.

This is what I have found out about this upgrade so far and I will post updates as they come.

VEvolution

Good luck with the upgrade. Something special about the Q45 calipers though?

aminus21

iTrader: (14)

2 piston..

es amixam, u state that there was about a fingers distance between the caliper and the wheel, does that mean it'll fit stock wheels????? if so, i guess ill be looking for some j30/q45 calipers..

es_amixam

iTrader: (9)

I didn't say the calipers are 2-piston? Oops!

Yes, they do fit the stock wheels, since the early (I think all 1st gen)Q45 wheels are also 15". That's what attracted me to this upgrade.

If you go to the original J30 conversion thread, there is more info+pics there.

Also, for those of you who are wondering, the Q45 caliper bracket is no thicker than the Maxima bracket.

internetautomar

iTrader: (30)

did you use the q45 rotors or the j30 rotors or max rotors?

JSutter

iTrader: (46)

well thats the same problem tilley ran into when he installed them on his 4th gen. does the q45 caliper fit into the stock tourque member?

es_amixam

iTrader: (9)

Brian: I used a Q45 rotor, but also tested the stock rotor to see how it would fit under the caliper.

Jon: The caliper does not fit, but it might with some grinding on the torque member. It hits the pad clip on both sides.

Oh yeah, one more thing I forgot to mention: If the stock caliper bracket is installed over the Q45 rotor, the pad clip rubs on the rotor from both sides. Also, the notches for the brake pads on the Q45 bracket are smaller than the Maxima bracket.

internetautomar

iTrader: (30)

so how did the stock rotor fit?

maxmaxima91

the stock rotor wouldnt work with the Q45/J30 caliper. Its because of the thickness. The stock rotor is only roughly 3/4 inch think and the J30 rotor is roughly 1-1/8 inch think. So if you put a j30 caliper on a maxima rotor the pistons would have to come 3/8 inch further out to make contact with the rotor. would probably not hurt anything with new pads, but as soon as the pads get some wear on them the piston would get pushed to far out from the cylinder, probably damaging it.

Jeremy

HTPerformance

iTrader: (6)

If y'all need Q45 calipers I can go get some. PM me and I will look into it.

Brian

505max94se

iTrader: (15)

haven't seen you here in a while. How's the svt focus?

HTPerformance

iTrader: (6)

I love it!

Much better commuting car for me in Boston. Had to take off my summer tires and put on the Artic Alpins a couple weeks ago.

-Brian

es_amixam

iTrader: (9)

The stock rotor had the same fitment issues with the Q45 caliper+bracket, since both rotors(stock and Q45) have the same diameter.

Using the stock rotor with the Q45 caliper would have two disadvantages. One, as Jeremy mentioned, is that the piston would be pushed out further. Two, and this is only my hypothesis, is that the stock rotor is designed to withstand the force of only one piston. The force of two pistons would possibly lead to premature warpage of the stock rotor, which is significantly thinner than the Q45 rotor. Again, this is purely hypothetical, and I may be wrong, so feel free to correct me.

DaWifey's90

iTrader: (3)

lemme see if i follow this correctly...

q45 caliper bolted on max - clears oem 15" wheel

stock max rotor diameter = stock q45 rotor diameter

q45 stock rotor thickness > maxima stock rotor thickness

can't use max brake pads on q45 calipers

q45 caliper grinds on stock/q45 rotor when installed on maxima


are the brackets between the two calipers interchangeable? i would think not but had to ask.

what part of the caliper hits the rotor? by machining the rotor down did u reduce the contact area of the pad?

es_amixam

iTrader: (9)

Correct

Yup

WAY thicker. As a reference, Z32(300ZX) rotors come in two sizes 26mm and 30mm. Q45 is 28mm.

Not if you use the Maxima TM

It's actually the bracket/TM which hits the rotor and actually jams it.

If you grind down the sides of the Q45 caliper, you can use it with the factory brackets/TMs. To use the factory TM, you need to also machine the inside of it, as well as use a 1/16" spacer behind the Q45 rotor so that is centers under the TM. This is how I set my brakes up.

Basically, the Q45 bracket/TM sits lower than the factory TM. Since the diameter of both rotors is the same, it gets stuck on the rotor. All that needs to be machined is about 3mm, which is needed for the rotor to just clear the TM, so I would say that the pad would fully contact the rotor.

DaWifey's90

iTrader: (3)

for a second i understood it...

so there's an up/down and a left/right ( inboard/outboard) adjustment that has to be made regardless of which bracket and t/m u use..

es_amixam

iTrader: (9)

Let me put it simply. There are two ways you can do the swap:
1. Mill 3mm off radius of rotor. Bolt Q45 rotor/caliper/TM on. End of story.

2. Grind sides of Q45 caliper to fit inside Maxima TM. Grind inside of Maxima TM to accomodate Q45 rotor. Space Q45 rotor out 1/16" from behind.

Hope this explains everything.

DaWifey's90

iTrader: (3)

yup...sorry for being a nuudge

es_amixam

iTrader: (9)

No problem, bro.

DaWifey's90

iTrader: (3)

ok..last one...what year q45/j30 applications? '94 right?

Jeff92se

iTrader: (82)

Here's a question. How do you actually like them?

es_amixam

iTrader: (9)

From what I can remember, all 1st gen Q45s(90-96) and all J30s(93-98) have the same calipers and rotors. I personally have tried calipers from a 91 and a 93.

es_amixam

iTrader: (9)

I haven't really driven the car in the past few weeks, and I still need to figure something out for the spacers behind the rotors, so I can't really say yet.

maxmaxima91

If you need a set of spacers.. i have some layin around....

Also, i know this questions wasnt directed at me... but im very happy with my brakes. They feel nearly stock with a bit more power. But knowing that there is alot more mass(to absorb heat) in the entire brake system makes me much more comfortable on the roadcourse.

Jeremy

es_amixam

iTrader: (9)

I'm interested in the spacers. PM me with details...e.g. cost, pics(if you have any), etc.

DaWifey's90

iTrader: (3)

what about the truck calipers...they're 2 piston as well...anyone measure the diameter of the 300zx, q45/j30 and truck pistons?