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| Rotor size http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=63447 |
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| Author: | Fern30 [ Mon Oct 31, 2011 12:55 pm ] |
| Post subject: | Rotor size |
Hi all, Have an awful brake judder when i press the pedal at over 50mph, slows down a little at slower speeds and becomes unnoticeable at 30mph or less. Guessing rotors/discs. Rang my local autoparts store and he says he has 2 sizes for a kj my year? One 280 something and one over 300mm in diameter. Without taking my discs off cant get an accurate measurement. I think they are 285-290mm in diameter. Does anyone know the size? 2002 KJ 2.5CRD. Manual. |
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| Author: | Fern30 [ Mon Oct 31, 2011 2:20 pm ] |
| Post subject: | Re: Rotor size |
I believe the 2 sizes are 288mm or 302mm.Think mine are the 288mm. |
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| Author: | Fern30 [ Mon Oct 31, 2011 3:02 pm ] |
| Post subject: | Re: Rotor size |
Right, after some digging the specs are for KJ's with 15" wheels disc/rotor size is 288mm. For 16" wheels size is 302mm.(At least here in uk?) Pretty sure mine are 288mm but i have 16" wheels? They look pretty new and were put on by the previous owner. Can you mix up the sizes? After all only 14mm difference in diameter between the 2? If mine should be 302mm and they've put 288mm ones on, could that cause the wobble? |
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| Author: | Fern30 [ Wed Nov 02, 2011 9:24 am ] |
| Post subject: | Re: Rotor size |
This is getting ridiculous! Nobody can tell me what flamin size my rotors should be! The dealer puts in my VIN number and all he can give me is a part number? Searching on the web with all the Mopart stores all the info i get back is 'Rotor' $130 etc no size.  Can anyone help me with the size of the rotor, part number;52128247AA? |
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| Author: | infernicus [ Wed Nov 02, 2011 12:34 pm ] |
| Post subject: | Re: Rotor size |
Hey, I think if you might have posted in the non-CRD section, you might have had more hits.. I don't think any KJs came with 15" rims. Mine came bone stock with the 16" Alloys. With that being said, according to NAPA I'm not sure which link will work, probably both. - http://www.napaonline.com/Catalog/Catal ... ecType%3aA) - http://www.napaonline.com/Catalog/Resul ... 38+2038037 Quote: Attributes: # of Bolt Holes : 5 Bolt Circle Diameter : 4.5" Brake Rotor Diameter : 11.34" Brake Rotor Discard Thickness : 1.02" Brake Rotor Thickness New : 1.1" Brake Rotor Type : Disc Brake Rotor Only Center Hole Diameter : 2.84" Height : 2.55" Maximum Lateral Runout : .002" Brake Rotor Diameter : 11.34 inches is 288mm, I hope this helps. I've used that brake rotor on my 2007, 3.7 gas Liberty. 
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| Author: | Sir Sam [ Wed Nov 02, 2011 1:22 pm ] |
| Post subject: | Re: Rotor size |
First things first, I don't know why anything shows a 15" option for wheels. NO KJs where ever sold with a 15" wheel. I show that the only option for rotors in has an outside diameter of 11.34500 in = 288.16300 millimeters If we go back a generation to the XJ(which is known as the cherokee both in the US and abroad, whereas the KJ is known as the liberty in the US, hence I was thinking it might have lead to some confusion in terminology for parts) the rotor size is 11.03 in = 280.16200 millimeters so its not being confused with the XJ rotor. When I look up the outside diameter for the Grand Cherokee(WJ) I get 12 in = 304.8 millimeters. So it may be that the rotors you are looking at are being confused between the grand cherokee (WJ) and the Liberty/Cherokee(KJ). In any case I show that the rotor diameter you need is 288mm, so I would go with that. |
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| Author: | Fern30 [ Wed Nov 02, 2011 1:36 pm ] |
| Post subject: | Re: Rotor size |
Cheers for the replies guys, going with the 288mm rotors. Hope this solves the judder? although the pads look almost new, would you replace them as well? Better to start with a new set of both pads and rotors? |
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| Author: | Sir Sam [ Wed Nov 02, 2011 1:54 pm ] |
| Post subject: | Re: Rotor size |
Fern30 wrote: Cheers for the replies guys, going with the 288mm rotors. Hope this solves the judder? although the pads look almost new, would you replace them as well? Better to start with a new set of both pads and rotors? I think what you are referring to as a "Judder" we would normally call warped rotors. In that case its usually just new rotors that are needed. Typically warped rotors are caused by excessive heavy braking, I see a lot of this in my state(the lowest point in the state is 1010m, and the highest is 3315m), with so many long downhill sections it is possible to get the rotors quite hot if you down know how to drive properly(which sadly many people do not). However in areas with much less elevation it is harder to get that type of workout on the rotors, in which case cheap or bad pads can cause glazing or other wear issues which contribute to the problem. So it may be possible that your pads contributed to the rotor "warpage" or it could just be that the rotors are old and have seen lots of use. If you could determine that the pads were of good quality then I would say keep them. If they are the cheapest thing you can buy, maybe invest in some better pads. |
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| Author: | jinstall [ Wed Nov 02, 2011 5:47 pm ] |
| Post subject: | Rotor size |
For all of you that say the KJ did not come with 15" wheels might want to look at the OP first post of where they are located, indeed the KJ was sold with 15" wheels. |
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| Author: | Sir Sam [ Wed Nov 02, 2011 6:11 pm ] |
| Post subject: | Re: Rotor size |
jinstall wrote: For all of you that say the KJ did not come with 15" wheels might want to look at the OP first post of where they are located, indeed the KJ was sold with 15" wheels. I looked very intently at his location, as evidence by my conversion to logical measurement units. I would love to see some proof. The Jeep parts fiches show no evidence of anything other than 16" or 17" wheels, and these are fiches that include export information. |
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| Author: | papaindigo [ Wed Nov 02, 2011 7:28 pm ] |
| Post subject: | Re: Rotor size |
Guys maybe I am missing something here. "judder" I take to mean shake which is warped rotors which I've seen with and without heating so I think we can agree rotors need replacing. As to rotor diameter I have no personal opinon but given the 2 possible options of 11.3" vs almost 12" I can tell the difference on the vehicle with 1 board and 2 carpenter squares; I'll leave it to the group to figure out how from there. After all the difference is nearly 3/4" which is huge. Of course that assumes the vehicle in question has the proper rotor size to begin with. |
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| Author: | Fern30 [ Thu Nov 03, 2011 11:35 am ] |
| Post subject: | Re: Rotor size |
Took it down the parts store, tried both rotors. 302mm wont go on by a smidge, just too big. Went with the 288mm ones. Anyway, wobble,judder,shimmy,shake or shudder, whatever you call it-GONE!  Cheers for the replies. 
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| Author: | Sir Sam [ Thu Nov 03, 2011 12:01 pm ] |
| Post subject: | Re: Rotor size |
Fern30 wrote: Took it down the parts store, tried both rotors. 302mm wont go on by a smidge, just too big. Went with the 288mm ones. Anyway, wobble,judder,shimmy,shake or shudder, whatever you call it-GONE! Cheers for the replies. No problem, make sure you read the noob guide and clean your MAP. |
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