Villeman Posted September 12, 2016 Share Posted September 12, 2016 (edited) Hi, i have a quick question, I just followed the article to adapt a 240sx gearbox with the help of a modified 280z 4 speed bellhousing to my Z. Question is, we opened the lower bearing from 58mm to 62mm but how much clearance do you need? My father argues that a H7 should be good, the mechanic used 1.5 hundredth (negative) , so its 61,985mm for the bearing to be pressed it... since the borrowed tool is still there, is a negative clearance okay with a aluminium bellhousing? I am refering to this article http://zhome.com/ZCMnL/tech/240SX5spd/transmission.htm they tell you to increase the size since the bearing will be pressed in by the shaft during assembly, but we ended witha bearing stuck in the bellhousing while disassembling it. Anybody done that before? Would hot assembly be an option? Edited September 12, 2016 by Villeman Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 12, 2016 Share Posted September 12, 2016 Can't tell if you're about to open the hole or you've already done it. You could measure the existing hole to see what Nissan did. I think that Nissan set their specs for a hot transmission case. For example, the countershaft bearing preload shim. Quote Link to comment Share on other sites More sharing options...
Villeman Posted September 12, 2016 Author Share Posted September 12, 2016 already did open it + don´t have proper measuring equipment (i know..... ) I was just interested because I assume with aluminium I have one shot of getting it right. Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 12, 2016 Share Posted September 12, 2016 You said said disssembly but it looks like you mean assembly. "we ended witha bearing stuck in the bellhousing while disassembling it. " Sounds like you used a .015 mm interference fit and now you cant' get the bearing in. .015 mm on a 62 mm bearing. Doesn't seem like it should be a problem. I know what I'd do but the pros would have a more valuable opinion. Good luck. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted September 12, 2016 Share Posted September 12, 2016 I don't know what my machinist set mine to but I know that it isn't an interference fit and slides right together. Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 12, 2016 Share Posted September 12, 2016 Some reading - http://www.nskamericas.com/cps/rde/dtr/na_en/na_literature_bearing/07_TechTalk__Getting_a_good_fit.pdf http://www.ntnamericas.com/en/product-support-and-training/shaft-and-housing-fits Quote Link to comment Share on other sites More sharing options...
Villeman Posted September 12, 2016 Author Share Posted September 12, 2016 (edited) Well, the bearing was stuck while we took the C gearbox apart, so i assumed it was meant to "stick". If it´s supposed not to be pressed then we screwed it up...should have checked before I haven´t tried to assemble it so far, we just still had the tools so we could have widened it some more. I guess it will be trial and file ...... Edit: NewZEd thanks for the read, that tells me I should have had more clearance right.... darn... Edited September 12, 2016 by Villeman Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 12, 2016 Share Posted September 12, 2016 Not necessarily. Consider the working temperature of the transmission,probably at least engine temperature. The aluminum will expand quite a bit. If it drops in with a little bit of heat, it will be a "loose" fit during usage. Quote Link to comment Share on other sites More sharing options...
Villeman Posted September 13, 2016 Author Share Posted September 13, 2016 I was just afraid the aluminium might crack while pressing in the bearing? Quote Link to comment Share on other sites More sharing options...
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