I need to change the taper in the cast sierra hub carrier for the bottom ball joint. I don't know how to specify. The taper on the 'new' hub carriers is currently from 17mm down to 13mm over a distance of 20mm. That makes a cone with an angle of 11.4 degrees at the pointy end. The bottom ball joint taper and old upright taper hole is a cone with a pointy end of about 5.6degrees and 18mm/16mm entry/exit diameters over a depth of 20mm.
Just how do you specify taper reamers?
Would you drill out to 16 mm with a normal parallel drill and then ream?
(Seems as if a reamer doing the job would find it hard work.)

[Edited on 18/6/12 by Dusty]

About 90% of automotive taper reamed holes are 1:6 or 1:8 i.e. 1 unit of diameter increase for every 6 (or 8) units of length. I'd be surprised if it's not one of these sizes.

Yes, you definitely start with a parallel hole.

Check THIS post.

I did read that post and found it unhelpful. Did you read it and the link it points to? Would you say they are suitable for the task? Which one do you advise I buy? The 12mm or the 19mm? They do have the right taper do they? I couldn't find a specification I could understand.

Parallel hole is good. I will have to re-measure the ball stud to check the taper.

Yes. yes,19mm and yes. I have reamed 3 pairs so far with mine and a lot of LCBers have used them.
These reamers have been discussed many times on here, and the conclusion is that they are suited to the job i.e they work.
Do a search for Axminster reamer, should be a couple of dozen threads by now

[Edited on 18-6-12 by 40inches]

I'm being stupid/blind. I can see no specification on the taper of this reamer. Something on it is 12mm or 19mm. My guess would be that is the largest end of the cutting area but it could be the taper ratio, 1:12 or 1:19. I asked the original question as a non engineer to try to discover how to specify what I need when ordering. Re-measuring the ball stub it seems to be a 1:8 taper. Is the 19mm reamer in the link a 1:8 taper?

Why worry about spec when everyone is telling you that the 19mm reamer in the link is the correct one to use, it's not like there is a choice of 19mm reamers there is only one. When you use it you ream a bit, try the ball joint for it, ream a bit more etc until the ball joint fits, you obviously don't just ream until you reach the end of the reamer. You should ream it out until the shoulder of the ball joint at the threaded end is slightly below the level of the upright - please correct me of I am wrong - so when you tighten the nut it can pull the taper.

quote:

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Originally posted by jabs
Why worry about spec when everyone is telling you that the 19mm reamer in the link is the correct one to use, it's not like there is a choice of 19mm reamers there is only one. When you use it you ream a bit, try the ball joint for it, ream a bit more etc until the ball joint fits, you obviously don't just ream until you reach the end of the reamer. You should ream it out until the shoulder of the ball joint at the threaded end is slightly below the level of the upright - please correct me of I am wrong - so when you tighten the nut it can pull the taper.

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a production car does not have full contact on its balljoints/tre's tapers thay are designed so the angles are slightly diffrent
you need a tiny bit more of an angle on the male part so you get a contact patch at the fat end if that makes sence

Like this?
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Description [/img]

Service from Axminster tools was next day. Fits the old taper perfectly so will reproduce that taper in the 'new' hubs. Result.
Thanks to all.