21 replies to this topic

[Cammy46]

Evening folks,

I am in the process of rebuilding a 998 A series and I’m currently at the stage of fitting the timing gears etc.

Today I put together the camshaft sprocket, locking washer and torqued the nut to the appropriate spec. However, on checking the end float I’m getting basically zero. I understand the spec to be 0.003 to 0.007 but I’m getting essentially no movement.

Everything is either new or refurbished, i.e new cam, new triangular retaining washer, new duplex sprockets. Any suggestions would be greatly appreciated.

Thanks, Cammy.

[Spider]

To check the end float, I'd suggest doing it with only the crank fitted and use a lever (I find a 18" tyre lever good for this), not so you can 'lay in to it' but be sure you are moving the crank across it's end float range.

 

Also, some of the thrust have their part numbers etc stamped in to the back of them, which can leave raises frazes around the stamping, a few wipes on an oil stone (or fine emery on a flat block) can soon sort these out.

[stoneface]

Hi Spider,

Camshaft not crankshaft :) easy mistake.

[imack]

Specsavers?

[Spider]

Hi Spider,

Camshaft not crankshaft :) easy mistake.

 

Hahaha,,,,, yeah, I saw that,,,,,

 

 

Specsavers?

 

 

I doubt that would even help !
 

[Spider]

Coming back to answer the question asked,,,,,

The common method is to machine some off the back of the Sprocket. If it's locked up on the thrust plate, you'll want to measure your thrust plate thickness and then the step to the face on the sprocket to see what the difference is and how much you need to machine off.

[imack]

Is there any end float without the oil pump fitted?

[Cammy46]

Coming back to answer the question asked,,,,,

The common method is to machine some off the back of the Sprocket. If it's locked up on the thrust plate, you'll want to measure your thrust plate thickness and then the step to the face on the sprocket to see what the difference is and how much you need to machine off.

Thanks Spider. I think that may be the only option…

The only other thing which is sticking with me is I used a fancy new alloy timing backplate but when installing I noted it was considerably thinner than the traditional steel back plates. Given that the triangular retaining sits on top of it I think it may be worth refitting everything with a steel backplate before machining the sprocket just to check.

[Cammy46]

Is there any end float without the oil pump fitted?

This is without the pump fitted, but nut torque to the required spec.

[nicklouse]

 

Coming back to answer the question asked,,,,,

The common method is to machine some off the back of the Sprocket. If it's locked up on the thrust plate, you'll want to measure your thrust plate thickness and then the step to the face on the sprocket to see what the difference is and how much you need to machine off.

Thanks Spider. I think that may be the only option…

The only other thing which is sticking with me is I used a fancy new alloy timing backplate but when installing I noted it was considerably thinner than the traditional steel back plates. Given that the triangular retaining sits on top of it I think it may be worth refitting everything with a steel backplate before machining the sprocket just to check.

 

Sounds like that is the issue.

 

sounds like a company that can’t make parts to the correct spec or it bypassed QC.

 

had no such issues with the alloy timing cover assy I fitted.

[Ethel]

Tying to visual it:

 

Surely the endfloat is the thickness of the triangle plate compared to the recess between the end of the cam & the sprocket?

 

That's either the plate itself or the sprocket being out of spec.

[KTS]

Tying to visual it:

 

Surely the endfloat is the thickness of the triangle plate compared to the recess between the end of the cam & the sprocket?

 

That's either the plate itself or the sprocket being out of spec.

 

i'd agree; the cam floats against the triangle plate

 

i have a vague recollection of thinner aftermarket timing plates causing problems getting the cam and crank sprockets lined up (solved by using thicker gaskets?)

[Cammy46]

Thanks for the replies folks, I went and investigated a little further this afternoon and you’re quite right the cam floats against the triangular plate and the timing backplate isn’t involved with cam end float.

After a bit of head scratching I turned down the cam sprocket “step” by 7 thou and that has now given me the required end float within specification.

Much appreciated for the input, you’ve saved me quite the headache!

Edited by Cammy46, 18 July 2023 - 04:21 PM.

[Spider]

Yes, I couldn't see how the thickness of the engine plate would have an effect here, unless the opening in it wasn't big enough for the front journal. It may put it in a slightly different location and that's all.

A lot of people knock some of these parts as not being fit for purpose etc when they don't fit out of the bag, however, some are supplied this way so the builder can adjust them (in this case by machining) to set them at the fit they are seeking.

[nicklouse]

So are your sprockets aligned? Can you remove enough spacers that were on the crank?