964 Tipo under full load
 

I've noticed if i'm using the Tipo to engine break downhill and drop into 2nd gear there is a momentary squeak from the rear that sounds like a belt slipping.

Anybody out there come across this or any ideas what it is ? I'm hoping it could just be a belt like an a/c belt slipping as the engine changes down and nothing serious.

Only happens when going down hill.

Could it be tire squeal? Your sudden shift to 2nd changes engine RPM so much that engine RPM no longer matches wheel speed?

Thanks for that. I guess it could be tyres. Just don't understand why it only happens on downhill sections.

If it is tires, it is because you are shifting into 2nd when you are going too fast for that gear. Slow down a bit more, then shift into 2nd.

What speed are you down shifting at?

Only about 65kmh but have noticed if i keep my foot on the accelerator hen i down shift it doesn't squeak.... i guess that's because the revs are higher ?

That speed should be ok. Yes, if you keep your foot on the accelerator, then you match revs. That would be similar to a heel and toe downshift if you were using a manual box.

On the other hand, I thought that tips did some rev-matching for you. Perhaps someone with a tip can respond. Would a tip rev-match for you in this situation?

Downshift
 

I don't have any squeal when downshifting. I'm guessing it could be belt slippage. I would lean more toward that, than tire squealing. At the most, the tires would bark and the revs would catch up really quickly. Can't say that I've had this actually happen. I would check for belt tension and wear.

The tip box doesn't match revs, but it's smart enough to not allow you to down shift if you are going too fast for the lower gears rev range.

Thanks for that. I've checked the belts and one could certainly do with tightening. Hopefully that's all it is.