Testarossa Clutch Shaft / Drive Gear Failure

Hi Guys, trust all is well and that you have all had a good Christmas.

Over the last few days we discovered a problem with our latest 88/89 Testarossa project. The 4 slot nut that secures the Drive Gear to the Clutch Shaft (at the back of the Bellhousing) had come loose. This has allowed the spline connection between the Drive Gear and Clutch Shaft to flog out and there is now excessive play in the connection between the gear and shaft. It can likely be made serviceable but our preference would be to replace the components, provided they are available and not too expensive.

A complete used bell-housing assembly would be first prize. Good used parts would also be a good option - in which case we would require a clutch shaft, drive gear, bearing, spacers and nut.

I see that Ferrari Parts have a used bellhousing assembly for sale on ebay at the moments - looks perfect but is says it is for a TR or 512M therefore not sure it fits the 88/89 Euro Spec Testarossa. A little bit of part number checking suggested they may be different.

Got a few related questions for the well informed Testarossa community our there:

1. Does anyone know if a TR bell housing and drop gear set will fit an 88/89 Testarossa?

2. Has anyone heard of a similar problems with TR's or Testarossas? This is a new one for me.

3. Can anyone help with the parts to put this right? A complete bell housing assembly or the components?

Let me know if you think you can help and have a great holiday season.
Best wishes
Sean

 

Thanks Guys, sorry I am more familiar with another site where they know me. Steve has helped me a great deal over the years so thanks again Steve. Name is Sean and I have the privilege of messing with quite a few old F cars mostly in Australia. TR's are about as new as I get and relatively new to me (thanks for the clarification on terms Melvok helps make things clear).

The car is a Euro spec car and is based on Australia - so no pickup of parts Im afraid Joe.

Didn't know the drop gear ratios were different Steve so will look out for that thanks.

The nut is a 4 slot type with a skirt that gets peened over on two sides into a bevel in the end of the shaft. This stops the nut from coming undone but does not stop it from coming loose - if that makes sense. Sounds like the same thing that happened to godabitibi - nut was loose but the peened skirt stopped it winding up the shaft. In our case however I think the spline may be a bit too damaged for green loctite.

Thanks for the help - very useful so far.

 

Hi Steve, thanks for your thoughts. My engine is a F113B - 17661 so a B series engine. Not sure what you are referring to with the different ratios. Travelling at present but will check the transfer gear ratios when I get back. Not sure how to do this but I will have a look at stampings etc and count teeth. Does this mean that the diff ratio was different in oder to keep the final drive the same? Or was the final drive indeed different.

The peening of the nut was not done very well. Stopped it rotating but not backing off a few degrees which was enough to allow the drive gear to start working against the splines on the shaft.

Thanks again and best wishes, Sean

 

I agree. Looks like someone had been in this one before. Didn't look as though it was factory assembled. Thanks for the observations.

 

Now this is very interesting Steve - many thanks.
Counted the teeth and confirm 27 on the Drive Gear (Uppermost) and 29 on the Final Gear (Lowermost). I have ordered a new Clutch Shaft and Drive gear (along with related bearings seals etc) in order to put things right. An interesting thought however - if I purchased the entire bell housing assembly from a US car I wonder if it will fit. If the only difference was a slightly "shorter" overall drive ratio that could be a good thing.

Does anyone happen to know if the assembly is interchangeable between the Euro and US cars?

Thanks once again Steve - much appreciated.

 

Hi Guys, sorry for the delayed update. Have ordered a new shaft, gear, bearings, seals etc. In the end it seemed the safest and best plan. Travelling but waiting for the parts now in any case.

I have included a couple of photos as requested but there is not much to see.

If you look carefully the splines on the shaft are quite badly worn except for two segments. These segments line up with two sections inside the gear which has no spline. When the gear is fitted to the spline in its original position there is rotational play (able to rotate a few mm each way) due to the excessive wear. If it is fitted to maximise the use of the good splines that remain on the shaft there is less movement but we figured that it just was not good enough to put back into service (even though there are some excellent Loctite products for this type of application). So now I have a very expensive clutch alignment tool!

Not sure why the gear does not have a 360 degree spline as it would be stronger. Sometimes gaps in splines are included to allow oil flow. I will re-look and the design to see if this makes sense.

Trust you find this entertaining.
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I still don't know if the entire bell housing assembly is interchangeable between the Euro and US cars? Obviously you would have to live with the different ratio (as Steve points out) but apart from that it would be good to know if they are interchangeable.

 

Be good to know - would appreciate you measuring a couple when you get back Romano. Many thanks, Sean

 

Thanks Brian, very cool to know that. Might be able to get a US bell housing assembly and make it work. Live with a different final drive ratio.
Many thanks for this. Learn something every day.
Sean

 

Nice to finish these stories. Got the new parts (Drive Shaft, Drive Gear, Bearing, Seal, Ring Nut) and installed them. Gear rotation was ok with the top cover off but the whole assembly was a little on the tight side with the cover fitted. A bit of measuring confirmed that the drop gears are a matched set and the new gear did not have quite enough lash. Off to the specialist gear grinding guy to get it match fitted to the others - lovely job came back perfect. Smooth as silk. Assembled to the right torque, loctite and peened.
All worked very well in the end.