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Prop hitting floor


Steve P
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During the run to the coast yesterday,two up in the Vitesse,when going over fairly large dips and bumps in the road,i could hear contact between the prop and the floor under the handbrake.

It`s a 2.5 engine with a Saloon box and home made rear box mount.It only did this once before when i did a wedding in it and it was 3 up.(big bride)

The car is lowered by a Triumphtune spring from back in the day.My question is:

Do i raise the rear with a new spring?,i have a new courier one in stock.Or do i modify the mount to get the box lower at the back.

I don`t understand how the rear suspension compression makes the prop position change  as the diff is fixed?.

Or maybe the gearbox mount is knackered again,i discovered yesterday that the handbrake is useless,which means the new wheel cylinders have lasted just over a year before spilling the fluid.

Anyone know where i can get cylinders that aren`t crap?.

Steve

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Steve, I had that issue with my vitesse (2.5, saloon box) and I ended up cutting and lifting the tunnel 1/2" as it was hitting the reinforcing plate thingy.

If you can lower the tail of the gearbox. That would be my preferred route, as like you I don't see how the rear spring could affect prop angles etc. But a sloppy gearbox mount could. 

My mount was a plate welded 3 sides, one edge being onto the little bridge piece.

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What Clive says. It’s actually the weight of your passenger flexing the floor (you might want to be careful telling your passenger 😛). The point of contact will be the reinforcement plate under the handbrake.

Dropping the back of the gearbox a few mm is the easy way - if you have any room to drop left. Another possibility is to put a bit a packing under the floor along the top of the middle outrigger to prop the floor up a little.

I’ve had this issue on a Herald with Dolly 1500 running gear and with my Vitesse with the long J-type box. Was able to lower the box both times.

Nick

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2 hours ago, Iain T said:

I had this problem after raising the nose of the diff to get a more parallel angle to the gearbox. The solution was a large hammer to the tunnel!!

Iain

I have some questions about this! I presume you now have the box and diff (flanges) parallel or as close to it as possible? Did you measure the working angle of the UJ's?

More interesting to me, how did tilting the rear spring affect the rear suspension? Or did the angle change get taken up in the spring eye bushes? (I am contemplating doing this, I have got the uj working angles down to 3 degrees, but a tad out of parallel, so lifting the diff nose is the only option I have)

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Hi Steve

I had prop clearance issues, so had one made up from a smaller diameter NOS prop the company had in stock.  Similar in weight so presumably thicker wall tube to compensate for the smaller diameter. Think some later Triumphs had smaller diameter props but could be wrong.I know your car is pushing out a lot of power/torque so if you went this route you would have to make sure it was up to the job.

Mark

IMG_2945.jpg

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Clive,

First I only did this to try and solve a severe driveline vibration problem which as it turned out had nothing to do with the prop.

I personally didn't do the work but measured the angles (I used an app on my phone) with the mechanic. I have a Type 9 gearbox so a sliding spline fit prop on the front and standard flange to the rear. It was about 2 years ago now but I think the difference in the diff to gearbox angle in side view was way over 3 degrees and as you say the only option is to lift the diff nose as it is impossible with a type 9 to raise the gearbox tail. I'm not sure how the mechanic did it but he modified the carrier/mounts to reduce the angle difference to about 1 degree. I also have a 1" spring spacer and was aware all this work could effect the suspension but all seems ok. The back end was always a bit harsh even though I replaced with adjustable shocks (must turn them down to minimum) and it is what it is, nothing broken or fallen off.......now that's really tempting fate!!!!!!! Having said that I did get the suspension professionally set up after the work.

If you ask me is this mod really necessary the answer is if your car drives ok, the prop doesn't hit anything and the driveline doesn't vibrate then no leave it alone.

Hope this helps

Iain

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3 hours ago, Mark B said:

I had prop clearance issues, so had one made up from a smaller diameter NOS prop the company had in stock.  Similar in weight so presumably thicker wall tube to compensate for the smaller diameter. Think some later Triumphs had smaller diameter props but could be wrong.I know your car is pushing out a lot of power/torque so if you went this route you would have to make sure it was up to the job.

Mark

Hello Mark,

I did think about looking for some sort of smaller diameter prop,maybe some race tuners do a version that could be made to measure??.Where was yours from please?.

Steve

Steve

 

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1 hour ago, Iain T said:

Clive,

First I only did this to try and solve a severe driveline vibration problem which as it turned out had nothing to do with the prop.

I personally didn't do the work but measured the angles (I used an app on my phone) with the mechanic. I have a Type 9 gearbox so a sliding spline fit prop on the front and standard flange to the rear. It was about 2 years ago now but I think the difference in the diff to gearbox angle in side view was way over 3 degrees and as you say the only option is to lift the diff nose as it is impossible with a type 9 to raise the gearbox tail. I'm not sure how the mechanic did it but he modified the carrier/mounts to reduce the angle difference to about 1 degree. I also have a 1" spring spacer and was aware all this work could effect the suspension but all seems ok. The back end was always a bit harsh even though I replaced with adjustable shocks (must turn them down to minimum) and it is what it is, nothing broken or fallen off.......now that's really tempting fate!!!!!!! Having said that I did get the suspension professionally set up after the work.

If you ask me is this mod really necessary the answer is if your car drives ok, the prop doesn't hit anything and the driveline doesn't vibrate then no leave it alone.

Hope this helps

Iain

I have a T9 box and scooby diff (much longer in the nose) I had a UJ fail 600 miles from home, so soon after spent a day in the garage lowering the tail of the box, which has put the box and diff out of parallel. So I need to tweek the diff front mounts, or if I could the rear mounts and hence the angle the diff sits in the chassis. Maybe time to rethink the diff mounts as they are welded to the scooby backplate. I have ideas (which is usually the precursor to something going wrong!)

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1 hour ago, Steve P said:

 

Hi Steve

Can't remember where I went off the top of my head, about 6 years ago now. Ill have a look through my folder of receipts to see if I can find one and let you know. 

Mark

 

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Hi Steve

Gone through my receipts, but haven't got one for the prop. It was a propshaft repair, balancing place. Googled propshaft repair and there are several that came up, but none range a bell. I just explained I had clearance issues, gave them the distance between gearbox and diff, engine size, approx power, and they made one up. From memory it cost around £100-120 6 years ago.

Mark

 

 

 

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Steve, 

I used Bailey Morris for my propshaft, talk to them as they will advise on tube specs/diameters. 

Clive, 

Both my diff and gearbox were pointing down so way out of parallel and theoretical parameters. As you know with a T9 it's nigh impossible to raise the gearbox tail in fact I have cut a portion of the tunnel out and replaced with a modified removable section to give more clearance. The only option is to raise the diff nose, I'll ask my guy exactly what he did and report back! 

Iain 

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I used Bailey Morris to rebalance the prop after I changed the UJ's as slight vibration at 70ish. Flash looking modern website etc, but inside the building it is reassuringly old fashioned, in a very good way. 

I would think cutting the upper rubber mount would work, but as I have a scooby diff I will have other options available, I can alter the cradle mount I made. Or as I intend, one day, to make a new rear digff plate, I could alter that to suit. But at present all is well even substantially into 3 figures.

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1 hour ago, clive said:

Subaru 😎 (impossible to break, despite me trying)

Interestink! My diff seems to be ok but not sure how it's going to fare with my 'new' engine, time will tell. Just bought an AEM afr meter to sort out the carbs so more tweaking! Is the Subaru (what version) a straight swap? Do you have to make a new carrier? 

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No changes to the chassis. It needs Rotoflex, and I have the rover shafts (that fit into the subaru inner CV's, and the Rover/mgf outer CV's)

There uis a cast diff backplate made in NZ, and a bracket too, though I made my own. Diffs cheap, and 3.5-4.4 ratios available. I have settled on 3.7 as a good all-rounder. (3.9 better on trackdays and autosolos, but I tend to do some long european touring too so swapped.)

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I contacted Bailey Morris and they have a branch near me in Feltham,i have been there before but forgot,taken the front off today and will get the back bolts out tomorrow and go and see them.

I can`t lower the box without replacing the mount as the speedo drive is touching already.I have an electronic speedo so no cable attached.Could blank  off the drive hole somehow.

Steve

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5 hours ago, Steve P said:

I contacted Bailey Morris and they have a branch near me in Feltham,i have been there before but forgot,taken the front off today and will get the back bolts out tomorrow and go and see them.

I can`t lower the box without replacing the mount as the speedo drive is touching already.I have an electronic speedo so no cable attached.Could blank  off the drive hole somehow.

Steve

Your new speedo is GPS?

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11 hours ago, SpitFire6 said:

Your new speedo is GPS?

Not GPS,i got it from Speedy cables in Wales made to order,it has a sensor which counts prop rotations and you calibrate it to your diff/tyre/wheel combo.Very accurate after testing with a sat nav.Changed the rev counter to a matching electronic one which connects via the coil at the same time.

Plan is to fit the 123 usb dizzy i have on the shelf

Steve

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