Overdrive Gearbox Mounts

[MarkB]

Hi All

I have a modified Vitesse gearbox fitted with a J type OD. It has the two studs for the standard Overdrive mount as used on the 1500 Spitfire. I fitted the engine and gearbox as one unit and have a few clearance issues. One thing that could be causing problems is the reproduction  engine mounts as the originals were spinning their studs. The sumps is very close to the crossmember and I think is catching the rack mount. The underside of the OD seems to be sitting on the mounting plate so the gearbox mount on the rear doesn't appear to be high enough. The car was not originally fitted with OD so it looks as if I will have to trim the tunnel cover to get to the prop nuts. I knew the tunnels are cut differently on the spits and GT6 on the OD models but thought all vitesse's were the same. Any thoughts? Thanks Mark

[Mark Hammond]

Nope, you'll have to cut out the tunnel and patch it over with a removable shaped cover.

M.

[Dogsbody47uk]

Quoted from Mark Hammond

Nope, you'll have to cut out the tunnel and patch it over with a removable shaped cover.

M.

Mark is correct. My Vitesse has o/d and there is an extra cutout with a cover held by self tappers.

[garyf]

You can buy shims to fit between the Rubber Engine Mounts and the Bracket that bolts to the Engine, I had a couple on each side on my Vitesse, this may help with the Sump clearance, they are the same as the Spacers for the Font lower Wishbone mounts and available from all the suppliers?

The 'J' Type Overdrive is a very tight fit inbetween the Chassis rails, I had to slightly cut and bend part of the Main rail lip on one side to stop it catching .

As stated by Mark you need to cut back the transmission cover about 100mm or so for access to the prop bolts, a cover can be made up out of shaped Aly or Stainless plate and fixed with Self tappers, Spire cliips and mastic or seam sealant to close the gap.

Can you not space out with washers between the Over=drive mounting studs and the Chassis plate to get sufficent clearance?  

[daver clasper]

Hi. I have j type on my Vitesse that was fitted by Canleys a while back before I had car.

To to reaffirm above info. they had cut about 4" out of tunnel and this gives access to PS bolts, and just squashed the cut out piece down a bit and fixed with self tappers.

they also must have fitted GB/OD like this, but I had to cut out a bit more to remove it?.

Also mines a bitza box apparently. The top shafts are some era of Dolly gearbox to accommodate the J type and apparently if a new clutch is needed, then it is only the friction plate from a Dolly or TR7 that is different.

Don't know if your set up is different, but have more exact info saved, from Mike Papworth who rebuilt original conversion and new box.

If any help

Cheers, Dave      

[Nick Jones]

Before my 5 speed I had a J-Type OD box based on a late 1850 Dolly box.  This was probably 1" longer than yours which seems to have the shorter OD adapter plate as used on the early Dolly box.

I used a Spitfire "Y" shaped gearbox mount.  The chassis mounting plate was a standard one with an extension piece welded on the back.  Getting the height right was tricky.  The natural inclination was to sit too high which was good from a chassis clearance aspect but meant that the propshaft would catch on the bottom of the handbrake housing in the floor - occasionally with just the driver, often with a skinny passenger, nearly all the time with a fat passenger......  Had to re-engineer the chassis mounting plate and cut and bend a section of the chassis lip to clear the speedo drive (it's the longer box remember).

Yes, you will have to cut a fairly hefty chunk out of the tunnel to access the prop bolts - and a bit more enable the box to be removed and installed.

As mentioned, you can use the camber adjustment shims under the engine mounts to increase clearance to the rack if needed - but a miss is as good as a mile.  If you have a Pheonix 6-3-1 then this will probably be the limiting factor that forces you to raise the engine as they seem to like to rest on the steering column.

Nick

[MarkB]

Hi all several problems to resolve

I moved the engine back about 8mm by mounting inside the uprights, put a 4 mm spacer under the now exstended gearbox mount and everything was looking good. Found a prop shaft measured the gap between the gearbox and diff and looked like it would fit. Tried fitting today and it does fit but the splined end that extends is already extending 3/4" leaving about 1/4" before it is at full stretch. Not sure how much free movement is needed and if it varies when the suspension is lowered more or the car is loaded. Also the prop shaft as Nick mentioned about his car, is hitting the underside of the tunnel, so that I can't mate it to the gearbox. I can't lower the gearbox more than a couple of mm as the angle drive will hit the chassis. I could lose the angle drive and get electronic dials made up. Another option would be to get a thinner prop shaft made up at the same time get the correct length. I am thinking of moving the engine a little further back, that would move more of the front end weight a little further back ,which I like, and resolve the prop length problem, then lower the gearbox and take a slice out of the chassis flange to accommodate the angle drive. Not happy about trimming the chassis though.

Whats your thoughts?

Mark

[Nick Jones]

1.  The diff won't move as it's bolted to the chassis.  You've only got the flex of the engine/gearbox/diff mounts to worry about and that is not alot.  Certainly less than 1/4".  Therefore prop length should work as it is, though I agree not ideal.

2.  I moved the engine back on mine by a). sitting the mounts behind the towers b). slotting the two holes in the engine mount brackets where the mount attaches.  Probably something like 15 - 18mm in total.  Engine is very close to the bulkhead now.

3.  Back of the gearbox needs to go down.  Can't remember what you have, but if single rail Dolly box based with J type and standard mainshaft I think you will have to notch the chassis for the angle drive or loose the angle drive altogether.  I notched the chassis (then re-instated it a few years later when I fitted the Toyota box).

Nick

[MarkB]

Hi All

Been working on the car trying to get the prop shaft to clear the tunnel. The problem is a combination of the engine being moved back inside the turrets and the modified Vitesse Overdrive gearbox. Initially the OD gearbox mount was extended by an inch to accommodate the new engine position and a 4mm spacer added so that the OD would clear the mounting plate. After the prop shaft hit the tunnel I removed the 4mm spacer and moved the engine back a fart more, so that the gearbox now clears the plate. Unfortunately the prop shaft still just touches the tunnel. As the engine is moved further back the angle of the prop shaft is more acute. This is a project and I enjoy making modifications and now that I have started would like to get the engine as far back as possible to get better weight distribution, but without mods to the bulk head. The engine is about 2" from the bulkhead at the moment and I can only think of the carbs or fuel injection being the limiting factor. I have made enquires to get a new prop shaft made up in a smaller diameter tubing, all i need to do is give them a measurement between gearbox and diff. At the moment I am thinking of moving it back another inch with a spacer  between the engine mount and turret. The angle drive is going to be redundant with out major chassis mods at this rate so I will go with an electronic type. Am I mad or do you think this is worthwhile modification. Thanks Mark

[Nick Jones]

Back of the box still wants to go lower.  ISTR that I fitted the gearbox mounting plate upside down from underneath the chassis flanges to achieve this.  The mounting plate was a modified non-OD one anyway.  Similar issues with my single rail gearbox Herald too - only way to get the prop to miss the bottom of the handbrake housing.

Nick

[MarkB]

Hi all

Moved the Engine as far back as possible without chopping the bulk head. Miss is as good as a mile 🙂  I made up a new O/D mount and had a short prop shaft made up to accommodate the new position and at the same time went for a smaller diameter tubing, so there is now plenty of clearance from the underside of the tunnel. Everything is bolted up and fits well. Going to have to modify the heater to squeeze it onto the bulkhead.

Mark

[Nick Jones]

That's further back than mine - how did you manage that engine mount wise?

Nick

[MarkB]

Hi Nick

I extended the mount on the engine, so that it is mirror image with elongated holes. There is adjustment forward and backwards if needed on both the engine an gearbox mounts. The sliding spline on the new prop shaft extends 2" as apposed the the original's approximate inch. The fitted length is set in the middle so there is an inch adjustment either way.

Mark

[Billus99]

I've just bought a complete gearbox / bell housing / overdrive assembly that was advertised as a GT6 / Vitesse unit. I've just got it home and have checked the code on the gearbox and it is "WE", which is Dolomite 1850, although the bell housing is definitely Vitesse. the overdrive is a J Type (like the one in Mark's pictures).
I had hoped I would be able to simply swap this into my Vitesse (which has its original gearbox and overdrive, which I assume is D type?) - looking at this thread, I'm wondering if it is going to be quite so simple as that!
Obviously it could have been a WE casing with Vitesse internals fitted, but is there any way to tell if the mainshaft that goes into the clutch is the correct one for a Vitesse (number of splines, etc.). are there any other issues that I'm going to face?

[Clive]

The dolly 3 rail box was the only one fitted with a j type OD. The clutch is the same, it should be a straight fit though check re mounting plate.

[garyf]

If you have an Early 3 Rail Dolomite Box that's a rare beasty and a good one to have

It will have the uprated Mainshaft and the J Type Overdrive is a bonus too!

You will need a Dolomite Clutch plate with the Fine Splines (21 I think) it is the same size as the Vitesse in all other respects but the Vitesse clutch plate has less splines (13?).

The box is very slightly longer than the normal Vitesse D Type Overdrive box but the Sliding Joint propshaft should take the extra length?

You may need to slightly cut the Chassis main rails in the vicinity of the Overdrive/solenoid to give sufficent clearance.

Had one in my Vitesse and it worked well

[Nick Jones]

Early 3 rail Dolly 1850 box has the J-type OD, but the internals are not significantly different from Vitesse/GT6 as the mainshaft has the same small tip.  This has the same coarse, square splines as the Vitesse/GT6 and is the same overall length.  Fitted with the right bell housing it is a direct swap.

The later single rail box has the stronger internals due to larger mainshaft tip and a fine 21 spline input shaft.  It is also 1" longer as the mainshaft and OD adaptor housing are 1" longer (I have no idea why!). It is possible to build the single rail internals into the 3 rail casing, which is useful as the Vitesse/GT6 bell housing doesn't fit the single rail casing without much messing about.  So if you have a fine spline input shaft beware of the length, which is likely to be 1" longer unless it has been built with a special aftermarket mainshaft and shorter OD adaptor housing.  These do exist but will be very rare.

Nick

[Billus99]

There are 10 splines on the input shaft, and another 1 3/4" tip, after the splines end. the gearbox number is WE24444, if that helps...
Are there any differences to the speedo drive output? I'm a bit loathed to pull the seats and tunnel out yet, as hoping for another outing or two beforehand, if the weather holds out!

[MarkB]

Hi

My Gearbox has the shorter OD adapter plate as used on the early Dolly box with modified internals, and would have fitted my Vitesse with the standard 43.5" OD propshaft. I complicated things as I moved the engine back, mounting it inside the turrets and then further back still which required the modified prop shaft. My gearbox has the fine spline input shaft and I use the dolomite clutch.

Mark    

[Billus99]

Thanks Mark - must say your Vitesse looks pretty tasty!

So, is the 10 spline shaft that I've got "standard" Vitesse?

[Clive]

Yep, as I mentioned earlier the whole box/od is a straight swap.
Have a look at tegh canley classics site, I think they may list a mounting plate for the J type conversion. Your d type on may fit, perhaps need re-drilling.