Friday, January 13, 2012

Overdrive Modification

As one or two of you may know I was having overdrive problems just before the last 10CR and tried (unsuccessfully) to fix it at the time.

After the run when it gave up completely I started to look around for a replacement unit and found this info on wikipedia,

"The first production vehicle to feature the Laycock system was the 1948 Standard Vanguard Saloon. The first unit to be created was the A-type overdrive, this was fitted to many sports cars during the 1950s. Several famous marques used A-type overdrives, including Jaguar, Aston Martin, Ferrari, Austin-Healey, Jensen, Bristol, AC and Armstrong Siddeley. Later the A-type overdrive was to be fitted to the entire range of TR cars.

In 1959, the Laycock Engineering Company introduced the D-type overdrive, which was fitted to a variety of motor cars including Volvo 120 and 1800s, Sunbeam Alpines and Rapiers, Triumph Spitfires, and also 1962-1967 MGBs (those with 3-synchro transmissions).

From 1967 the LH-type overdrive was introduced, and this featured in a variety of models, including 1968-1980 MGBs, the MGC, the Ford Zephyr, early Reliant Scimitars, TVRs, and Gilberns.

The J-type overdrive was introduced in the early 1970s, and was adapted to fit Volvo, Triumph, Vauxhall/Opel, American Motors and Chrysler motorcars, and Ford Transit vans.

The P-type overdrive marked the last updates and included both a Gear Vendors U.S. version and a Volvo version. The Volvo version kept the same package size as the J-type but with the updated 18 element freewheel and stronger splines through the planet carrier. The Gear Vendors U.S. version uses a larger 1.375 outer diameter output shaft for higher capacity and a longer rear case."

Suggesting that the last and possibly the best unit made was a P/Type overdrive for the Volvo fitted to the 740 turbo of around 160bhp and 175 ft/lb torque.

Looking through ebay I spotted this unit and thought it looked very similar to the J/Type fitted to my GT6.

ebay pic 1

ebaty pic 2

ebay pic3

It was described as a new old stock unit that had been in storage for some time and possibly kicked around the garage floor a bit too!!!

OK as you can see there is no provision for a speedo drive output, (the volvo speedo is driven via a propshaft sensor) I would cross that one when I had too.

I hoped that it would all just bolt onto my existing GT6 gearbox and with a change over of the rear propshaft flange be a straight forward fit. (Arn't I the optimistic type :) )

Once the overdrive arrived I took off the rear housing and had a look to see if there was a speedo worm drive under the spot where the casing was not machined for the speedo drive spigot, no such luck only a spacer between the bearings, however on the bright side of things the inside of the unit looked brand new and still had traces of some sort of red test fluid (possibly ATF).

All I had to do now was take out the GT6 gearbox and get cracking................................................

That was the beginning of October,

Ok I'm a lazy Git I admit it !!!

It only took me 3 months to get around too it................................................. (Thanks Gaz)

Around too it

Here are a few pics of the gearbox and the new overdrive side by side for comparison.

Start Comparison

Start Side By Side

Before Swap

Start Side by Side

Thankfully the swap over was just as straight forward as I had hoped, I took off the rear housing and propshaft flange from the new P/J Type overdrive.

Then removed the old unit from my gearbox and removed the propshaft output flange, speedo worm drive and speedo drive spigot.

Still follow me :-/

Then it was just a case of fitting the old rear cover and associated speedo bits to the back of the new unit and fitting it back to my gearbox.........................

eerrrrrrrrrr not quite but only a small problem of the studs in the volvo nit being to long to be able to get everything bolted up.

A quick swap over of the studs and all was well, even the rear propshaft output flange is a perfect fit.

Here are some pics of it all swapped over,

Swap Complete

Swap complete Side by side

Swap Complete

Next I ran it up on my test rig to see if it was working.........

Don't Laugh too hard it works.

Test Rig

I used ATF to run the pressure test thinking that it is relatively thin when cold and would simulate gear oil when warm (and clean out my gearbox too).

Result of the pressure test was that it was running at 380 psi, I then shimmed the relief valve and it upped it to 490 psi.

I believe the Stag J/Type runs at around 550 psi and will set it to that eventually if that is correct as I have also modified the gear linkage to allow me to use overdrive in second gear and the extra pressure should help the overdrive not to slip in second gear. ( I hope )

Here are some pics of how you get to the relief valve and what it looks like.

Sump removed showing primary filter.

Sump Filter

Primary filter removed showing access to, Top main filter, middle is the pump/piston assy and removing the bottom plug reveals the relief valve.

Sump 2

Pressure relief valve

Relief Valve

I have tried to show the relief valve parts laid out in sequence. The little washers in the middle are in fact the adjusting shims to increase the pressure.

Simply add shims to up the pressure or remove them to decrease pressure if you go to far. it only takes a thin shim to up the pressure considerably, I put one in that at a guess was about 12 - 15 thou and that upped it by around 100 psi.

Relief Valve Detail

Here is a close up of the part number/ID Tag showing it to be ( I believe ) a 27% overdrive.

P/J Tag

In the end not a bad result for a new overdrive unit (providing it all works as expected on the car) for a punt on Ebay of 81 beer tokens.

Now I just have to strip the box and sort out a possibly bearing related grumbly first gear ;D

Saturday, April 3, 2010

About time for an update!!!

It's been quite a while since my last update but for the moment I have put my engine upgrades on hold until I get the chassis/running gear sorted out to my liking.

On that note I have recently fitted vented discs to the front end and as they are only the same diameter as standard they won't improve the braking but they should run cooler and stop any brake fade when they are used in real anger like when we were on the Club Triumph 10 Countries Run, we did get brake fade once or twice coming down the long descents from the mountains.

Also yesterday afternoon before going up to my local CT meeting at the Old Stone Trough in Kelbrook I fitted some uprated front springs. I thought I may have gone too far at a rating of 650lbs but they are a revalation they have transformed the front end of the car and it just seems to go where you put it with very little body roll. It is certainly much better on wet greasy roads. I still need to try it on dry tarmac. I was amazed at the difference because the springs I took off were already stronger than standard at a rating of 480lb. I can only put this down to the fact that the rear of my car is very stiffly sprung (really a bit too hard for my liking) and that fitting even stiffer springs at the front has balanced the car up instead of the front of the car trying to do most of the work.

Also I have ordered a full retrim kit in leather for my seats and headrests from Park Lane Classics as my seats don't hold me in place when pushing on around the twisties anymore.
I could of gone for the cheaper option of MX5 seats or bucket seats but I still think reupholstered originals are best. Rob Southerns newly upholstered Spitfire seats were used in my car on the last RBRR and were superb, allowing the passenger to recline full length and get some sleep. I don't think I will get my seats done in time for the HCR as it is going to take at least 3 weeks for my seat covers to be made and delivered. So Rob and I may be using his seats again in my car.

Tuesday, August 11, 2009

The next thing for my GT6

I now have almost all the stuff required to change my tired old 2 litre sixpot sometime after the Club Triumph 10 Countries run in September (more on that later)

I have been following Stephen Attenborough's GT6 blog
with much interest as I am going down the PI route. (may or may not convert to efi later)

I know that I'm pushing it with the transmission but I'll cross that bridge when/if I break it but I'm sure Nick Jones CV drive shafts are up to the job at the rear.

What I'm after at the moment is any pics of GT6/Spitfire engine bays fitted with the Lucas setup just for Ideas of what to look for and to be a little more prepared for possible problems like bulkhead and bonnet clearance issues and how best to deal with it.
I'm after fitting the engine and PI setup in a fairly short time and then sorting out any running issues, fuel pressure/surge etc once it is in place.

The manifolds are the later type, maybe not as much outright power but easier to setup?

The metering unit has been reconditioned to run unleaded and the rest of the stuff is a bit secondhand but mostly all there from what I can see.

Here's hoping it's a fairly straightforward learning curve and fitment but something tells me there will be one or two things to work out.

I intend to update this as I go along so as to help out anyone contemplating a similar conversion.

A few pics of the parts

Nice clean manifolds

Ready for unleaded metering unit

The rest of the bits are a bit tatty but I reckon usable, the Lucas fuel pump makes a noise but how well will it work!!!

Monday, July 20, 2009

Northern Area Camping Weekend

I just want to say THANKYOU Rob Southern (bobbyspit) for a wonderful weekend Louise Anna and I enjoyed ourselves immensely, the wigwams and the campsite were fandabbydozy as was the company.

It was nice to meet Ed (notfinishedyet on the Club Triumph forum) and his wife Jill and their son George. They had a beatiful blue herald that has only done 320 miles since being rebuilt.

Ed admitted to a few teething troubles or as I call it "character". I'm sure you'll sort out the little niggles soon Ed.

I'm ashamed to say that we went up in the modern.................not enough room for all the weekends crap in a GT6 and/or three people. We didn't go on the run around the Lake District on the Saturday for a couple of reasons,

1. My wife Louise had a very fuzzy head after a boozy friday night.
2. I was also meeting my mate Gary (Gaz) Seddon who arrived early on Saturday afternoon with his two kids and another in tow. (Brave, brave man!!!)
I'm still aching all over from playing football and volleyball with Rhys my mate Gaz's football daft son who has enough energy to power a large city. Gary will be my co pilot on the 10CR and came along for the fun and to meet some of the people going on that trip.
Mr Acclaim himself was there (Barry McGrath) with his sons James and Alex in one of his many Honda's............................erm TRIUMPH Acclaims, sorry Barry it was "Ginger" I think.
The other Triumph to turn up apart from Rob's was a nice white Spitfire Belonging to Neil who will be Rob's co pilot on the 10CR. It used to belong to Craig Gingell's wife, If your reading this Craig it has gone to a good home.
As for the weather we only had a couple of showers here and there, I even got a little sunburn on the Saturday. Of course once the barbecues came out on Saturday evening we had a rather heavy shower that almost put out the barbecues untill Gaz's daughter Natasha and her friend came to the rescue with their umberellas.

Matt was also there from the P&P keeping us all topped up with lots of goodies and was the only Gentleman there to offer my wife Louise a proper wine glass.Louise says thanks Matt .

Last but most certainly not least it was good to see Marcus again who met up with the cars on the run around the Lake District and came to the campsite for the evening and had us all in stitches with some of his stories, especially the one about the goat and his neighbour.

The campsite comes highly recommended and is in a great place to visit the Lake District, The North Pennines and Hadrians Wall.
Again Rob thanks for a great weekend and a fantastic location and I think you should be unopposed for the next Pendle and Pennine bonus point.
Steve Thompson (tiggrr1)

Monday, July 13, 2009

A couple of more little jobs done

I thought it was about time I got round to fixing a small water leak that my GT6 has had since the 2008 Round Britain Reliability Run.
It has needed topping up every 200 miles or so but has been getting steadily worse and almost not getting me home from the last Pendle and Pennine Club Triumph meeting.

I changed the water pump about a month ago thinking that the leak was from the water pump seal, as it happens I was close it was actually coming from the water pump to cylinder head joint. The repair was as simple as popping off the water pump and fitting a new gasket.

While I was at it I also fitted a new powder coated aluminum radiator shroud sourced from ebay and well worth the £28 + postage as it must be forcing more air through the radiator as the water temperature has dropped on the gauge to sit between 1/3 and 1/2 of the needle sweep even during the recent hot weather!
SNC00069 (Medium).jpg

I also managed to break my front number plate which was mounted far too low on the front spoiler so as not to restrict the airflow through the grille to the radiator. Belive it or not on the step up and ramp into the garage in the background. I usually put a couple of thin planks down to help lift the front of the car over the lip into the garage. That will teach me not to be so lazy next time................................................


So now it looks like this, I do think it is very difficult to get the front number plate looking right on the spitfire & GT6 but that seems to be the best I have had it so far


Saturday, July 11, 2009


First off I would like to say a big thank you to Nick Jones for supplying me with this excellent driveshaft conversion for my rotoflex GT6.

The inner joint is brand new and the driveshaft and outer CV joint are refurbished items but as you can see from the picture they look brand new!

Also the hub has been machined to take the more modern MGF wheel bearing which should be stronger. Fitting of the driveshafts was pretty straightforward as it is literally a case of taking the old ones off and bolting in the new ones, also it is much easier to get the upright mounted to the spring as the rotoflex rubber is not holding the driveshaft under tension.



While I was at it I also completely stripped the back end including the diff to polybush everything. Some of the old bushes were knackered.Now the rear of the car is much more firmly planted through the twisties and the transmission feels much more direct without the rotoflex rubbers in place, however the tradeoff is a little more diff/roadnoise transmitted into the car particularly at 2200-2300rpm there is a slight diff whine but at all other speeds it is fine . It does gives me the excuse to add a little soundproofing as there is only carpet fitted to the car at the moment.

Saturday, May 30, 2009

Got there in the end

On my last blog update I had the misfortune of my nearside front upright snapping just before I was going to visit Marcus in Maryport, Cumbria.
Any way I went to visit him last Sunday to pick up a set of Alloy wheels he had agreed to sell me.

Apart from picking up the wheels I had to have a closer look at his fantastic GT6.

It may upset the purists (but I like it).

I'm sure some people would probably say the setup was all wrong,
wide tyres 205/50 x 15 and two front antiroll bars & 600lb springs at the front.
It should understeer and clash and bang over the potholes but it doesn't. It is very well sorted.
Omex engine management system combining with a 268 degree cam and electric engine management and EFI combine to give an Impressive rolling road printout!

Marcus was daft enough..........................err sorry Marcus, kind enough to ask me if I wanted too drive it.
Does a bear poo in the woods, is the Pope a Catholic!

Was I impressed. You bet I was It goes like stink as the rolling road printout would suggest and sticks to the tamac like brown smelly stuff to a blanket.

Needless to say I'm now being a bit of a pest and asking lots of questions.
Here is a link to more pics and a better quality rolling road print out that you can make out more clearly.