Off Road Racing - Automatic Gearbox Help

[mgmark]

Hi all,

           Sorry to have been off line for a while, but I'm still waiting for an internet account with the new job (which is manic) so have had little time available for contributing to the forum.   I could do with a little help/advice if anyone knows of any suitable companies that can rebuild and modify automatic gearboxes.   For those that remember from earlier posts, I'm co-driving an offroad racer, based on a spaceframe powered by a 2.5litre BMW turbo diesel (from a 3-series BMW), mid-mounted, running at 1.5bar boost and mated to a standard ZF auto box from a Range Rover.   The latter half of this season has been very successful, culminating in outright wins against opposition with much larger engines (i.e. 5.7 litre Chevy V8 powered stuff).   Piccy of the beastie in action below.

          Now that the season is finished and we are in the winter rebuild time, we are aiming to sort out the gearbox.   It is being used effectively as a manual by shifting 1-2-3-4 rather than using the standard "leave it in drive" position.   This has worked well and we are aiming to get the box re-valved so that the change is quicker and the stall rate on torque converter raised so that we can keep out of low revs turbo lag territory.   The other issue is that only first, second and third are much use as gears, as third is the 1:1 ratio and fourth is an overdrive ratio of 0.72:1, so it is pretty much zero use in accelerating     Not knowing too much about the internal magic of an automatic gearbox, I don't know whether it is feasible, or if parts are available, to change ratios such that fourth becomes the top 1:1 ratio instead of third and then space the other ratios to give us a nice even power band.

       Basic question in all of this really is does anyone know enough to be able to advise and/or know of a good company that not only rebuilds and but also modifies automatic gearboxes?   all the best and ta,

Mark

[Black Widow]

Hi Mark

Where are you based?  There are a couple of places near me in the Hampshire area.  One is Kingsley Cross Country (Land Rover specialists), web address is www.kingsleycrosscountry.com.  Or there is JTM Racing, at Fernhust, W. Sussex.  Web address is www.racecar.com/jtm/services. Alternatively, try Quaife, Tran-X or the Gearboxman (competition gearbox specialists), www.gearboxman.co.uk.  Another route might be to talk to the guys at the All Wheel Drive Club.  Hope you have some luck

"Beastie"

[smokie]

I know nothing...as ever.

But try a post on the Technical forum at www.honestjohn.co.uk. There's all kinds of levels of skill and contacts there. A bloke called Aprilia might know of someone, I think that's his line.

[Steve Pyro]

I know nothing...as ever.

I didn't realise you were from Barcelona, Smokie ?

[mgmark]

Hi Mark

Where are you based?  There are a couple of places near me in the Hampshire area.  One is Kingsley Cross Country (Land Rover specialists), web address is www.kingsleycrosscountry.com.  Or there is JTM Racing, at Fernhust, W. Sussex.  Web address is www.racecar.com/jtm/services. Alternatively, try Quaife, Tran-X or the Gearboxman (competition gearbox specialists), www.gearboxman.co.uk.  Another route might be to talk to the guys at the All Wheel Drive Club.  Hope you have some luck

"Beastie"

Based near Huntingdon, but travel within reason isn't a problem.   Thanks for the leads, I've followed up a couple of them and I'll see what I get back from them.   Quaife would be lovely, but they do tend to be massively expensive and manual.   One of the main reasons we are using an automatic is that it helps cushion the drivetrain - over the course of last season, we had no broken drivshafts or diffs, which compared to the competition was unique.   Plus my dirver only has two pedals to worry about.....

Mark

[Matt Harper]

I'll never claim to be an auto trans expert, but I did a couple of mods to my own car to beef it up for 1/4 mile bracket racing.
Was this motor/tranny straight out of a turbo deisel Range Rover?
Not sure about avaiability of hi-stall torque converters for Range Rovers anymore, but Overfinch used to do one for their 350 Chev small block to RR transmission conversion.
I also installed a Transgo shift kit, which in the case of a Chevy LS1, re-maps shift points in relation to flywheel and road speed and re-valves so that the amount of time the converter is soaking-up the torque is reduced quite significantly, making much quicker and more positive (a bit too positive actually) up shifts. My car really digs-in under hard accelleration, as a result.
Not at all sure about changing ratios in the trans itself - it would be much easier to swap out your diff ratios and live with a really short first gear.

[mgmark]

Hi Guys,

            Sorry not to have posted earlier, but work has been pretty manic and a lot of the festive break has been taken up with fettling the spaceframe ready for next season.   Thanks for the advice, which gave us some very useful pointers and contacts (who gave us useful info) and, in the case of one firm in Birmingham, got the job of converting the  torque converter to a higher stall setting, so that drive will come in at the point that the turbo starts kicking in - should help us no end out of slow corners.   Should get the converter back in a week or so, then we can start building back up to try it out.   One little thing that we did find out was that keeping the kickdown cable connected is still v. important.   Ours was disconnected, as we reasoned that because we were using the box as a manual shifter, the kickdown wasn't necessary.   Well, apparently the first inch or so of cable movement before the "click" when it kicks down actually regulates the pressure within the gearbox according to the throttle position - this would explain why the gearbox pressure gauge swings wildy between about 20 and 120 psi.   So for anyone out there with a kit car or the like who thought like us that the kickdown cable wasn't important, think again.....

Oh, and on the basis that the good Mr Brown will probably read this, no, I haven't fitted a V8 to the MGA yet, but I am most of the way through converting it to run with an early MGB gearbox, fitted with a close-ratio gear set and overdrive - should be on the road at the end of next weekend

All the best for now,

Mark

[Steve Pyro]

Morning Mark, looks like you've been a busy chap.
I run a GM TH350 auto on the the back of my Pontiac in the cob - and yes, I use a kickdown cable (and very effective it is too).
Does your box have a vacuum modulator?

If so, you can use an adjustable modulator to vary the shift point to your liking - it's basically a diaphragm with an adjustable back stop.

Sounds like you've been busy with the MGA too, is the gearbox the early 3 rail type without syncromesh on 1st?
My mate Andy 3 Cobras has a Rover V8 in his workshop lying around just itching to be transplanted into a new project - or maybe a COMMER  

[Andy Zarse]

Morning Mark, looks like you've been a busy chap.
I run a GM TH350 auto on the the back of my Pontiac in the cob - and yes, I use a kickdown cable (and very effective it is too).
Does your box have a vacuum modulator?

If so, you can use an adjustable modulator to vary the shift point to your liking - it's basically a diaphragm with an adjustable back stop.

Sounds like you've been busy with the MGA too, is the gearbox the early 3 rail type without syncromesh on 1st?
My mate Andy 3 Cobras has a Rover V8 in his workshop lying around just itching to be transplanted into a new project - or maybe a COMMER  

Look! I keep telling you, a V8 won't fit in the engine bay! Even if it did, it'd strip the crownwheel and pinion in a nanosecond. Now, a diesel transit engine is a different matter, though whether or not I'd choose and adjustable backstop diaphragm is a moot point.

[Steve Pyro]

Look! I keep telling you, a V8 won't fit in the engine bay! Even if it did, it'd strip the crownwheel and pinion in a nanosecond. Now, a diesel transit engine is a different matter, though whether or not I'd choose and adjustable backstop diaphragm is a moot point.

I keep telling you - bullshit - we have the technology.  

[mgmark]

Indeed we do have the technology..... and that technology has seen plenty of over the last couple of weeks on the gearbox region of the chassis and on the transmission tunnel, along with the gearbox bell-housing, followed up with MIG and TIG weldeing.   Its the gearbox from an early MGB, so retains the smaller input shaft and the non-synchro first gear like the MGA's original gearbox and, after a small mod to the starter motor mount slots straight onto the MGA engine.

A V8 has been dropped into an MGA, twice to my knowledge.  In the early 60s, one of the club racers transplanted a Daimler 250 V8 engine and gearbox into an MGA and, more recently, Warren Marsh fittefd a Rover SDI V8 plus gearbox into one.   In the latter case, however, this was at considerable expense and some extreme mods to the chassis, suspension, brakes, bodywork etc.    All the best for now,

Mark

[mgmark]

Morning Mark, looks like you've been a busy chap.
I run a GM TH350 auto on the the back of my Pontiac in the cob - and yes, I use a kickdown cable (and very effective it is too).
Does your box have a vacuum modulator?

If so, you can use an adjustable modulator to vary the shift point to your liking - it's basically a diaphragm with an adjustable back stop.

Sounds like you've been busy with the MGA too, is the gearbox the early 3 rail type without syncromesh on 1st?
My mate Andy 3 Cobras has a Rover V8 in his workshop lying around just itching to be transplanted into a new project - or maybe a COMMER  

[mgmark]

Morning Mark, looks like you've been a busy chap.
I run a GM TH350 auto on the the back of my Pontiac in the cob - and yes, I use a kickdown cable (and very effective it is too).
Does your box have a vacuum modulator?
 
If so, you can use an adjustable modulator to vary the shift point to your liking - it's basically a diaphragm with an adjustable back stop.

Steve - sorry hit post before typing on the last one.   Never heard of an adjustable modulator, and I'm pretty sure that the ZF box we use doesn't have one - what the heck does it fit in line with?

Mark

[Steve Pyro]

Mark, on my TH350, the vacuum modulator sits on the RH side of the gearbox and is connected to the carb by a vacuum pipe.  The varying vacuum signal moves the ported valve within the trans and thus alters the oil flow to the various parts of the valve body.


On later gearboxs, instead of being vacuum controlled, the modulator is solenoid or electronically controlled.

[Steve Pyro]

.....a Daimler 250 V8 engine and gearbox  ....

Now there's an engine  
I remember a few of these hemi engines running on nitromethane at Santa Pod in the 70's and 80's.