How much Hp/torque before drive train gives trouble
Posted By : Philip Charlton, 20-Oct-2006, 12:10pm
you should be alright upto 160 bhp/ 160lb/ft. Then you might start experiencing problems i reckon.
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How much Hp/torque before drive train gives trouble
Posted By : Piero Franchi, 20-Oct-2006, 12:44pm
What would be the first thing to go???
Crown wheel and pinion????
What is the weakest link in the set up????-
How much Hp/torque before drive train gives trouble
Posted By : Andy Vowell, 20-Oct-2006, 04:15pm
TSSC Race Spits are running 130bhp no problems and I think the GT6s in excess of 160 though they seem to get through a diff every couple of years I think. Hopefully the current TSSC champion the mighty Dave Thompson will see this thread and give first hand experience from racing his GT6.
In my spit I see the weak links as the UJs and clutch (I still run std 6 1/2") which helpfully are cheap.
Andy-
How much Hp/torque before drive train gives trouble
Posted By : Nigel Gibbins, 20-Oct-2006, 04:22pm
I run a Ford Escort 16v Clutch in mine (like a Mexico clutch) but you need to re-drill the flywheel.
I've seen a few gearbox problems though with our 130Bhp race cars so uprating what you can is always a good thing.
Diff should be fine - but the ol' halfshafts and UJs are still a weak link...-
How much Hp/torque before drive train gives trouble
Posted By : Piero Franchi, 20-Oct-2006, 06:54pm
Gear box/clutch is no problem, as this is not a triumph model.
prop should be fine, as this is made to order (ujs as well)
its from the diff back to the wheels that I need your experiance with.
as I said, it will have limited slip diff, so this will spred the power to both wheels.
I will use the same high quality ujs on the diff, although they will spin at a differant rpm to the prop, so not sure how they will cope.
Am happy to change the half shafts (rotoflex) to the new type slidding shafts.
so my only real worry is the 1500 crown wheel and pinion (1500 diff said to be the stronest)
Or is there some thing I have missed or forgotten about??????
Ps, whats the spits with 130 bhp like for speed?????
would you guys like more or does it suit the car plenty????
Thanks -
How much Hp/torque before drive train gives trouble
Posted By : Richard Briscoe, 20-Oct-2006, 06:56pm
I have suffered from 2 weak spots on my GT6 which is a mk1 running around 105 HP.
The woodruff keys in the shafts break wrecking the hub and shaft, record was 60 miles on a set from a dealer specialising in fast road parts!! (waranty was rubbish too!!)
I have also gone through 3 diffs in 10 years. One went at 70 (ish) on the M62 on my GT6, the gear oil vaporised and the back wheels locked up, mind you it was a Herald one!! (Great acceleration though!!!!!), got to Stafford by stopping every 20 miles and filling it up with oil
U/J's will give you warning as they wear (unless you run rotoflex) but are easy enough to change. (I haven't had one go on the road.)
Bear in mind that when launched the Triumph dealer network was swamped with warranty claims for GT6's with blown diffs!
The gearbox should be fine up to around 120 BHP without problems, The diff was designed for a Herald with around 50 BHP and later modified to cope with 95 BHP for the Vitesse MK1 and GT6 Mk1.
Basically keep some spares around the house and be prepared to put the odd day in to do repairs!
One word of caution - if you buy an "uprated" part buy it from a local supplier who has beem recommended by a number of people you know. There are some out there flogging standard units as upgraded and you can't see any diffence on the casings.
Richard
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How much Hp/torque before drive train gives trouble
Posted By : Piero Franchi, 20-Oct-2006, 07:23pm
Hi, and thanks for your experiance with your gt6.
I am hoping to be putting around the 180bhp through the set up.
As I have said, most of it is uprated (by me)
I have NO experiance of the power the diff can handle, mainly crown wheel and pinion, and output shafts/flanges.
As said, can always change the half shafts.
But hubs/splins/woodruff keys, again have NO experiance.
need your advive.-
How much Hp/torque before drive train gives trouble
Posted By : David Thompson, 20-Oct-2006, 07:42pm
I use a hybrid diff on the racer. Not sure what the case was originally but it is large input and output but with only 4 stud holes on the top for the leaf spring. The internals are dolomite CRP and Quaiffe ATB. In this form its lasted this year fine so far. Last year it had a small CRP and that blew apart. I've had a universal joint break this season on a drive shaft (I have rotoflex). I'm putting in the high end of the power figs quoted. To be honest I think that to a great extent the life of the drive train is down to how you drive. Dump the clutch at 6000rpm with 170Lbft torque too often and non of it is going to last long.-
How much Hp/torque before drive train gives trouble
Posted By : Steve Smith, 20-Oct-2006, 07:57pm
I'm using 3.89 and 3.65 diffs in my racer with virtually no problems. One's a Quaife ATB and the other is welded. I found the heat treat a bit suspect in the late 60's pieces but it got much better towards the end. Perhaps that's why they say the 1500's are stronger?
Like Dave, I'm putting out at the top end of the range and don't baby the car at all. I don't worry about diff's. -
How much Hp/torque before drive train gives trouble
Posted By : Piero Franchi, 20-Oct-2006, 07:58pm
Thanks David.
It would have been GR8 if you new were the diff housing came from
was the distance between halfshafts the same???
was the housing a triumph one??
and were the out put flanges and splines on this diff any bigger than a 1500, as they have the big type.
thanks-
How much Hp/torque before drive train gives trouble
Posted By : Nigel Gibbins, 24-Oct-2006, 12:59pm
The diff housing will be standard triumph ones... as that's what the regulations say it has to be... doesn't it Dave...
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How much Hp/torque before drive train gives trouble
Posted By : David Thompson, 25-Oct-2006, 10:01am
Certainly is Nig feel free to send the scrutineering police over any time. What I meant was that I don't know which model Spitfire/GT6/Herald the casing originated from but suffice to say it's large input and output with adjustable endfloat i.e. not the collapsible 1500 type and has only 4 studs on top to mount the spring. I'm sure someone with a lrge anorak would be able to figure it out.
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How much Hp/torque before drive train gives trouble
Posted By : Richard Briscoe, 20-Oct-2006, 08:25pm
Hi Piero,
The diffs that have gone on my car have all blown in different ways (Please bear in mind that I don't spin the wheels in 1st, I get moving then accelerate in 2nd and 3rd!!)
1 The front casing vibrated loose whilst doing 3800rpm (75 MPH ish) - oil vaporised, wheels locked up car behind not impressed. The cause was the diff internal componets coming loose and shaking the diff apart.
2 Front seal went on a nearly new diff, lost the oil on a long run and this caused a horrible grating noise to be emitted eventuall resulting in a petrol saving trip home on a recovery truck.
3 Crown wheel (is that the big gear?) broke up in the casing whilst accelerting, again not a pleasant experiance, but it saved me the petrol on the way home.
Confusingly the dealers I have spoken to all say it is the planet gears in the diff that give problems!
Sorry I haven't any experience with 180bhp through the diff, but the racing crew seem to have this about covered, they all seem really helpful and might recommend where to get the bits from and how to asemble them together - (Might even make a good article for the courier!!!!!!!!!!)
The woodruff key in the shaft is in my experiance the weakest link in the drive train, If you think it through, all the torque is transmitted through this 25x5x5mm (rough guess) piece of metal. On a standard diff the whole of the Torque is theoretically transmitted through one side if the other wheel spins so they may last longer with a limited slip diff. The trouble with the woodruff key is it snaps and allows the shaft to turn in the hub with jagged bits of steel flailing about; this wrecks both the hub and the shaft. Even if your shaft looks ok, the sharp machined corners will have rounded off and will cause the keyway to be a sloppy fit with the hub, this results in a continual clonking and very fast wear of the new components. I have ofetn wondered if someone could manufacture a stronger woodruff key. It might be worth checking them carefully before use as I have seen 2 or 3 with signs of air bubbles in the break indicating manufacturing isues (anyone got an X ray at home????). Alternatively would it be possible to get both your hub and shaft machined to take a second key to spread the torque?
As the parts suppliers are re-manufacturing shafts and aluminium hubs, could they not manufacture a shaft / hub combination that has splines instead? They don't need to slide but they would be effective for transmitting power.
Hope these ramblings were of some help
Richard-
How much Hp/torque before drive train gives trouble
Posted By : Piero Franchi, 20-Oct-2006, 08:41pm
Thanks Richard
But I feel you may have missunderstood the point of a woodroff key.
It is there to locate to items together, not to stop them spining on one and other. if they spin, this is because the items are not tight enough OR there fit with one and other is not spot on.
Two keys would only make matters worse, as the cutting of an other hole so to speak, will weaken the item it is cut into.
Dont take my points as to mean I did not apreciate your advice, as it is just that that I want.
Bit of "who has had what go wrong"
and even better "how did they fix it"
Thanks-
How much Hp/torque before drive train gives trouble
Posted By : Piero Franchi, 22-Oct-2006, 01:50pm
Any one else have any thoughts to say on the power through thr rear wheels issue????-
How much Hp/torque before drive train gives trouble
Posted By : Martin Flint, 22-Oct-2006, 05:41pm
I've got about 180-185 at the flywheel with the V8 into a rover 5 speed, with standard prop/uj's and rotoflex via a 3.6 spitfire diff.
it's not fell out yet and i do give it some stick.
tends to blow oil out of the breather hole after 90mph though.
Cheers
Martin
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How much Hp/torque before drive train gives trouble
Posted By : Julian Belcher, 02-Nov-2006, 03:26pm
I know all about diff problems. The Vitesse has non standard rear drive shafts and causes no problems. Unfortunately I have broken two quarter shafts in four races and so I am now taking that diff out and am in the process of fitting one from an Impreza.
Mind you the power output is approximately 230bhp at the wheels, so I suppose that it has every right to snap a few bits. The crown wheel and pinion however seem to cope with the load, and so does the rest of the diff (inc Quaiffe diff)-
How much Hp/torque before drive train gives trouble
Posted By : Andy Vowell, 02-Nov-2006, 03:35pm
Hi Julian
You said your were using non standard rear drive shafts, what type are you using?I'm gathering all possible info on alternative options to swing axles.
Cheers
Andy-
How much Hp/torque before drive train gives trouble
Posted By : Julian Belcher, 03-Nov-2006, 05:56pm
Andy,
I knew someone would evenually ask. I don't know where they come from as they were on the car when I bought it. One theory is that they originate from a stag. You are very welcome to come along and look, measure, photo etc (it is all in bits at the moment)
P.S. Want to buy a slipper?
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How much Hp/torque before drive train gives trouble
Posted By : Piero Franchi, 04-Nov-2006, 09:19pm
Hi Julian,
would you be kind enough to post a few photos of your half shafts so every one can see.
If they are stag, they should be easy to spot.
many thanks
Piero
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