Beefing up the rear axle
Posted By : Chris Gray, 27-Apr-2004, 03:39pm
Stuart.
I'm installing a Rover V8 in my Spitty 1500, and wasn't planning on doing anything to beef up the rear end. If I ever tune my engine at all, then I'll look into it, but for now I think (I hope
) it should be strong enough.
Tim Willis at Willow Triumph has a Rover V8 in his Spitfire, and other than swapping to a GT6 diff, I don't think he's modified his rear end, and he's apparently not had any problems with it.
Chris.
I'm installing a Rover V8 in my Spitty 1500, and wasn't planning on doing anything to beef up the rear end. If I ever tune my engine at all, then I'll look into it, but for now I think (I hope
) it should be strong enough.Tim Willis at Willow Triumph has a Rover V8 in his Spitfire, and other than swapping to a GT6 diff, I don't think he's modified his rear end, and he's apparently not had any problems with it.
Chris.
-
Beefing up the rear axle
Posted By : Stuart Waters, 28-Apr-2004, 06:12am
Thanks Chris - on two points. Firstly I can relax a bit regarding the longevity of the parts, but secondly because I half expected to get the usual "looking down the nose" reaction from purists!! It's good to know that other folk have made this modification successfully.
What gearbox are you using for the transplant? I have a 5 speed manual box from a Rover SD1, but I don't know what the fit is going to be like. I understand that it is possible to use the 2.5PI box as it fits easier between the chassis rails. What has Tim Willis used?
Also, where are you mounting the engine? Are you making any modified brackets on the chassis or altering the block mounts?
Maybe if you have any contact details I could ask Tim Willis too. I'm in the planning stages at the moment, assembling parts and getting components cleaned up etc, and I'm keen to get this right first time.
Thanks again and I look forward to hearing from you.
Stuart-
Beefing up the rear axle
Posted By : David Styles, 28-Apr-2004, 09:20am
Hi...
the guy at www.picton-sportscars.co.uk has a monster (Triumph) engine in a Spit.
I know he had one diff blow up on him initially...
I don't think he's ever had drive shaft problems, but if I remember correctly he *might* have had some special ones made up.
Might be worth giving him a ring to see what he's done about his back end ?
-
Beefing up the rear axle
Posted By : Stuart Waters, 28-Apr-2004, 10:49am
Many thanks David. Will do!-
Beefing up the rear axle
Posted By : Andy Vowell, 28-Apr-2004, 11:01am
Stuart
Its not totally clear from your first post, are you intending to fit late rotoflex type rear axle or keep the Mk3 Spit swing axles?
The swing axles do break and most TSSC racers can give you many examples (I have 4 in my garage!) So if you are going to keep the early type back end, then I would recommend uprated axles of some kind.
Rotoflex race cars do not suffer the same indignity of losing wheels at speed. (as long as hub nuts stay tight)
With Diffs we tend to use later items with the large flanges and 9/16 AF head bolts (can't remember the thread size)
Cheers
Andy-
Beefing up the rear axle
Posted By : Chris Herridge, 28-Apr-2004, 01:40pm
beefing up the rear axle is something floating around in my mind too.
My current car (which just passed it's MOT first time!) is fine and i enjoy it's rather scary handling,
But my project (like most, a Mk3 with large engine) will certainly require something bigger. When i asked before somebody said something rather interesting about taking an entirely new system and plonking it onto the chassis.
It seems Jagaur, BMW, Ford Sierra and other IRS's are all easily available and used quite alot in Kit cars like the Cateram's, Tiger's e.t.c.
but even with faily extensive searching i've been unable to find any detailed explainations of spitfire conversions with these...
So...
Anybody know about these?
Anybody done it?
Or should i just take 2 sets of front suspension off Dolomite, use the Pony gearbox, link the rear steering through a reduction box to the front, and have a 4WD, 4 wheel steer'd spitfire?!?!?!?
(okay, i'm really going mad)-
Beefing up the rear axle
Posted By : Tim Willis, 28-Apr-2004, 11:08pm
Hmm,
I agree with the point mentioned earlier about reluctance to divulge info on projects. I always kept my V8 project quiet until I new the person I was talking to was receptive to that kind of thing. I got so much criticism in the early stages from people who I now know knew sod all!
As regards the rear end, well I was always just going to try it and see how long it lasted. I really expected to break something fairly quick. However, up till now all is well.
Maybe the tall 3.27 diff reduces the torque loading on the shafts (unlike racers with low ratio diffs) or maybe the tyres breaking free is just saving me. Goodyear GT2's nothing too sticky. I don't do hard standing starts as a rule, it wouldn't achieve much and firm, moderate revs starts are far more effective with the torquey motor.
At a recent track day she really got some grief, downshifting and turning into a corner was causing the rear (which isn't yet sorted right) to lift the inside wheel and lock up. No LSD so the wheel would have been trying to go backwards and I was cringing (through the red mist) and waiting for the snap.
Now I'm not saying that the racers are wrong, far from it, just that if your drive train is in good order it should handle it, just don't go too daft.
I have considered using something like a Sierra unit and fabricating a complete new rear, but it wouldn't be simple, the chassis is kind of in the way and I can see a complete new rear subframe being required.
Seems to be a few people going down the V8 route lately, maybe I should copyright mine?!
Good luck
Any questions just ask. Or book it in and I'll do it for you!
Tim
Willow Triumph-
Beefing up the rear axle
Posted By : Chris Gray, 29-Apr-2004, 00:01am
Tim,
Just out of interest, what sort of price would you charge to do that?
I need someone to do the things I can't do myself (which is probably a fair bit), and while I do know a mechanic nearer to home who is willing to put the engine in for me, he's not done a Spitfire V8 conversion before...
Plus, I'd really like to help out as much as I can - although I appreciate you may not want people getting in your way while you're working.
Chris.-
Beefing up the rear axle
Posted By : Stuart Waters, 29-Apr-2004, 02:25am
Tim,
lots of good points, and I think I will follow your advice and stick with a standard setup, after making sure that everything is in good order.
I appreciate Andy's advice, and think that his suggestions are correct for a racer, but I'm just going to be using the car for occasional driving and to club dates so I'll swap to a swing spring, a nice tall diff and leave it at that. I've always been one for the sound of a low revving deep burble anyway, so everything looks good.
Thanks all!!
Stuart-
Beefing up the rear axle
Posted By : Tim Everitt, 29-Apr-2004, 05:34pm
OK, so here goes.
I had the intention of building a 2.5 l Spit. I have the GT6 rolling chassis and the rust free american Spit tub which has now been converted to RHD. I wanted to retain the Spit handling characteristics and the Spit bonnet line. So I've been looking at mounting the 6 cyl engine about 6 ins further back in the chassis. This seems to involve an awful lot of chassis cutting and strengthening (particularly if I want to fit an O/D gearbox). It also seems that a lot of bulkhead modification will also be necessary unless I switch to a PI system.
The simple question is - is it easier to fit the Rover V8 ? I have an awful lot of experience with this engine in various Land Rovers and recently TVRs - and I like it very much - but does it fit?-
Beefing up the rear axle
Posted By : Tim Willis, 29-Apr-2004, 10:37pm
Tim
Well yes it does fit, surprisingly easily. Thats not to say it's an easy conversion.
You don't need to do much in the way of chassis mods, but my main worry is that you want a standard bonnet line. If you were prepared to do a bit of chopping you could get the Rover either back enough (bulkhead in the way) or low enough (steering rack in the way). I put mine where it comfortably sat which is also nicely back in the bay, consider the engine is only the length of a four pot + a bit so you don't have that weight ahead of the axle line like the GT6.
If you used a GT6 bonnet you will get the engine under it fairly easily but you will need to use a Holley carb or similar and there will be precious little room for an air filter. My air filter sticks through about 30mm at the front
After that it is just the usual problem with transplants of connecting everything, cooling and the exhaust system.
Mind you Spit handling characteristics kind of go out of the window when you can go so much faster so much more quickly, hanging on and brakes suddenly become very important!
Something to think about?
Tim
Willow Triumph-
Beefing up the rear axle
Posted By : Tim Everitt, 30-Apr-2004, 09:35am
Tim,
Hmmmmm.......
Don't be altogether surprised if I get in touch to have a look at yours, if you don't mind?
-
Beefing up the rear axle
Posted By : Stuart Waters, 30-Apr-2004, 01:22pm
Not at all. Only problem is that you'll have to wait until next summer, 'cos until then I am the club's only member in China!!
I aim to be at Stafford 2005, so listen out for the car alarms going off as I approach (fingers crossed!)
Stuart
-
-
-
-
Beefing up the rear axle
Posted By : Christopher King, 30-Apr-2004, 09:20am
Hi,
Sorry to just appear in this conversation, particularly as I am a novice to all this, but there is an old Range Rover my Dad's barn and I've always been tempted...
On the rear axel problem, an I right to assume that the Spit diff ( ok, maybe at a different ratio) and drive shafts would be fine for a raod car if the tyres are kept 'thin'? Wouldn't all the excess torque just be transfered from the diff to wheel spin, meaning the only thing that would go quickly is the rubber? Or am I being a little naive?
Chris-
Beefing up the rear axle
Posted By : Stuart Waters, 30-Apr-2004, 01:29pm
Hi Chris,
Burning rubber or cracking driveshafts - it's all expensive if it becomes a habit!
To be honest, I'm an amateur too, and have to ask these guys for the skinny on this stuff, but from the sound of it, as long as we realise that we are putting far more power than was intended to go through the drivetrain, and treat it with the appropriate respect, everything should be just fine.........probably!!
-
-
-
-
-
-
Beefing up the rear axle
Posted By : Stuart Waters, 28-Apr-2004, 03:03pm
Andy,
thanks. I'm now thinking the rotoflex might be better! Nothing worse than suddenly ony having 3 wheels on your wagon, although originally I had considered maintaining the swing axle as a) I'm not going to race the beast, and b) I do not want to have to swap the suspension to Rotoflex.
I had thought that stronger driveshafts would be required, but is the strength required in the splines and hub, or in the shaft itself?
In other words, could I take any old driveshaft of thicker proportions and get the length altered and splines / thread machined in, or is it more difficult than that?
It's really hard to find this info on the web, as Chris said, so you guys are such a valuable resource. In 2005 I hope to bring the beast to Stafford, so I'll buy you a beer then!!
Cheers
Stuart
-
Beefing up the rear axle
Posted By : Andy Vowell, 28-Apr-2004, 08:54pm
Standard halfshafts are connected to the drive flange/hub on a taper with a keyway (ie not splines) They break about halfway along the keyway at the end of the key (which is only half the length of the keyway). The crack is initiated by a 'nick' put in the shaft to locate the key.
Snappages happen under hard acceleration indicating that the design and material of the shaft cannot handle the torque/power. Splined shafts have been tried using the same material and size, but were not very successful.
If you go bigger it may help, but you would need to redesign the hub too. And as the bearings run on the shaft as well, you would need bigger bearings and housing as well. It all gets very complicated.
Simple fix is to go rotoflex or a similar system without the doughnuts using TR4/Triumph 2000 sliding spline axles. But I understand your reluctance as I know once set up the swing axles work extremly well and are a lot lighter.
I have heard that the mid 80's 3 series BMWs swing axles may fit but can't give any details.
I have got some axles from America that have the shaft and hub built all in one piece, so completly removes the problem area. They came at a price though of &163;900+ (including import tax)
If you want details for these send me a mail (spit50@blueyonder.co.uk)
Andy
Beefing up the rear axle
-
-
-
-
-
Beefing up the rear axle
Posted By : Chris Gray, 28-Apr-2004, 02:32pm
Stuart,
I'm still in the planning stages myself - well, still trying to obtain all the parts I need, really. I will also be using the SD1 5-speed gearbox - it's actually the part I've been having most trouble getting my hands on - hopefully got one sorted now though. Tim has also used an SD1 5-speed box.
Tim does read the messageboard, but sometimes not very often - I think he's pretty busy. If you want to email him, his address is binpleb@ntlworld.com. I also went to see his V8 Spitty a couple of months ago, and took some pictures of how he's done various bits. You can see them online at
http://www.chris-gray.co.uk/spitfire/3500project/p...
I also have higher resolution versions of the pictures on my computer which you're welcome to copies of if you want - just drop me an email. I'm also on MSN a lot of the time if you have that - the details are in my profile.
Hope this is of some help...
Chris.
-