TR7 axle into dolomite?

[cliftyhanger]

Just an idle idea. Does the TR7 5 speed axle fit (with or without fettling) into a dolomite?
Looking at ratios, seems the TR7 5 speed has a wide range of ratios available, down to 2.84 and 3.08
My mind is wandering, thinking about jag v6 engines.......

[cleverusername]

I just had a look at this because the TR7 axle does look very like a Dolly Axle, i suppose not much of a surprise there. It appears to be 20cm wider than a Dolly axle, I suppose you could flare the wheels.

The other issue is the location of the tiebar mounts is different on the TR7 axle and whether the suspension arm mounts line up, no idea. Still he owns a welded and an angle grinder can get round such things.

It seems the diff is a 3.9:1 ratio.

[cliftyhanger]

Ah, 20cm is a lot, I was hoping it would be a lot closer.
Maybe I was being hopeful....

[Carledo]

I had a 7 axle till recently, couldn't give it away so it got binned when I lost the workshop.

I bought it to try in the Carledo before I found a scrap Sprint rolling shell and used that axle instead.

By my reckoning the error is more like 10cm (4") over the hub flanges and across the trailing arm mounts, near enough the same.

Still a bit dubious over whether you'd need arch extensions, but it'd certainly help you fill them!

The axle I had had a 3.63 in it but there are several more advantageous choices. the upper tie bars would convert easily, you might even get away with 7 upper tie bars, I had those too but think they met a similar fate!

Steve

[cleverusername]

I had a 7 axle till recently, couldn't give it away so it got binned when I lost the workshop.

I bought it to try in the Carledo before I found a scrap Sprint rolling shell and used that axle instead.

By my reckoning the error is more like 10cm (4") over the hub flanges and across the trailing arm mounts, near enough the same.

Still a bit dubious over whether you'd need arch extensions, but it'd certainly help you fill them!

The axle I had had a 3.63 in it but there are several more advantageous choices. the upper tie bars would convert easily, you might even get away with 7 upper tie bars, I had those too but think they met a similar fate!

Steve

I was basing the different in width on measurements that people on the TR7 forum had taken and compared it to numbers on here. It is surprisingly difficult to get accurate specs on axle widths, I suppose you don't normally need those numbers.

The diff ratios came from here https://www.revingtontr.com/the-tr-seri ... nge-points, interestingly it seems later US spec TR7s got the same diff as the 6 cylinder SD1s. I don't know much about that engine but I assume it must have put out a decent amount of torque and the diff must be pretty tough.

[gmsclassics]

But what can be made to fit is a Ford English axle from an Escort / Capri. That is about half an inch difference in width, drum face to drum face.

I used one in the Sprint I raced for at least ten years after the original Sprint item destroyed itself. We had to gas axe the four mounting points off the Sprint axle and weld them to a cleaned up Capri 3L axle. Chose the Capri as it comes with 9” rear drums, so same size as Sprint. Had the welding professionally done and with careful measuring it was surprisingly easy. Handbrake and hydraulic pipework was simple to adapt to the Ford axle.

We drilled the hubs (and drum) to the Sprint PCD. Alternatively if we had wanted to change wheels we could have retained the rear Ford PCD and bought a front hub conversion to use that all round. That would have opened up a wider variety of secondhand wheels. I did use uprated studs all round and spacers to position the wider tyres (195) central to the Sprint wheel arches.

The front flange on the Capri diff bolted straight to the Sprint prop.

Advantages of the Ford axle are
1) the huge variety of diff ratios available both new and secondhand.
2) The fact the whole diff head can be removed from the diff housing (still in the car) and changed as one unit.
3) LSDs and parts to rebuild them are more readily available and usually cheaper
4) Thicker diameter halfshafts are available off the shelf which are better when racing and no drums full of diff oil as Sprint ones are prone.

Just a thought...

Geoff

[cliftyhanger]

I was just thinking about jag aj30 engines. Seemingly popular in certain circles, Rocketeer are using them in MX5's and others in kitcars.
240 bhp std, easily tickled up towards 300, and good for more if wallet is heavy.

Downside is the std manual gearbox has top gear as straight through. So hopeless unless a very long ratio diff, something around 2.8 would be needed I reckon.
Rocketeer use the MX5 box, however, that needs a custom flywheel to fit.
Other alternatives are the RX8 box via an adaptor plate, and then the flywheel from a mondeo st200, which are near-impossible to find.

Bearing in mind my thoughts are a bit of a "budget" build, things could easily get out of hand! So it looks like a simpler 4 pot engine is a safer bet if the car is ever to actually reach the road with a new engine. I keep looking at the st170 engine I have in the garage.... so same as in my spitfire. At least I know (more or less!) what I am doing with that

Cheers All

and I am especially surprised that triumph props have the same pcd as ford. NOBODY has ever mentioned that before.

Clive

[SprintV8]

Are those AJ engines heavy around 200kgs and wide at the top.

Would they even go into a Dolomite engine bay without mods.

I’ll go ST170 it’s lighter and I’ll bet more fun when done.

[cleverusername]

But what can be made to fit is a Ford English axle from an Escort / Capri. That is about half an inch difference in width, drum face to drum face.

I used one in the Sprint I raced for at least ten years after the original Sprint item destroyed itself. We had to gas axe the four mounting points off the Sprint axle and weld them to a cleaned up Capri 3L axle. Chose the Capri as it comes with 9” rear drums, so same size as Sprint. Had the welding professionally done and with careful measuring it was surprisingly easy. Handbrake and hydraulic pipework was simple to adapt to the Ford axle.

We drilled the hubs (and drum) to the Sprint PCD. Alternatively if we had wanted to change wheels we could have retained the rear Ford PCD and bought a front hub conversion to use that all round. That would have opened up a wider variety of secondhand wheels. I did use uprated studs all round and spacers to position the wider tyres (195) central to the Sprint wheel arches.

The front flange on the Capri diff bolted straight to the Sprint prop.

Advantages of the Ford axle are
1) the huge variety of diff ratios available both new and secondhand.
2) The fact the whole diff head can be removed from the diff housing (still in the car) and changed as one unit.
3) LSDs and parts to rebuild them are more readily available and usually cheaper
4) Thicker diameter halfshafts are available off the shelf which are better when racing and no drums full of diff oil as Sprint ones are prone.

Just a thought...

Geoff

it is an interesting idea, the only problem I can see is ford bits seem to go for silly money these days.

[cliftyhanger]

Are those AJ engines heavy around 200kgs and wide at the top.

Would they even go into a Dolomite engine bay without mods.

I’ll go ST170 it’s lighter and I’ll bet more fun when done.

From the kitcar site I frequent I had the bare aj30 as approx 125 with flywheel. With of engine (no manifolds, but they are tucked away) as 530mm.


But the gearbox issue is a real stumbling block, plus the ST conversion is pretty straightforward for me. Still, will be 50-70bhp and a bunch of torque down. However, I suspect the sprint axle may be too stressed as well with the V6, but the st won't trouble it.

[Carledo]

What about the Vauxhall V6? 217 bhp and bags of torque out of the box for the 3.2. Lots of tuning goodies now available for this engine and the gearbox is tough, short, light and 5th gear is overdriven. I saw a pic of a bare motor offered for sale which rekindled my interest recently as it looked rather narrower than i'd thought. I'm guessing its a 60 degree V6 with quad cams and 24 valves. Omega donor cars are cheap as chips ATM. I have the wiring diagrams to make it all work too!

I dropped the V6 as a plan as the Z20LET 2.0 turbo can put out similar bhp figures for less weight, i'm just undecided about forced induction, i'm an NA man at heart!

Steve

[cliftyhanger]

What about the Vauxhall V6? 217 bhp and bags of torque out of the box for the 3.2. Lots of tuning goodies now available for this engine and the gearbox is tough, short, light and 5th gear is overdriven. I saw a pic of a bare motor offered for sale which rekindled my interest recently as it looked rather narrower than i'd thought. I'm guessing its a 60 degree V6 with quad cams and 24 valves. Omega donor cars are cheap as chips ATM. I have the wiring diagrams to make it all work too!

I dropped the V6 as a plan as the Z20LET 2.0 turbo can put out similar bhp figures for less weight, i'm just undecided about forced induction, i'm an NA man at heart!

Steve

ha, I don't see Omegas under 1K at all. Obviously wrong end of the country again. But after much deliberation, the ST is "the chosen one"

[sprint95m]

and I am especially surprised that triumph props have the same pcd as ford. NOBODY has ever mentioned that before.

You need to tread carefully here Clive.

Ford UK changed from imperial to metric in the early seventies (during the production of the mark 3 Cortina,
I am not sure when that corresponds to in the Capri production).
Triumph in the 70s used at two UJ sizes with corresponding flanges, so used two PCDs.

Dolomites use the smaller size. T2000 used the larger size for the driveshaft (and the smaller on the prop).

A Dolomite prop won't fit a Capri 2.8 diff. (I have just tried)
It is possible that a Dolomite prop could fit a mark 2 Cortina or mark one Escort diff though?
Therefore I am thinking it may be possible to use a mark 2 Cortina diff flange on a very early mark one Capri three litre differential?
Whether a Dolomite flange could fit the Capri diff is another question? I suspect yes.....


The thing is Clive, you are surely going to have a bespoke propshaft anyway?


thanks,
Ian

[cliftyhanger]

and I am especially surprised that triumph props have the same pcd as ford. NOBODY has ever mentioned that before.

You need to tread carefully here Clive.

Ford UK changed from imperial to metric in the early seventies (during the production of the mark 3 Cortina,
I am not sure when that corresponds to in the Capri production).
Triumph in the 70s used at two UJ sizes with corresponding flanges, so used two PCDs.

Dolomites use the smaller size. T2000 used the larger size for the driveshaft (and the smaller on the prop).

A Dolomite prop won't fit a Capri 2.8 diff. (I have just tried)
It is possible that a Dolomite prop could fit a mark 2 Cortina or mark one Escort diff though?
Therefore I am thinking it may be possible to use a mark 2 Cortina diff flange on a very early mark one Capri three litre differential?
Whether a Dolomite flange could fit the Capri diff is another question? I suspect yes.....


The thing is Clive, you are surely going to have a bespoke propshaft anyway?


thanks,
Ian

Thank you for the additional info. It makes sense... I know mk2 escorts (I think) were about the change from 7/16unf wheel studs over to M12. So what you say makes sense.
As an aside, the heralds and early spitfires have 5/16 prop and driveshaft bolts, later spitfires and the 2 litre cars used 3/8. And teh subaru diff I have in my spitfire, from a 320bhp turbocharged car?? 8mm, which is "the same" as 5/16. So must be strong enough. (I did take care and used grade 10.9 cap-head bolts, having to buy over-length and cut down so the unthreaded section was long enough to go past the join.
Anyway, the sprint axle should work fine with the ST engine. I will use an MT75 gearbox as oppsosed to T9 as (a) it is stronger bu some margin (2) it has a low, 3,68 ratio first gear so better suited to the sprint axle and (3) I happen to have an MT75 sitting here.

I am off tomorrow to collect the new ECU. At the same time I will have a look at the chaps car. He has an Avenger Tiger, plus a sumbea he is fitting an AJ30 engine into. That will be exciting to drive when done!

[jikovron]

I reckon a 2.4 duratorq '4 bolt' gearbox and its gkn propshaft would be the easiest and cheapest solution, and I have a gut feeling that they use the same prop series as an LDV 200 propshaft, of which has the same diff flange as a sprint axle albeit with the large size UJ spider.