TR7 rear Axle

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Murrayminor
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TR7 rear Axle

Post by Murrayminor »

Morning
I'm thinking way ahead here on my current project, but it was mentioned in a telephone conversation yesterday that changing the front drums to discs can give me the option to change the PCD on the wheels, so taking this a bit further I thought of changing the rear hubs to suit the front.

And this in turn led to me exploring the possibility of changing the rear axle completely to give me more of a choice, for wheel fitment, bigger brakes, stronger halfshafts.

I have tried to search and have found some talk of the TR7 axle conversion to the Minor giving the option of 8" rear brakes to compliment the front discs, stronger halfshafts and better wheel options (size, style, availability etc).

Would anyone have any knowledge of the above?

I live close to S&S Preparations and know they have at least thirty TR7 in their yard so finding an axle shouldn't be an issue.

Regards

Dermot.
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philthehill
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Re: TR7 rear Axle

Post by philthehill »

In the Owen Burton booklet 'Marina to Minor' he talks about using Triumph Dolomite rear axles (with axle ratios stated) so it may be of benefit to have read. The Dolomite axle will give you the same track width as the Minor and will allow you an excellent choice of diff ratios and wheel selection. The Dolomite rear axle is very similar to the Marina rear axle and according to Owen Burton capable of transmitting over 100bhp. Whether the TR7 axle is the same or similar I do not know but both are worth looking into.

Phil

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twincamman
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Re: TR7 rear Axle

Post by twincamman »

The 4-speed TR7 uses the Dolomite/Marina axle (though the width may be different). The 5-speed TR7 uses a different axle, which is a 4-stud version of the SD1 axle. This will take V8 power, and not just Rover V8 either. The downside is that the diff is not a 'banjo' type like the Minor, Marina and Escort axles have. To change the diff ratio, you need to change the crown and pinion in situ. The 5-speed TR7 uses a 3.9:1 ratio as far as I know.
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Re: TR7 rear Axle

Post by Murrayminor »

philthehill wrote: Mon Jun 01, 2020 9:31 am In the Owen Burton booklet 'Marina to Minor' he talks about using Triumph Dolomite rear axles (with axle ratios stated) so it may be of benefit to have read. The Dolomite axle will give you the same track width as the Minor and will allow you an excellent choice of diff ratios and wheel selection. The Dolomite rear axle is very similar to the Marina rear axle and according to Owen Burton capable of transmitting over 100bhp. Whether the TR7 axle is the same or similar I do not know but both are worth looking into.

Phil
Thanks Phil
I have ordered a copy of the Owen Burton publication, so will have a read and see what they say.
Both the Dolomite and TR7 axles appear to have control arms and from the few images I have seen both appear very similar, but as you say the width will be the limiting factor.
I will conduct more research into the subject, it may be a cost affective way of getting round the weak Minor half shaft issue when used in competition, as hardened half shafts are currently circa £600 a pair.

Regards

Dermot.
Proud owner of my first Morris Minor
Murrayminor
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Re: TR7 rear Axle

Post by Murrayminor »

twincamman wrote: Mon Jun 01, 2020 9:55 am The 4-speed TR7 uses the Dolomite/Marina axle (though the width may be different). The 5-speed TR7 uses a different axle, which is a 4-stud version of the SD1 axle. This will take V8 power, and not just Rover V8 either. The downside is that the diff is not a 'banjo' type like the Minor, Marina and Escort axles have. To change the diff ratio, you need to change the crown and pinion in situ. The 5-speed TR7 uses a 3.9:1 ratio as far as I know.
That's interesting information, I was planning on staying with the standard Minor Gearbox, I may ask S&S for the measurements of the TR7 4 speed axle.
Would I be right in thinking the Minor 1000 gearbox will sustain the power from a 1330 engine say about 80bhp?
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philthehill
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Re: TR7 rear Axle

Post by philthehill »

In my opinion and experience the Minor 1000 gearbox & even the 1098cc will not sustain 80bhp for long.
If you want to keep the BMC gearbox look and feel you would be better off with the 1275cc Midget/Sprite gearbox though there are limits to what the Midget/Sprite gearbox will transmit. The 1275cc Midget/Sprite gearbox fitted to my Minor could not sustain the power and that is why I fitted a Ford 2000E 4 speed gearbox way back. I have never looked back. :D

As an aside the 4 speed Ford 2000E gearbox is a cheaper way of getting Ford reliability against the cost of a Ford Type 9 5 speed and it is quite capable of transmitting all the power you can make. You also get synchro on first gear. Parts are readily available.

https://www.ebay.co.uk/itm/ORIGINAL-FOR ... Sw2d5eg0EN



Phil
Last edited by philthehill on Mon Jun 01, 2020 10:47 am, edited 1 time in total.

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Re: TR7 rear Axle

Post by Murrayminor »

philthehill wrote: Mon Jun 01, 2020 10:36 am In my opinion and experience the Minor 1000 gearbox & even the 1098cc will not sustain 80bhp for long.
If you want to keep the BMC gearbox look and feel you would be better off with the 1275cc Midget/Sprite gearbox though there are limits to what the Midget/Sprite gearbox will transmit. The 1275cc Midget/Sprite gearbox fitted to my Minor could not sustain the power and that is why I fitted a Ford 2000E 4 speed gearbox way back. I have never looked back. :D

As an aside the 4 speed Ford 2000E gearbox is a cheaper way of getting Ford reliability against the cost of a Ford Type 9 5 speed and it is quite capable of transmitting all the power you can make. You also get synchro on first gear. Parts are readily available.

Phil
Apologies I should have said its a 1098 gearbox but from your experience I may revise my gearbox choice as well.


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Dermot.
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philthehill
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Re: TR7 rear Axle

Post by philthehill »

From this:-

https://www.ebay.co.uk/itm/ORIGINAL-FOR ... Sw2d5eg0EN

To this:-

Same box as above but metamorphized into a Quaife unit
Quaife box 2.jpg
Quaife box 2.jpg (1.12 MiB) Viewed 2108 times

Murrayminor
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Re: TR7 rear Axle

Post by Murrayminor »

That's very interesting, I would really have no need for a 5 speed box so the more cost effective 4 speed makes perfect sense.

Thanks for the information, as I stated in my original post its very early days in my particular build but I can see how the car is shaping up already.

Regards

Dermot.
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philthehill
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Re: TR7 rear Axle

Post by philthehill »

Before I fitted the 4 speed gearbox to my Minor I had a long test drive of the CS Autoclassics Minor fitted with the Ford 4 speed box and it drove magnificently - a much nicer box all round than the 'A' Series box. The bell housing was supplied by CS Autoclassics and the rest was sourced by me. I even used the original Morris gearbox cross member fitted with a Minor rear leaf spring pad as the rear gearbox mount.
Whilst top gear will be still 1 - 1 the other gears are of a close ratio style and suit the Minor engine power output well.

Phil

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Re: TR7 rear Axle

Post by kevin s »

I have my tr7v8 on a 4 post lift undergoing body repairs in the garage if you want any photòs or pictures.

They have a 4 link axle set up with the top links angled to give lateral location and the bottom link has the spring reacting onto it.

I wouldn't bother with the 4 speed axle it's not up to much and parts are difficult to find.

5 speed Standard is 3.9:1 for manual or 3.45 : 1 for auto, any sd1 ratio will also fit.
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Re: TR7 rear Axle

Post by philthehill »

Here is a TR7 rear axle on 'e' bay.
https://www.ebay.co.uk/itm/Triumph-TR7- ... Sw2yNbP0le

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Re: TR7 rear Axle

Post by Murrayminor »

Thanks for all the information, I'm still deciding on which route to take at the moment but up to now I think a ford 4 speed box mated to either a Triumph Dolomite/TR7 rear axle.
The engine I'm building will only be a 1330 and wont be subject to hard starts such as those in Hillclimbing but I wouldn't want to shear a halfshaft half way up a muddy hill with a bit of wheelspin so I have some thinking and measuring to do.



Thanks

Dermot.
Proud owner of my first Morris Minor
philthehill
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Re: TR7 rear Axle

Post by philthehill »

Dermot
If you are thinking of using your Minor in Production Car Trials or trials the Minor rear axle is more than adequate. My Minor was used for production car trials before speed hill climbing and never once had any problems with the axle. or axle shafts. I still have a dent in the rear where having ground to a halt slid back into a tree. I left the dent in place as a reminder of what went before.
Phil

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Re: TR7 rear Axle

Post by Murrayminor »

philthehill wrote: Tue Jun 02, 2020 8:37 am Dermot
If you are thinking of using your Minor in Production Car Trials or trials the Minor rear axle is more than adequate. My Minor was used for production car trials before speed hill climbing and never once had any problems with the axle. or axle shafts. I still have a dent in the rear where having ground to a halt slid back into a tree. I left the dent in place as a reminder of what went before.
Phil
Phil
In that case would you suggest a set of these would work and save me a load of work swapping axles?

https://www.petermayengineering.com/pro ... a-a-653mm/

Along with a 4 speed ford gearbox?

Regards

Dermot.
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philthehill
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Re: TR7 rear Axle

Post by philthehill »

Plain and simple - yes.

Just for interest/information - the OE half shafts in my Minor were purchased new and heat treated before being put into use and after heat treatment were guaranteed to transmit 178 bhp. They have been used for hundreds of standing starts over the years without problem.
They were heat treated in the 1970s and unfortunately I do not have a contact address for the company that did the job anymore.

Phil

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Re: TR7 rear Axle

Post by Murrayminor »

philthehill wrote: Tue Jun 02, 2020 9:15 am Plain and simple - yes.

Just for interest/information - the OE half shafts in my Minor were purchased new and heat treated before being put into use and after heat treatment were guaranteed to transmit 178 bhp. They have been used for hundreds of standing starts over the years without problem.
They were heat treated in the 1970s and unfortunately I do not have a contact address for the company that did the job anymore.

Phil
Believe it or not there is a heat treatment works just down the road from me, I may call in and ask if they can do anything for me.

https://www.wallworkht.co.uk/
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twincamman
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Re: TR7 rear Axle

Post by twincamman »

Murrayminor wrote: Mon Jun 01, 2020 11:12 am That's very interesting, I would really have no need for a 5 speed box so the more cost effective 4 speed makes perfect sense.

Thanks for the information, as I stated in my original post its very early days in my particular build but I can see how the car is shaping up already.

Regards

Dermot.
Might I recommend the 4-speed from a Mk3/4/5 Cortina 1600. They're available quite cheaply as everyone wants 5-speeds, and they shift really nicely. Also, if you're going for a 3.9:1 diff, you'll be able to fit a 1000tpm speedo and be pretty much spot-on reading-wise. 1000tpm speedos were fitted to Series 2 Minors if you ant a direct bolt-in swap. Yes, they only go up to 80mph, but at 80mph, you know you're speeding, right?
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Re: TR7 rear Axle

Post by Murrayminor »

Twincamman is this the type of gearbox you're referring to?

https://www.ebay.co.uk/itm/Ford-4-speed ... Sw0~de1TmS

On the same theme, is the Midget/sprite gearbox any stronger than the Minor box?
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Re: TR7 rear Axle

Post by philthehill »

Murrayminor

You do need the Ford 4 speed gearbox with the detachable bell housing.

The gearbox in the link above does not have the detachable bell housing as in my link above and below:-

https://www.ebay.co.uk/itm/ORIGINAL-FOR ... Sw2d5eg0EN

The MG Midget gearbox is stronger than the 948cc/1098cc Minor gearbox but the Ford gearbox will suit your needs better and more importantly last longer.

Phil

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