RX-7 to TR-7 Front suspension

[Reddragon]

First off has any one looked into adapting the RX-7 front suspension to a TR-7?

This is what I have learned so far; the 1st gen RX-7 front suspension is very similar to the TR-7 including the ball joint. Measuring the taper of the two are the same. Problem with this, other than having hubs with 4 x 100mm is that of the same weak spindle same small brakes. Though I have found a company that makes an adapter to bolt onto the RX-7 strut, which allows the use of the gen II hub.

The gen II has a more robust spindle, way bigger brakes, and the hub is 5 x 114 leading to a larger selection of wheels. The struts will fit with in the same area with the possibility of up-rated springs to 156 lbs and using the TR-7 top hat.

Where the problem lies is in mounting of the spindle to the control arm. The RX-7 uses a straight ball joint that measures 0.709 fitting into the bottom of the spindle and held by a pinch bolt on the center of the ball joint. This ball joint would need a new fabricated control arm to make this work. All measurements are in inches.

The TR-7 ball joint has a taper before the threads that measures 0.642 with the threads at 0.496. The lower part of the taper, measures 0.705, which is very close to the measurement of the RX-7 ball joint. The area of the bottom where the ball joints mount to is 1.013.

What I am thinking here, this is where I ask of the collected wisdom of this forum, if a sleeve was made to fill the area between the RX-7 spindle, using the pinch bolt to secure the sleeve, with the taper locking the sleeve to the TR-7 ball joint. This way the stock TR-7 control arm could be used with out having to re-engineer the front suspension angles.

Thoughts and thank you.

Nov 23 2011 up date. Sleeve to thin at bottom. Looking at Option B.

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Dale
1974 TR6
1977 TR7 FHC

[dycecooper]

I am impressed!!

Im not sure about the spacer though, I would preffer changing the arm for one that fits the strut, there are a few companies do moddified ones for other makes of rally cars so there may well be something out there.


Off for a look. [:)]

[Beans]

Looks like a lot of work for something that hasn't given me any problems in the past 23 years [:p]
B.t.w. I presume that with spindle you are refering to the front strut's axle stub?

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[Reddragon]

(B.t.w. I presume that with spindle you are refering to the front strut's axle stub?)

Beans

That is correct, the RX-7 has a separte strut assembly that bolts to the spindle / axle stub.

You have to remember, over here the cost of the big brake kit you have is way to much with shipping. I am looking at altneratives.

Dale
1974 TR6
1977 TR7 FHC

[bare]

Just this AM saw where someone was wanting to machine a Fresh Stub axle for their Triumph Upright to enable the use of Mazda hubs Brakes and wheels.
Might be a simpler more direct/.. fewer collateral damage issues.. route than retrofitting an alien upright with likely Vastly Differing suspension geometries??

[Jolyon39]

I have seen Triumph Stag struts adapted to the TR7 because they have a removable stub axle. If you want to use an alternative hub with rotor you can machine up a new stub to make it fit perfectly to your Triumph stag strut.

The Stag strut is apparently identical to the Triumph 2.5 saloon strut.... so I am told.

Jolyon

[Stag76]

Rover SD1 Struts can also be fitted. This changes the front to a 5-stud pattern, and the rear (5-Speed Salisbury type) can be changed by shortening and re-splining SD1 axles.

TR7 Convertible
Sprint Motor
MegaSquirt EFI

[Beans]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Reddragon</i>

... You have to remember, over here the cost of the big brake kit you have is way to much with shipping. I am looking at altneratives ... <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
That does make sense [;)]

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[Reddragon]

Thanks to all who have replied so far.

Dycecooper, I was hoping that you would come back with some more info on conversions. The sleeve may be a weak link, I will be using harden steel for this item and it will be capture with in the hub assembly by the pinch bolt and the nut for the TR-7 ball joint. In every thing there is a weak link somewhere the idea is to minimize them.

One item I was looking at was to use the stock RX-7 ball joint arm into a new lower control arm. This is where some one with a lot more knowledge of suspension geometric then I have would come into play. That is why I backed up to the simpler approach. the sleeve. The use of the RX-7 hub is very close to that of the TR-7 strut. Mounting point of the ball joint and distance to the rear face for the hub inner race are almost identical. The track distance may change less than a +or - ¼â€￾.

Bare, in my opinion to machine, unless one had access to machining equipment, a new stub would be more complicated. What I am trying to do here is be able to use off the shelf re-built or factory parts. I have always used the K.I.S.S. principle. Keep It Simple Sam.

Stag 76 & Jolyon 39, looked into using the Rover SD-1 struts, this once again came to a cost issue and parts availability over here in the colonies.

Thanks again.

Dale
1974 TR6
1977 TR7 FHC

[bare]

Without intention of pedantry
Swapping in a 'foreign' upright is a Can of worms not to be easily dissmised. McPherson strut setups are a massive series of design 'compromises'.. Easily messed.
If not right your car could be a handful or even frightening to drive as result.
The few $ saved may not feel so good in the pocket at that point.

[dycecooper]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Reddragon</i>

Thanks to all who have replied so far.

Dycecooper, I was hoping that you would come back with some more info on conversions. The sleeve may be a weak link, I will be using harden steel for this item and it will be capture with in the hub assembly by the pinch bolt and the nut for the TR-7 ball joint. In every thing there is a weak link somewhere the idea is to minimize them.

One item I was looking at was to use the stock RX-7 ball joint arm into a new lower control arm. This is where some one with a lot more knowledge of suspension geometric then I have would come into play. That is why I backed up to the simpler approach. the sleeve. The use of the RX-7 hub is very close to that of the TR-7 strut. Mounting point of the ball joint and distance to the rear face for the hub inner race are almost identical. The track distance may change less than a +or - ¼â€￾.

Bare, in my opinion to machine, unless one had access to machining equipment, a new stub would be more complicated. What I am trying to do here is be able to use off the shelf re-built or factory parts. I have always used the K.I.S.S. principle. Keep It Simple Sam.

Stag 76 & Jolyon 39, looked into using the Rover SD-1 struts, this once again came to a cost issue and parts availability over here in the colonies.

Thanks again.

Dale
1974 TR6
1977 TR7 FHC
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">


I have been working overseas and been a bit busy, sadly I have just been paid off but on the plus side I have loads of time on my hands at the moment so will see what I can find out.

[mrpatatomoto]

Im still looking for measurements and stuff like that, But I think if you add the mount for the camber adjustment the Nissan S15 front suspension could work too (I want to put a SR20DET engine into my car down the road so I keep looking at other parts from the S15 that can switch over too... I figure one donor car is better than certain parts of multiple cars.



~Mike
1975 TR7 FHC ACL5526UC