Our TVR Tamora has Gaz Gold Pro suspension fitted. These were fitted for the previous owner by TrackVRoad in July 2011 at a cost of £700 since one of the original dampers was leaking. This suspension was fitted at 13,349 miles, and we bought the car at 13,474 miles, so only had 125 miles on the suspension when purchased, and still less than 800 miles just under 3 months later when it returned to TrackVRoad for ride height checks under warranty.
I suspected the suspension had ‘settled’ a bit since we bought the car. I first measured the front splitter at 100mm then, but it failed to get over a 76mm obstruction with 2 of us in the car a couple of months later.
Gaz suspension is a popular for for many TVRs at a competitive prices (Gold Pro at ~ £650 fitted), but is viewed as below the top-tier manufacturers (e.g. Nitron) and has a mixed reputation for reliability, although reports indicate that it has improved in recent years. I have even heard a tale of a misbehaving car, the source of which was identified as Gaz shocks that should have been the same but with different internals. For my driving, it should be perfectly adequate.
I returned to TrackVRoad 3 months after buying the car, and Ian took a look at the suspension. The front had settled to 20 mm below where it should be. When you only have a little ground clearance, those 20 mm are important. The rear ride height was correct.
Adjusting the suspension was a relatively simple job, and while it was being done Ian showed me around the underside of my car (all is well under the car), explaining everything, and told me about the suspension settings they use:
- Rear toe-in = 3 mm
- Rear camber = 1.25 degrees negative
- Front toe-in = 1.5 mm (which changes to ~ 0 mm when driving)
- Front camber = 0.5 to 0.75 degrees negative
- Rake = 3/4 to 1 inch
- Damping set to 10 clicks front, 8 back.
A discussion with a chap at Gaz on 08/05/2012 when asking about C-spanners (apparently 2 1/4″) he suggested slightly firmer damping:
- 12 front and 10 back for normal driving
- 12 front and 12 back when carrying luggage for a road trip
- Clicks are from soft (turned fully anti-clockwise when facing the adjuster)
The chap at Gaz also answered my question on spring rates, which are 400 lb/inch on the front, and 325 lb/in on the rear. He said that he also ran Tamoras with 350 lb/in springs on the rear. A second question via e-mail on 01/11/2012 prompted a response saying 400lb front and 350 lb rear, with some customers going up on the rear for track and touring with luggage.
New springs from Gaz are a very reasonable £25 + VAT / corner (so £30) and delivery is £11.25.
While their standard kit is 400 / 350, some people go up to 450 / 375. Apparently the dampers fitted by TVR to the Tamora / T350 are a bit short relative to the springs used, and this effectively gave the spring some pre-load. This maintained ride height but at the expense of a ‘chattery’ ride.
The Gaz setup does not do this, so should could a more compliant ride in the initial part of the travel. The damping I am running (12/10) at the moment could be turned down a little if stiffer springs were fitted.
Some additional information was provided. Apparently the front springs are mounted very nearly straight, and the rear springs are at a significant angle. This means that the spring rate for the front may go from 400 to 375 effective, but the rear could lose nearly 40% of its spring rate. Therefore some people just put a 400 on the rear to match the front.
This is all useful information to discuss with Chris at Center Gravity.
Some information on Tuscan spring rates was posted here
In April 2012, TVR Power raised the rear slightly having considered it a bit low.
The ride height increases from Track V Road and TVR Power seems to have reduced the risk of grounding (see this link), with no real grounding incidents since it went up.
Centre Gravity (CG) is run by a suspension specialist called Chris who has done a lot of work on fast cars for track and road. His speciality is Porsches, but he has worked on a range of TVRs, and my Supra-driving friend credits Chris with transforming the handling of his car.
For the sun of £450 + VAT (£540), Chris (with me in attendance to learn about the suspension) will spend 8 to 12 hours to set the car for a balance of our requirements which are fast A-road use, touring, the occasional trackday and sufficient ride-height for speed bumps, and hopefully even ferries.
From our discussion, the following points seemed to be the plan:
- Drive and inspect the car / suspension / tyres to see how it behaves currently
- Measure the car’s current setup
- Take the wheels off to free up all suspension fittings, disconnect the roll bars, free the rear tow adjusters, see if any engineering work needs to be done (normally only necessary for cars being lowered a lot)
- Set the ride height for our requirements (thinks the suspension will have plenty of adjustability)
- Set the rake (nose-down attitude) to the correct 0.75 to 1.0 degrees
- Corner-weight balance the car across the diagonals
- Set geometry to achieve desired handling
- Drive the car to see how it handles after the work
Apparently TVRs can handle at the limits with understeer and can then be provoked into flick-oversteer with the throttle. The aim would be for a more neutral-handling car that could allow smear-oversteer with throttle application.
Chris suggested that, during my visit to TrackVRoad, they inspect the front and rear wishbone bushes for wear. If they need changing, then he can order the parts from Racing Green (who he uses) to fit on the day. On inspection, there were some new bushes, some old bushes, but all were ok.
We also discussed tyre choices, the option of slightly higher profile tyres on the front, and that Toyo T1-Rs were a little more compliant than Bridgestone Potenza RE050A, and should make a fine choice for the car.
Initial ride height (before TrackVRoad suspension correction on 27/01/2012)
I measured the ride height before any adjustments, and after 800 miles of driving with the new suspension.
I used a stack of DVDs, with some very thin DVDs to see what could be slid under the relevant part of the car. I then measured the height of this stack with a ruler. This is probably accurate to a few mm.
The measured heights, on an empty car with a full fuel tank, were as follows:
- Centre of front splitter – 95 mm
- Sill behind front wheel – 130 mm
- Sill in-front of rear wheel – 136 mm
- Rear diffuser behind rear wheel – 135 mm
- Lowest point of exhaust / centre of rear diffuser = 163 mm
- Front overhang from wheel centre ~ 77 cm (gives an approach angle of 7.1 degrees)
Given these are an empty car, add 2 people and the heights will go lower.
Suspension work (or work that I think is suspension) that is listed in the records I have for the car is:
October 2008 (10,272 miles) APM Automotive
- Customer’s own suspension fitted
- Replace lower Rose bearing in shocks(£51.6)
- Note – Rear track adjusters siezed
May 2010 (12,353 miles) TrackVRoad
- Replace 4 road springs (£120 labour, £168 parts)
- Replace both top rear wishbone bushes (£120 labour, £18 parts)
- Remove both rear wishbone bushes, free-off track adjusters (£240 labour)
- 4 new thrust washers
- 1 new rear wheel toe adjuster (£5.50)
- 1 new short drop link stud (£29)
July 2011 (13,349 miles), TrackVRoad
- Fit 4 Gaz Dampers and Springs (£75 labour, £625 parts)
- Replace N/S Steering rack gaiter (£33 labour, £16 parts)