Monogram Lola T70 Rebuild - Electric Dreams

Posted September 7, 2009

A Technical Article From the Electric Dream Team:

Monogram’s Lola T70

Fixing the Designers’ Mistakes

by L. Owen Fast

Monogram actually came a lot closer to getting its reborn Lola T70 right than you might think at first glance or even a first drive. All the right pieces are there so you have to wonder why the parts of it look so right but the assembled car somehow looks – well, just wrong. Specifically, why did they mount the body so stratospherically high on the chassis? And why did they design the chassis for a tire diameter that is only a couple of paper thicknesses larger than the diameter of the spur gear? None of it has to be that way. There’s room inside the body for larger diameter tires, and there’s no reason why they couldn’t have mounted the magnet lower to keep it within proper downforce distance of the track.

I have no idea about the tires, but at least I think I know why they put the body up so high. I think they simply forgot that they had to have all those little electronic bits on top of the motor to prevent broadcast TV interference if they wanted to sell it anywhere but in the US. So, when the designers produced a prototype model with the body down over the chassis where it’s supposed to be, just clearing the top of the motor, somebody asked the inconvenient question, “Where are you going to put all the interference suppressors?”

Oops.

Anyway, you’ll be happy to know that correcting the mistakes turns out to be fairly easy and turns the model into the truly beautiful piece of automotive art it was meant to be. Not only can you make it look like it’s supposed to; you can also make a very good runner out of it.

The easiest part is the rear tires. A pair of Indy Grips 1308 or Ortmann 50G tires will slip onto the rear wheels and solve the gear clearance problem. However, the increase in tire diameter moves the magnet up enough to lose a lot of downforce. If you race non-magnet the extra ride height won’t really matter much, but for the 90-odd percent of our readers who race with magnets there’s a quick and easy fix. All you need is a small piece of .040″ sheet styrene, a little CA glue, and a Professor Motor PMTR1063 magnet.

Remove the entire stock magnet assembly. Save the black rectangular plastic spacer that holds the stock magnet in either the forward or aft position. Cut a rectangular piece of the sheet styrene and CA glue it into the rear of the magnet pocket. Next, glue the black plastic spacer in over it at the rear of the magnet pocket, creating a flat surface just forward of the motor. Use sandpaper or an emery board to roughen one side of the Professor Motor magnet and CA glue it in place as shown. The magnet is just thick enough to give you good grip without sticking the car down too much. If you want more grip you can glue the magnet to the bottom of the chassis just aft of the motor and directly below the rear axle, but that will probably stick the car down more than most people will prefer. If you want a bit less grip you can use a PMTR1030 which is half a millimeter thinner.

The revised magnet installation using a Professor Motor magnet makes a big difference in the car’s handling.

The first step in lowering the body is to get rid of all the superfluous electronic bits on top of the motor. Remember, all they do is suppress interference with broadcast TV caused by arcing between the motor brushes and the commutator. They make no difference in the car’s performance, and you probably have cable TV, which is not affected by slot car motors.

With a soldering iron, carefully disconnect the lead wires from the metal tabs on the endbell. Then snip the little electronic bits off the lead wires. Then, unsolder the bits from the endbell tabs and the top of the can.Be sure to remove the two blobs of solder on the can as completely as possible.While doing this, try not to heat the can up any more than necessary.

The removal of all the hardware from atop the motor makes room to lower the body.

This will leave you with two lead wires that are too short. I have an organizer drawer full of odd scraps of lead wire, so, being the cheapskate I am, I simply found a couple of pieces of the needed lengths and grafted them onto the existing lead wires. If you don’t have leftover lead wire lying around or don’t want to bother with splicing wire you can simply buy a Slot It SISP03 and replace the lead wires entirely. Be sure to allow enough length for the lead wires to go around the interior tub and let the guide rotate freely.

While I was at it I replaced the stock guide and braid with a Slot It SICH06 guide and Ninco 80102 copper braid. This eliminates the wobble of the stock guide and provides much better electrical contact than the original braid. The Slot It guide also makes much better use of the depth of the slot on my Scalextric Sport track.The guide change required replacement of the eyelet connectors on the ends of the lead wires. I used Slot It SISP17 connectors (the same ones that come with the lead wire in an SISP03 package).I stripped about 1/4″ of insulation off the end of each lead wire.Then I ran the end connector up onto the insulated part of the wire with the stripped end extending past the end of the connector.Then I used needle-nose pliers to crimp just the end of the connector onto the wire.This attaches the connector securely to the lead wire and gives it a wedge-shaped end that makes it much easier to insert into the guide. With the stripped portion of the lead wire folded back alongside the connector, when the connector is inserted into the guide the result is a nice tight fit and excellent electrical contact between the connector and the braid inside the guide combined with much easier installation and removal of the braid and lead wire. The Ninco braid I used needed to be folded at the end to allow a double thickness to be inserted into the guide for a snug lead wire-to-guide fit.Other braid may not require this.

With the wiring squared away it’s time to work on the body itself. Start by grinding down the two front body posts until they are even with the portion of the front valence that slips over them.Also cut away the two small L-shaped ribs next to the posts as shown.You will also need to grind down the two sockets for the mounting posts on the front corners of the chassis until they are flat on top, as shown below.

Modification to front body post and adjacent l-shaped rib.

Modification to front body post sockets on chassis: before (L.) and after.

Next, take 3/32″ off the length of the rear body posts. Then, cut the top two ribs off the silver-colored radiator insert at the front of the chassis. Finally, put a small drop of light plastic-compatible oil in each of the axle bushings and motor shaft bushings if you haven’t already done it.

Now you can mount the body back onto the chassis. Everything should fit together with the body riding suitably low on the chassis.Put the car on the track and give it a few test laps. Take the body off and look for any black marks on the inner edges of the wheel openings.If you see any they are signs of tire rubbing. Remove a small amount of material from the inside of the body at each point where you see a black mark. I used a Moto-tool with a sanding drum at low speed, but you can also scrape material away as needed with a hobby knife.Be careful not to grind or scrape all the way through the body, especially when using the Moto-tool.

Once you have eliminated any tire rubbing you will have a Lola T70 that is much faster, better handling and better looking than it was out of the box. I found that after these modifications the car’s performance was competitive with my Flyhistoric cars modified with Indy Grips tires, Scalextric gears, and Scalextric traction magnets, even though its tires are a little narrower than the ones on the Fly cars. Some mild radiusing and flaring of the rear wheel openings would allow a set of Fly Lola wheels with wider Indy Grips 3003 tires to be used. The modified Lola is easy and fun to drive and looks really good on the track.It will make a great addition to your collection of 60s and 70s sports-racing cars.